From cd92bae42f78b4ea69ef39d7827fc827230ce0f3 Mon Sep 17 00:00:00 2001
From: Mark Freeman <mark@golang.org>
Date: Wed, 4 Feb 2026 16:46:40 -0500
Subject: [PATCH] go/types, types2: mechanically replace read accesses to
 operand.mode_

Change-Id: Ib832f4f9fde45b1308208f05756960191953e8f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/742081
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Mark Freeman <markfreeman@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
 .../compile/internal/types2/assignments.go    | 24 +++---
 src/cmd/compile/internal/types2/builtins.go   | 62 ++++++++--------
 src/cmd/compile/internal/types2/call.go       | 32 ++++----
 src/cmd/compile/internal/types2/const.go      |  4 +-
 .../compile/internal/types2/conversions.go    |  4 +-
 src/cmd/compile/internal/types2/expr.go       | 74 +++++++++----------
 src/cmd/compile/internal/types2/index.go      | 24 +++---
 src/cmd/compile/internal/types2/infer.go      |  4 +-
 src/cmd/compile/internal/types2/literals.go   |  6 +-
 src/cmd/compile/internal/types2/operand.go    | 24 +++---
 src/cmd/compile/internal/types2/range.go      |  6 +-
 src/cmd/compile/internal/types2/recording.go  |  8 +-
 src/cmd/compile/internal/types2/stmt.go       | 22 +++---
 src/cmd/compile/internal/types2/typexpr.go    |  8 +-
 src/go/types/assignments.go                   | 24 +++---
 src/go/types/builtins.go                      | 62 ++++++++--------
 src/go/types/call.go                          | 34 ++++-----
 src/go/types/const.go                         |  4 +-
 src/go/types/conversions.go                   |  4 +-
 src/go/types/expr.go                          | 74 +++++++++----------
 src/go/types/index.go                         | 24 +++---
 src/go/types/infer.go                         |  4 +-
 src/go/types/literals.go                      |  6 +-
 src/go/types/operand.go                       | 24 +++---
 src/go/types/range.go                         |  6 +-
 src/go/types/recording.go                     |  8 +-
 src/go/types/stmt.go                          | 26 +++----
 src/go/types/typexpr.go                       |  8 +-
 28 files changed, 309 insertions(+), 301 deletions(-)

diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 1e00dade6a..5903a5a310 100644
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -21,7 +21,7 @@ import (
 func (check *Checker) assignment(x *operand, T Type, context string) {
 	check.singleValue(x)
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		return // error reported before
 	case nilvalue:
@@ -116,7 +116,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 }
 
 func (check *Checker) initConst(lhs *Const, x *operand) {
-	if x.mode_ == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
+	if x.mode() == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
 		}
@@ -124,7 +124,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 	}
 
 	// rhs must be a constant
-	if x.mode_ != constant_ {
+	if x.mode() != constant_ {
 		check.errorf(x, InvalidConstInit, "%s is not constant", x)
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
@@ -139,7 +139,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 	}
 
 	check.assignment(x, lhs.typ, "constant declaration")
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -151,7 +151,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 // or Typ[Invalid] in case of an error.
 // If the initialization check fails, x.mode is set to invalid.
 func (check *Checker) initVar(lhs *Var, x *operand, context string) {
-	if x.mode_ == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
+	if x.mode() == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
 		}
@@ -216,13 +216,13 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
 		check.usedVars[v] = v_used // restore v.used
 	}
 
-	if x.mode_ == invalid || !isValid(x.typ()) {
+	if x.mode() == invalid || !isValid(x.typ()) {
 		return Typ[Invalid]
 	}
 
 	// spec: "Each left-hand side operand must be addressable, a map index
 	// expression, or the blank identifier. Operands may be parenthesized."
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		return Typ[Invalid]
 	case variable, mapindex:
@@ -231,7 +231,7 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
 		if sel, ok := x.expr.(*syntax.SelectorExpr); ok {
 			var op operand
 			check.expr(nil, &op, sel.X)
-			if op.mode_ == mapindex {
+			if op.mode() == mapindex {
 				check.errorf(&x, UnaddressableFieldAssign, "cannot assign to struct field %s in map", ExprString(x.expr))
 				return Typ[Invalid]
 			}
@@ -441,7 +441,7 @@ func (check *Checker) initVars(lhs []*Var, orig_rhs []syntax.Expr, returnStmt sy
 		}
 		// Only record comma-ok expression if both initializations succeeded
 		// (go.dev/issue/59371).
-		if commaOk && rhs[0].mode_ != invalid && rhs[1].mode_ != invalid {
+		if commaOk && rhs[0].mode() != invalid && rhs[1].mode() != invalid {
 			check.recordCommaOkTypes(orig_rhs[0], rhs)
 		}
 		return
@@ -449,7 +449,7 @@ func (check *Checker) initVars(lhs []*Var, orig_rhs []syntax.Expr, returnStmt sy
 
 	// In all other cases we have an assignment mismatch.
 	// Only report a mismatch error if there are no other errors on the rhs.
-	if rhs[0].mode_ != invalid {
+	if rhs[0].mode() != invalid {
 		if returnStmt != nil {
 			check.returnError(returnStmt, lhs, rhs)
 		} else {
@@ -505,7 +505,7 @@ func (check *Checker) assignVars(lhs, orig_rhs []syntax.Expr) {
 		}
 		// Only record comma-ok expression if both assignments succeeded
 		// (go.dev/issue/59371).
-		if commaOk && rhs[0].mode_ != invalid && rhs[1].mode_ != invalid {
+		if commaOk && rhs[0].mode() != invalid && rhs[1].mode() != invalid {
 			check.recordCommaOkTypes(orig_rhs[0], rhs)
 		}
 		return
@@ -513,7 +513,7 @@ func (check *Checker) assignVars(lhs, orig_rhs []syntax.Expr) {
 
 	// In all other cases we have an assignment mismatch.
 	// Only report a mismatch error if there are no other errors on the rhs.
-	if rhs[0].mode_ != invalid {
+	if rhs[0].mode() != invalid {
 		check.assignError(orig_rhs, l, r)
 	}
 	check.useLHS(lhs...)
diff --git a/src/cmd/compile/internal/types2/builtins.go b/src/cmd/compile/internal/types2/builtins.go
index f64758a92b..c975767fc6 100644
--- a/src/cmd/compile/internal/types2/builtins.go
+++ b/src/cmd/compile/internal/types2/builtins.go
@@ -53,7 +53,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		args = check.exprList(argList)
 		nargs = len(args)
 		for _, a := range args {
-			if a.mode_ == invalid {
+			if a.mode() == invalid {
 				return
 			}
 		}
@@ -151,7 +151,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		switch t := arrayPtrDeref(x.typ().Underlying()).(type) {
 		case *Basic:
 			if isString(t) && id == _Len {
-				if x.mode_ == constant_ {
+				if x.mode() == constant_ {
 					mode = constant_
 					val = constant.MakeInt64(int64(len(constant.StringVal(x.val))))
 				} else {
@@ -297,7 +297,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			//    both of them to float64 since they must have the
 			//    same type to succeed (this will result in an error
 			//    because shifts of floats are not permitted)
-			if x.mode_ == constant_ && y.mode_ == constant_ {
+			if x.mode() == constant_ && y.mode() == constant_ {
 				toFloat := func(x *operand) {
 					if isNumeric(x.typ()) && constant.Sign(constant.Imag(x.val)) == 0 {
 						x.typ_ = Typ[UntypedFloat]
@@ -312,7 +312,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 				// and check below
 			}
 		}
-		if x.mode_ == invalid || y.mode_ == invalid {
+		if x.mode() == invalid || y.mode() == invalid {
 			return
 		}
 
@@ -345,13 +345,13 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		// if both arguments are constants, the result is a constant
-		if x.mode_ == constant_ && y.mode_ == constant_ {
+		if x.mode() == constant_ && y.mode() == constant_ {
 			x.val = constant.BinaryOp(constant.ToFloat(x.val), token.ADD, constant.MakeImag(constant.ToFloat(y.val)))
 		} else {
 			x.mode_ = value
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ(), x.typ()))
 		}
 
@@ -438,7 +438,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 		*x = *args[1] // key
 		check.assignment(x, key, "argument to delete")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -453,7 +453,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 
 		// convert or check untyped argument
 		if isUntyped(x.typ()) {
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				// an untyped constant number can always be considered
 				// as a complex constant
 				if isNumeric(x.typ()) {
@@ -466,7 +466,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 				// result in an error (shift of complex value)
 				check.convertUntyped(x, Typ[Complex128])
 				// x should be invalid now, but be conservative and check
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 			}
@@ -499,7 +499,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		// if the argument is a constant, the result is a constant
-		if x.mode_ == constant_ {
+		if x.mode() == constant_ {
 			if id == _Real {
 				x.val = constant.Real(x.val)
 			} else {
@@ -509,7 +509,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			x.mode_ = value
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ()))
 		}
 
@@ -585,7 +585,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		for i, a := range args {
-			if a.mode_ == invalid {
+			if a.mode() == invalid {
 				return
 			}
 
@@ -597,7 +597,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			// The first argument is already in x and there's nothing left to do.
 			if i > 0 {
 				check.matchTypes(x, a)
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 
@@ -606,7 +606,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 					return
 				}
 
-				if x.mode_ == constant_ && a.mode_ == constant_ {
+				if x.mode() == constant_ && a.mode() == constant_ {
 					if constant.Compare(a.val, op, x.val) {
 						*x = *a
 					}
@@ -617,11 +617,11 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		// If nargs == 1, make sure x.mode is either a value or a constant.
-		if x.mode_ != constant_ {
+		if x.mode() != constant_ {
 			x.mode_ = value
 			// A value must not be untyped.
 			check.assignment(x, &emptyInterface, "argument to built-in "+bin.name)
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				return
 			}
 		}
@@ -631,7 +631,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			check.updateExprType(a.expr, x.typ(), true)
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			types := make([]Type, nargs)
 			for i := range types {
 				types[i] = x.typ()
@@ -645,7 +645,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		arg := argList[0]
 		check.exprOrType(x, arg, false)
 		check.exclude(x, 1<<novalue|1<<builtin)
-		switch x.mode_ {
+		switch x.mode() {
 		case invalid:
 			return
 		case typexpr:
@@ -656,7 +656,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			if isUntyped(x.typ()) {
 				// check for overflow and untyped nil
 				check.assignment(x, nil, "argument to new")
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 				assert(isTyped(x.typ()))
@@ -688,7 +688,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		check.assignment(x, &emptyInterface, "argument to panic")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -705,7 +705,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			params = make([]Type, nargs)
 			for i, a := range args {
 				check.assignment(a, nil, "argument to built-in "+predeclaredFuncs[id].name)
-				if a.mode_ == invalid {
+				if a.mode() == invalid {
 					return
 				}
 				params[i] = a.typ()
@@ -730,7 +730,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		check.verifyVersionf(call.Fun, go1_17, "unsafe.Add")
 
 		check.assignment(x, Typ[UnsafePointer], "argument to unsafe.Add")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -748,7 +748,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
 		check.assignment(x, nil, "argument to unsafe.Alignof")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -776,7 +776,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		}
 
 		check.expr(nil, x, selx.X)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -806,7 +806,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// record the selector expression (was bug - go.dev/issue/47895)
 		{
 			mode := value
-			if x.mode_ == variable || indirect {
+			if x.mode() == variable || indirect {
 				mode = variable
 			}
 			check.record(&operand{mode, selx, obj.Type(), nil, 0})
@@ -836,7 +836,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -901,7 +901,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		check.verifyVersionf(call.Fun, go1_20, "unsafe.String")
 
 		check.assignment(x, NewPointer(universeByte), "argument to unsafe.String")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -921,7 +921,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		check.verifyVersionf(call.Fun, go1_20, "unsafe.StringData")
 
 		check.assignment(x, Typ[String], "argument to unsafe.StringData")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -935,7 +935,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// assert(pred) causes a typechecker error if pred is false.
 		// The result of assert is the value of pred if there is no error.
 		// Note: assert is only available in self-test mode.
-		if x.mode_ != constant_ || !isBoolean(x.typ()) {
+		if x.mode() != constant_ || !isBoolean(x.typ()) {
 			check.errorf(x, Test, invalidArg+"%s is not a boolean constant", x)
 			return
 		}
@@ -967,7 +967,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			check.dump("%v: %s", atPos(x1), x1)
 			x1 = &t // use incoming x only for first argument
 		}
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		// trace is only available in test mode - no need to record signature
@@ -976,7 +976,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		panic("unreachable")
 	}
 
