make every func literal expression allocate,

so that == on func means that the
functions originated in the same
execution of a func literal or definition.

before, there was an inconsistency:

	func() {x++} != func() {x++}

but

	func() {} == func() {}

this CL makes the second case != too,
just like

	make(map[int]int) != make(map[int]int)

R=r
DELTA=202  (71 added, 62 deleted, 69 changed)
OCL=32393
CL=32398

src/cmd/gc/dcl.c

@@ -553,9 +553,6 @@ funclit1(Node *ntype, NodeList *body)
 	// as we referred to variables from the outer function,
 	// we accumulated a list of PHEAP names in func->cvars.
 	narg = 0;
-	if(func->cvars == nil)
-		ft = type;
-	else {
 	// add PHEAP versions as function arguments.
 	in = nil;
 	for(l=func->cvars; l; l=l->next) {
@@ -583,7 +580,7 @@ funclit1(Node *ntype, NodeList *body)
 	}
 
 	// add a dummy arg for the closure's caller pc
-		d = nod(ODCLFIELD, a, N);
+	d = nod(ODCLFIELD, N, N);
 	d->type = types[TUINTPTR];
 	in = list(in, d);
 
@@ -622,7 +619,6 @@ funclit1(Node *ntype, NodeList *body)
 
 	ft = functype(N, in, out);
 	ft->outnamed = type->outnamed;
-	}
 
 	// declare function.
 	vargen++;
@@ -642,10 +638,6 @@ funclit1(Node *ntype, NodeList *body)
 	funcdepth--;
 	autodcl = func->dcl;
 
-	// if there's no closure, we can use f directly
-	if(func->cvars == nil)
-		return f;
-
 	// build up type for this instance of the closure func.
 	in = nil;
 	d = nod(ODCLFIELD, N, N);	// siz

src/pkg/runtime/386/closure.c

@@ -43,6 +43,8 @@ sys·closure(int32 siz, byte *fn, byte *arg0)
 	p = mal(n);
 	*ret = p;
 	q = p + n - siz;
+
+	if(siz > 0) {
 		mcpy(q, (byte*)&arg0, siz);
 
 		// SUBL $siz, SP
@@ -79,6 +81,7 @@ sys·closure(int32 siz, byte *fn, byte *arg0)
 			*p++ = 0xf3;
 			*p++ = 0xa5;
 		}
+	}
 
 	// call fn
 	pcrel = fn - (p+5);

src/pkg/runtime/amd64/closure.c

@@ -43,6 +43,8 @@ sys·closure(int32 siz, byte *fn, byte *arg0)
 	p = mal(n);
 	*ret = p;
 	q = p + n - siz;
+
+	if(siz > 0) {
 		mcpy(q, (byte*)&arg0, siz);
 
 		// SUBQ $siz, SP
@@ -82,7 +84,7 @@ sys·closure(int32 siz, byte *fn, byte *arg0)
 			*p++ = 0x48;
 			*p++ = 0xa5;
 		}
-
+	}
 
 	// call fn
 	pcrel = fn - (p+5);

test/closure.go

@@ -73,6 +73,10 @@ func h() {
 	f(500);
 }
 
+func newfunc() (func(int) int) {
+	return func(x int) int { return x }
+}
+
 
 func main() {
 	go f();
@@ -85,4 +89,12 @@ func main() {
 
 	go h();
 	check([]int{100,200,101,201,500,101,201,500});
+
+	x, y := newfunc(), newfunc();
+	if x == y {
+		panicln("newfunc returned same func");
+	}
+	if x(1) != 1 || y(2) != 2 {
+		panicln("newfunc returned broken funcs");
+	}
 }