From: Robert Griesemer <gri@golang.org>
Date: Wed, 17 May 2023 00:24:16 +0000 (-0700)
Subject: go/types, types2: assert that builtin reports valid operand mode upon success
X-Git-Tag: go1.21rc1~458
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8e3dfe783ab5ed110b6b338662ee1dee6a7dc51b;p=gostls13.git

go/types, types2: assert that builtin reports valid operand mode upon success

Fix a case where x.mode == invalid was returned despite builtin
returning true.

Change-Id: Iae9c18aac16bcbadc3530d341b380e05c8743fcc
Reviewed-on: https://go-review.googlesource.com/c/go/+/495299
Auto-Submit: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/cmd/compile/internal/types2/builtins.go b/src/cmd/compile/internal/types2/builtins.go
index 63b62a66d2..de74da0bac 100644
--- a/src/cmd/compile/internal/types2/builtins.go
+++ b/src/cmd/compile/internal/types2/builtins.go
@@ -200,12 +200,15 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 			}
 		}
 
-		if mode == invalid && under(x.typ) != Typ[Invalid] {
-			code := InvalidCap
-			if id == _Len {
-				code = InvalidLen
+		if mode == invalid {
+			// avoid error if underlying type is invalid
+			if under(x.typ) != Typ[Invalid] {
+				code := InvalidCap
+				if id == _Len {
+					code = InvalidLen
+				}
+				check.errorf(x, code, invalidArg+"%s for %s", x, bin.name)
 			}
-			check.errorf(x, code, invalidArg+"%s for %s", x, bin.name)
 			return
 		}
 
@@ -850,6 +853,7 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		unreachable()
 	}
 
+	assert(x.mode != invalid)
 	return true
 }
 
diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 63a59262df..64d34e51cb 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -201,12 +201,15 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			}
 		}
 
-		if mode == invalid && under(x.typ) != Typ[Invalid] {
-			code := InvalidCap
-			if id == _Len {
-				code = InvalidLen
+		if mode == invalid {
+			// avoid error if underlying type is invalid
+			if under(x.typ) != Typ[Invalid] {
+				code := InvalidCap
+				if id == _Len {
+					code = InvalidLen
+				}
+				check.errorf(x, code, invalidArg+"%s for %s", x, bin.name)
 			}
-			check.errorf(x, code, invalidArg+"%s for %s", x, bin.name)
 			return
 		}
 
@@ -851,6 +854,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		unreachable()
 	}
 
+	assert(x.mode != invalid)
 	return true
 }