-	assert(x.mode_ != invalid)
+	assert(x.mode() != invalid)
 	return true
 }
 
diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index 0de514f4f4..0e73c25f25 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -175,7 +175,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 			// Delay function instantiation to argument checking,
 			// where we combine type and value arguments for type
 			// inference.
-			assert(x.mode_ == value)
+			assert(x.mode() == value)
 			inst = iexpr
 		}
 		x.expr = iexpr
@@ -185,7 +185,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 	}
 	// x.typ may be generic
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		check.use(call.ArgList...)
 		x.expr = call
@@ -194,7 +194,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 	case typexpr:
 		// conversion
 		check.nonGeneric(nil, x)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return conversion
 		}
 		T := x.typ()
@@ -209,7 +209,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 			check.errorf(call, WrongArgCount, "missing argument in conversion to %s", T)
 		case 1:
 			check.expr(nil, x, call.ArgList[0])
-			if x.mode_ != invalid {
+			if x.mode() != invalid {
 				if t, _ := T.Underlying().(*Interface); t != nil && !isTypeParam(T) {
 					if !t.IsMethodSet() {
 						check.errorf(call, MisplacedConstraintIface, "cannot use interface %s in conversion (contains specific type constraints or is comparable)", T)
@@ -237,7 +237,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 		}
 		x.expr = call
 		// a non-constant result implies a function call
-		if x.mode_ != invalid && x.mode_ != constant_ {
+		if x.mode() != invalid && x.mode() != constant_ {
 			check.hasCallOrRecv = true
 		}
 		return predeclaredFuncs[id].kind
@@ -245,7 +245,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 
 	// ordinary function/method call
 	// signature may be generic
-	cgocall := x.mode_ == cgofunc
+	cgocall := x.mode() == cgofunc
 
 	// If the operand type is a type parameter, all types in its type set
 	// must have a common underlying type, which must be a signature.
@@ -341,7 +341,7 @@ func (check *Checker) callExpr(x *operand, call *syntax.CallExpr) exprKind {
 
 	// if type inference failed, a parameterized result must be invalidated
 	// (operands cannot have a parameterized type)
-	if x.mode_ == value && sig.TypeParams().Len() > 0 && isParameterized(sig.TypeParams().list(), x.typ()) {
+	if x.mode() == value && sig.TypeParams().Len() > 0 && isParameterized(sig.TypeParams().list(), x.typ()) {
 		x.mode_ = invalid
 	}
 
@@ -417,7 +417,7 @@ func (check *Checker) genericExprList(elist []syntax.Expr) (resList []*operand,
 			// x is not a function instantiation (it may still be a generic function).
 			check.rawExpr(nil, &x, e, nil, true)
 			check.exclude(&x, 1<<novalue|1<<builtin|1<<typexpr)
-			if t, ok := x.typ().(*Tuple); ok && x.mode_ != invalid {
+			if t, ok := x.typ().(*Tuple); ok && x.mode() != invalid {
 				// x is a function call returning multiple values; it cannot be generic.
 				resList = make([]*operand, t.Len())
 				for i, v := range t.vars {
@@ -788,7 +788,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 	}
 
 	check.exprOrType(x, e.X, false)
-	switch x.mode_ {
+	switch x.mode() {
 	case builtin:
 		check.errorf(e.Pos(), UncalledBuiltin, "invalid use of %s in selector expression", x)
 		goto Error
@@ -822,7 +822,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 		goto Error
 	}
 
-	obj, index, indirect = lookupFieldOrMethod(x.typ(), x.mode_ == variable, check.pkg, sel, false)
+	obj, index, indirect = lookupFieldOrMethod(x.typ(), x.mode() == variable, check.pkg, sel, false)
 	if obj == nil {
 		// Don't report another error if the underlying type was invalid (go.dev/issue/49541).
 		if !isValid(x.typ().Underlying()) {
@@ -836,7 +836,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 		}
 
 		if indirect {
-			if x.mode_ == typexpr {
+			if x.mode() == typexpr {
 				check.errorf(e.Sel, InvalidMethodExpr, "invalid method expression %s.%s (needs pointer receiver (*%s).%s)", x.typ(), sel, x.typ(), sel)
 			} else {
 				check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ())
@@ -848,7 +848,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 		if isInterfacePtr(x.typ()) {
 			why = check.interfacePtrError(x.typ())
 		} else {
-			alt, _, _ := lookupFieldOrMethod(x.typ(), x.mode_ == variable, check.pkg, sel, true)
+			alt, _, _ := lookupFieldOrMethod(x.typ(), x.mode() == variable, check.pkg, sel, true)
 			why = check.lookupError(x.typ(), sel, alt, false)
 		}
 		check.errorf(e.Sel, MissingFieldOrMethod, "%s.%s undefined (%s)", x.expr, sel, why)
@@ -858,14 +858,14 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 
 	switch obj := obj.(type) {
 	case *Var:
-		if x.mode_ == typexpr {
+		if x.mode() == typexpr {
 			check.errorf(e.X, MissingFieldOrMethod, "operand for field selector %s must be value of type %s", sel, x.typ())
 			goto Error
 		}
 
 		// field value
 		check.recordSelection(e, FieldVal, x.typ(), obj, index, indirect)
-		if x.mode_ == variable || indirect {
+		if x.mode() == variable || indirect {
 			x.mode_ = variable
 		} else {
 			x.mode_ = value
@@ -876,7 +876,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, wantType bool
 		check.objDecl(obj) // ensure fully set-up signature
 		check.addDeclDep(obj)
 
-		if x.mode_ == typexpr {
+		if x.mode() == typexpr {
 			// method expression
 			check.recordSelection(e, MethodExpr, x.typ(), obj, index, indirect)
 
@@ -1001,5 +1001,5 @@ func (check *Checker) use1(e syntax.Expr, lhs bool) bool {
 	default:
 		check.rawExpr(nil, &x, e, nil, true)
 	}
-	return x.mode_ != invalid
+	return x.mode() != invalid
 }
diff --git a/src/cmd/compile/internal/types2/const.go b/src/cmd/compile/internal/types2/const.go
index 271c659c0c..875386d6ba 100644
--- a/src/cmd/compile/internal/types2/const.go
+++ b/src/cmd/compile/internal/types2/const.go
@@ -18,7 +18,7 @@ import (
 // For untyped constants, it checks that the value doesn't become
 // arbitrarily large.
 func (check *Checker) overflow(x *operand, opPos syntax.Pos) {
-	assert(x.mode_ == constant_)
+	assert(x.mode() == constant_)
 
 	if x.val.Kind() == constant.Unknown {
 		// TODO(gri) We should report exactly what went wrong. At the
@@ -250,7 +250,7 @@ func (check *Checker) representable(x *operand, typ *Basic) {
 //
 // If no such representation is possible, it returns a non-zero error code.
 func (check *Checker) representation(x *operand, typ *Basic) (constant.Value, Code) {
-	assert(x.mode_ == constant_)
+	assert(x.mode() == constant_)
 	v := x.val
 	if !representableConst(x.val, check, typ, &v) {
 		if isNumeric(x.typ()) && isNumeric(typ) {
diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index 329878be5a..40f982c332 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -15,7 +15,7 @@ import (
 // conversion type-checks the conversion T(x).
 // The result is in x.
 func (check *Checker) conversion(x *operand, T Type) {
-	constArg := x.mode_ == constant_
+	constArg := x.mode() == constant_
 
 	constConvertibleTo := func(T Type, val *constant.Value) bool {
 		switch t, _ := T.Underlying().(*Basic); {
@@ -110,7 +110,7 @@ func (check *Checker) conversion(x *operand, T Type) {
 			// ok
 		} else if isNonTypeParamInterface(T) || constArg && !isConstType(T) || !isTypes2 && x.isNil() {
 			final = Default(x.typ()) // default type of untyped nil is untyped nil
-		} else if x.mode_ == constant_ && isInteger(x.typ()) && allString(T) {
+		} else if x.mode() == constant_ && isInteger(x.typ()) && allString(T) {
 			final = x.typ()
 		}
 		check.updateExprType(x.expr, final, true)
diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index d35d108b5a..7925dbfb05 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -129,7 +129,7 @@ var op2str2 = [...]string{
 
 func (check *Checker) unary(x *operand, e *syntax.Operation) {
 	check.expr(nil, x, e.X)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -138,7 +138,7 @@ func (check *Checker) unary(x *operand, e *syntax.Operation) {
 	case syntax.And:
 		// spec: "As an exception to the addressability
 		// requirement x may also be a composite literal."
-		if _, ok := syntax.Unparen(e.X).(*syntax.CompositeLit); !ok && x.mode_ != variable {
+		if _, ok := syntax.Unparen(e.X).(*syntax.CompositeLit); !ok && x.mode() != variable {
 			check.errorf(x, UnaddressableOperand, invalidOp+"cannot take address of %s", x)
 			x.mode_ = invalid
 			return
@@ -174,7 +174,7 @@ func (check *Checker) unary(x *operand, e *syntax.Operation) {
 		return
 	}
 
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		if x.val.Kind() == constant.Unknown {
 			// nothing to do (and don't cause an error below in the overflow check)
 			return
@@ -387,7 +387,7 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 		// If x is a constant, it must be representable as a value of typ.
 		c := operand{old.mode, x, old.typ, old.val, 0}
 		check.convertUntyped(&c, typ)
-		if c.mode_ == invalid {
+		if c.mode() == invalid {
 			return
 		}
 	}
@@ -411,7 +411,7 @@ func (check *Checker) updateExprVal(x syntax.Expr, val constant.Value) {
 // If x is a constant operand, the returned constant.Value will be the
 // representation of x in this context.
 func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, constant.Value, Code) {
-	if x.mode_ == invalid || isTyped(x.typ()) || !isValid(target) {
+	if x.mode() == invalid || isTyped(x.typ()) || !isValid(target) {
 		return x.typ(), nil, 0
 	}
 	// x is untyped
@@ -434,7 +434,7 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 
 	switch u := target.Underlying().(type) {
 	case *Basic:
-		if x.mode_ == constant_ {
+		if x.mode() == constant_ {
 			v, code := check.representation(x, u)
 			if code != 0 {
 				return nil, nil, code
@@ -569,7 +569,7 @@ func (check *Checker) comparison(x, y *operand, op syntax.Operator, switchCase b
 	}
 
 	// comparison is ok
-	if x.mode_ == constant_ && y.mode_ == constant_ {
+	if x.mode() == constant_ && y.mode() == constant_ {
 		x.val = constant.MakeBool(constant.Compare(x.val, op2tok[op], y.val))
 		// The operands are never materialized; no need to update
 		// their types.
@@ -630,7 +630,7 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 	// TODO(gri) This function seems overly complex. Revisit.
 
 	var xval constant.Value
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		xval = constant.ToInt(x.val)
 	}
 
