cmd/compile: simplify parsing of type aliases

Change-Id: Ia86841cf84bc17ff6ecc6e5ac4cec86384a0da00
Reviewed-on: https://go-review.googlesource.com/31719
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/cmd/compile/internal/gc/noder.go b/src/cmd/compile/internal/gc/noder.go
index 59a8d1f0d2b69df1818659c6b024ce0b275c8ac4..6dc082410fbf61006ab3398ecead69baf510a7fc 100644 (file)
--- a/src/cmd/compile/internal/gc/noder.go
+++ b/src/cmd/compile/internal/gc/noder.go
@@ -90,11 +90,6 @@ 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("type aliases using = not supported")
-                               break
-                       }
                        l = append(l, p.typeDecl(decl))
 
                case *syntax.FuncDecl:

diff --git a/src/cmd/compile/internal/syntax/nodes.go b/src/cmd/compile/internal/syntax/nodes.go
index 792b207ef1dabe1e9f66dd5a6cea6350c4e8198f..b88d16e113ad00ab6ab2d24ed1c404624c24348d 100644 (file)
--- a/src/cmd/compile/internal/syntax/nodes.go
+++ b/src/cmd/compile/internal/syntax/nodes.go
@@ -89,7 +89,6 @@ type (
        TypeDecl struct {
                Name   *Name
                Type   Expr
-               Alias  bool
                Group  *Group // nil means not part of a group
                Pragma Pragma
                decl

diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index 1eb85fb7eebe77c2348eaf68071934e074640a1f..d0dec3ab1b6e9165345f0837c063351165211ff7 100644 (file)
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -322,7 +322,8 @@ func (p *parser) aliasDecl(tok token, name *Name, group *Group) Decl {
        d := new(AliasDecl)
        d.initFrom(&name.node)
 
-       p.want(_Rarrow)
+       // lhs identifier and "=>" have been consumed already
+
        d.Tok = tok
        d.Name = name
        d.Orig = p.dotname(p.name())
@@ -338,7 +339,7 @@ func (p *parser) constDecl(group *Group) Decl {
        }
 
        name := p.name()
-       if p.tok == _Rarrow {
+       if p.got(_Rarrow) {
                return p.aliasDecl(Const, name, group)
        }
 
@@ -364,7 +365,8 @@ func (p *parser) typeDecl(group *Group) Decl {
        }
 
        name := p.name()
-       if p.tok == _Rarrow {
+       // permit both: type T => p.T and: type T = p.T for now
+       if p.got(_Rarrow) || p.got(_Assign) {
                return p.aliasDecl(Type, name, group)
        }
 
@@ -372,9 +374,6 @@ func (p *parser) typeDecl(group *Group) Decl {
        d.initFrom(&name.node)
 
        d.Name = name
-       // accept "type T = p.T" for now so we can experiment
-       // with a type-alias only approach as well
-       d.Alias = p.got(_Assign)
        d.Type = p.tryType()
        if d.Type == nil {
                p.syntax_error("in type declaration")
@@ -393,7 +392,7 @@ func (p *parser) varDecl(group *Group) Decl {
        }
 
        name := p.name()
-       if p.tok == _Rarrow {
+       if p.got(_Rarrow) {
                return p.aliasDecl(Var, name, group)
        }
 
@@ -449,7 +448,7 @@ func (p *parser) funcDecl() Decl {
        }
 
        name := p.name()
-       if recv == nil && p.tok == _Rarrow {
+       if recv == nil && p.got(_Rarrow) {
                return p.aliasDecl(Func, name, nil)
        }
 

diff --git a/src/cmd/compile/internal/syntax/printer.go b/src/cmd/compile/internal/syntax/printer.go
index de2afe0499c442ea408c523a2dfc8355ab2bae68..8f127073048956ea408a9ae52082db682ad17d2e 100644 (file)
--- a/src/cmd/compile/internal/syntax/printer.go
+++ b/src/cmd/compile/internal/syntax/printer.go
@@ -625,11 +625,7 @@ func (p *printer) printRawNode(n Node) {
                if n.Group == nil {
                        p.print(_Type, blank)
                }
-               p.print(n.Name, blank)
-               if n.Alias {
-                       p.print(_Assign, blank)
-               }
-               p.print(n.Type)
+               p.print(n.Name, blank, n.Type)
 
        case *VarDecl:
                if n.Group == nil {