From 61361af9e8ca4c4c5c34e668e9ad1d996ccfa26f Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Sun, 19 Oct 2008 20:13:37 -0700
Subject: [PATCH] unnamed substructures - not complete

R=r
OCL=17437
CL=17437
---
 src/cmd/gc/dcl.c  |  1 +
 src/cmd/gc/go.h   |  2 ++
 src/cmd/gc/go.y   | 20 ++++++++------
 src/cmd/gc/walk.c | 69 ++++++++++++++++++++++++++++++-----------------
 4 files changed, 60 insertions(+), 32 deletions(-)

diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index b65d8c0bb6a..95f4e020cb7 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -471,6 +471,7 @@ loop:
 
 	if(n->left != N && n->left->op == ONAME) {
 		f->nname = n->left;
+		f->embedded = n->embedded;
 	} else {
 		vargen++;
 		snprint(buf, sizeof(buf), "_e%s_%.3ld", filename, vargen);
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 42b068c8d0d..c72dbb8c671 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -124,6 +124,7 @@ struct	Type
 	uchar	trecur;		// to detect loops
 	uchar	methptr;	// 1=direct 2=pointer
 	uchar	printed;
+	uchar	embedded;	// TFIELD embedded type
 
 	// TFUNCT
 	uchar	thistuple;
@@ -161,6 +162,7 @@ struct	Node
 	uchar	class;		// PPARAM, PAUTO, PEXTERN, PSTATIC
 	uchar	method;		// OCALLMETH name
 	uchar	iota;		// OLITERAL made from iota
+	uchar	embedded;	// ODCLFIELD embedded type
 
 	// most nodes
 	Node*	left;
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index 4afc1c6e841..3e1c073bc82 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -1378,15 +1378,19 @@ structdcl:
 		$$ = nod(ODCLFIELD, $1, N);
 		$$->type = $2;
 	}
-|	new_name
+|	LATYPE
 	{
-		// must be  latype
-		$$ = nod(ODCLFIELD, N, N);
-		$$->type = $1->sym->otype;
-		if($1->sym->lexical != LATYPE) {
-			yyerror("unnamed structure field must be a type");
-			$$->type = types[TINT32];
-		};
+		$$ = nod(ODCLFIELD, newname($1), N);
+		$$->type = oldtype($1);
+		$$->embedded = 1;
+	}
+|	lpack '.' LATYPE
+	{
+		$$ = newname(lookup($3->name));
+		$$ = nod(ODCLFIELD, $$, N);
+		$$->type = oldtype($3);
+		$$->embedded = 1;
+		context = nil;
 	}
 
 interfacedcl:
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 610051a50b3..1acbd90c692 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1390,38 +1390,57 @@ walkselect(Node *sel)
 	lineno = lno;
 }
 
-/*
- * allowable type combinations for
- * normal binary operations.
- */
 Type*
-lookdot(Node *n, Type *f)
+lookdot(Node *n, Type *f, int d)
 {
-	Type *r;
-	Sym *s;
+	Type *r, *r1;
+	Sym *s, *sf;
 
 	r = T;
 	s = n->sym;
 
 	for(; f!=T; f=f->down) {
-		if(f->sym == S)
+		sf = f->sym;
+		if(sf == S)
 			continue;
-	//	if(strcmp(f->sym->name, s->name) != 0)
-		if(f->sym != s)
-			continue;
-		if(r != T) {
-			yyerror("ambiguous DOT reference %S", s);
-			break;
+
+		// depth=0 -- look directly in structure
+		if(d == 0) {
+			if(sf != s)
+				continue;
+			if(r != T)
+				goto ambig;
+			r = f;
+			n->xoffset = f->width;
+		}
+
+		// depth>0 -- look into unnamed substructures
+		if(d > 0 && f->embedded) {
+			if(f->type == T)
+				continue;
+			if(f->type->etype != TSTRUCT && f->type->etype != TINTER)
+				continue;
+			r1 = lookdot(n, f->type->type, d-1);
+			if(r1 == T)
+				continue;
+			if(r != T)
+				goto ambig;
+			r = r1;
+			n->xoffset += f->width;
 		}
-		r = f;
 	}
 	return r;
+
+ambig:
+	yyerror("ambiguous DOT reference %S", s);
+	return r;
 }
 
 void
 walkdot(Node *n)
 {
 	Type *t, *f;
+	int d;
 
 	if(n->left == N || n->right == N)
 		return;
@@ -1447,14 +1466,16 @@ walkdot(Node *n)
 	}
 
 	if(t->etype == TSTRUCT || t->etype == TINTER) {
-		f = lookdot(n->right, t->type);
-		if(f != T) {
-			n->xoffset = f->width;
-			n->right = f->nname;		// substitute real name
-			n->type = f->type;
-			if(t->etype == TINTER)
-				n->op = ODOTINTER;
-			return;
+		for(d=0; d<=5; d++) {
+			f = lookdot(n->right, t->type, d);
+			if(f != T) {
+				n->xoffset = n->right->xoffset;
+				n->right = f->nname;		// substitute real name
+				n->type = f->type;
+				if(t->etype == TINTER)
+					n->op = ODOTINTER;
+				return;
+			}
 		}
 	}
 
@@ -1462,7 +1483,7 @@ walkdot(Node *n)
 	f = T;
 	t = ismethod(n->left->type);
 	if(t != T)
-		f = lookdot(n->right, t->method);
+		f = lookdot(n->right, t->method, 0);
 	if(f == T) {
 		yyerror("undefined DOT %S on %T", n->right->sym, n->left->type);
 		return;