@@ -650,7 +650,7 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 	// Check that constants are representable by uint, but do not convert them
 	// (see also go.dev/issue/47243).
 	var yval constant.Value
-	if y.mode_ == constant_ {
+	if y.mode() == constant_ {
 		// Provide a good error message for negative shift counts.
 		yval = constant.ToInt(y.val) // consider -1, 1.0, but not -1.1
 		if yval.Kind() == constant.Int && constant.Sign(yval) < 0 {
@@ -663,7 +663,7 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 			// Caution: Check for representability here, rather than in the switch
 			// below, because isInteger includes untyped integers (was bug go.dev/issue/43697).
 			check.representable(y, Typ[Uint])
-			if y.mode_ == invalid {
+			if y.mode() == invalid {
 				x.mode_ = invalid
 				return
 			}
@@ -680,7 +680,7 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 			// This is incorrect, but preserves pre-existing behavior.
 			// See also go.dev/issue/47410.
 			check.convertUntyped(y, Typ[Uint])
-			if y.mode_ == invalid {
+			if y.mode() == invalid {
 				x.mode_ = invalid
 				return
 			}
@@ -691,8 +691,8 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 		}
 	}
 
-	if x.mode_ == constant_ {
-		if y.mode_ == constant_ {
+	if x.mode() == constant_ {
+		if y.mode() == constant_ {
 			// if either x or y has an unknown value, the result is unknown
 			if x.val.Kind() == constant.Unknown || y.val.Kind() == constant.Unknown {
 				x.val = constant.MakeUnknown()
@@ -794,10 +794,10 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 	check.expr(nil, x, lhs)
 	check.expr(nil, &y, rhs)
 
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
-	if y.mode_ == invalid {
+	if y.mode() == invalid {
 		x.mode_ = invalid
 		x.expr = y.expr
 		return
@@ -809,7 +809,7 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 	}
 
 	check.matchTypes(x, &y)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -839,14 +839,14 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 
 	if op == syntax.Div || op == syntax.Rem {
 		// check for zero divisor
-		if (x.mode_ == constant_ || allInteger(x.typ())) && y.mode_ == constant_ && constant.Sign(y.val) == 0 {
+		if (x.mode() == constant_ || allInteger(x.typ())) && y.mode() == constant_ && constant.Sign(y.val) == 0 {
 			check.error(&y, DivByZero, invalidOp+"division by zero")
 			x.mode_ = invalid
 			return
 		}
 
 		// check for divisor underflow in complex division (see go.dev/issue/20227)
-		if x.mode_ == constant_ && y.mode_ == constant_ && isComplex(x.typ()) {
+		if x.mode() == constant_ && y.mode() == constant_ && isComplex(x.typ()) {
 			re, im := constant.Real(y.val), constant.Imag(y.val)
 			re2, im2 := constant.BinaryOp(re, token.MUL, re), constant.BinaryOp(im, token.MUL, im)
 			if constant.Sign(re2) == 0 && constant.Sign(im2) == 0 {
@@ -857,7 +857,7 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
 		}
 	}
 
-	if x.mode_ == constant_ && y.mode_ == constant_ {
+	if x.mode() == constant_ && y.mode() == constant_ {
 		// if either x or y has an unknown value, the result is unknown
 		if x.val.Kind() == constant.Unknown || y.val.Kind() == constant.Unknown {
 			x.val = constant.MakeUnknown()
@@ -932,11 +932,11 @@ func (check *Checker) matchTypes(x, y *operand) {
 
 	if mayConvert(x, y) {
 		check.convertUntyped(x, y.typ())
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		check.convertUntyped(y, x.typ())
-		if y.mode_ == invalid {
+		if y.mode() == invalid {
 			x.mode_ = invalid
 			return
 		}
@@ -1003,7 +1003,7 @@ func (check *Checker) rawExpr(T *target, x *operand, e syntax.Expr, hint Type, a
 // from a non-nil target T, nonGeneric reports an error and invalidates x.mode and x.typ.
 // Otherwise it leaves x alone.
 func (check *Checker) nonGeneric(T *target, x *operand) {
-	if x.mode_ == invalid || x.mode_ == novalue {
+	if x.mode() == invalid || x.mode() == novalue {
 		return
 	}
 	var what string
@@ -1057,19 +1057,19 @@ func (check *Checker) exprInternal(T *target, x *operand, e syntax.Expr, hint Ty
 			goto Error // error reported during parsing
 		}
 		check.basicLit(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *syntax.FuncLit:
 		check.funcLit(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *syntax.CompositeLit:
 		check.compositeLit(x, e, hint)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
@@ -1089,19 +1089,19 @@ func (check *Checker) exprInternal(T *target, x *operand, e syntax.Expr, hint Ty
 			}
 			check.funcInst(T, e.Pos(), x, e, true)
 		}
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *syntax.SliceExpr:
 		check.sliceExpr(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *syntax.AssertExpr:
 		check.expr(nil, x, e.X)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 		// x.(type) expressions are encoded via TypeSwitchGuards
@@ -1169,7 +1169,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e syntax.Expr, hint Ty
 			if e.Op == syntax.Mul {
 				// pointer indirection
 				check.exprOrType(x, e.X, false)
-				switch x.mode_ {
+				switch x.mode() {
 				case invalid:
 					goto Error
 				case typexpr:
@@ -1203,7 +1203,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e syntax.Expr, hint Ty
 			}
 
 			check.unary(x, e)
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				goto Error
 			}
 			if e.Op == syntax.Recv {
@@ -1215,7 +1215,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e syntax.Expr, hint Ty
 
 		// binary expression
 		check.binary(x, e, e.X, e.Y, e.Op)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
@@ -1333,7 +1333,7 @@ func (check *Checker) multiExpr(e syntax.Expr, allowCommaOk bool) (list []*opera
 	check.rawExpr(nil, &x, e, nil, false)
 	check.exclude(&x, 1<<novalue|1<<builtin|1<<typexpr)
 
-	if t, ok := x.typ().(*Tuple); ok && x.mode_ != invalid {
+	if t, ok := x.typ().(*Tuple); ok && x.mode() != invalid {
 		// multiple values
 		list = make([]*operand, t.Len())
 		for i, v := range t.vars {
@@ -1344,9 +1344,9 @@ func (check *Checker) multiExpr(e syntax.Expr, allowCommaOk bool) (list []*opera
 
 	// exactly one (possibly invalid or comma-ok) value
 	list = []*operand{&x}
-	if allowCommaOk && (x.mode_ == mapindex || x.mode_ == commaok || x.mode_ == commaerr) {
+	if allowCommaOk && (x.mode() == mapindex || x.mode() == commaok || x.mode() == commaerr) {
 		x2 := &operand{mode_: value, expr: e, typ_: Typ[UntypedBool]}
-		if x.mode_ == commaerr {
+		if x.mode() == commaerr {
 			x2.typ_ = universeError
 		}
 		list = append(list, x2)
@@ -1379,10 +1379,10 @@ func (check *Checker) exprOrType(x *operand, e syntax.Expr, allowGeneric bool) {
 // exclude reports an error if x.mode is in modeset and sets x.mode to invalid.
 // The modeset may contain any of 1<<novalue, 1<<builtin, 1<<typexpr.
 func (check *Checker) exclude(x *operand, modeset uint) {
-	if modeset&(1<<x.mode_) != 0 {
+	if modeset&(1<<x.mode()) != 0 {
 		var msg string
 		var code Code
-		switch x.mode_ {
+		switch x.mode() {
 		case novalue:
 			if modeset&(1<<typexpr) != 0 {
 				msg = "%s used as value"
@@ -1406,7 +1406,7 @@ func (check *Checker) exclude(x *operand, modeset uint) {
 
 // singleValue reports an error if x describes a tuple and sets x.mode to invalid.
 func (check *Checker) singleValue(x *operand) {
-	if x.mode_ == value {
+	if x.mode() == value {
 		// tuple types are never named - no need for underlying type below
 		if t, ok := x.typ().(*Tuple); ok {
 			assert(t.Len() != 1)
diff --git a/src/cmd/compile/internal/types2/index.go b/src/cmd/compile/internal/types2/index.go
index 12d89e9cae..68a7e62075 100644
--- a/src/cmd/compile/internal/types2/index.go
+++ b/src/cmd/compile/internal/types2/index.go
@@ -19,7 +19,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	check.exprOrType(x, e.X, true)
 	// x may be generic
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		check.use(e.Index)
 		return false
@@ -43,7 +43,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 
 	// x should not be generic at this point, but be safe and check
 	check.nonGeneric(nil, x)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
@@ -76,7 +76,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	case *Basic:
 		if isString(typ) {
 			valid = true
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				length = int64(len(constant.StringVal(x.val)))
 			}
 			// an indexed string always yields a byte value
@@ -89,7 +89,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 	case *Array:
 		valid = true
 		length = typ.len
-		if x.mode_ != variable {
+		if x.mode() != variable {
 			x.mode_ = value
 		}
 		x.typ_ = typ.elem
@@ -142,7 +142,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 			case *Array:
 				l = t.len
 				e = t.elem
-				if x.mode_ != variable {
+				if x.mode() != variable {
 					mode = value
 				}
 			case *Pointer:
@@ -230,7 +230,7 @@ func (check *Checker) indexExpr(x *operand, e *syntax.IndexExpr) (isFuncInst boo
 
 func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 	check.expr(nil, x, e.X)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		check.use(e.Index[:]...)
 		return
 	}
@@ -301,7 +301,7 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 				return
 			}
 			valid = true
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				length = int64(len(constant.StringVal(x.val)))
 			}
 			// spec: "For untyped string operands the result
@@ -314,7 +314,7 @@ func (check *Checker) sliceExpr(x *operand, e *syntax.SliceExpr) {
 	case *Array:
 		valid = true
 		length = u.len
-		if x.mode_ != variable {
+		if x.mode() != variable {
 			check.errorf(x, NonSliceableOperand, "cannot slice unaddressable value %s", x)
 			x.mode_ = invalid
 			return
@@ -427,7 +427,7 @@ func (check *Checker) index(index syntax.Expr, max int64) (typ Type, val int64)
 		return
 	}
 
-	if x.mode_ != constant_ {
+	if x.mode() != constant_ {
 		return x.typ(), -1
 	}
 
@@ -451,13 +451,13 @@ func (check *Checker) index(index syntax.Expr, max int64) (typ Type, val int64)
 // If the operand is not valid, an error is reported (using what as context)
 // and the result is false.
 func (check *Checker) isValidIndex(x *operand, code Code, what string, allowNegative bool) bool {
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
 	// spec: "a constant index that is untyped is given type int"
 	check.convertUntyped(x, Typ[Int])
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
@@ -467,7 +467,7 @@ func (check *Checker) isValidIndex(x *operand, code Code, what string, allowNega
 		return false
 	}
 
