From: Russ Cox <rsc@golang.org>
Date: Wed, 23 Dec 2009 21:48:44 +0000 (-0800)
Subject: go_spec: use PrimaryExpr as type switch expression
X-Git-Tag: weekly.2010-01-05~41
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=c1045db1d891ffe9492d57672d64076b869d6027;p=gostls13.git

go_spec: use PrimaryExpr as type switch expression

Without this change, the spec parses <-c.(type) as (<-c).(type)
but parses <-c.(int) as <-(c.(int)).

With this change, the former parses as <-(c.(type)).

All three parsers already implement this rule, because
they look for the "type" word during parsing of a standard
type assertion.  This change merely brings the
spec in line with the implementations.

http://code.google.com/p/go/source/browse/src/cmd/gc/go.y#801
http://code.google.com/p/go/source/browse/src/pkg/go/parser/parser.go#900
http://gcc.gnu.org/viewcvs/branches/gccgo/gcc/go/parse.cc?revision=155389&view=markup#l2469

Pointed out by Brett Kail on golang-nuts.

R=gri
CC=golang-dev
https://golang.org/cl/182044
---

diff --git a/doc/go_spec.html b/doc/go_spec.html
index 5aed74e00a..ed740187b9 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -3611,7 +3611,7 @@ in the type assertion.
 
 <pre class="ebnf">
 TypeSwitchStmt  = "switch" [ SimpleStmt ";" ] TypeSwitchGuard "{" { TypeCaseClause } "}" .
-TypeSwitchGuard = [ identifier ":=" ] Expression "." "(" "type" ")" .
+TypeSwitchGuard = [ identifier ":=" ] PrimaryExpr "." "(" "type" ")" .
 TypeCaseClause  = TypeSwitchCase ":" { Statement ";" } .
 TypeSwitchCase  = "case" TypeList | "default" .
 TypeList        = Type { "," Type } .