gc: remove non-blocking send, receive syntax

R=ken2
CC=golang-dev
https://golang.org/cl/4126043

src/cmd/gc/builtin.c.boot

@@ -66,10 +66,8 @@ char *runtimeimport =
 	"func \"\".mapiter2 (hiter *any) (key any, val any)\n"
 	"func \"\".makechan (elem *uint8, hint int64) chan any\n"
 	"func \"\".chanrecv1 (hchan <-chan any) any\n"
-	"func \"\".chanrecv2 (hchan <-chan any) (elem any, pres bool)\n"
 	"func \"\".chanrecv3 (hchan <-chan any) (elem any, closed bool)\n"
 	"func \"\".chansend1 (hchan chan<- any, elem any)\n"
-	"func \"\".chansend2 (hchan chan<- any, elem any) bool\n"
 	"func \"\".closechan (hchan any)\n"
 	"func \"\".closedchan (hchan any) bool\n"
 	"func \"\".selectnbsend (hchan chan<- any, elem any) bool\n"

src/cmd/gc/go.h

@@ -356,7 +356,7 @@ enum
 	OARRAY,
 	OARRAYBYTESTR, OARRAYRUNESTR,
 	OSTRARRAYBYTE, OSTRARRAYRUNE,
-	OAS, OAS2, OAS2MAPW, OAS2FUNC, OAS2RECV, OAS2RECVCLOSED, OAS2MAPR, OAS2DOTTYPE, OASOP,
+	OAS, OAS2, OAS2MAPW, OAS2FUNC, OAS2RECVCLOSED, OAS2MAPR, OAS2DOTTYPE, OASOP,
 	OBAD,
 	OCALL, OCALLFUNC, OCALLMETH, OCALLINTER,
 	OCAP,
@@ -383,7 +383,7 @@ enum
 	ONOT, OCOM, OPLUS, OMINUS,
 	OOROR,
 	OPANIC, OPRINT, OPRINTN,
-	OSEND, OSENDNB,
+	OSEND,
 	OSLICE, OSLICEARR, OSLICESTR,
 	ORECOVER,
 	ORECV,

src/cmd/gc/go.y

@@ -764,6 +764,7 @@ expr:
 	{
 		$$ = nod(ORSH, $1, $3);
 	}
+	/* not an expression anymore, but left in so we can give a good error */
 |	expr LCOMM expr
 	{
 		$$ = nod(OSEND, $1, $3);

src/cmd/gc/runtime.go

@@ -92,10 +92,8 @@ func mapiter2(hiter *any) (key any, val any)
 // *byte is really *runtime.Type
 func makechan(elem *byte, hint int64) (hchan chan any)
 func chanrecv1(hchan <-chan any) (elem any)
-func chanrecv2(hchan <-chan any) (elem any, pres bool)
 func chanrecv3(hchan <-chan any) (elem any, closed bool)
 func chansend1(hchan chan<- any, elem any)
-func chansend2(hchan chan<- any, elem any) (pres bool)
 func closechan(hchan any)
 func closedchan(hchan any) bool
 

src/cmd/gc/sinit.c

@@ -94,7 +94,6 @@ init1(Node *n, NodeList **out)
 		case OAS2FUNC:
 		case OAS2MAPR:
 		case OAS2DOTTYPE:
-		case OAS2RECV:
 		case OAS2RECVCLOSED:
 			if(n->defn->initorder)
 				break;

src/cmd/gc/typecheck.c

@@ -668,10 +668,7 @@ reswitch:
 		goto ret;
 
 	case OSEND:
-		if(0 && top == Erv) {
-			// can happen because grammar for if header accepts
-			// simple_stmt for condition.  Falling through would give
-			// an error "c <- v used as value" but we can do better.
+		if(top & Erv) {
 			yyerror("send statement %#N used as value; use select for non-blocking send", n);
 			goto error;
 		}
@@ -698,10 +695,6 @@ reswitch:
 		// TODO: more aggressive
 		n->etype = 0;
 		n->type = T;
-		if(top & Erv) {
-			n->op = OSENDNB;
-			n->type = types[TBOOL];
-		}
 		goto ret;
 
