[dev.typeparams] cmd/compile: make types2 report better error for invalid untyped operation

This ports the fix in CL 328050 for typecheck to types2.

The fix is not identical, due to code structure differences between
typecheck and types2, but the idea is the same. We only do the untyped
conversion when both operands can be mixed.

Updates #46749

Change-Id: Ib2c63ba0d5dd8bf02318b1bfdfe51dcaeeeb7f82
Reviewed-on: https://go-review.googlesource.com/c/go/+/328053
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

6 files changed, 12 insertions, 12 deletions

diff --git a/src/cmd/compile/internal/types2/testdata/check/const0.src b/src/cmd/compile/internal/types2/testdata/check/const0.src
index 5608b1549b..3cffdf904c 100644
--- a/src/cmd/compile/internal/types2/testdata/check/const0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/const0.src
@@ -27,7 +27,7 @@ const (
 	ub1 = true
 	ub2 = 2 < 1
 	ub3 = ui1 == uf1
-	ub4 = true /* ERROR "cannot convert" */ == 0
+	ub4 = true /* ERROR "mismatched types untyped bool and untyped int" */ == 0
 
 	// integer values
 	ui0 = 0
diff --git a/src/cmd/compile/internal/types2/testdata/check/decls1.src b/src/cmd/compile/internal/types2/testdata/check/decls1.src
index e6beb78358..1167ced366 100644
--- a/src/cmd/compile/internal/types2/testdata/check/decls1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/decls1.src
@@ -83,7 +83,7 @@ var (
 
 // Constant expression initializations
 var (
-	v1 = 1 /* ERROR "cannot convert" */ + "foo"
+	v1 = 1 /* ERROR "mismatched types untyped int and untyped string" */ + "foo"
 	v2 = c + 255
 	v3 = c + 256 /* ERROR "overflows" */
 	v4 = r + 2147483647
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr1.src b/src/cmd/compile/internal/types2/testdata/check/expr1.src
index 4ead815158..85ad234bbb 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr1.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr1.src
@@ -111,10 +111,10 @@ type mystring string
 func _(x, y string, z mystring) {
 	x = x + "foo"
 	x = x /* ERROR not defined */ - "foo"
-	x = x + 1 // ERROR cannot convert
+	x = x + 1 // ERROR mismatched types string and untyped int
 	x = x + y
 	x = x /* ERROR not defined */ - y
-	x = x * 10 // ERROR cannot convert
+	x = x * 10 // ERROR mismatched types string and untyped int
 }
 
 func f() (a, b int) { return }
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr2.src b/src/cmd/compile/internal/types2/testdata/check/expr2.src
index 0c959e8011..f9726b5de5 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr2.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr2.src
@@ -10,7 +10,7 @@ func _bool() {
 	const t = true == true
 	const f = true == false
 	_ = t /* ERROR "cannot compare" */ < f
-	_ = 0 /* ERROR "cannot convert" */ == t
+	_ = 0 /* ERROR "mismatched types untyped int and untyped bool" */ == t
 	var b bool
 	var x, y float32
 	b = x < y
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr3.src b/src/cmd/compile/internal/types2/testdata/check/expr3.src
index eab3f72c4d..fd28421dc8 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr3.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr3.src
@@ -104,7 +104,7 @@ func indexes() {
 	var ok mybool
 	_, ok = m["bar"]
 	_ = ok
-	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "cannot convert"
+	_ = m[0 /* ERROR "cannot use 0" */ ] + "foo" // ERROR "mismatched types int and untyped string"
 
 	var t string
 	_ = t[- /* ERROR "negative" */ 1]
diff --git a/src/cmd/compile/internal/types2/testdata/check/stmt0.src b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
index bedcbe5fce..d744f2ba81 100644
--- a/src/cmd/compile/internal/types2/testdata/check/stmt0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
@@ -49,18 +49,18 @@ func assignments1() {
 	b = true
 
 	i += 1
-	i += "foo" /* ERROR "cannot convert.*int" */
+	i += "foo" /* ERROR "mismatched types int and untyped string" */
 
 	f -= 1
 	f /= 0
 	f = float32(0)/0 /* ERROR "division by zero" */
-	f -= "foo" /* ERROR "cannot convert.*float64" */
+	f -= "foo" /* ERROR "mismatched types float64 and untyped string" */
 
 	c *= 1
 	c /= 0
 
 	s += "bar"
-	s += 1 /* ERROR "cannot convert.*string" */
+	s += 1 /* ERROR "mismatched types string and untyped int" */
 
 	var u64 uint64
 	u64 += 1<<u64
@@ -937,13 +937,13 @@ func issue6766b() {
 // errors reported).
 func issue10148() {
 	for y /* ERROR declared but not used */ := range "" {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 	for range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 	for y := range 1 /* ERROR cannot range over 1 */ {
-		_ = "" /* ERROR cannot convert */ + 1
+		_ = "" /* ERROR mismatched types untyped string and untyped int*/ + 1
 	}
 }