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		// spec: "a constant index must be non-negative ..."
 		if !allowNegative && constant.Sign(x.val) < 0 {
 			check.errorf(x, code, invalidArg+"%s %s must not be negative", what, x)
diff --git a/src/cmd/compile/internal/types2/infer.go b/src/cmd/compile/internal/types2/infer.go
index 0cd6aaf999..3aeace192e 100644
--- a/src/cmd/compile/internal/types2/infer.go
+++ b/src/cmd/compile/internal/types2/infer.go
@@ -62,7 +62,7 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type,
 	// If we have invalid (ordinary) arguments, an error was reported before.
 	// Avoid additional inference errors and exit early (go.dev/issue/60434).
 	for _, arg := range args {
-		if arg.mode_ == invalid {
+		if arg.mode() == invalid {
 			return nil
 		}
 	}
@@ -162,7 +162,7 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type,
 	}
 
 	for i, arg := range args {
-		if arg.mode_ == invalid {
+		if arg.mode() == invalid {
 			// An error was reported earlier. Ignore this arg
 			// and continue, we may still be able to infer all
 			// targs resulting in fewer follow-on errors.
diff --git a/src/cmd/compile/internal/types2/literals.go b/src/cmd/compile/internal/types2/literals.go
index 5459d7f5c1..c52e070e44 100644
--- a/src/cmd/compile/internal/types2/literals.go
+++ b/src/cmd/compile/internal/types2/literals.go
@@ -62,7 +62,7 @@ func (check *Checker) basicLit(x *operand, e *syntax.BasicLit) {
 		}
 	}
 	x.setConst(e.Kind, e.Value)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		// The parser already establishes syntactic correctness.
 		// If we reach here it's because of number under-/overflow.
 		// TODO(gri) setConst (and in turn the go/constant package)
@@ -261,10 +261,10 @@ func (check *Checker) compositeLit(x *operand, e *syntax.CompositeLit, hint Type
 			}
 			check.exprWithHint(x, kv.Key, utyp.key)
 			check.assignment(x, utyp.key, "map literal")
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				continue
 			}
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				duplicate := false
 				xkey := keyVal(x.val)
 				if keyIsInterface {
diff --git a/src/cmd/compile/internal/types2/operand.go b/src/cmd/compile/internal/types2/operand.go
index 1d29810a72..fe06fc7861 100644
--- a/src/cmd/compile/internal/types2/operand.go
+++ b/src/cmd/compile/internal/types2/operand.go
@@ -60,12 +60,16 @@ type operand struct {
 	id    builtinId
 }
 
+func (x *operand) mode() operandMode {
+	return x.mode_
+}
+
 func (x *operand) typ() Type {
 	return x.typ_
 }
 
 func (x *operand) isValid() bool {
-	return x.mode_ != invalid
+	return x.mode() != invalid
 }
 
 // Pos returns the position of the expression corresponding to x.
@@ -117,7 +121,7 @@ func (x *operand) Pos() syntax.Pos {
 func operandString(x *operand, qf Qualifier) string {
 	// special-case nil
 	if isTypes2 {
-		if x.mode_ == nilvalue {
+		if x.mode() == nilvalue {
 			switch x.typ() {
 			case nil, Typ[Invalid]:
 				return "nil (with invalid type)"
@@ -128,7 +132,7 @@ func operandString(x *operand, qf Qualifier) string {
 			}
 		}
 	} else { // go/types
-		if x.mode_ == value && x.typ() == Typ[UntypedNil] {
+		if x.mode() == value && x.typ() == Typ[UntypedNil] {
 			return "nil"
 		}
 	}
@@ -139,7 +143,7 @@ func operandString(x *operand, qf Qualifier) string {
 	if x.expr != nil {
 		expr = ExprString(x.expr)
 	} else {
-		switch x.mode_ {
+		switch x.mode() {
 		case builtin:
 			expr = predeclaredFuncs[x.id].name
 		case typexpr:
@@ -157,7 +161,7 @@ func operandString(x *operand, qf Qualifier) string {
 
 	// <untyped kind>
 	hasType := false
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid, novalue, builtin, typexpr:
 		// no type
 	default:
@@ -173,10 +177,10 @@ func operandString(x *operand, qf Qualifier) string {
 	}
 
 	// <mode>
-	buf.WriteString(operandModeString[x.mode_])
+	buf.WriteString(operandModeString[x.mode()])
 
 	// <val>
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		if s := x.val.String(); s != expr {
 			buf.WriteByte(' ')
 			buf.WriteString(s)
@@ -301,9 +305,9 @@ func (x *operand) setConst(k syntax.LitKind, lit string) {
 // isNil reports whether x is the (untyped) nil value.
 func (x *operand) isNil() bool {
 	if isTypes2 {
-		return x.mode_ == nilvalue
+		return x.mode() == nilvalue
 	} else { // go/types
-		return x.mode_ == value && x.typ() == Typ[UntypedNil]
+		return x.mode() == value && x.typ() == Typ[UntypedNil]
 	}
 }
 
@@ -314,7 +318,7 @@ func (x *operand) isNil() bool {
 // if assignableTo is invoked through an exported API call, i.e., when all
 // methods have been type-checked.
 func (x *operand) assignableTo(check *Checker, T Type, cause *string) (bool, Code) {
-	if x.mode_ == invalid || !isValid(T) {
+	if x.mode() == invalid || !isValid(T) {
 		return true, 0 // avoid spurious errors
 	}
 
diff --git a/src/cmd/compile/internal/types2/range.go b/src/cmd/compile/internal/types2/range.go
index c6f7be3319..1135066af8 100644
--- a/src/cmd/compile/internal/types2/range.go
+++ b/src/cmd/compile/internal/types2/range.go
@@ -34,7 +34,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *syntax.ForStmt, no
 	check.hasCallOrRecv = false
 	check.expr(nil, &x, rangeVar)
 
-	if isTypes2 && x.mode_ != invalid && sValue == nil && !check.hasCallOrRecv {
+	if isTypes2 && x.mode() != invalid && sValue == nil && !check.hasCallOrRecv {
 		if t, ok := arrayPtrDeref(x.typ().Underlying()).(*Array); ok {
 			for {
 				// Put constant info on the thing inside parentheses.
@@ -61,7 +61,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *syntax.ForStmt, no
 
 	// determine key/value types
 	var key, val Type
-	if x.mode_ != invalid {
+	if x.mode() != invalid {
 		k, v, cause, ok := rangeKeyVal(check, x.typ(), func(v goVersion) bool {
 			return check.allowVersion(v)
 		})
@@ -169,7 +169,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *syntax.ForStmt, no
 				// If the assignment succeeded, if x was untyped before, it now
 				// has a type inferred via the assignment. It must be an integer.
 				// (go.dev/issues/67027)
-				if x.mode_ != invalid && !isInteger(x.typ()) {
+				if x.mode() != invalid && !isInteger(x.typ()) {
 					check.softErrorf(lhs, InvalidRangeExpr, "cannot use iteration variable of type %s", x.typ())
 				}
 			} else {
diff --git a/src/cmd/compile/internal/types2/recording.go b/src/cmd/compile/internal/types2/recording.go
index c6eaed9077..8144bb55ee 100644
--- a/src/cmd/compile/internal/types2/recording.go
+++ b/src/cmd/compile/internal/types2/recording.go
@@ -17,7 +17,7 @@ func (check *Checker) record(x *operand) {
 	// TODO(gri) this code can be simplified
 	var typ Type
 	var val constant.Value
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		typ = Typ[Invalid]
 	case novalue:
@@ -33,9 +33,9 @@ func (check *Checker) record(x *operand) {
 	if isUntyped(typ) {
 		// delay type and value recording until we know the type
 		// or until the end of type checking
-		check.rememberUntyped(x.expr, false, x.mode_, typ.(*Basic), val)
+		check.rememberUntyped(x.expr, false, x.mode(), typ.(*Basic), val)
 	} else {
-		check.recordTypeAndValue(x.expr, x.mode_, typ, val)
+		check.recordTypeAndValue(x.expr, x.mode(), typ, val)
 	}
 }
 
@@ -94,7 +94,7 @@ func (check *Checker) recordBuiltinType(f syntax.Expr, sig *Signature) {
 func (check *Checker) recordCommaOkTypes(x syntax.Expr, a []*operand) {
 	assert(x != nil)
 	assert(len(a) == 2)
-	if a[0].mode_ == invalid {
+	if a[0].mode() == invalid {
 		return
 	}
 	t0, t1 := a[0].typ(), a[1].typ()
diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index 1c18a6278b..ecc202ddad 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -238,20 +238,20 @@ L:
 	for _, e := range values {
 		var v operand
 		check.expr(nil, &v, e)
-		if x.mode_ == invalid || v.mode_ == invalid {
+		if x.mode() == invalid || v.mode() == invalid {
 			continue L
 		}
 		check.convertUntyped(&v, x.typ())
-		if v.mode_ == invalid {
+		if v.mode() == invalid {
 			continue L
 		}
 		// Order matters: By comparing v against x, error positions are at the case values.
 		res := v // keep original v unchanged
 		check.comparison(&res, x, syntax.Eql, true)
-		if res.mode_ == invalid {
+		if res.mode() == invalid {
 			continue L
 		}
-		if v.mode_ != constant_ {
+		if v.mode() != constant_ {
 			continue L // we're done
 		}
 		// look for duplicate values
@@ -444,7 +444,7 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		kind := check.rawExpr(nil, &x, s.X, nil, false)
 		var msg string
 		var code Code
-		switch x.mode_ {
+		switch x.mode() {
 		default:
 			if kind == statement {
 				return
@@ -464,7 +464,7 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		var ch, val operand
 		check.expr(nil, &ch, s.Chan)
 		check.expr(nil, &val, s.Value)
-		if ch.mode_ == invalid || val.mode_ == invalid {
+		if ch.mode() == invalid || val.mode() == invalid {
 			return
 		}
 		if elem := check.chanElem(s, &ch, false); elem != nil {
@@ -477,7 +477,7 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 			// (no need to call unpackExpr as s.Lhs must be single-valued)
 			var x operand
 			check.expr(nil, &x, s.Lhs)
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				return
 			}
 			if !allNumeric(x.typ()) {
@@ -592,7 +592,7 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		check.simpleStmt(s.Init)
 		var x operand
 		check.expr(nil, &x, s.Cond)
-		if x.mode_ != invalid && !allBoolean(x.typ()) {
+		if x.mode() != invalid && !allBoolean(x.typ()) {
 			check.error(s.Cond, InvalidCond, "non-boolean condition in if statement")
 		}
 		check.stmt(inner, s.Then)
@@ -694,7 +694,7 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		if s.Cond != nil {
 			var x operand
 			check.expr(nil, &x, s.Cond)
-			if x.mode_ != invalid && !allBoolean(x.typ()) {
+			if x.mode() != invalid && !allBoolean(x.typ()) {
 				check.error(s.Cond, InvalidCond, "non-boolean condition in for statement")
 			}
 		}
@@ -721,7 +721,7 @@ func (check *Checker) switchStmt(inner stmtContext, s *syntax.SwitchStmt) {
 		// By checking assignment of x to an invisible temporary
 		// (as a compiler would), we get all the relevant checks.
 		check.assignment(&x, nil, "switch expression")
-		if x.mode_ != invalid && !Comparable(x.typ()) && !hasNil(x.typ()) {
+		if x.mode() != invalid && !Comparable(x.typ()) && !hasNil(x.typ()) {
 			check.errorf(&x, InvalidExprSwitch, "cannot switch on %s (%s is not comparable)", &x, x.typ())
 			x.mode_ = invalid
 		}
@@ -785,7 +785,7 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
 	{
 		var x operand
 		check.expr(nil, &x, guard.X)
-		if x.mode_ != invalid {
+		if x.mode() != invalid {
 			if isTypeParam(x.typ()) {
 				check.errorf(&x, InvalidTypeSwitch, "cannot use type switch on type parameter value %s", &x)
 			} else if IsInterface(x.typ()) {
diff --git a/src/cmd/compile/internal/types2/typexpr.go b/src/cmd/compile/internal/types2/typexpr.go
index 69d1d76174..a9575230cf 100644
--- a/src/cmd/compile/internal/types2/typexpr.go
+++ b/src/cmd/compile/internal/types2/typexpr.go
@@ -248,7 +248,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *TypeName) (T Type) {
 		var x operand
 		check.ident(&x, e, true)
 
-		switch x.mode_ {
+		switch x.mode() {
 		case typexpr:
 			return x.typ()
 		case invalid:
@@ -263,7 +263,7 @@ func (check *Checker) typInternal(e0 syntax.Expr, def *TypeName) (T Type) {
 		var x operand
 		check.selector(&x, e, true)
 
