go/types, types2: use orig. compiler error message for a shift error

Slightly better for cases such as string(1 << s).
Leaves type-checker tests alone for now because
there are multiple dozens.

For golang#45117.

Change-Id: I47b314c713fabe424c2158674bf965416a8a6f5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/379274
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

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

@@ -504,8 +504,11 @@ func (check *Checker) invalidConversion(code errorCode, x *operand, target Type)
 // Also, if x is a constant, it must be representable as a value of typ,
 // and if x is the (formerly untyped) lhs operand of a non-constant
 // shift, it must be an integer value.
-//
 func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
+	check.updateExprType0(nil, x, typ, final)
+}
+
+func (check *Checker) updateExprType0(parent, x syntax.Expr, typ Type, final bool) {
 	old, found := check.untyped[x]
 	if !found {
 		return // nothing to do
@@ -548,7 +551,7 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 		// No operands to take care of.
 
 	case *syntax.ParenExpr:
-		check.updateExprType(x.X, typ, final)
+		check.updateExprType0(x, x.X, typ, final)
 
 	// case *syntax.UnaryExpr:
 	// 	// If x is a constant, the operands were constants.
@@ -559,7 +562,7 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 	// 	if old.val != nil {
 	// 		break
 	// 	}
-	// 	check.updateExprType(x.X, typ, final)
+	// 	check.updateExprType0(x, x.X, typ, final)
 
 	case *syntax.Operation:
 		if x.Y == nil {
@@ -580,7 +583,7 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 			if old.val != nil {
 				break
 			}
-			check.updateExprType(x.X, typ, final)
+			check.updateExprType0(x, x.X, typ, final)
 			break
 		}
 
@@ -594,11 +597,11 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 		} else if isShift(x.Op) {
 			// The result type depends only on lhs operand.
 			// The rhs type was updated when checking the shift.
-			check.updateExprType(x.X, typ, final)
+			check.updateExprType0(x, x.X, typ, final)
 		} else {
 			// The operand types match the result type.
-			check.updateExprType(x.X, typ, final)
-			check.updateExprType(x.Y, typ, final)
+			check.updateExprType0(x, x.X, typ, final)
+			check.updateExprType0(x, x.Y, typ, final)
 		}
 
 	default:
@@ -622,7 +625,11 @@ func (check *Checker) updateExprType(x syntax.Expr, typ Type, final bool) {
 		// We already know from the shift check that it is representable
 		// as an integer if it is a constant.
 		if !allInteger(typ) {
-			check.errorf(x, invalidOp+"shifted operand %s (type %s) must be integer", x, typ)
+			if check.conf.CompilerErrorMessages {
+				check.errorf(x, invalidOp+"%s (shift of type %s)", parent, typ)
+			} else {
+				check.errorf(x, invalidOp+"shifted operand %s (type %s) must be integer", x, typ)
+			}
 			return
 		}
 		// Even if we have an integer, if the value is a constant we

src/go/types/expr.go

@@ -472,8 +472,11 @@ func (check *Checker) invalidConversion(code errorCode, x *operand, target Type)
 // Also, if x is a constant, it must be representable as a value of typ,
 // and if x is the (formerly untyped) lhs operand of a non-constant
 // shift, it must be an integer value.
-//
 func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
+	check.updateExprType0(nil, x, typ, final)
+}
+
+func (check *Checker) updateExprType0(parent, x ast.Expr, typ Type, final bool) {
 	old, found := check.untyped[x]
 	if !found {
 		return // nothing to do
@@ -515,7 +518,7 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		// No operands to take care of.
 
 	case *ast.ParenExpr:
-		check.updateExprType(x.X, typ, final)
+		check.updateExprType0(x, x.X, typ, final)
 
 	case *ast.UnaryExpr:
 		// If x is a constant, the operands were constants.
@@ -526,7 +529,7 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		if old.val != nil {
 			break
 		}
-		check.updateExprType(x.X, typ, final)
+		check.updateExprType0(x, x.X, typ, final)
 
 	case *ast.BinaryExpr:
 		if old.val != nil {
@@ -538,11 +541,11 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		} else if isShift(x.Op) {
 			// The result type depends only on lhs operand.
 			// The rhs type was updated when checking the shift.
-			check.updateExprType(x.X, typ, final)
+			check.updateExprType0(x, x.X, typ, final)
 		} else {
 			// The operand types match the result type.
-			check.updateExprType(x.X, typ, final)
-			check.updateExprType(x.Y, typ, final)
+			check.updateExprType0(x, x.X, typ, final)
+			check.updateExprType0(x, x.Y, typ, final)
 		}
 
 	default:
@@ -566,7 +569,11 @@ func (check *Checker) updateExprType(x ast.Expr, typ Type, final bool) {
 		// We already know from the shift check that it is representable
 		// as an integer if it is a constant.
 		if !allInteger(typ) {
-			check.invalidOp(x, _InvalidShiftOperand, "shifted operand %s (type %s) must be integer", x, typ)
+			if compilerErrorMessages {
+				check.invalidOp(x, _InvalidShiftOperand, "%s (shift of type %s)", parent, typ)
+			} else {
+				check.invalidOp(x, _InvalidShiftOperand, "shifted operand %s (type %s) must be integer", x, typ)
+			}
 			return
 		}
 		// Even if we have an integer, if the value is a constant we

test/fixedbugs/issue28079c.go

@@ -11,5 +11,5 @@ package p
 import "unsafe"
 
 func f() {
-	_ = complex(1<<uintptr(unsafe.Pointer(nil)), 0) // ERROR "invalid operation: .*shift of type float64.*|non-integer type for left operand of shift|shifted operand .* must be integer"
+	_ = complex(1<<uintptr(unsafe.Pointer(nil)), 0) // ERROR "invalid operation: .*shift of type float64.*|non-integer type for left operand of shift"
 }