cmd/compile, types2: better error message for invalid type assertion
This CL addresses the 2nd part of the issue below.
- For types2, now use the same error messages as the compiler in this case.
- Make the mechanism for reporting clarifying error messages handle the case
where we don't have additional position information.
- Provide context information (type assertion vs type switch).
Fixes #49005.
Change-Id: I4eeaf4f0c3f2f8735b63993778f58d713fef21ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/356512
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/src/cmd/compile/internal/types2/errors.go b/src/cmd/compile/internal/types2/errors.go
index ea43fab..0c8a4a9 100644
--- a/src/cmd/compile/internal/types2/errors.go
+++ b/src/cmd/compile/internal/types2/errors.go
@@ -61,7 +61,10 @@
for i := range err.desc {
p := &err.desc[i]
if i > 0 {
- fmt.Fprintf(&buf, "\n\t%s: ", p.pos)
+ fmt.Fprint(&buf, "\n\t")
+ if p.pos.IsKnown() {
+ fmt.Fprintf(&buf, "%s: ", p.pos)
+ }
}
buf.WriteString(sprintf(qf, p.format, p.args...))
}
diff --git a/src/cmd/compile/internal/types2/errors_test.go b/src/cmd/compile/internal/types2/errors_test.go
index 72a2ce3..ac73ca4 100644
--- a/src/cmd/compile/internal/types2/errors_test.go
+++ b/src/cmd/compile/internal/types2/errors_test.go
@@ -19,7 +19,7 @@
t.Errorf("simple error: got %q, want %q", got, want)
}
- want = "<unknown position>: foo 42\n\t<unknown position>: bar 43"
+ want = "<unknown position>: foo 42\n\tbar 43"
err.errorf(nopos, "bar %d", 43)
if got := err.String(); got != want {
t.Errorf("simple error: got %q, want %q", got, want)
diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index 3a3a139..2d22c02 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -1463,7 +1463,7 @@
if T == Typ[Invalid] {
goto Error
}
- check.typeAssertion(posFor(x), x, xtyp, T)
+ check.typeAssertion(e, x, xtyp, T, false)
x.mode = commaok
x.typ = T
@@ -1605,26 +1605,32 @@
}
// typeAssertion checks that x.(T) is legal; xtyp must be the type of x.
-func (check *Checker) typeAssertion(pos syntax.Pos, x *operand, xtyp *Interface, T Type) {
+func (check *Checker) typeAssertion(e syntax.Expr, x *operand, xtyp *Interface, T Type, typeSwitch bool) {
method, wrongType := check.assertableTo(xtyp, T)
if method == nil {
return
}
+
var msg string
if wrongType != nil {
if Identical(method.typ, wrongType.typ) {
- msg = fmt.Sprintf("missing method %s (%s has pointer receiver)", method.name, method.name)
+ msg = fmt.Sprintf("%s method has pointer receiver", method.name)
} else {
- msg = fmt.Sprintf("wrong type for method %s (have %s, want %s)", method.name, wrongType.typ, method.typ)
+ msg = fmt.Sprintf("wrong type for method %s: have %s, want %s", method.name, wrongType.typ, method.typ)
}
} else {
- msg = "missing method " + method.name
+ msg = fmt.Sprintf("missing %s method", method.name)
}
- if check.conf.CompilerErrorMessages {
- check.errorf(pos, "impossible type assertion: %s (%s)", x, msg)
+
+ var err error_
+ if typeSwitch {
+ err.errorf(e.Pos(), "impossible type switch case: %s", e)
+ err.errorf(nopos, "%s cannot have dynamic type %s (%s)", x, T, msg)
} else {
- check.errorf(pos, "%s cannot have dynamic type %s (%s)", x, T, msg)
+ err.errorf(e.Pos(), "impossible type assertion: %s", e)
+ err.errorf(nopos, "%s does not implement %s (%s)", T, x.typ, msg)
}
+ check.report(&err)
}
// expr typechecks expression e and initializes x with the expression value.
diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index f3f345f..e826f35 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -306,7 +306,7 @@
}
seen[T] = e
if T != nil {
- check.typeAssertion(e.Pos(), x, xtyp, T)
+ check.typeAssertion(e, x, xtyp, T, true)
}
}
return
@@ -347,7 +347,7 @@
// }
// seen[hash] = e
// if T != nil {
-// check.typeAssertion(e.Pos(), x, xtyp, T)
+// check.typeAssertion(e, x, xtyp, T, true)
// }
// }
// return
diff --git a/src/cmd/compile/internal/types2/testdata/check/expr3.src b/src/cmd/compile/internal/types2/testdata/check/expr3.src
index fd28421..df4cf6a 100644
--- a/src/cmd/compile/internal/types2/testdata/check/expr3.src
+++ b/src/cmd/compile/internal/types2/testdata/check/expr3.src
@@ -459,9 +459,9 @@
var t I
_ = t /* ERROR "use of .* outside type switch" */ .(type)
- _ = t /* ERROR "missing method m" */ .(T)
+ _ = t /* ERROR "m method has pointer receiver" */ .(T)
_ = t.(*T)
- _ = t /* ERROR "missing method m" */ .(T1)
+ _ = t /* ERROR "missing m method" */ .(T1)
_ = t /* ERROR "wrong type for method m" */ .(T2)
_ = t /* STRICT "wrong type for method m" */ .(I2) // only an error in strict mode (issue 8561)
diff --git a/src/cmd/compile/internal/types2/testdata/check/issues.src b/src/cmd/compile/internal/types2/testdata/check/issues.src
index d83a95a..dfd5100 100644
--- a/src/cmd/compile/internal/types2/testdata/check/issues.src
+++ b/src/cmd/compile/internal/types2/testdata/check/issues.src
@@ -132,12 +132,12 @@
var x I1
x = T1 /* ERROR cannot use .*: missing method foo \(foo has pointer receiver\) */ {}
- _ = x /* ERROR .* cannot have dynamic type T1 \(missing method foo \(foo has pointer receiver\)\) */ .(T1)
+ _ = x. /* ERROR impossible type assertion: x.\(T1\)\n\tT1 does not implement I1 \(foo method has pointer receiver\) */ (T1)
T1{}.foo /* ERROR cannot call pointer method foo on T1 */ ()
x.Foo /* ERROR "x.Foo undefined \(type I1 has no field or method Foo, but does have foo\)" */ ()
- _ = i2 /* ERROR i2 .* cannot have dynamic type \*T1 \(wrong type for method foo \(have func\(\), want func\(x int\)\)\) */ .(*T1)
+ _ = i2. /* ERROR impossible type assertion: i2.\(\*T1\)\n\t\*T1 does not implement I2 \(wrong type for method foo: have func\(\), want func\(x int\)\) */ (*T1)
i1 = i0 /* ERROR cannot use .* missing method foo */
i1 = t0 /* ERROR cannot use .* missing method foo */
diff --git a/src/cmd/compile/internal/types2/testdata/check/stmt0.src b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
index d744f2b..5ec37b4 100644
--- a/src/cmd/compile/internal/types2/testdata/check/stmt0.src
+++ b/src/cmd/compile/internal/types2/testdata/check/stmt0.src
@@ -715,7 +715,7 @@
var t I
switch t.(type) {
case T:
- case T1 /* ERROR "missing method m" */ :
+ case T1 /* ERROR "missing m method" */ :
case T2 /* ERROR "wrong type for method m" */ :
case I2 /* STRICT "wrong type for method m" */ : // only an error in strict mode (issue 8561)
}
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49005.go b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49005.go
new file mode 100644
index 0000000..6225e68
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue49005.go
@@ -0,0 +1,34 @@
+// 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.
+
+// This file is tested when running "go test -run Manual"
+// without source arguments. Use for one-off debugging.
+
+package p
+
+type T1 interface{ M() }
+
+func F1() T1
+
+var _ = F1().(*X1 /* ERROR undeclared name: X1 */)
+
+func _() {
+ switch F1().(type) {
+ case *X1 /* ERROR undeclared name: X1 */ :
+ }
+}
+
+type T2 interface{ M() }
+
+func F2() T2
+
+var _ = F2(). /* ERROR impossible type assertion: F2\(\).\(\*X2\)\n\t\*X2 does not implement T2 \(missing M method\) */ (*X2)
+
+type X2 struct{}
+
+func _() {
+ switch F2().(type) {
+ case * /* ERROR impossible type switch case: \*X2\n\tF2\(\) \(value of type T2\) cannot have dynamic type \*X2 \(missing M method\) */ X2:
+ }
+}
diff --git a/test/fixedbugs/issue49005b.go b/test/fixedbugs/issue49005b.go
new file mode 100644
index 0000000..9bff4e9
--- /dev/null
+++ b/test/fixedbugs/issue49005b.go
@@ -0,0 +1,15 @@
+// errorcheck
+
+// 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
+
+type T interface{ M() }
+
+func F() T
+
+var _ = F().(*X) // ERROR "impossible type assertion:( F\(\).\(\*X\))?\n\t\*X does not implement T \(missing M method\)"
+
+type X struct{}
diff --git a/test/switch6.go b/test/switch6.go
index 4f95d02..b9d9800 100644
--- a/test/switch6.go
+++ b/test/switch6.go
@@ -15,7 +15,7 @@
// Verify that type switch statements with impossible cases are detected by the compiler.
func f0(e error) {
switch e.(type) {
- case int: // ERROR "impossible type switch case: e \(type error\) cannot have dynamic type int \(missing Error method\)|impossible type assertion"
+ case int: // ERROR "impossible type switch case: (int\n\t)?e \(.*type error\) cannot have dynamic type int \(missing Error method\)"
}
}
@@ -41,6 +41,6 @@
func f2() {
var i I
switch i.(type) {
- case X: // ERROR "impossible type switch case: i \(type I\) cannot have dynamic type X \(Foo method has pointer receiver\)|impossible type assertion"
+ case X: // ERROR "impossible type switch case: (X\n\t)?i \(.*type I\) cannot have dynamic type X \(Foo method has pointer receiver\)"
}
}