-		switch x.mode_ {
+		switch x.mode() {
 		case typexpr:
 			return x.typ()
 		case invalid:
@@ -482,8 +482,8 @@ func (check *Checker) arrayLength(e syntax.Expr) int64 {
 
 	var x operand
 	check.expr(nil, &x, e)
-	if x.mode_ != constant_ {
-		if x.mode_ != invalid {
+	if x.mode() != constant_ {
+		if x.mode() != invalid {
 			check.errorf(&x, InvalidArrayLen, "array length %s must be constant", &x)
 		}
 		return -1
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 2b9c2d5065..36413ff312 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -24,7 +24,7 @@ import (
 func (check *Checker) assignment(x *operand, T Type, context string) {
 	check.singleValue(x)
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		return // error reported before
 	case nilvalue:
@@ -119,7 +119,7 @@ func (check *Checker) assignment(x *operand, T Type, context string) {
 }
 
 func (check *Checker) initConst(lhs *Const, x *operand) {
-	if x.mode_ == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
+	if x.mode() == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
 		}
@@ -127,7 +127,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 	}
 
 	// rhs must be a constant
-	if x.mode_ != constant_ {
+	if x.mode() != constant_ {
 		check.errorf(x, InvalidConstInit, "%s is not constant", x)
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
@@ -142,7 +142,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 	}
 
 	check.assignment(x, lhs.typ, "constant declaration")
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -154,7 +154,7 @@ func (check *Checker) initConst(lhs *Const, x *operand) {
 // or Typ[Invalid] in case of an error.
 // If the initialization check fails, x.mode is set to invalid.
 func (check *Checker) initVar(lhs *Var, x *operand, context string) {
-	if x.mode_ == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
+	if x.mode() == invalid || !isValid(x.typ()) || !isValid(lhs.typ) {
 		if lhs.typ == nil {
 			lhs.typ = Typ[Invalid]
 		}
@@ -219,13 +219,13 @@ func (check *Checker) lhsVar(lhs ast.Expr) Type {
 		check.usedVars[v] = v_used // restore v.used
 	}
 
-	if x.mode_ == invalid || !isValid(x.typ()) {
+	if x.mode() == invalid || !isValid(x.typ()) {
 		return Typ[Invalid]
 	}
 
 	// spec: "Each left-hand side operand must be addressable, a map index
 	// expression, or the blank identifier. Operands may be parenthesized."
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		return Typ[Invalid]
 	case variable, mapindex:
@@ -234,7 +234,7 @@ func (check *Checker) lhsVar(lhs ast.Expr) Type {
 		if sel, ok := x.expr.(*ast.SelectorExpr); ok {
 			var op operand
 			check.expr(nil, &op, sel.X)
-			if op.mode_ == mapindex {
+			if op.mode() == mapindex {
 				check.errorf(&x, UnaddressableFieldAssign, "cannot assign to struct field %s in map", ExprString(x.expr))
 				return Typ[Invalid]
 			}
@@ -444,7 +444,7 @@ func (check *Checker) initVars(lhs []*Var, orig_rhs []ast.Expr, returnStmt ast.S
 		}
 		// Only record comma-ok expression if both initializations succeeded
 		// (go.dev/issue/59371).
-		if commaOk && rhs[0].mode_ != invalid && rhs[1].mode_ != invalid {
+		if commaOk && rhs[0].mode() != invalid && rhs[1].mode() != invalid {
 			check.recordCommaOkTypes(orig_rhs[0], rhs)
 		}
 		return
@@ -452,7 +452,7 @@ func (check *Checker) initVars(lhs []*Var, orig_rhs []ast.Expr, returnStmt ast.S
 
 	// In all other cases we have an assignment mismatch.
 	// Only report a mismatch error if there are no other errors on the rhs.
-	if rhs[0].mode_ != invalid {
+	if rhs[0].mode() != invalid {
 		if returnStmt != nil {
 			check.returnError(returnStmt, lhs, rhs)
 		} else {
@@ -508,7 +508,7 @@ func (check *Checker) assignVars(lhs, orig_rhs []ast.Expr) {
 		}
 		// Only record comma-ok expression if both assignments succeeded
 		// (go.dev/issue/59371).
-		if commaOk && rhs[0].mode_ != invalid && rhs[1].mode_ != invalid {
+		if commaOk && rhs[0].mode() != invalid && rhs[1].mode() != invalid {
 			check.recordCommaOkTypes(orig_rhs[0], rhs)
 		}
 		return
@@ -516,7 +516,7 @@ func (check *Checker) assignVars(lhs, orig_rhs []ast.Expr) {
 
 	// In all other cases we have an assignment mismatch.
 	// Only report a mismatch error if there are no other errors on the rhs.
-	if rhs[0].mode_ != invalid {
+	if rhs[0].mode() != invalid {
 		check.assignError(orig_rhs, l, r)
 	}
 	check.useLHS(lhs...)
diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 146e8d6574..1f55368826 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -56,7 +56,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		args = check.exprList(argList)
 		nargs = len(args)
 		for _, a := range args {
-			if a.mode_ == invalid {
+			if a.mode() == invalid {
 				return
 			}
 		}
@@ -154,7 +154,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		switch t := arrayPtrDeref(x.typ().Underlying()).(type) {
 		case *Basic:
 			if isString(t) && id == _Len {
-				if x.mode_ == constant_ {
+				if x.mode() == constant_ {
 					mode = constant_
 					val = constant.MakeInt64(int64(len(constant.StringVal(x.val))))
 				} else {
@@ -300,7 +300,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			//    both of them to float64 since they must have the
 			//    same type to succeed (this will result in an error
 			//    because shifts of floats are not permitted)
-			if x.mode_ == constant_ && y.mode_ == constant_ {
+			if x.mode() == constant_ && y.mode() == constant_ {
 				toFloat := func(x *operand) {
 					if isNumeric(x.typ()) && constant.Sign(constant.Imag(x.val)) == 0 {
 						x.typ_ = Typ[UntypedFloat]
@@ -315,7 +315,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 				// and check below
 			}
 		}
-		if x.mode_ == invalid || y.mode_ == invalid {
+		if x.mode() == invalid || y.mode() == invalid {
 			return
 		}
 
@@ -348,13 +348,13 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		// if both arguments are constants, the result is a constant
-		if x.mode_ == constant_ && y.mode_ == constant_ {
+		if x.mode() == constant_ && y.mode() == constant_ {
 			x.val = constant.BinaryOp(constant.ToFloat(x.val), token.ADD, constant.MakeImag(constant.ToFloat(y.val)))
 		} else {
 			x.mode_ = value
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ(), x.typ()))
 		}
 
@@ -441,7 +441,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 		*x = *args[1] // key
 		check.assignment(x, key, "argument to delete")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -456,7 +456,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 
 		// convert or check untyped argument
 		if isUntyped(x.typ()) {
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				// an untyped constant number can always be considered
 				// as a complex constant
 				if isNumeric(x.typ()) {
@@ -469,7 +469,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 				// result in an error (shift of complex value)
 				check.convertUntyped(x, Typ[Complex128])
 				// x should be invalid now, but be conservative and check
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 			}
@@ -502,7 +502,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		// if the argument is a constant, the result is a constant
-		if x.mode_ == constant_ {
+		if x.mode() == constant_ {
 			if id == _Real {
 				x.val = constant.Real(x.val)
 			} else {
@@ -512,7 +512,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			x.mode_ = value
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			check.recordBuiltinType(call.Fun, makeSig(resTyp, x.typ()))
 		}
 
@@ -588,7 +588,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		for i, a := range args {
-			if a.mode_ == invalid {
+			if a.mode() == invalid {
 				return
 			}
 
@@ -600,7 +600,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			// The first argument is already in x and there's nothing left to do.
 			if i > 0 {
 				check.matchTypes(x, a)
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 
@@ -609,7 +609,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 					return
 				}
 
-				if x.mode_ == constant_ && a.mode_ == constant_ {
+				if x.mode() == constant_ && a.mode() == constant_ {
 					if constant.Compare(a.val, op, x.val) {
 						*x = *a
 					}
@@ -620,11 +620,11 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		// If nargs == 1, make sure x.mode is either a value or a constant.
-		if x.mode_ != constant_ {
+		if x.mode() != constant_ {
 			x.mode_ = value
 			// A value must not be untyped.
 			check.assignment(x, &emptyInterface, "argument to built-in "+bin.name)
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				return
 			}
 		}
@@ -634,7 +634,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			check.updateExprType(a.expr, x.typ(), true)
 		}
 
-		if check.recordTypes() && x.mode_ != constant_ {
+		if check.recordTypes() && x.mode() != constant_ {
 			types := make([]Type, nargs)
 			for i := range types {
 				types[i] = x.typ()
@@ -648,7 +648,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		arg := argList[0]
 		check.exprOrType(x, arg, false)
 		check.exclude(x, 1<<novalue|1<<builtin)
-		switch x.mode_ {
+		switch x.mode() {
 		case invalid:
 			return
 		case typexpr:
@@ -659,7 +659,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			if isUntyped(x.typ()) {
 				// check for overflow and untyped nil
 				check.assignment(x, nil, "argument to new")
-				if x.mode_ == invalid {
+				if x.mode() == invalid {
 					return
 				}
 				assert(isTyped(x.typ()))
@@ -691,7 +691,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		check.assignment(x, &emptyInterface, "argument to panic")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -708,7 +708,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			params = make([]Type, nargs)
 			for i, a := range args {
 				check.assignment(a, nil, "argument to built-in "+predeclaredFuncs[id].name)
-				if a.mode_ == invalid {
+				if a.mode() == invalid {
 					return
 				}
 				params[i] = a.typ()
@@ -733,7 +733,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		check.verifyVersionf(call.Fun, go1_17, "unsafe.Add")
 
 		check.assignment(x, Typ[UnsafePointer], "argument to unsafe.Add")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -751,7 +751,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 	case _Alignof:
 		// unsafe.Alignof(x T) uintptr
 		check.assignment(x, nil, "argument to unsafe.Alignof")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -779,7 +779,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		check.expr(nil, x, selx.X)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -809,7 +809,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// record the selector expression (was bug - go.dev/issue/47895)
 		{
 			mode := value
-			if x.mode_ == variable || indirect {
+			if x.mode() == variable || indirect {
 				mode = variable
 			}
 			check.record(&operand{mode, selx, obj.Type(), nil, 0})
@@ -839,7 +839,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 	case _Sizeof:
 		// unsafe.Sizeof(x T) uintptr
 		check.assignment(x, nil, "argument to unsafe.Sizeof")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -904,7 +904,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		check.verifyVersionf(call.Fun, go1_20, "unsafe.String")
 
 		check.assignment(x, NewPointer(universeByte), "argument to unsafe.String")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -924,7 +924,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		check.verifyVersionf(call.Fun, go1_20, "unsafe.StringData")
 
 		check.assignment(x, Typ[String], "argument to unsafe.StringData")
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 
@@ -938,7 +938,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		// assert(pred) causes a typechecker error if pred is false.
 		// The result of assert is the value of pred if there is no error.
 		// Note: assert is only available in self-test mode.
-		if x.mode_ != constant_ || !isBoolean(x.typ()) {
+		if x.mode() != constant_ || !isBoolean(x.typ()) {
 			check.errorf(x, Test, invalidArg+"%s is not a boolean constant", x)
 			return
 		}
@@ -970,7 +970,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			check.dump("%v: %s", x1.Pos(), x1)
 			x1 = &t // use incoming x only for first argument
 		}
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		// trace is only available in test mode - no need to record signature
@@ -979,7 +979,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		panic("unreachable")
 	}
 
