gc: fix import width bug

Fixes #1705.

R=ken2
CC=golang-dev
https://golang.org/cl/4443060

src/cmd/5g/cgen.c

@@ -43,6 +43,8 @@ cgen(Node *n, Node *res)
 	}
 
 	if(isfat(n->type)) {
+		if(n->type->width < 0)
+			fatal("forgot to compute width for %T", n->type);
 		sgen(n, res, n->type->width);
 		goto ret;
 	}

src/cmd/6g/cgen.c

@@ -47,6 +47,8 @@ cgen(Node *n, Node *res)
 	}
 
 	if(isfat(n->type)) {
+		if(n->type->width < 0)
+			fatal("forgot to compute width for %T", n->type);
 		sgen(n, res, n->type->width);
 		goto ret;
 	}

src/cmd/8g/cgen.c

@@ -78,6 +78,8 @@ cgen(Node *n, Node *res)
 
 	// structs etc get handled specially
 	if(isfat(n->type)) {
+		if(n->type->width < 0)
+			fatal("forgot to compute width for %T", n->type);
 		sgen(n, res, n->type->width);
 		return;
 	}

src/cmd/gc/dcl.c

@@ -684,6 +684,10 @@ ok:
 	pt->nod = n;
 	pt->sym = n->sym;
 	pt->sym->lastlineno = parserline();
+	pt->siggen = 0;
+	pt->printed = 0;
+	pt->deferwidth = 0;
+	pt->local = 0;
 	declare(n, PEXTERN);
 
 	checkwidth(pt);

src/cmd/gc/walk.c

@@ -142,7 +142,9 @@ walkdeftype(Node *n)
 	}
 
 	// copy new type and clear fields
-	// that don't come along
+	// that don't come along.
+	// anything zeroed here must be zeroed in
+	// typedcl2 too.
 	maplineno = n->type->maplineno;
 	embedlineno = n->type->embedlineno;
 	*n->type = *t;

test/fixedbugs/bug335.dir/a.go

+// Copyright 2011 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 a
+
+import "./b"
+
+var Bar = b.Foo

test/fixedbugs/bug335.dir/b.go

+// Copyright 2011 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 b
+
+type T interface{}
+
+func f() T { return nil }
+
+var Foo T = f()

test/fixedbugs/bug335.go

+// $G $D/$F.dir/b.go && $G $D/$F.dir/a.go
+// rm -f a.$A b.$A
+
+// Copyright 2011 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.
+
+// Issue 1705.
+
+unused (see script at top of file)