 	case OSLICE:
@@ -2383,8 +2376,6 @@ typecheckas2(Node *n)
 			n->op = OAS2MAPR;
 			goto common;
 		case ORECV:
-			n->op = OAS2RECV;
-			goto common;
 			yyerror("cannot use multiple-value assignment for non-blocking receive; use select");
 			goto out;
 		case ODOTTYPE:

src/cmd/gc/walk.c

@@ -403,7 +403,6 @@ walkstmt(Node **np)
 	case OAS:
 	case OAS2:
 	case OAS2DOTTYPE:
-	case OAS2RECV:
 	case OAS2RECVCLOSED:
 	case OAS2FUNC:
 	case OAS2MAPW:
@@ -823,19 +822,6 @@ walkexpr(Node **np, NodeList **init)
 		n = liststmt(concat(concat(list1(r), ll), lpost));
 		goto ret;
 
-	case OAS2RECV:
-		// a,b = <-c
-		*init = concat(*init, n->ninit);
-		n->ninit = nil;
-		r = n->rlist->n;
-		walkexprlistsafe(n->list, init);
-		walkexpr(&r->left, init);
-		fn = chanfn("chanrecv2", 2, r->left->type);
-		r = mkcall1(fn, getoutargx(fn->type), init, r->left);
-		n->rlist->n = r;
-		n->op = OAS2FUNC;
-		goto as2func;
-
 	case OAS2RECVCLOSED:
 		// a = <-c; b = closed(c) but atomic
 		*init = concat(*init, n->ninit);
@@ -1421,10 +1407,6 @@ walkexpr(Node **np, NodeList **init)
 		n = mkcall1(chanfn("chansend1", 2, n->left->type), T, init, n->left, n->right);
 		goto ret;
 
-	case OSENDNB:
-		n = mkcall1(chanfn("chansend2", 2, n->left->type), n->type, init, n->left, n->right);
-		goto ret;
-
 	case OCLOSURE:
 		n = walkclosure(n, init);
 		goto ret;

src/pkg/runtime/chan.c

@@ -402,25 +402,6 @@ runtime·chansend1(Hchan* c, ...)
 	runtime·chansend(c, ae, nil);
 }
 
-// chansend2(hchan *chan any, elem any) (pres bool);
-#pragma textflag 7
-void
-runtime·chansend2(Hchan* c, ...)
-{
-	int32 o;
-	byte *ae, *ap;
-
-	if(c == nil)
-		runtime·panicstring("send to nil channel");
-
-	o = runtime·rnd(sizeof(c), c->elemalign);
-	ae = (byte*)&c + o;
-	o = runtime·rnd(o+c->elemsize, Structrnd);
-	ap = (byte*)&c + o;
-
-	runtime·chansend(c, ae, ap);
-}
-
 // chanrecv1(hchan *chan any) (elem any);
 #pragma textflag 7
 void
@@ -435,28 +416,6 @@ runtime·chanrecv1(Hchan* c, ...)
 	runtime·chanrecv(c, ae, nil, nil);
 }
 
-// chanrecv2(hchan *chan any) (elem any, pres bool);
-#pragma textflag 7
-void
-runtime·chanrecv2(Hchan* c, ...)
-{
-	int32 o;
-	byte *ae, *ap;
-
-	if(c == nil)
-		runtime·panicstring("receive from nil channel");
-
-	o = runtime·rnd(sizeof(c), Structrnd);
-	ae = (byte*)&c + o;
-	o = runtime·rnd(o+c->elemsize, 1);
-	ap = (byte*)&c + o;
-
-	runtime·chanrecv(c, ae, ap, nil);
-	
-	if(!*ap)
-		c->elemalg->copy(c->elemsize, ae, nil);
-}
-
 // chanrecv3(hchan *chan any) (elem any, closed bool);
 #pragma textflag 7
 void

test/syntax/chan1.go

@@ -0,0 +1,17 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2010 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 main
+
+var c chan int
+var v int
+
+func main() {
+	if c <- v { // ERROR "send statement.*value.*select"
+	}
+}
+
+var _ = c <- v // ERROR "send statement.*value.*select"