-	assert(x.mode_ != invalid)
+	assert(x.mode() != invalid)
 	return true
 }
 
diff --git a/src/go/types/call.go b/src/go/types/call.go
index c19aebb1f0..d9368c618d 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -176,7 +176,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 			// Delay function instantiation to argument checking,
 			// where we combine type and value arguments for type
 			// inference.
-			assert(x.mode_ == value)
+			assert(x.mode() == value)
 		} else {
 			ix = nil
 		}
@@ -187,7 +187,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 	}
 	// x.typ may be generic
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		check.use(call.Args...)
 		x.expr = call
@@ -196,7 +196,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 	case typexpr:
 		// conversion
 		check.nonGeneric(nil, x)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return conversion
 		}
 		T := x.typ()
@@ -211,7 +211,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 			check.errorf(inNode(call, call.Rparen), WrongArgCount, "missing argument in conversion to %s", T)
 		case 1:
 			check.expr(nil, x, call.Args[0])
-			if x.mode_ != invalid {
+			if x.mode() != invalid {
 				if hasDots(call) {
 					check.errorf(call.Args[0], BadDotDotDotSyntax, "invalid use of ... in conversion to %s", T)
 					break
@@ -239,7 +239,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 		}
 		x.expr = call
 		// a non-constant result implies a function call
-		if x.mode_ != invalid && x.mode_ != constant_ {
+		if x.mode() != invalid && x.mode() != constant_ {
 			check.hasCallOrRecv = true
 		}
 		return predeclaredFuncs[id].kind
@@ -247,7 +247,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 
 	// ordinary function/method call
 	// signature may be generic
-	cgocall := x.mode_ == cgofunc
+	cgocall := x.mode() == cgofunc
 
 	// If the operand type is a type parameter, all types in its type set
 	// must have a common underlying type, which must be a signature.
@@ -343,7 +343,7 @@ func (check *Checker) callExpr(x *operand, call *ast.CallExpr) exprKind {
 
 	// if type inference failed, a parameterized result must be invalidated
 	// (operands cannot have a parameterized type)
-	if x.mode_ == value && sig.TypeParams().Len() > 0 && isParameterized(sig.TypeParams().list(), x.typ()) {
+	if x.mode() == value && sig.TypeParams().Len() > 0 && isParameterized(sig.TypeParams().list(), x.typ()) {
 		x.mode_ = invalid
 	}
 
@@ -419,7 +419,7 @@ func (check *Checker) genericExprList(elist []ast.Expr) (resList []*operand, tar
 			// x is not a function instantiation (it may still be a generic function).
 			check.rawExpr(nil, &x, e, nil, true)
 			check.exclude(&x, 1<<novalue|1<<builtin|1<<typexpr)
-			if t, ok := x.typ().(*Tuple); ok && x.mode_ != invalid {
+			if t, ok := x.typ().(*Tuple); ok && x.mode() != invalid {
 				// x is a function call returning multiple values; it cannot be generic.
 				resList = make([]*operand, t.Len())
 				for i, v := range t.vars {
@@ -790,7 +790,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 	}
 
 	check.exprOrType(x, e.X, false)
-	switch x.mode_ {
+	switch x.mode() {
 	case builtin:
 		// types2 uses the position of '.' for the error
 		check.errorf(e.Sel, UncalledBuiltin, "invalid use of %s in selector expression", x)
@@ -825,7 +825,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 		goto Error
 	}
 
-	obj, index, indirect = lookupFieldOrMethod(x.typ(), x.mode_ == variable, check.pkg, sel, false)
+	obj, index, indirect = lookupFieldOrMethod(x.typ(), x.mode() == variable, check.pkg, sel, false)
 	if obj == nil {
 		// Don't report another error if the underlying type was invalid (go.dev/issue/49541).
 		if !isValid(x.typ().Underlying()) {
@@ -839,7 +839,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 		}
 
 		if indirect {
-			if x.mode_ == typexpr {
+			if x.mode() == typexpr {
 				check.errorf(e.Sel, InvalidMethodExpr, "invalid method expression %s.%s (needs pointer receiver (*%s).%s)", x.typ(), sel, x.typ(), sel)
 			} else {
 				check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ())
@@ -851,7 +851,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 		if isInterfacePtr(x.typ()) {
 			why = check.interfacePtrError(x.typ())
 		} else {
-			alt, _, _ := lookupFieldOrMethod(x.typ(), x.mode_ == variable, check.pkg, sel, true)
+			alt, _, _ := lookupFieldOrMethod(x.typ(), x.mode() == variable, check.pkg, sel, true)
 			why = check.lookupError(x.typ(), sel, alt, false)
 		}
 		check.errorf(e.Sel, MissingFieldOrMethod, "%s.%s undefined (%s)", x.expr, sel, why)
@@ -861,14 +861,14 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 
 	switch obj := obj.(type) {
 	case *Var:
-		if x.mode_ == typexpr {
+		if x.mode() == typexpr {
 			check.errorf(e.X, MissingFieldOrMethod, "operand for field selector %s must be value of type %s", sel, x.typ())
 			goto Error
 		}
 
 		// field value
 		check.recordSelection(e, FieldVal, x.typ(), obj, index, indirect)
-		if x.mode_ == variable || indirect {
+		if x.mode() == variable || indirect {
 			x.mode_ = variable
 		} else {
 			x.mode_ = value
@@ -879,7 +879,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 		check.objDecl(obj) // ensure fully set-up signature
 		check.addDeclDep(obj)
 
-		if x.mode_ == typexpr {
+		if x.mode() == typexpr {
 			// method expression
 			check.recordSelection(e, MethodExpr, x.typ(), obj, index, indirect)
 
@@ -938,7 +938,7 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, wantType bool) {
 				// any incomplete interfaces so they are available to NewMethodSet
 				// (which assumes that interfaces have been completed already).
 				typ := x.typ_
-				if x.mode_ == variable {
+				if x.mode() == variable {
 					// If typ is not an (unnamed) pointer or an interface,
 					// use *typ instead, because the method set of *typ
 					// includes the methods of typ.
@@ -1047,5 +1047,5 @@ func (check *Checker) use1(e ast.Expr, lhs bool) bool {
 	default:
 		check.rawExpr(nil, &x, e, nil, true)
 	}
-	return x.mode_ != invalid
+	return x.mode() != invalid
 }
diff --git a/src/go/types/const.go b/src/go/types/const.go
index 285f286a9d..5162aac22c 100644
--- a/src/go/types/const.go
+++ b/src/go/types/const.go
@@ -20,7 +20,7 @@ import (
 // For untyped constants, it checks that the value doesn't become
 // arbitrarily large.
 func (check *Checker) overflow(x *operand, opPos token.Pos) {
-	assert(x.mode_ == constant_)
+	assert(x.mode() == constant_)
 
 	if x.val.Kind() == constant.Unknown {
 		// TODO(gri) We should report exactly what went wrong. At the
@@ -252,7 +252,7 @@ func (check *Checker) representable(x *operand, typ *Basic) {
 //
 // If no such representation is possible, it returns a non-zero error code.
 func (check *Checker) representation(x *operand, typ *Basic) (constant.Value, Code) {
-	assert(x.mode_ == constant_)
+	assert(x.mode() == constant_)
 	v := x.val
 	if !representableConst(x.val, check, typ, &v) {
 		if isNumeric(x.typ()) && isNumeric(typ) {
diff --git a/src/go/types/conversions.go b/src/go/types/conversions.go
index 905f722545..7f0bc8efb2 100644
--- a/src/go/types/conversions.go
+++ b/src/go/types/conversions.go
@@ -18,7 +18,7 @@ import (
 // conversion type-checks the conversion T(x).
 // The result is in x.
 func (check *Checker) conversion(x *operand, T Type) {
-	constArg := x.mode_ == constant_
+	constArg := x.mode() == constant_
 
 	constConvertibleTo := func(T Type, val *constant.Value) bool {
 		switch t, _ := T.Underlying().(*Basic); {
@@ -113,7 +113,7 @@ func (check *Checker) conversion(x *operand, T Type) {
 			// ok
 		} else if isNonTypeParamInterface(T) || constArg && !isConstType(T) || !isTypes2 && x.isNil() {
 			final = Default(x.typ()) // default type of untyped nil is untyped nil
-		} else if x.mode_ == constant_ && isInteger(x.typ()) && allString(T) {
+		} else if x.mode() == constant_ && isInteger(x.typ()) && allString(T) {
 			final = x.typ()
 		}
 		check.updateExprType(x.expr, final, true)
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 72ecefc7e9..840452dcc0 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -128,7 +128,7 @@ var op2str2 = [...]string{
 // The unary expression e may be nil. It's passed in for better error messages only.
 func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 	check.expr(nil, x, e.X)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -137,7 +137,7 @@ func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 	case token.AND:
 		// spec: "As an exception to the addressability
 		// requirement x may also be a composite literal."
-		if _, ok := ast.Unparen(e.X).(*ast.CompositeLit); !ok && x.mode_ != variable {
+		if _, ok := ast.Unparen(e.X).(*ast.CompositeLit); !ok && x.mode() != variable {
 			check.errorf(x, UnaddressableOperand, invalidOp+"cannot take address of %s", x)
 			x.mode_ = invalid
 			return
@@ -173,7 +173,7 @@ func (check *Checker) unary(x *operand, e *ast.UnaryExpr) {
 		return
 	}
 
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		if x.val.Kind() == constant.Unknown {
 			// nothing to do (and don't cause an error below in the overflow check)
 			return
@@ -362,7 +362,7 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		// If x is a constant, it must be representable as a value of typ.
 		c := operand{old.mode, x, old.typ, old.val, 0}
 		check.convertUntyped(&c, typ)
-		if c.mode_ == invalid {
+		if c.mode() == invalid {
 			return
 		}
 	}
@@ -386,7 +386,7 @@ func (check *Checker) updateExprVal(x ast.Expr, val constant.Value) {
 // If x is a constant operand, the returned constant.Value will be the
 // representation of x in this context.
 func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, constant.Value, Code) {
-	if x.mode_ == invalid || isTyped(x.typ()) || !isValid(target) {
+	if x.mode() == invalid || isTyped(x.typ()) || !isValid(target) {
 		return x.typ(), nil, 0
 	}
 	// x is untyped
@@ -401,7 +401,7 @@ func (check *Checker) implicitTypeAndValue(x *operand, target Type) (Type, const
 
 	switch u := target.Underlying().(type) {
 	case *Basic:
-		if x.mode_ == constant_ {
+		if x.mode() == constant_ {
 			v, code := check.representation(x, u)
 			if code != 0 {
 				return nil, nil, code
@@ -558,7 +558,7 @@ func (check *Checker) comparison(x, y *operand, op token.Token, switchCase bool)
 	}
 
 	// comparison is ok
-	if x.mode_ == constant_ && y.mode_ == constant_ {
+	if x.mode() == constant_ && y.mode() == constant_ {
 		x.val = constant.MakeBool(constant.Compare(x.val, op, y.val))
 		// The operands are never materialized; no need to update
 		// their types.
@@ -619,7 +619,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 	// TODO(gri) This function seems overly complex. Revisit.
 
 	var xval constant.Value
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		xval = constant.ToInt(x.val)
 	}
 
@@ -639,7 +639,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 	// Check that constants are representable by uint, but do not convert them
 	// (see also go.dev/issue/47243).
 	var yval constant.Value
-	if y.mode_ == constant_ {
+	if y.mode() == constant_ {
 		// Provide a good error message for negative shift counts.
 		yval = constant.ToInt(y.val) // consider -1, 1.0, but not -1.1
 		if yval.Kind() == constant.Int && constant.Sign(yval) < 0 {
@@ -652,7 +652,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 			// Caution: Check for representability here, rather than in the switch
 			// below, because isInteger includes untyped integers (was bug go.dev/issue/43697).
 			check.representable(y, Typ[Uint])
-			if y.mode_ == invalid {
+			if y.mode() == invalid {
 				x.mode_ = invalid
 				return
 			}
@@ -669,7 +669,7 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 			// This is incorrect, but preserves pre-existing behavior.
 			// See also go.dev/issue/47410.
 			check.convertUntyped(y, Typ[Uint])
-			if y.mode_ == invalid {
+			if y.mode() == invalid {
 				x.mode_ = invalid
 				return
 			}
@@ -680,8 +680,8 @@ func (check *Checker) shift(x, y *operand, e ast.Expr, op token.Token) {
 		}
 	}
 
