From: Robert Griesemer <gri@golang.org>
Date: Fri, 19 Feb 2021 17:39:01 +0000 (-0800)
Subject: [dev.typeparams] cmd/compile/internal/types2: resolve decl cycle the same way as... 
X-Git-Tag: go1.17beta1~1473^2~1
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=6521c7b3786a69bc6ad3840ef2e3ba2088ad1cae;p=gostls13.git

[dev.typeparams] cmd/compile/internal/types2: resolve decl cycle the same way as in go/types

Minor adjustment to match go/types more closely.

Change-Id: Id79c51f0ecd8cda0f5b68f6e961500f7f22f7115
Reviewed-on: https://go-review.googlesource.com/c/go/+/294270
Reviewed-by: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>
---

diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index a284c8c8b6..584b8ee6a0 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -59,11 +59,16 @@ the type (and constant value, if any) is recorded via Info.Types, if present.
 
 type opPredicates map[syntax.Operator]func(Type) bool
 
-var unaryOpPredicates = opPredicates{
-	syntax.Add: isNumeric,
-	syntax.Sub: isNumeric,
-	syntax.Xor: isInteger,
-	syntax.Not: isBoolean,
+var unaryOpPredicates opPredicates
+
+func init() {
+	// Setting unaryOpPredicates in init avoids declaration cycles.
+	unaryOpPredicates = opPredicates{
+		syntax.Add: isNumeric,
+		syntax.Sub: isNumeric,
+		syntax.Xor: isInteger,
+		syntax.Not: isBoolean,
+	}
 }
 
 func (check *Checker) op(m opPredicates, x *operand, op syntax.Operator) bool {
@@ -896,20 +901,25 @@ func (check *Checker) shift(x, y *operand, e syntax.Expr, op syntax.Operator) {
 	x.mode = value
 }
 
-var binaryOpPredicates = opPredicates{
-	syntax.Add: isNumericOrString,
-	syntax.Sub: isNumeric,
-	syntax.Mul: isNumeric,
-	syntax.Div: isNumeric,
-	syntax.Rem: isInteger,
+var binaryOpPredicates opPredicates
 
-	syntax.And:    isInteger,
-	syntax.Or:     isInteger,
-	syntax.Xor:    isInteger,
-	syntax.AndNot: isInteger,
+func init() {
+	// Setting binaryOpPredicates in init avoids declaration cycles.
+	binaryOpPredicates = opPredicates{
+		syntax.Add: isNumericOrString,
+		syntax.Sub: isNumeric,
+		syntax.Mul: isNumeric,
+		syntax.Div: isNumeric,
+		syntax.Rem: isInteger,
 
-	syntax.AndAnd: isBoolean,
-	syntax.OrOr:   isBoolean,
+		syntax.And:    isInteger,
+		syntax.Or:     isInteger,
+		syntax.Xor:    isInteger,
+		syntax.AndNot: isInteger,
+
+		syntax.AndAnd: isBoolean,
+		syntax.OrOr:   isBoolean,
+	}
 }
 
 // If e != nil, it must be the binary expression; it may be nil for non-constant expressions
diff --git a/src/cmd/compile/internal/types2/type.go b/src/cmd/compile/internal/types2/type.go
index 1025c18b23..52bd99deab 100644
--- a/src/cmd/compile/internal/types2/type.go
+++ b/src/cmd/compile/internal/types2/type.go
@@ -881,16 +881,7 @@ func (t *top) String() string       { return TypeString(t, nil) }
 // If it doesn't exist, the result is Typ[Invalid].
 // under must only be called when a type is known
 // to be fully set up.
-//
-// under is set to underf to avoid an initialization cycle.
-// TODO(gri) this doesn't happen in go/types - investigate
-var under func(Type) Type
-
-func init() {
-	under = underf
-}
-
-func underf(t Type) Type {
+func under(t Type) Type {
 	// TODO(gri) is this correct for *Sum?
 	if n := asNamed(t); n != nil {
 		return n.under()