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go/types: improve errors for method calls with pointer receivers

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The compiler has better error messages for methods called without a
pointer receiver when one is expected. This change is similar to
CL 229801, but for method calls.

Also, added better error messages for functions called with the wrong
capitalization. I left the third TODO in this switch statement almost
as-is because I'm not sure that the extra complexity is worth it -
I adjusted the error to look like the one the compiler reports.

Fixes golang/go#38658

Change-Id: Ie0ca2503e12f3659f112f0135cc27db1b027fdcb
Reviewed-on: https://go-review.googlesource.com/c/go/+/230380
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Rebecca Stambler 2020-04-27 19:41:14 -04:00
parent 7be3f09deb
commit 5c22c01d45
7 changed files with 44 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
src/go/types/call.go
View File

@ -9,6 +9,7 @@ package types
import (
"go/ast"
"go/token"
"unicode"
)
func (check *Checker) call(x *operand, e *ast.CallExpr) exprKind {
@ -375,12 +376,24 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
switch {
case index != nil:
// TODO(gri) should provide actual type where the conflict happens
check.errorf(e.Sel.Pos(), "ambiguous selector %s", sel)
check.errorf(e.Sel.Pos(), "ambiguous selector %s.%s", x.expr, sel)
case indirect:
// TODO(gri) be more specific with this error message
check.errorf(e.Sel.Pos(), "%s is not in method set of %s", sel, x.typ)
check.errorf(e.Sel.Pos(), "cannot call pointer method %s on %s", sel, x.typ)
default:
// TODO(gri) should check if capitalization of sel matters and provide better error message in that case
// Check if capitalization of sel matters and provide better error
// message in that case.
if len(sel) > 0 {
var changeCase string
if r := rune(sel[0]); unicode.IsUpper(r) {
changeCase = string(unicode.ToLower(r)) + sel[1:]
} else {
changeCase = string(unicode.ToUpper(r)) + sel[1:]
}
if obj, _, _ = check.lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, changeCase); obj != nil {
check.errorf(e.Sel.Pos(), "%s.%s undefined (type %s has no field or method %s, but does have %s)", x.expr, sel, x.typ, sel, changeCase)
break
}
}
check.errorf(e.Sel.Pos(), "%s.%s undefined (type %s has no field or method %s)", x.expr, sel, x.typ, sel)
}
goto Error

18
src/go/types/testdata/decls3.src vendored
View File

@ -19,7 +19,7 @@ func _() {
)
var t T3
_ = t.X /* ERROR "ambiguous selector" */
_ = t.X /* ERROR "ambiguous selector t.X" */
}
func _() {
@ -31,7 +31,7 @@ func _() {
)
var t T4
_ = t.X /* ERROR "ambiguous selector" */
_ = t.X /* ERROR "ambiguous selector t.X" */
}
func issue4355() {
@ -44,7 +44,7 @@ func issue4355() {
)
var t T5
_ = t.X /* ERROR "ambiguous selector" */
_ = t.X /* ERROR "ambiguous selector t.X" */
}
func _() {
@ -54,7 +54,7 @@ func _() {
type T struct{ A; B }
var t T
_ = t.State /* ERROR "ambiguous selector" */
_ = t.State /* ERROR "ambiguous selector t.State" */
}
// Embedded fields can be predeclared types.
@ -221,16 +221,16 @@ func _() {
_ = S2{}.B
_ = S2{}.C
_ = S2{}.D /* ERROR "no field or method" */
_ = S3{}.S1 /* ERROR "ambiguous selector" */
_ = S3{}.S1 /* ERROR "ambiguous selector \(S3 literal\).S1" */
_ = S3{}.A
_ = S3{}.B /* ERROR "ambiguous selector" */
_ = S3{}.B /* ERROR "ambiguous selector" \(S3 literal\).B */
_ = S3{}.D
_ = S3{}.E
_ = S4{}.A
_ = S4{}.B /* ERROR "no field or method" */
_ = S5{}.X /* ERROR "ambiguous selector" */
_ = S5{}.X /* ERROR "ambiguous selector \(S5 literal\).X" */
_ = S5{}.Y
_ = S10{}.X /* ERROR "ambiguous selector" */
_ = S10{}.X /* ERROR "ambiguous selector \(S10 literal\).X" */
_ = S10{}.Y
}
@ -306,4 +306,4 @@ type R22 R21
type R23 R21
type R24 R21
var _ = R0{}.X /* ERROR "ambiguous selector" */
var _ = R0{}.X /* ERROR "ambiguous selector \(R0 literal\).X" */