-	if x.mode_ == constant_ {
-		if y.mode_ == constant_ {
+	if x.mode() == constant_ {
+		if y.mode() == constant_ {
 			// if either x or y has an unknown value, the result is unknown
 			if x.val.Kind() == constant.Unknown || y.val.Kind() == constant.Unknown {
 				x.val = constant.MakeUnknown()
@@ -783,10 +783,10 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 	check.expr(nil, x, lhs)
 	check.expr(nil, &y, rhs)
 
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
-	if y.mode_ == invalid {
+	if y.mode() == invalid {
 		x.mode_ = invalid
 		x.expr = y.expr
 		return
@@ -798,7 +798,7 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 	}
 
 	check.matchTypes(x, &y)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return
 	}
 
@@ -832,14 +832,14 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 
 	if op == token.QUO || op == token.REM {
 		// check for zero divisor
-		if (x.mode_ == constant_ || allInteger(x.typ())) && y.mode_ == constant_ && constant.Sign(y.val) == 0 {
+		if (x.mode() == constant_ || allInteger(x.typ())) && y.mode() == constant_ && constant.Sign(y.val) == 0 {
 			check.error(&y, DivByZero, invalidOp+"division by zero")
 			x.mode_ = invalid
 			return
 		}
 
 		// check for divisor underflow in complex division (see go.dev/issue/20227)
-		if x.mode_ == constant_ && y.mode_ == constant_ && isComplex(x.typ()) {
+		if x.mode() == constant_ && y.mode() == constant_ && isComplex(x.typ()) {
 			re, im := constant.Real(y.val), constant.Imag(y.val)
 			re2, im2 := constant.BinaryOp(re, token.MUL, re), constant.BinaryOp(im, token.MUL, im)
 			if constant.Sign(re2) == 0 && constant.Sign(im2) == 0 {
@@ -850,7 +850,7 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
 		}
 	}
 
-	if x.mode_ == constant_ && y.mode_ == constant_ {
+	if x.mode() == constant_ && y.mode() == constant_ {
 		// if either x or y has an unknown value, the result is unknown
 		if x.val.Kind() == constant.Unknown || y.val.Kind() == constant.Unknown {
 			x.val = constant.MakeUnknown()
@@ -924,11 +924,11 @@ func (check *Checker) matchTypes(x, y *operand) {
 
 	if mayConvert(x, y) {
 		check.convertUntyped(x, y.typ())
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		check.convertUntyped(y, x.typ())
-		if y.mode_ == invalid {
+		if y.mode() == invalid {
 			x.mode_ = invalid
 			return
 		}
@@ -995,7 +995,7 @@ func (check *Checker) rawExpr(T *target, x *operand, e ast.Expr, hint Type, allo
 // from a non-nil target T, nonGeneric reports an error and invalidates x.mode and x.typ.
 // Otherwise it leaves x alone.
 func (check *Checker) nonGeneric(T *target, x *operand) {
-	if x.mode_ == invalid || x.mode_ == novalue {
+	if x.mode() == invalid || x.mode() == novalue {
 		return
 	}
 	var what string
@@ -1043,19 +1043,19 @@ func (check *Checker) exprInternal(T *target, x *operand, e ast.Expr, hint Type)
 
 	case *ast.BasicLit:
 		check.basicLit(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *ast.FuncLit:
 		check.funcLit(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *ast.CompositeLit:
 		check.compositeLit(x, e, hint)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
@@ -1076,19 +1076,19 @@ func (check *Checker) exprInternal(T *target, x *operand, e ast.Expr, hint Type)
 			}
 			check.funcInst(T, e.Pos(), x, ix, true)
 		}
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *ast.SliceExpr:
 		check.sliceExpr(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
 	case *ast.TypeAssertExpr:
 		check.expr(nil, x, e.X)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 		// x.(type) expressions are handled explicitly in type switches
@@ -1123,7 +1123,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e ast.Expr, hint Type)
 
 	case *ast.StarExpr:
 		check.exprOrType(x, e.X, false)
-		switch x.mode_ {
+		switch x.mode() {
 		case invalid:
 			goto Error
 		case typexpr:
@@ -1156,7 +1156,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e ast.Expr, hint Type)
 
 	case *ast.UnaryExpr:
 		check.unary(x, e)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 		if e.Op == token.ARROW {
@@ -1166,7 +1166,7 @@ func (check *Checker) exprInternal(T *target, x *operand, e ast.Expr, hint Type)
 
 	case *ast.BinaryExpr:
 		check.binary(x, e, e.X, e.Y, e.Op, e.OpPos)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			goto Error
 		}
 
@@ -1284,7 +1284,7 @@ func (check *Checker) multiExpr(e ast.Expr, allowCommaOk bool) (list []*operand,
 	check.rawExpr(nil, &x, e, nil, false)
 	check.exclude(&x, 1<<novalue|1<<builtin|1<<typexpr)
 
-	if t, ok := x.typ().(*Tuple); ok && x.mode_ != invalid {
+	if t, ok := x.typ().(*Tuple); ok && x.mode() != invalid {
 		// multiple values
 		list = make([]*operand, t.Len())
 		for i, v := range t.vars {
@@ -1295,9 +1295,9 @@ func (check *Checker) multiExpr(e ast.Expr, allowCommaOk bool) (list []*operand,
 
 	// exactly one (possibly invalid or comma-ok) value
 	list = []*operand{&x}
-	if allowCommaOk && (x.mode_ == mapindex || x.mode_ == commaok || x.mode_ == commaerr) {
+	if allowCommaOk && (x.mode() == mapindex || x.mode() == commaok || x.mode() == commaerr) {
 		x2 := &operand{mode_: value, expr: e, typ_: Typ[UntypedBool]}
-		if x.mode_ == commaerr {
+		if x.mode() == commaerr {
 			x2.typ_ = universeError
 		}
 		list = append(list, x2)
@@ -1330,10 +1330,10 @@ func (check *Checker) exprOrType(x *operand, e ast.Expr, allowGeneric bool) {
 // exclude reports an error if x.mode is in modeset and sets x.mode to invalid.
 // The modeset may contain any of 1<<novalue, 1<<builtin, 1<<typexpr.
 func (check *Checker) exclude(x *operand, modeset uint) {
-	if modeset&(1<<x.mode_) != 0 {
+	if modeset&(1<<x.mode()) != 0 {
 		var msg string
 		var code Code
-		switch x.mode_ {
+		switch x.mode() {
 		case novalue:
 			if modeset&(1<<typexpr) != 0 {
 				msg = "%s used as value"
@@ -1357,7 +1357,7 @@ func (check *Checker) exclude(x *operand, modeset uint) {
 
 // singleValue reports an error if x describes a tuple and sets x.mode to invalid.
 func (check *Checker) singleValue(x *operand) {
-	if x.mode_ == value {
+	if x.mode() == value {
 		// tuple types are never named - no need for underlying type below
 		if t, ok := x.typ().(*Tuple); ok {
 			assert(t.Len() != 1)
diff --git a/src/go/types/index.go b/src/go/types/index.go
index 064d162653..8dc46f0783 100644
--- a/src/go/types/index.go
+++ b/src/go/types/index.go
@@ -20,7 +20,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 	check.exprOrType(x, e.x, true)
 	// x may be generic
 
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		check.use(e.indices...)
 		return false
@@ -44,7 +44,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 
 	// x should not be generic at this point, but be safe and check
 	check.nonGeneric(nil, x)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
@@ -77,7 +77,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 	case *Basic:
 		if isString(typ) {
 			valid = true
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				length = int64(len(constant.StringVal(x.val)))
 			}
 			// an indexed string always yields a byte value
@@ -90,7 +90,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 	case *Array:
 		valid = true
 		length = typ.len
-		if x.mode_ != variable {
+		if x.mode() != variable {
 			x.mode_ = value
 		}
 		x.typ_ = typ.elem
@@ -143,7 +143,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 			case *Array:
 				l = t.len
 				e = t.elem
-				if x.mode_ != variable {
+				if x.mode() != variable {
 					mode = value
 				}
 			case *Pointer:
@@ -232,7 +232,7 @@ func (check *Checker) indexExpr(x *operand, e *indexedExpr) (isFuncInst bool) {
 
 func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 	check.expr(nil, x, e.X)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		check.use(e.Low, e.High, e.Max)
 		return
 	}
@@ -306,7 +306,7 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 				return
 			}
 			valid = true
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				length = int64(len(constant.StringVal(x.val)))
 			}
 			// spec: "For untyped string operands the result
@@ -319,7 +319,7 @@ func (check *Checker) sliceExpr(x *operand, e *ast.SliceExpr) {
 	case *Array:
 		valid = true
 		length = u.len
-		if x.mode_ != variable {
+		if x.mode() != variable {
 			check.errorf(x, NonSliceableOperand, "cannot slice unaddressable value %s", x)
 			x.mode_ = invalid
 			return
@@ -427,7 +427,7 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
 		return
 	}
 
-	if x.mode_ != constant_ {
+	if x.mode() != constant_ {
 		return x.typ(), -1
 	}
 
@@ -447,13 +447,13 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
 }
 
 func (check *Checker) isValidIndex(x *operand, code Code, what string, allowNegative bool) bool {
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
 	// spec: "a constant index that is untyped is given type int"
 	check.convertUntyped(x, Typ[Int])
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		return false
 	}
 
@@ -463,7 +463,7 @@ func (check *Checker) isValidIndex(x *operand, code Code, what string, allowNega
 		return false
 	}
 
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		// spec: "a constant index must be non-negative ..."
 		if !allowNegative && constant.Sign(x.val) < 0 {
 			check.errorf(x, code, invalidArg+"%s %s must not be negative", what, x)
diff --git a/src/go/types/infer.go b/src/go/types/infer.go
index db960723ca..6a49be7079 100644
--- a/src/go/types/infer.go
+++ b/src/go/types/infer.go
@@ -65,7 +65,7 @@ func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type,
 	// If we have invalid (ordinary) arguments, an error was reported before.
 	// Avoid additional inference errors and exit early (go.dev/issue/60434).
 	for _, arg := range args {
-		if arg.mode_ == invalid {
+		if arg.mode() == invalid {
 			return nil
 		}
 	}
@@ -165,7 +165,7 @@ func (check *Checker) infer(posn positioner, tparams []*TypeParam, targs []Type,
 	}
 
 	for i, arg := range args {
-		if arg.mode_ == invalid {
+		if arg.mode() == invalid {
 			// An error was reported earlier. Ignore this arg
 			// and continue, we may still be able to infer all
 			// targs resulting in fewer follow-on errors.
diff --git a/src/go/types/literals.go b/src/go/types/literals.go
index 2bcd229358..11366f1d45 100644
--- a/src/go/types/literals.go
+++ b/src/go/types/literals.go
@@ -66,7 +66,7 @@ func (check *Checker) basicLit(x *operand, e *ast.BasicLit) {
 		}
 	}
 	x.setConst(e.Kind, e.Value)
-	if x.mode_ == invalid {
+	if x.mode() == invalid {
 		// The parser already establishes syntactic correctness.
 		// If we reach here it's because of number under-/overflow.
 		// TODO(gri) setConst (and in turn the go/constant package)
@@ -265,10 +265,10 @@ func (check *Checker) compositeLit(x *operand, e *ast.CompositeLit, hint Type) {
 			}
 			check.exprWithHint(x, kv.Key, utyp.key)
 			check.assignment(x, utyp.key, "map literal")
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				continue
 			}
-			if x.mode_ == constant_ {
+			if x.mode() == constant_ {
 				duplicate := false
 				xkey := keyVal(x.val)
 				if keyIsInterface {
diff --git a/src/go/types/operand.go b/src/go/types/operand.go
index 3de2455899..b5c24a802c 100644
--- a/src/go/types/operand.go
+++ b/src/go/types/operand.go
@@ -64,12 +64,16 @@ type operand struct {
 	id    builtinId
 }
 
