gc: return of ideal bool

This is a manual undo of CL 5674098.
It does not implement the even less strict spec
that we just agreed on, but it gets us back where
we were at the last weekly.

R=ken2
CC=golang-dev
https://golang.org/cl/5683069

src/cmd/gc/const.c

@@ -668,6 +668,7 @@ evconst(Node *n)
 			n->diag = 1;
 		}
 		return;
+
 	case TUP(OADD, CTCPLX):
 		mpaddfltflt(&v.u.cval->real, &rv.u.cval->real);
 		mpaddfltflt(&v.u.cval->imag, &rv.u.cval->imag);
@@ -943,7 +944,7 @@ nodlit(Val v)
 		n->type = idealstring;
 		break;
 	case CTBOOL:
-		n->type = types[TBOOL];
+		n->type = idealbool;
 		break;
 	case CTINT:
 	case CTRUNE:
@@ -1032,7 +1033,7 @@ defaultlit(Node **np, Type *t)
 			defaultlit(&n->left, t);
 			defaultlit(&n->right, t);
 		}
-		if(n->type == types[TBOOL] || n->type == idealstring)
+		if(n->type == idealbool || n->type == idealstring)
 			n->type = types[n->type->etype];
 		else
 			n->type = n->left->type;

src/cmd/gc/export.c

@@ -122,7 +122,7 @@ reexportdep(Node *n)
 
 	case OLITERAL:
 		t = n->type;
-		if(t != types[n->type->etype] && t != idealstring) {
+		if(t != types[n->type->etype] && t != idealbool && t != idealstring) {
 			if(isptr[t->etype])
 				t = t->type;
 			if (t && t->sym && t->sym->def && t->sym->pkg != localpkg  && t->sym->pkg != builtinpkg) {

src/cmd/gc/fmt.c

@@ -602,7 +602,7 @@ typefmt(Fmt *fp, Type *t)
 	}
 
 	if(t->etype < nelem(basicnames) && basicnames[t->etype] != nil) {
-		if(fmtmode == FErr && t == idealstring)
+		if(fmtmode == FErr && (t == idealbool || t == idealstring))
 			fmtstrcpy(fp, "ideal ");
 		return fmtstrcpy(fp, basicnames[t->etype]);
 	}
@@ -1086,7 +1086,7 @@ exprfmt(Fmt *f, Node *n, int prec)
 			return fmtprint(f, "%S", n->sym);
 		if(n->val.ctype == CTNIL)
 			n = n->orig; // if this node was a nil decorated with at type, print the original naked nil
-		if(n->type != types[n->type->etype] && n->type != idealstring) {
+		if(n->type != types[n->type->etype] && n->type != idealbool && n->type != idealstring) {
 			// Need parens when type begins with what might
 			// be misinterpreted as a unary operator: * or <-.
 			if(isptr[n->type->etype] || (n->type->etype == TCHAN && n->type->chan == Crecv))

src/cmd/gc/go.h

@@ -775,6 +775,7 @@ EXTERN	Idir*	idirs;
 
 EXTERN	Type*	types[NTYPE];
 EXTERN	Type*	idealstring;
+EXTERN	Type*	idealbool;
 EXTERN	Type*	bytetype;
 EXTERN	Type*	runetype;
 EXTERN	Type*	errortype;

src/cmd/gc/lex.c

@@ -1824,16 +1824,17 @@ lexinit(void)
 	// this is the ideal form
 	// (the type of x in const x = "hello").
 	idealstring = typ(TSTRING);
+	idealbool = typ(TBOOL);
 
 	s = pkglookup("true", builtinpkg);
 	s->def = nodbool(1);
 	s->def->sym = lookup("true");
-	s->def->type = types[TBOOL];
+	s->def->type = idealbool;
 
 	s = pkglookup("false", builtinpkg);
 	s->def = nodbool(0);
 	s->def->sym = lookup("false");
-	s->def->type = types[TBOOL];
+	s->def->type = idealbool;
 
 	s = lookup("_");
 	s->block = -100;

src/cmd/gc/subr.c

@@ -768,7 +768,7 @@ nodbool(int b)
 	c = nodintconst(0);
 	c->val.ctype = CTBOOL;
 	c->val.u.bval = b;
-	c->type = types[TBOOL];
+	c->type = idealbool;
 	return c;
 }
 
@@ -929,7 +929,7 @@ isideal(Type *t)
 {
 	if(t == T)
 		return 0;
-	if(t == idealstring)
+	if(t == idealstring || t == idealbool)
 		return 1;
 	switch(t->etype) {
 	case TNIL:

test/fixedbugs/bug285.go

@@ -20,6 +20,7 @@ func main() {
 	type B bool
 	b := B(false)
 	mb := make(map[B]int)
+	mb[false] = 42 // this should work: false is assignment compatible with B
 	mb[b] = 42
 
 	type Z int

test/named.go

@@ -31,6 +31,7 @@ func asString(String) {}
 
 func (Map) M() {}
 
+
 // These functions check at run time that the default type
 // (in the absence of any implicit conversion hints)
 // is the given type.
@@ -46,7 +47,7 @@ func isString(x interface{}) { _ = x.(String) }
 func main() {
 	var (
 		a     Array
-		b     Bool   = Bool(true)
+		b     Bool   = true
 		c     Chan   = make(Chan)
 		f     Float  = 1
 		i     Int    = 1
@@ -66,6 +67,7 @@ func main() {
 	isBool(b)
 	asBool(!b)
 	isBool(!b)
+	asBool(true)
 	asBool(*&b)
 	isBool(*&b)
 	asBool(Bool(true))

test/named1.go

@@ -26,7 +26,7 @@ type String string
 
 func main() {
 	var (
-		b    Bool = Bool(true)
+		b    Bool = true
 		i, j int
 		c    = make(chan int)
 		m    = make(Map)
@@ -34,7 +34,7 @@ func main() {
 
 	asBool(b)
 	asBool(!b)
-	asBool(true) // ERROR "cannot use.*type bool.*as type Bool"
+	asBool(true)
 	asBool(*&b)
 	asBool(Bool(true))
 	asBool(1 != 2) // ERROR "cannot use.*type bool.*as type Bool"