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 5aed74e00aeb26bd6f858346ce7e32679b36e21b..ed740187b9164abbf8ca1279a4fc579c5563c6d0 100644 (file)
--- 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 } .