cmd/compile: print expression for invalid operation errors

For #48472

Change-Id: I5072ebcf53e03fb5515c51a2ad01f02d72b30719
Reviewed-on: https://go-review.googlesource.com/c/go/+/350929
Reviewed-by: Robert Griesemer <[email protected]>
Trust: David Chase <[email protected]>

src/cmd/compile/internal/types2/expr.go

@@ -1019,7 +1019,7 @@ func (check *Checker) binary(x *operand, e syntax.Expr, lhs, rhs syntax.Expr, op
  // only report an error if we have valid types
  // (otherwise we had an error reported elsewhere already)
  if x.typ != Typ[Invalid] && y.typ != Typ[Invalid] {
- check.errorf(x, invalidOp+"mismatched types %s and %s", x.typ, y.typ)
+ check.errorf(x, invalidOp+"%s (mismatched types %s and %s)", e, x.typ, y.typ)
  }
  x.mode = invalid
  return

src/cmd/compile/internal/types2/testdata/fixedbugs/issue48472.go2

@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func g() {
+ var s string
+ var i int
+ _ = s /* ERROR invalid operation: s \+ i \(mismatched types string and int\) */ + i
+}

src/go/types/expr.go

@@ -994,7 +994,7 @@ func (check *Checker) binary(x *operand, e ast.Expr, lhs, rhs ast.Expr, op token
  if e != nil {
  posn = e
  }
- check.invalidOp(posn, _MismatchedTypes, "mismatched types %s and %s", x.typ, y.typ)
+ check.invalidOp(posn, _MismatchedTypes, "%s (mismatched types %s and %s)", e, x.typ, y.typ)
  }
  x.mode = invalid
  return

src/go/types/testdata/fixedbugs/issue48472.go2

@@ -0,0 +1,11 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+func g() {
+ var s string
+ var i int
+ _ = s /* ERROR invalid operation: s \+ i \(mismatched types string and int\) */ + i
+}