From f4d3d22a942bb1553f648474c80434e10389a423 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 21 May 2009 17:32:44 -0700
Subject: [PATCH] enforce channel direction

R=ken
OCL=29209
CL=29216
---
 src/cmd/gc/builtin.c.boot | 18 +++++++-------
 src/cmd/gc/go.h           |  6 ++---
 src/cmd/gc/subr.c         |  7 ++++++
 src/cmd/gc/sys.go         | 18 +++++++-------
 src/cmd/gc/walk.c         | 51 ++++++++++++++++++++++++++++++---------
 5 files changed, 68 insertions(+), 32 deletions(-)

diff --git a/src/cmd/gc/builtin.c.boot b/src/cmd/gc/builtin.c.boot
index 38c8b4cb5e3..aa51b97b535 100644
--- a/src/cmd/gc/builtin.c.boot
+++ b/src/cmd/gc/builtin.c.boot
@@ -48,16 +48,16 @@ char *sysimport =
 	"func sys.mapiter1 (hiter *any) (key any)\n"
 	"func sys.mapiter2 (hiter *any) (key any, val any)\n"
 	"func sys.newchan (elemsize int, elemalg int, hint int) (hchan chan any)\n"
-	"func sys.chanrecv1 (hchan chan any) (elem any)\n"
-	"func sys.chanrecv2 (hchan chan any) (elem any, pres bool)\n"
-	"func sys.chanrecv3 (hchan chan any, elem *any) (pres bool)\n"
-	"func sys.chansend1 (hchan chan any, elem any)\n"
-	"func sys.chansend2 (hchan chan any, elem any) (pres bool)\n"
-	"func sys.closechan (hchan chan any)\n"
-	"func sys.closedchan (hchan chan any) (? bool)\n"
+	"func sys.chanrecv1 (hchan <-chan any) (elem any)\n"
+	"func sys.chanrecv2 (hchan <-chan any) (elem any, pres bool)\n"
+	"func sys.chanrecv3 (hchan <-chan any, elem *any) (pres bool)\n"
+	"func sys.chansend1 (hchan chan<- any, elem any)\n"
+	"func sys.chansend2 (hchan chan<- any, elem any) (pres bool)\n"
+	"func sys.closechan (hchan any)\n"
+	"func sys.closedchan (hchan any) (? bool)\n"
 	"func sys.newselect (size int) (sel *uint8)\n"
-	"func sys.selectsend (sel *uint8, hchan chan any, elem any) (selected bool)\n"
-	"func sys.selectrecv (sel *uint8, hchan chan any, elem *any) (selected bool)\n"
+	"func sys.selectsend (sel *uint8, hchan chan<- any, elem any) (selected bool)\n"
+	"func sys.selectrecv (sel *uint8, hchan <-chan any, elem *any) (selected bool)\n"
 	"func sys.selectdefault (sel *uint8) (selected bool)\n"
 	"func sys.selectgo (sel *uint8)\n"
 	"func sys.newarray (nel int, cap int, width int) (ary []any)\n"
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 4d4ff3ef30d..71aa57190bf 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -390,9 +390,9 @@ enum
 {
 	/* types of channel */
 	Cxxx,
-	Cboth,
-	Crecv,
-	Csend,
+	Crecv = 1<<0,
+	Csend = 1<<1,
+	Cboth = Crecv | Csend,
 };
 
 enum
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 38226a25c5d..3afaa5ba29e 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -1067,6 +1067,8 @@ Tpretty(Fmt *fp, Type *t)
 		case Crecv:
 			return fmtprint(fp, "<-chan %T", t->type);
 		case Csend:
+			if(t->type != T && t->type->etype == TCHAN)
+				return fmtprint(fp, "chan<- (%T)", t->type);
 			return fmtprint(fp, "chan<- %T", t->type);
 		}
 		return fmtprint(fp, "chan %T", t->type);
@@ -1704,6 +1706,11 @@ eqtype1(Type *t1, Type *t2, int d, int names)
 		if(t1->bound == t2->bound)
 			break;
 		return 0;
+
+	case TCHAN:
+		if(t1->chan == t2->chan)
+			break;
+		return 0;
 	}
 	return eqtype1(t1->type, t2->type, d+1, names);
 }
diff --git a/src/cmd/gc/sys.go b/src/cmd/gc/sys.go
index b5a6ddc2bb2..c3c715b7eaa 100644
--- a/src/cmd/gc/sys.go
+++ b/src/cmd/gc/sys.go
@@ -62,17 +62,17 @@ func	mapiter1(hiter *any) (key any);
 func	mapiter2(hiter *any) (key any, val any);
 
