reflect: check that types match without calling TypeOf

gccgo fails this test before CL 115577.

Updates #25284

Change-Id: Id4550b7b3e268f3c294420ed31c57ad3f1002b5e
Reviewed-on: https://go-review.googlesource.com/115635
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

src/reflect/all_test.go

@@ -3918,8 +3918,8 @@ func TestOverflow(t *testing.T) {
 	}
 }
 
-func checkSameType(t *testing.T, x, y interface{}) {
-	if TypeOf(x) != TypeOf(y) {
+func checkSameType(t *testing.T, x Type, y interface{}) {
+	if x != TypeOf(y) || TypeOf(Zero(x).Interface()) != TypeOf(y) {
 		t.Errorf("did not find preexisting type for %s (vs %s)", TypeOf(x), TypeOf(y))
 	}
 }
@@ -4048,7 +4048,7 @@ func TestArrayOf(t *testing.T) {
 
 	// check that type already in binary is found
 	type T int
-	checkSameType(t, Zero(ArrayOf(5, TypeOf(T(1)))).Interface(), [5]T{})
+	checkSameType(t, ArrayOf(5, TypeOf(T(1))), [5]T{})
 }
 
 func TestArrayOfGC(t *testing.T) {
@@ -4184,7 +4184,7 @@ func TestSliceOf(t *testing.T) {
 
 	// check that type already in binary is found
 	type T1 int
-	checkSameType(t, Zero(SliceOf(TypeOf(T1(1)))).Interface(), []T1{})
+	checkSameType(t, SliceOf(TypeOf(T1(1))), []T1{})
 }
 
 func TestSliceOverflow(t *testing.T) {
@@ -4398,7 +4398,7 @@ func TestStructOf(t *testing.T) {
 		})
 	})
 	// check that type already in binary is found
-	checkSameType(t, Zero(StructOf(fields[2:3])).Interface(), struct{ Y uint64 }{})
+	checkSameType(t, StructOf(fields[2:3]), struct{ Y uint64 }{})
 }
 
 func TestStructOfExportRules(t *testing.T) {
@@ -4943,7 +4943,7 @@ func TestChanOf(t *testing.T) {
 
 	// check that type already in binary is found
 	type T1 int
-	checkSameType(t, Zero(ChanOf(BothDir, TypeOf(T1(1)))).Interface(), (chan T1)(nil))
+	checkSameType(t, ChanOf(BothDir, TypeOf(T1(1))), (chan T1)(nil))
 }
 
 func TestChanOfDir(t *testing.T) {
@@ -4954,8 +4954,8 @@ func TestChanOfDir(t *testing.T) {
 
 	// check that type already in binary is found
 	type T1 int
-	checkSameType(t, Zero(ChanOf(RecvDir, TypeOf(T1(1)))).Interface(), (<-chan T1)(nil))
-	checkSameType(t, Zero(ChanOf(SendDir, TypeOf(T1(1)))).Interface(), (chan<- T1)(nil))
+	checkSameType(t, ChanOf(RecvDir, TypeOf(T1(1))), (<-chan T1)(nil))
+	checkSameType(t, ChanOf(SendDir, TypeOf(T1(1))), (chan<- T1)(nil))
 
 	// check String form of ChanDir
 	if crt.ChanDir().String() != "<-chan" {
@@ -5031,7 +5031,7 @@ func TestMapOf(t *testing.T) {
 	}
 
 	// check that type already in binary is found
-	checkSameType(t, Zero(MapOf(TypeOf(V(0)), TypeOf(K("")))).Interface(), map[V]K(nil))
+	checkSameType(t, MapOf(TypeOf(V(0)), TypeOf(K(""))), map[V]K(nil))
 
 	// check that invalid key type panics
 	shouldPanic(func() { MapOf(TypeOf((func())(nil)), TypeOf(false)) })
@@ -5161,7 +5161,7 @@ func TestFuncOf(t *testing.T) {
 		{in: []Type{TypeOf(int(0))}, out: []Type{TypeOf(false), TypeOf("")}, want: (func(int) (bool, string))(nil)},
 	}
 	for _, tt := range testCases {
-		checkSameType(t, Zero(FuncOf(tt.in, tt.out, tt.variadic)).Interface(), tt.want)
+		checkSameType(t, FuncOf(tt.in, tt.out, tt.variadic), tt.want)
 	}
 
 	// check that variadic requires last element be a slice.