Commit 1b0cf430 authored by Robert Griesemer's avatar Robert Griesemer

cmd/compile: implement package-level aliases (no export yet)

Requires -newparser=1.

For #17487.
For #16339.

Change-Id: I156fb0c0f8a97e8c72dbbfbd7fe821efee12b957
Reviewed-on: https://go-review.googlesource.com/31597Reviewed-by: default avatarMatthew Dempsky <mdempsky@google.com>
parent 7e9f420d
......@@ -943,6 +943,8 @@ func mkpackage(pkgname string) {
s.Def.Name.Pack.Used = true
}
// TODO(gri) This will also affect exported aliases.
// Need to fix this.
s.Def = nil
continue
}
......
......@@ -61,7 +61,7 @@ func (p *noder) decls(decls []syntax.Decl) (l []*Node) {
p.importDecl(decl)
case *syntax.AliasDecl:
yyerror("alias declarations not yet implemented")
p.aliasDecl(decl)
case *syntax.VarDecl:
l = append(l, p.varDecl(decl)...)
......@@ -90,8 +90,9 @@ func (p *noder) decls(decls []syntax.Decl) (l []*Node) {
lastConstGroup = decl.Group
case *syntax.TypeDecl:
// TODO(gri) remove this notation - we're not going to use it after all
if decl.Alias {
yyerror("alias declarations not yet implemented")
yyerror("type aliases using = not supported")
break
}
l = append(l, p.typeDecl(decl))
......@@ -153,6 +154,92 @@ func (p *noder) importDecl(imp *syntax.ImportDecl) {
my.Block = 1 // at top level
}
func (p *noder) aliasDecl(decl *syntax.AliasDecl) {
// Because alias declarations must refer to imported entities
// which are already set up, we can do all checks right here.
// We won't know anything about entities that have not been
// declared yet, but since they cannot have been imported, we
// know there's an error and we don't care about the details.
// The original entity must be denoted by a qualified identifier.
// (The parser doesn't make this restriction to be more error-
// tolerant.)
qident, ok := decl.Orig.(*syntax.SelectorExpr)
if !ok {
// TODO(gri) This prints a dot-imported object with qualification
// (confusing error). Fix this.
yyerror("invalid alias: %v is not a package-qualified identifier", p.expr(decl.Orig))
return
}
pkg := p.expr(qident.X)
if pkg.Op != OPACK {
yyerror("invalid alias: %v is not a package", pkg)
return
}
pkg.Used = true
orig := oldname(restrictlookup(qident.Sel.Value, pkg.Name.Pkg))
// An alias declaration must not refer to package unsafe.
if orig.Sym.Pkg == unsafepkg {
yyerror("invalid alias: %v refers to package unsafe (%v)", decl.Name.Value, orig)
return
}
// The aliased entity must be from a matching constant, type, variable,
// or function declaration, respectively.
var what string
switch decl.Tok {
case syntax.Const:
if orig.Op != OLITERAL {
what = "constant"
}
case syntax.Type:
if orig.Op != OTYPE {
what = "type"
}
case syntax.Var:
if orig.Op != ONAME || orig.Class != PEXTERN {
what = "variable"
}
case syntax.Func:
if orig.Op != ONAME || orig.Class != PFUNC {
what = "function"
}
default:
Fatalf("unexpected token: %s", decl.Tok)
}
if what != "" {
yyerror("invalid alias: %v is not a %s", orig, what)
return
}
// don't declare blank aliases
if decl.Name.Value == "_" {
return
}
// declare alias
// (this is similar to handling dot imports)
asym := p.name(decl.Name)
if asym.Def != nil {
redeclare(asym, "in alias declaration")
return
}
asym.Def = orig
asym.Block = block
asym.Lastlineno = lineno
if exportname(asym.Name) {
yyerror("cannot export alias %v: not yet implemented", asym)
// TODO(gri) newname(asym) is only needed to satisfy exportsym
// (and indirectly, exportlist). We should be able to just
// collect the Syms, eventually.
// exportsym(newname(asym))
}
}
func (p *noder) varDecl(decl *syntax.VarDecl) []*Node {
names := p.declNames(decl.NameList)
......
......@@ -140,6 +140,7 @@ func TestStdTest(t *testing.T) {
}
testTestDir(t, filepath.Join(runtime.GOROOT(), "test"),
"alias2.go", // excluded until we can handle alias declarations
"cmplxdivide.go", // also needs file cmplxdivide1.go - ignore
"sigchld.go", // don't work on Windows; testTestDir should consult build tags
)
......
// errorcheck -newparser=1
// Copyright 2016 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.
// Test basic restrictions on alias declarations.
package p
import (
"fmt" // use at most once (to test "imported but not used" error)
"go/build"
. "go/build"
"io"
"math"
"unsafe"
)
// helper
var before struct {
f
}
// aliases must refer to package-qualified identifiers
// TODO(gri) should only see one error for declaration below - fix this
const _ => 0 // ERROR "unexpected literal 0|_ is not a package-qualified identifier"
type _ => _ // ERROR "_ is not a package-qualified identifier"
type t => _ // ERROR "_ is not a package-qualified identifier"
const _ => iota // ERROR "iota is not a package-qualified identifier"
type _ => int // ERROR "int is not a package-qualified identifier"
const c => iota // ERROR "iota is not a package-qualified identifier"
type t => int // ERROR "int is not a package-qualified identifier"
// dot-imported identifiers are not qualified identifiers
// TODO(gri) fix error printing - should not print a qualified identifier...
var _ => Default // ERROR "build\.Default is not a package-qualified identifier"
// qualified identifiers must start with a package
var _ => before.f // ERROR "before is not a package"
func _ => before.f // ERROR "before is not a package"
var _ => after.m // ERROR "after is not a package"
func _ => after.m // ERROR "after is not a package"
var v => before.f // ERROR "before is not a package"
func f => before.f // ERROR "before is not a package"
var v => after.m // ERROR "after is not a package"
func f => after.m // ERROR "after is not a package"
// TODO(gri) fix error printing - should not print a qualified identifier...
var _ => Default.ARCH // ERROR "build.Default is not a package"
// aliases may not refer to package unsafe
type ptr => unsafe.Pointer // ERROR "ptr refers to package unsafe"
func size => unsafe.Sizeof // ERROR "size refers to package unsafe"
// aliases must refer to entities of the same kind
const _ => math.Pi
const pi => math.Pi
const pi1 => math.Sin // ERROR "math.Sin is not a constant"
type _ => io.Writer
type writer => io.Writer
type writer1 => math.Sin // ERROR "math.Sin is not a type"
var _ => build.Default
var def => build.Default
var def1 => build.Import // ERROR "build.Import is not a variable"
func _ => math.Sin
func sin => math.Sin
func sin1 => math.Pi // ERROR "math.Pi is not a function"
// alias reference to a package marks package as used
func _ => fmt.Println
// TODO(gri) aliased cannot be exported yet - fix this
const Pi => math.Pi // ERROR "cannot export alias Pi"
type Writer => io.Writer // ERROR "cannot export alias Writer"
var Def => build.Default // ERROR "cannot export alias Def"
func Sin => math.Sin // ERROR "cannot export alias Sin"
// type aliases denote identical types
type myPackage => build.Package
var pkg myPackage
var _ build.Package = pkg // valid assignment
var _ *build.Package = &pkg // valid assignment
// helper
type after struct{}
func (after) m() {}
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment