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cmd/compile/types2, go/types: add position for "have" in failed inter…
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…face satisfaction

With this change, we shall now see:

    *myS does not implement S (wrong type for DoSomething method)
        have DoSomething() (string, error) at ./main.go:9:14
	want DoSomething() (int, error)

instead of previously:

    *myS does not implement S (wrong type for DoSomething method)
        have DoSomething() (string, error)
	want DoSomething() (int, error)

Fixes golang#42841
Fixes golang#45813

Change-Id: I66990929e39b0d36f2e91da0d92f60586a9b84e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/373634
Trust: Robert Findley <[email protected]>
Trust: Emmanuel Odeke <[email protected]>
Run-TryBot: Emmanuel Odeke <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>
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@odeke-em @griesemer
odeke-em authored and griesemer committed Jan 12, 2022
1 parent 1ee70da commit 8070e70
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Showing 4 changed files with 20 additions and 19 deletions.
14 changes: 7 additions & 7 deletions src/cmd/compile/internal/types2/lookup.go
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Original file line number Diff line number Diff line change
Expand Up @@ -428,18 +428,18 @@ func (check *Checker) missingMethodReason(V, T Type, m, wrongType *Func) string
if wrongType != nil {
if Identical(m.typ, wrongType.typ) {
if m.Name() == wrongType.Name() {
r = check.sprintf("(%s has pointer receiver)", mname)
r = check.sprintf("(%s has pointer receiver) at %s", mname, wrongType.Pos())
} else {
r = check.sprintf("(missing %s)\n\t\thave %s^^%s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, m.Name(), m.typ)
r = check.sprintf("(missing %s)\n\t\thave %s^^%s at %s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, wrongType.Pos(), m.Name(), m.typ)
}
} else {
if check.conf.CompilerErrorMessages {
r = check.sprintf("(wrong type for %s)\n\t\thave %s^^%s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, m.Name(), m.typ)
r = check.sprintf("(wrong type for %s)\n\t\thave %s^^%s at %s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, wrongType.Pos(), m.Name(), m.typ)
} else {
r = check.sprintf("(wrong type for %s: have %s, want %s)",
mname, wrongType.typ, m.typ)
r = check.sprintf("(wrong type for %s)\n\thave %s at %s\n\twant %s",
mname, wrongType.typ, wrongType.Pos(), m.typ)
}
}
// This is a hack to print the function type without the leading
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2 changes: 1 addition & 1 deletion src/cmd/compile/internal/types2/testdata/check/issues.src
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ func issue10260() {
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 impossible type assertion: i2.\(\*T1\)\n\t\*T1 does not implement I2 \(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 \(wrong type for method foo\)\n\thave func\(\) at \w+.+\d+.\d+\n\twant func\(x int\) */ (*T1)

i1 = i0 /* ERROR cannot use .* missing method foo */
i1 = t0 /* ERROR cannot use .* missing method foo */
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15 changes: 8 additions & 7 deletions src/go/types/lookup.go
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Original file line number Diff line number Diff line change
Expand Up @@ -400,20 +400,21 @@ func (check *Checker) missingMethodReason(V, T Type, m, wrongType *Func) string
mname = "method " + m.Name()
}
if wrongType != nil {
pos := check.fset.Position(wrongType.Pos())
if Identical(m.typ, wrongType.typ) {
if m.Name() == wrongType.Name() {
r = check.sprintf("(%s has pointer receiver)", mname)
r = check.sprintf("(%s has pointer receiver) at %s", mname, pos)
} else {
r = check.sprintf("(missing %s)\n\t\thave %s^^%s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, m.Name(), m.typ)
r = check.sprintf("(missing %s)\n\t\thave %s^^%s at %s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, pos, m.Name(), m.typ)
}
} else {
if compilerErrorMessages {
r = check.sprintf("(wrong type for %s)\n\t\thave %s^^%s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, m.Name(), m.typ)
r = check.sprintf("(wrong type for %s)\n\t\thave %s^^%s at %s\n\t\twant %s^^%s",
mname, wrongType.Name(), wrongType.typ, pos, m.Name(), m.typ)
} else {
r = check.sprintf("(wrong type for %s: have %s, want %s)",
mname, wrongType.typ, m.typ)
r = check.sprintf("(wrong type for %s)\n\thave %s at %s\nwant %s",
mname, wrongType.typ, pos, m.typ)
}
}
// This is a hack to print the function type without the leading
Expand Down
8 changes: 4 additions & 4 deletions test/fixedbugs/issue48471.go
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Original file line number Diff line number Diff line change
Expand Up @@ -29,12 +29,12 @@ func g() {
var i I
i = new(T) // ERROR "cannot use new\(T\) \(.*type \*T\) as type I in assignment:\n\t\*T does not implement I \(missing M method\)"
i = I(new(T)) // ERROR "cannot convert new\(T\) \(.*type \*T\) to type I:\n\t\*T does not implement I \(missing M method\)"
i = new(T2) // ERROR "cannot use new\(T2\) \(.*type \*T2\) as type I in assignment:\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
i = new(T3) // ERROR "cannot use new\(T3\) \(.*type \*T3\) as type I in assignment:\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
i = new(T2) // ERROR "cannot use new\(T2\) \(.*type \*T2\) as type I in assignment:\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\) at \w+.+\d.\d+\n\t\twant M\(int\)"
i = new(T3) // ERROR "cannot use new\(T3\) \(.*type \*T3\) as type I in assignment:\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\) at \w+.+\d.\d+\n\t\twant M\(int\)"
i = T4{} // ERROR "cannot use T4\{\} \(.*type T4\) as type I in assignment:\n\tT4 does not implement I \(M method has pointer receiver\)"
i = new(I) // ERROR "cannot use new\(I\) \(.*type \*I\) as type I in assignment:\n\t\*I does not implement I \(type \*I is pointer to interface, not interface\)"
_ = i.(*T2) // ERROR "impossible type assertion: i.\(\*T2\)\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\)\n\t\twant M\(int\)"
_ = i.(*T3) // ERROR "impossible type assertion: i.\(\*T3\)\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\)\n\t\twant M\(int\)"
_ = i.(*T2) // ERROR "impossible type assertion: i.\(\*T2\)\n\t\*T2 does not implement I \(missing M method\)\n\t\thave m\(int\) at \w+.+\d.\d+\n\t\twant M\(int\)"
_ = i.(*T3) // ERROR "impossible type assertion: i.\(\*T3\)\n\t\*T3 does not implement I \(wrong type for M method\)\n\t\thave M\(string\) at \w+.+\d.\d+\n\t\twant M\(int\)"
var t *T4
t = i // ERROR "cannot use i \(variable of type I\) as type \*T4 in assignment:\n\tneed type assertion"
_ = i
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