4
src/go/types/testdata/decls4.src vendored
View File

@ -190,8 +190,8 @@ type eD struct {
}
var (
_ = eD{}.xf /* ERROR ambiguous selector */
_ = eD{}.xm /* ERROR ambiguous selector */
_ = eD{}.xf /* ERROR ambiguous selector \(eD literal\).xf */
_ = eD{}.xm /* ERROR ambiguous selector \(eD literal\).xm */
)
var (

4
src/go/types/testdata/expr3.src vendored
View File

@ -155,10 +155,10 @@ func (*T) m() {}
func method_expressions() {
_ = T.a /* ERROR "no field or method" */
_ = T.x /* ERROR "has no method" */
_ = T.m /* ERROR "not in method set" */
_ = T.m /* ERROR "cannot call pointer method m on T" */
_ = (*T).m
var f func(*T) = T.m /* ERROR "not in method set" */
var f func(*T) = T.m /* ERROR "cannot call pointer method m on T" */
var g func(*T) = (*T).m
_, _ = f, g

4
src/go/types/testdata/issue28251.src vendored
View File

@ -41,7 +41,7 @@ type (
)
func (T4) m4() {}
func _() { (T{}).m4 /* ERROR m4 is not in method set of T */ () }
func _() { (T{}).m4 /* ERROR "cannot call pointer method m4 on T" */ () }
func _() { (&T{}).m4() }
type (
@ -51,7 +51,7 @@ type (
)
func (T6) m6() {}
func _() { (T{}).m6 /* ERROR m6 is not in method set of T */ () }
func _() { (T{}).m6 /* ERROR "cannot call pointer method m6 on T" */ () }
func _() { (&T{}).m6() }
type (

8
src/go/types/testdata/issues.src vendored
View File

@ -130,9 +130,13 @@ func issue10260() {
t2 *T2
)
var x I1 = T1 /* ERROR cannot use .*: missing method foo \(foo has pointer receiver\) */ {}
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)
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)
i1 = i0 /* ERROR cannot use .* missing method foo */
@ -341,7 +345,7 @@ type E1 struct{ f int }
type E2 struct{ f int }
func issue26234b(x T) {
_ = x.f /* ERROR ambiguous selector f */
_ = x.f /* ERROR ambiguous selector x.f */
}
func issue26234c() {

12
src/go/types/testdata/methodsets.src vendored
View File

@ -29,7 +29,7 @@ type T3 struct {
func _() {
var (
_ func(T0) = T0.v0
_ = T0.p0 /* ERROR "not in method set" */
_ = T0.p0 /* ERROR "cannot call pointer method p0 on T0" */
_ func (*T0) = (*T0).v0
_ func (*T0) = (*T0).p0
@ -40,7 +40,7 @@ func _() {
_ func(T2) = T2.p2
_ func(T3) = T3.v0
_ func(T3) = T3.p0 /* ERROR "not in method set" */
_ func(T3) = T3.p0 /* ERROR "cannot call pointer method p0 on T3" */
_ func(T3) = T3.v1
_ func(T3) = T3.p1
_ func(T3) = T3.v2
@ -135,7 +135,7 @@ func _() {
func _() {
var (
_ func() = T0{}.v0
_ func() = T0{}.p0 /* ERROR "not in method set" */
_ func() = T0{}.p0 /* ERROR "cannot call pointer method p0 on T0" */
_ func() = (&T0{}).v0
_ func() = (&T0{}).p0
@ -145,7 +145,7 @@ func _() {
// no values for T2
_ func() = T3{}.v0
_ func() = T3{}.p0 /* ERROR "not in method set" */
_ func() = T3{}.p0 /* ERROR "cannot call pointer method p0 on T3" */
_ func() = T3{}.v1
_ func() = T3{}.p1
_ func() = T3{}.v2
@ -163,7 +163,7 @@ func _() {
// Method calls with value receivers
func _() {
T0{}.v0()
T0{}.p0 /* ERROR "not in method set" */ ()
T0{}.p0 /* ERROR "cannot call pointer method p0 on T0" */ ()
(&T0{}).v0()
(&T0{}).p0()
@ -173,7 +173,7 @@ func _() {
// no values for T2
T3{}.v0()
T3{}.p0 /* ERROR "not in method set" */ ()
T3{}.p0 /* ERROR "cannot call pointer method p0 on T3" */ ()
T3{}.v1()
T3{}.p1()
T3{}.v2()