cmd/compile/internal/types2: use ExprString instead of syntax.String

This further reduces the differences between go/types and types2.

Change-Id: I1426c2f7c58e2d1123d93f68fbdda01b0cc2d46e
Reviewed-on: https://go-review.googlesource.com/c/go/+/562836
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>

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

@@ -152,7 +152,7 @@ func TestValuesInfo(t *testing.T) {
 		// look for expression
 		var expr syntax.Expr
 		for e := range info.Types {
-			if syntax.String(e) == test.expr {
+			if ExprString(e) == test.expr {
 				expr = e
 				break
 			}
@@ -424,7 +424,7 @@ func TestTypesInfo(t *testing.T) {
 		// look for expression type
 		var typ Type
 		for e, tv := range info.Types {
-			if syntax.String(e) == test.expr {
+			if ExprString(e) == test.expr {
 				typ = tv.Type
 				break
 			}
@@ -1135,8 +1135,8 @@ func TestPredicatesInfo(t *testing.T) {
 		// look for expression predicates
 		got := "<missing>"
 		for e, tv := range info.Types {
-			//println(name, syntax.String(e))
-			if syntax.String(e) == test.expr {
+			//println(name, ExprString(e))
+			if ExprString(e) == test.expr {
 				got = predString(tv)
 				break
 			}

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

@@ -218,7 +218,7 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
 			var op operand
 			check.expr(nil, &op, sel.X)
 			if op.mode == mapindex {
-				check.errorf(&x, UnaddressableFieldAssign, "cannot assign to struct field %s in map", syntax.String(x.expr))
+				check.errorf(&x, UnaddressableFieldAssign, "cannot assign to struct field %s in map", ExprString(x.expr))
 				return Typ[Invalid]
 			}
 		}
@@ -248,7 +248,7 @@ func (check *Checker) assignVar(lhs, rhs syntax.Expr, x *operand, context string
 		// avoid calling syntax.String if not needed
 		if T != nil {
 			if _, ok := under(T).(*Signature); ok {
-				target = newTarget(T, syntax.String(lhs))
+				target = newTarget(T, ExprString(lhs))
 			}
 		}
 		x = new(operand)

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

@@ -207,7 +207,7 @@ func testBuiltinSignature(t *testing.T, name, src0, want string) {
 		// the recorded type for the built-in must match the wanted signature
 		typ := types[fun].Type
 		if typ == nil {
-			t.Errorf("%s: no type recorded for %s", src0, syntax.String(fun))
+			t.Errorf("%s: no type recorded for %s", src0, ExprString(fun))
 			return
 		}
 		if got := typ.String(); got != want {

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

@@ -102,7 +102,7 @@ func sprintf(qf Qualifier, tpSubscripts bool, format string, args ...interface{}
 		case syntax.Pos:
 			arg = a.String()
 		case syntax.Expr:
-			arg = syntax.String(a)
+			arg = ExprString(a)
 		case []syntax.Expr:
 			var buf strings.Builder
 			buf.WriteByte('[')
@@ -110,7 +110,7 @@ func sprintf(qf Qualifier, tpSubscripts bool, format string, args ...interface{}
 				if i > 0 {
 					buf.WriteString(", ")
 				}
-				buf.WriteString(syntax.String(x))
+				buf.WriteString(ExprString(x))
 			}
 			buf.WriteByte(']')
 			arg = buf.String()

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

@@ -698,14 +698,14 @@ func TestIssue51093(t *testing.T) {
 				n++
 				tpar, _ := tv.Type.(*TypeParam)
 				if tpar == nil {
-					t.Fatalf("%s: got type %s, want type parameter", syntax.String(x), tv.Type)
+					t.Fatalf("%s: got type %s, want type parameter", ExprString(x), tv.Type)
 				}
 				if name := tpar.Obj().Name(); name != "P" {
-					t.Fatalf("%s: got type parameter name %s, want P", syntax.String(x), name)
+					t.Fatalf("%s: got type parameter name %s, want P", ExprString(x), name)
 				}
 				// P(val) must not be constant
 				if tv.Value != nil {
-					t.Errorf("%s: got constant value %s (%s), want no constant", syntax.String(x), tv.Value, tv.Value.String())
+					t.Errorf("%s: got constant value %s (%s), want no constant", ExprString(x), tv.Value, tv.Value.String())
 				}
 			}
 		}

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

@@ -124,7 +124,7 @@ func operandString(x *operand, qf Qualifier) string {
 
 	var expr string
 	if x.expr != nil {
-		expr = syntax.String(x.expr)
+		expr = ExprString(x.expr)
 	} else {
 		switch x.mode {
 		case builtin:

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

@@ -23,3 +23,6 @@ func cmpPos(p, q syntax.Pos) int { return p.Cmp(q) }
 
 // hasDots reports whether the last argument in the call is followed by ...
 func hasDots(call *syntax.CallExpr) bool { return call.HasDots }
+
+// ExprString returns a string representation of x.
+func ExprString(x syntax.Node) string { return syntax.String(x) }