cmd/compile: use "method T.m already declared" for method redeclaration errors

Compromise between old compiler error "T.m redeclared in this block"
(where the "in this block" is not particularly helpful) and the old
type-checker error "method m already declared for type T ...".
In the case where we have position information for the original
declaration, the error message is "method T.m already declared at
<position>". The new message is both shorter and more precise.

For #55326.

Change-Id: Id4a7f326fe631b11db9e8030eccb417c72d6c7db
Reviewed-on: https://go-review.googlesource.com/c/go/+/435016
Run-TryBot: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index f9d1431b82115f1b956b4558eac4207da87b94e1..ebce3ee2e250125826bee6d037fdd30271449db3 100644 (file)
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -675,15 +675,11 @@ func (check *Checker) collectMethods(obj *TypeName) {
                // to it must be unique."
                assert(m.name != "_")
                if alt := mset.insert(m); alt != nil {
-                       var err error_
-                       err.code = _DuplicateMethod
-                       if check.conf.CompilerErrorMessages {
-                               err.errorf(m.pos, "%s.%s redeclared in this block", obj.Name(), m.name)
+                       if alt.Pos().IsKnown() {
+                               check.errorf(m.pos, _DuplicateMethod, "method %s.%s already declared at %s", obj.Name(), m.name, alt.Pos())
                        } else {
-                               err.errorf(m.pos, "method %s already declared for %s", m.name, obj)
+                               check.errorf(m.pos, _DuplicateMethod, "method %s.%s already declared", obj.Name(), m.name)
                        }
-                       err.recordAltDecl(alt)
-                       check.report(&err)
                        continue
                }
 

diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index a370c5c64685ff14599717bf084ce88e9d162a12..87d4f3fdf4381fa7bd3866ce94803ab302a76ec9 100644 (file)
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -749,8 +749,11 @@ func (check *Checker) collectMethods(obj *TypeName) {
                // to it must be unique."
                assert(m.name != "_")
                if alt := mset.insert(m); alt != nil {
-                       check.errorf(m, _DuplicateMethod, "method %s already declared for %s", m.name, obj)
-                       check.reportAltDecl(alt)
+                       if alt.Pos().IsValid() {
+                               check.errorf(m, _DuplicateMethod, "method %s.%s already declared at %s", obj.Name(), m.name, alt.Pos())
+                       } else {
+                               check.errorf(m, _DuplicateMethod, "method %s.%s already declared", obj.Name(), m.name)
+                       }
                        continue
                }
 

diff --git a/test/alias2.go b/test/alias2.go
index 61c7551f79903223e61547a43c9f0f4366b54079..d7101420bdcafd2a054817ec017cecd59b343e94 100644 (file)
--- a/test/alias2.go
+++ b/test/alias2.go
@@ -36,9 +36,9 @@ type (
 
 // Methods can be declared on the original named type and the alias.
 func (T0) m1()  {} // GCCGO_ERROR "previous"
-func (*T0) m1() {} // ERROR "method redeclared: T0\.m1|T0\.m1 redeclared in this block|redefinition of .m1."
-func (A0) m1()  {} // ERROR "T0\.m1 redeclared in this block|redefinition of .m1."
-func (A0) m1()  {} // ERROR "T0\.m1 redeclared in this block|redefinition of .m1."
+func (*T0) m1() {} // ERROR "method redeclared: T0\.m1|T0\.m1 already declared|redefinition of .m1."
+func (A0) m1()  {} // ERROR "T0\.m1 already declared|redefinition of .m1."
+func (A0) m1()  {} // ERROR "T0\.m1 already declared|redefinition of .m1."
 func (A0) m2()  {}
 
 // Type aliases and the original type name can be used interchangeably.

diff --git a/test/fixedbugs/bug350.go b/test/fixedbugs/bug350.go
index 39f91d43a93e7e764b29a6fa15f581e93ebbd53d..0a8401770274b3498b3d7a19cd1e6c191d90954f 100644 (file)
--- a/test/fixedbugs/bug350.go
+++ b/test/fixedbugs/bug350.go
@@ -9,7 +9,7 @@ package main
 type T int
 
 func (T) m() {} // GCCGO_ERROR "previous"
-func (T) m() {} // ERROR "T[.]m redeclared|redefinition"
+func (T) m() {} // ERROR "T\.m already declared|redefinition"
 
 func (*T) p() {} // GCCGO_ERROR "previous"
-func (*T) p() {} // ERROR "[(][*]T[)][.]p redeclared|redefinition|redeclared"
+func (*T) p() {} // ERROR "T\.p already declared|redefinition"

diff --git a/test/fixedbugs/issue18655.go b/test/fixedbugs/issue18655.go
index 13762f1a94b9e666d1fc66dade33d244d856f2c2..f34e5a9aeba05746ab60e09c70e6560229c5f24f 100644 (file)
--- a/test/fixedbugs/issue18655.go
+++ b/test/fixedbugs/issue18655.go
@@ -11,12 +11,12 @@ type A = T
 type B = T
 
 func (T) m() {}
-func (T) m() {} // ERROR "redeclared|redefinition"
-func (A) m() {} // ERROR "redeclared|redefinition"
-func (A) m() {} // ERROR "redeclared|redefinition"
-func (B) m() {} // ERROR "redeclared|redefinition"
-func (B) m() {} // ERROR "redeclared|redefinition"
+func (T) m() {} // ERROR "already declared|redefinition"
+func (A) m() {} // ERROR "already declared|redefinition"
+func (A) m() {} // ERROR "already declared|redefinition"
+func (B) m() {} // ERROR "already declared|redefinition"
+func (B) m() {} // ERROR "already declared|redefinition"
 
-func (*T) m() {} // ERROR "redeclared|redefinition"
-func (*A) m() {} // ERROR "redeclared|redefinition"
-func (*B) m() {} // ERROR "redeclared|redefinition"
+func (*T) m() {} // ERROR "already declared|redefinition"
+func (*A) m() {} // ERROR "already declared|redefinition"
+func (*B) m() {} // ERROR "already declared|redefinition"

diff --git a/test/method1.go b/test/method1.go
index bb8c81d7461865d6107f9d1556e8b4d4325b2861..badfa55a7e203f456f83420a6bc9c23435310d8b 100644 (file)
--- a/test/method1.go
+++ b/test/method1.go
@@ -12,10 +12,10 @@ package main
 type T struct{}
 
 func (t *T) M(int, string)  // GCCGO_ERROR "previous"
-func (t *T) M(int, float64) {} // ERROR "redeclared|redefinition"
+func (t *T) M(int, float64) {} // ERROR "already declared|redefinition"
 
 func (t T) H()  // GCCGO_ERROR "previous"
-func (t *T) H() {} // ERROR "redeclared|redefinition"
+func (t *T) H() {} // ERROR "already declared|redefinition"
 
 func f(int, string)  // GCCGO_ERROR "previous"
 func f(int, float64) {} // ERROR "redeclared|redefinition"