[dev.typeparams] cmd/compile/internal/types2: must not import a packa…

…ge called "init"

Updates #43962.

Change-Id: I070153c55baec62d13ca9284f02781b8c1276844
Reviewed-on: https://go-review.googlesource.com/c/go/+/287494
Trust: Robert Griesemer <[email protected]>
Run-TryBot: Robert Griesemer <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

src/cmd/compile/internal/types2/resolver.go

@@ -250,14 +250,6 @@ func (check *Checker) collectObjects() {
  continue
  }
 
- // add package to list of explicit imports
- // (this functionality is provided as a convenience
- // for clients; it is not needed for type-checking)
- if !pkgImports[imp] {
- pkgImports[imp] = true
- pkg.imports = append(pkg.imports, imp)
- }
-
  // local name overrides imported package name
  name := imp.name
  if s.LocalPkgName != nil {
@@ -267,10 +259,19 @@ func (check *Checker) collectObjects() {
  check.errorf(s.LocalPkgName, `cannot rename import "C"`)
  continue
  }
- if name == "init" {
- check.errorf(s.LocalPkgName, "cannot declare init - must be func")
- continue
- }
+ }
+
+ if name == "init" {
+ check.errorf(s.LocalPkgName, "cannot import package as init - init must be a func")
+ continue
+ }
+
+ // add package to list of explicit imports
+ // (this functionality is provided as a convenience
+ // for clients; it is not needed for type-checking)
+ if !pkgImports[imp] {
+ pkgImports[imp] = true
+ pkg.imports = append(pkg.imports, imp)
  }
 
  pkgName := NewPkgName(s.Pos(), pkg, name, imp)

src/cmd/compile/internal/types2/testdata/importdecl0/importdecl0a.src

@@ -10,7 +10,7 @@ import (
  // we can have multiple blank imports (was bug)
  _ "math"
  _ "net/rpc"
- init /* ERROR "cannot declare init" */ "fmt"
+ init /* ERROR "cannot import package as init" */ "fmt"
  // reflect defines a type "flag" which shows up in the gc export data
  "reflect"
  . /* ERROR "imported but not used" */ "reflect"

test/fixedbugs/issue43962.dir/a.go

@@ -0,0 +1,5 @@
+// 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 init

test/fixedbugs/issue43962.dir/b.go

@@ -0,0 +1,7 @@
+// 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 b
+
+import "./a" // ERROR "cannot import package as init"

test/fixedbugs/issue43962.go

@@ -0,0 +1,9 @@
+// errorcheckdir
+
+// 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.
+
+// Issue 43962: Importing a package called "init" is an error.
+
+package ignored