 func	newchan(elemsize int, elemalg int, hint int) (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) (pres bool);
-func	chansend1(hchan chan any, elem any);
-func	chansend2(hchan chan any, elem any) (pres bool);
-func	closechan(hchan chan any);
-func	closedchan(hchan chan any) bool;
+func	chanrecv1(hchan <-chan any) (elem any);
+func	chanrecv2(hchan <-chan any) (elem any, pres bool);
+func	chanrecv3(hchan <-chan any, elem *any) (pres 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;
 
 func	newselect(size int) (sel *byte);
-func	selectsend(sel *byte, hchan chan any, elem any) (selected bool);
-func	selectrecv(sel *byte, hchan chan any, elem *any) (selected bool);
+func	selectsend(sel *byte, hchan chan<- any, elem any) (selected bool);
+func	selectrecv(sel *byte, hchan <-chan any, elem *any) (selected bool);
 func	selectdefault(sel *byte) (selected bool);
 func	selectgo(sel *byte);
 
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index e20f0c75ce5..a6303a82fc4 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1335,6 +1335,11 @@ selcase(Node *n, Node *var)
 	if(t == T)
 		return N;
 
+	if(!(t->chan & Csend)) {
+		yyerror("cannot send on %T", t);
+		return N;
+	}
+
 	convlit(c->right, t->type);
 	if(!ascompat(t->type, c->right->type)) {
 		badtype(c->op, t->type, c->right->type);
@@ -1365,6 +1370,11 @@ recv:
 	if(t == T)
 		return N;
 
+	if(!(t->chan & Crecv)) {
+		yyerror("cannot receive from %T", t);
+		return N;
+	}
+
 	// selectrecv(sel *byte, hchan *chan any, elem *any) (selected bool);
 	on = syslook("selectrecv", 1);
 	argtype(on, t->type);
@@ -1389,6 +1399,11 @@ recv2:
 	if(t == T)
 		return N;
 
+	if(!(t->chan & Crecv)) {
+		yyerror("cannot receive from %T", t);
+		return N;
+	}
+
 	walktype(c->left, Elv);	// elem
 	convlit(c->left, t->type);
 	if(!ascompat(t->type, c->left->type)) {
@@ -2103,6 +2118,14 @@ ascompat(Type *dst, Type *src)
 	if(dst == T || src == T)
 		return 0;
 
+	if(dst->etype == TCHAN && src->etype == TCHAN) {
+		if(!eqtype(dst->type, src->type))
+			return 0;
+		if(dst->chan & ~src->chan)
+			return 0;
+		return 1;
+	}
+
 	if(isslice(dst)
 	&& isptr[src->etype]
 	&& isfixedarray(src->type)
@@ -2634,7 +2657,7 @@ chanop(Node *n, int top)
 		r = a;
 
 		on = syslook("closechan", 1);
-		argtype(on, t->type);	// any-1
+		argtype(on, t);	// any-1
 
 		r = nod(OCALL, on, r);
 		walktype(r, top);
@@ -2651,7 +2674,7 @@ chanop(Node *n, int top)
 		r = a;
 
 		on = syslook("closedchan", 1);
-		argtype(on, t->type);	// any-1
+		argtype(on, t);	// any-1
 
 		r = nod(OCALL, on, r);
 		walktype(r, top);
@@ -2704,6 +2727,11 @@ chanop(Node *n, int top)
 		if(t == T)
 			break;
 
+		if(!(t->chan & Crecv)) {
+			yyerror("cannot receive from %T", t);
+			break;
+		}
+
 		a = n->right->left;			// chan
 		r = a;
 
@@ -2727,6 +2755,11 @@ chanop(Node *n, int top)
 		if(t == T)
 			break;
 
+		if(!(t->chan & Crecv)) {
+			yyerror("cannot receive from %T", t);
+			break;
+		}
+
 		a = n->left;			// chan
 		r = a;
 
@@ -2769,14 +2802,15 @@ chanop(Node *n, int top)
 		t = fixchan(n->left->type);
 		if(t == T)
 			break;
+		if(!(t->chan & Csend)) {
+			yyerror("cannot send to %T", t);
+			break;
+		}
+
 		if(top != Etop)
 			goto send2;
 
 		// chansend1(hchan *chan any, elem any);
-		t = fixchan(n->left->type);
-		if(t == T)
-			break;
-
 		a = n->right;			// e
 		r = a;
 		a = n->left;			// chan
@@ -2791,10 +2825,6 @@ chanop(Node *n, int top)
 
 	send2:
 		// chansend2(hchan *chan any, val any) (pres bool);
-		t = fixchan(n->left->type);
-		if(t == T)
-			break;
-
 		a = n->right;			// e
 		r = a;
 		a = n->left;			// chan
@@ -4144,7 +4174,6 @@ maplit(Node *n, Node *var)
 	if(r != N && r->op == OEMPTY)
 		r = N;
 
-loop:
 	while(r != N) {
 		if(r == N)
 			break;