+func (x *operand) mode() operandMode {
+	return x.mode_
+}
+
 func (x *operand) typ() Type {
 	return x.typ_
 }
 
 func (x *operand) isValid() bool {
-	return x.mode_ != invalid
+	return x.mode() != invalid
 }
 
 // Pos returns the position of the expression corresponding to x.
@@ -121,7 +125,7 @@ func (x *operand) Pos() token.Pos {
 func operandString(x *operand, qf Qualifier) string {
 	// special-case nil
 	if isTypes2 {
-		if x.mode_ == nilvalue {
+		if x.mode() == nilvalue {
 			switch x.typ() {
 			case nil, Typ[Invalid]:
 				return "nil (with invalid type)"
@@ -132,7 +136,7 @@ func operandString(x *operand, qf Qualifier) string {
 			}
 		}
 	} else { // go/types
-		if x.mode_ == value && x.typ() == Typ[UntypedNil] {
+		if x.mode() == value && x.typ() == Typ[UntypedNil] {
 			return "nil"
 		}
 	}
@@ -143,7 +147,7 @@ func operandString(x *operand, qf Qualifier) string {
 	if x.expr != nil {
 		expr = ExprString(x.expr)
 	} else {
-		switch x.mode_ {
+		switch x.mode() {
 		case builtin:
 			expr = predeclaredFuncs[x.id].name
 		case typexpr:
@@ -161,7 +165,7 @@ func operandString(x *operand, qf Qualifier) string {
 
 	// <untyped kind>
 	hasType := false
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid, novalue, builtin, typexpr:
 		// no type
 	default:
@@ -177,10 +181,10 @@ func operandString(x *operand, qf Qualifier) string {
 	}
 
 	// <mode>
-	buf.WriteString(operandModeString[x.mode_])
+	buf.WriteString(operandModeString[x.mode()])
 
 	// <val>
-	if x.mode_ == constant_ {
+	if x.mode() == constant_ {
 		if s := x.val.String(); s != expr {
 			buf.WriteByte(' ')
 			buf.WriteString(s)
@@ -305,9 +309,9 @@ func (x *operand) setConst(k token.Token, lit string) {
 // isNil reports whether x is the (untyped) nil value.
 func (x *operand) isNil() bool {
 	if isTypes2 {
-		return x.mode_ == nilvalue
+		return x.mode() == nilvalue
 	} else { // go/types
-		return x.mode_ == value && x.typ() == Typ[UntypedNil]
+		return x.mode() == value && x.typ() == Typ[UntypedNil]
 	}
 }
 
@@ -318,7 +322,7 @@ func (x *operand) isNil() bool {
 // if assignableTo is invoked through an exported API call, i.e., when all
 // methods have been type-checked.
 func (x *operand) assignableTo(check *Checker, T Type, cause *string) (bool, Code) {
-	if x.mode_ == invalid || !isValid(T) {
+	if x.mode() == invalid || !isValid(T) {
 		return true, 0 // avoid spurious errors
 	}
 
diff --git a/src/go/types/range.go b/src/go/types/range.go
index cbe2c37535..05ef827eec 100644
--- a/src/go/types/range.go
+++ b/src/go/types/range.go
@@ -37,7 +37,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *ast.RangeStmt, noN
 	check.hasCallOrRecv = false
 	check.expr(nil, &x, rangeVar)
 
-	if isTypes2 && x.mode_ != invalid && sValue == nil && !check.hasCallOrRecv {
+	if isTypes2 && x.mode() != invalid && sValue == nil && !check.hasCallOrRecv {
 		if t, ok := arrayPtrDeref(x.typ().Underlying()).(*Array); ok {
 			for {
 				// Put constant info on the thing inside parentheses.
@@ -64,7 +64,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *ast.RangeStmt, noN
 
 	// determine key/value types
 	var key, val Type
-	if x.mode_ != invalid {
+	if x.mode() != invalid {
 		k, v, cause, ok := rangeKeyVal(check, x.typ(), func(v goVersion) bool {
 			return check.allowVersion(v)
 		})
@@ -172,7 +172,7 @@ func (check *Checker) rangeStmt(inner stmtContext, rangeStmt *ast.RangeStmt, noN
 				// If the assignment succeeded, if x was untyped before, it now
 				// has a type inferred via the assignment. It must be an integer.
 				// (go.dev/issues/67027)
-				if x.mode_ != invalid && !isInteger(x.typ()) {
+				if x.mode() != invalid && !isInteger(x.typ()) {
 					check.softErrorf(lhs, InvalidRangeExpr, "cannot use iteration variable of type %s", x.typ())
 				}
 			} else {
diff --git a/src/go/types/recording.go b/src/go/types/recording.go
index d440259c28..809246bb05 100644
--- a/src/go/types/recording.go
+++ b/src/go/types/recording.go
@@ -20,7 +20,7 @@ func (check *Checker) record(x *operand) {
 	// TODO(gri) this code can be simplified
 	var typ Type
 	var val constant.Value
-	switch x.mode_ {
+	switch x.mode() {
 	case invalid:
 		typ = Typ[Invalid]
 	case novalue:
@@ -36,9 +36,9 @@ func (check *Checker) record(x *operand) {
 	if isUntyped(typ) {
 		// delay type and value recording until we know the type
 		// or until the end of type checking
-		check.rememberUntyped(x.expr, false, x.mode_, typ.(*Basic), val)
+		check.rememberUntyped(x.expr, false, x.mode(), typ.(*Basic), val)
 	} else {
-		check.recordTypeAndValue(x.expr, x.mode_, typ, val)
+		check.recordTypeAndValue(x.expr, x.mode(), typ, val)
 	}
 }
 
@@ -97,7 +97,7 @@ func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
 func (check *Checker) recordCommaOkTypes(x ast.Expr, a []*operand) {
 	assert(x != nil)
 	assert(len(a) == 2)
-	if a[0].mode_ == invalid {
+	if a[0].mode() == invalid {
 		return
 	}
 	t0, t1 := a[0].typ(), a[1].typ()
diff --git a/src/go/types/stmt.go b/src/go/types/stmt.go
index a449feb220..ee2f872577 100644
--- a/src/go/types/stmt.go
+++ b/src/go/types/stmt.go
@@ -239,20 +239,20 @@ L:
 	for _, e := range values {
 		var v operand
 		check.expr(nil, &v, e)
-		if x.mode_ == invalid || v.mode_ == invalid {
+		if x.mode() == invalid || v.mode() == invalid {
 			continue L
 		}
 		check.convertUntyped(&v, x.typ())
-		if v.mode_ == invalid {
+		if v.mode() == invalid {
 			continue L
 		}
 		// Order matters: By comparing v against x, error positions are at the case values.
 		res := v // keep original v unchanged
 		check.comparison(&res, x, token.EQL, true)
-		if res.mode_ == invalid {
+		if res.mode() == invalid {
 			continue L
 		}
-		if v.mode_ != constant_ {
+		if v.mode() != constant_ {
 			continue L // we're done
 		}
 		// look for duplicate values
@@ -445,7 +445,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		kind := check.rawExpr(nil, &x, s.X, nil, false)
 		var msg string
 		var code Code
-		switch x.mode_ {
+		switch x.mode() {
 		default:
 			if kind == statement {
 				return
@@ -465,7 +465,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		var ch, val operand
 		check.expr(nil, &ch, s.Chan)
 		check.expr(nil, &val, s.Value)
-		if ch.mode_ == invalid || val.mode_ == invalid {
+		if ch.mode() == invalid || val.mode() == invalid {
 			return
 		}
 		if elem := check.chanElem(inNode(s, s.Arrow), &ch, false); elem != nil {
@@ -486,7 +486,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 
 		var x operand
 		check.expr(nil, &x, s.X)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		if !allNumeric(x.typ()) {
@@ -496,7 +496,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 
 		Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
 		check.binary(&x, nil, s.X, Y, op, s.TokPos)
-		if x.mode_ == invalid {
+		if x.mode() == invalid {
 			return
 		}
 		check.assignVar(s.X, nil, &x, "assignment")
@@ -528,7 +528,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 			}
 			var x operand
 			check.binary(&x, nil, s.Lhs[0], s.Rhs[0], op, s.TokPos)
-			if x.mode_ == invalid {
+			if x.mode() == invalid {
 				return
 			}
 			check.assignVar(s.Lhs[0], nil, &x, "assignment")
@@ -609,7 +609,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		check.simpleStmt(s.Init)
 		var x operand
 		check.expr(nil, &x, s.Cond)
-		if x.mode_ != invalid && !allBoolean(x.typ()) {
+		if x.mode() != invalid && !allBoolean(x.typ()) {
 			check.error(s.Cond, InvalidCond, "non-boolean condition in if statement")
 		}
 		check.stmt(inner, s.Body)
@@ -636,7 +636,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 			// By checking assignment of x to an invisible temporary
 			// (as a compiler would), we get all the relevant checks.
 			check.assignment(&x, nil, "switch expression")
-			if x.mode_ != invalid && !Comparable(x.typ()) && !hasNil(x.typ()) {
+			if x.mode() != invalid && !Comparable(x.typ()) && !hasNil(x.typ()) {
 				check.errorf(&x, InvalidExprSwitch, "cannot switch on %s (%s is not comparable)", &x, x.typ())
 				x.mode_ = invalid
 			}
@@ -728,7 +728,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		{
 			var x operand
 			check.expr(nil, &x, expr.X)
-			if x.mode_ != invalid {
+			if x.mode() != invalid {
 				if isTypeParam(x.typ()) {
 					check.errorf(&x, InvalidTypeSwitch, "cannot use type switch on type parameter value %s", &x)
 				} else if IsInterface(x.typ()) {
@@ -837,7 +837,7 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 		if s.Cond != nil {
 			var x operand
 			check.expr(nil, &x, s.Cond)
-			if x.mode_ != invalid && !allBoolean(x.typ()) {
+			if x.mode() != invalid && !allBoolean(x.typ()) {
 				check.error(s.Cond, InvalidCond, "non-boolean condition in for statement")
 			}
 		}
diff --git a/src/go/types/typexpr.go b/src/go/types/typexpr.go
index 848d662f10..79b7f6b5ca 100644
--- a/src/go/types/typexpr.go
+++ b/src/go/types/typexpr.go
@@ -246,7 +246,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *TypeName) (T Type) {
 		var x operand
 		check.ident(&x, e, true)
 
-		switch x.mode_ {
+		switch x.mode() {
 		case typexpr:
 			return x.typ()
 		case invalid:
@@ -261,7 +261,7 @@ func (check *Checker) typInternal(e0 ast.Expr, def *TypeName) (T Type) {
 		var x operand
 		check.selector(&x, e, true)
 
-		switch x.mode_ {
+		switch x.mode() {
 		case typexpr:
 			return x.typ()
 		case invalid:
@@ -478,8 +478,8 @@ func (check *Checker) arrayLength(e ast.Expr) int64 {
 
 	var x operand
 	check.expr(nil, &x, e)
-	if x.mode_ != constant_ {
-		if x.mode_ != invalid {
+	if x.mode() != constant_ {
+		if x.mode() != invalid {
 			check.errorf(&x, InvalidArrayLen, "array length %s must be constant", &x)
 		}
 		return -1
-- 
2.52.0