allow forward declaration of struct in another file

(in the same package).

allow forward method declaration to be satisfied
by implementation in another file (in the same package).
all methods must be declared in the same file
as the receiver type.

R=ken
OCL=30864
CL=30869

src/cmd/ar/ar.c

@@ -1216,7 +1216,7 @@ longt(Armember *bp)
 	pmode(strtoul(bp->hdr.mode, 0, 8));
 	Bprint(&bout, "%3ld/%1ld", strtol(bp->hdr.uid, 0, 0), strtol(bp->hdr.gid, 0, 0));
 	Bprint(&bout, "%7ld", bp->size);
-	cp = ctime(bp->date);
+	cp = ctime(&bp->date);
 	Bprint(&bout, " %-12.12s %-4.4s ", cp+4, cp+24);
 }
 
@@ -1455,7 +1455,6 @@ typedef struct Import Import;
 struct Import
 {
 	Import *hash;	// next in hash table
-	char *export;	// marked as export or package?
 	char *prefix;	// "type", "var", "func", "const"
 	char *name;
 	char *def;
@@ -1485,58 +1484,65 @@ ilookup(char *name)
 	return x;
 }
 
+/*
+ * a and b don't match.
+ * is one a forward declaration and the other a valid completion?
+ * if so, return the one to keep.
+ */
+char*
+forwardfix(char *a, char *b)
+{
+	char *t;
+
+	if(strlen(a) > strlen(b)) {
+		t = a;
+		a = b;
+		b = t;
+	}
+	if(strcmp(a, "struct") == 0 && strncmp(b, "struct ", 7) == 0)
+		return b;
+	if(strcmp(a, "interface") == 0 && strncmp(b, "interface ", 10) == 0)
+		return b;
+	return nil;
+}
+
 int parsemethod(char**, char*, char**);
-int parsepkgdata(char**, char*, char**, char**, char**, char**);
+int parsepkgdata(char**, char*, char**, char**, char**);
 
 void
 loadpkgdata(char *data, int len)
 {
-	char *export;
-	char *p, *ep, *prefix, *name, *def;
+	char *p, *ep, *prefix, *name, *def, *ndef;
 	Import *x;
 
 	p = data;
 	ep = data + len;
-	while(parsepkgdata(&p, ep, &export, &prefix, &name, &def) > 0) {
+	while(parsepkgdata(&p, ep, &prefix, &name, &def) > 0) {
 		x = ilookup(name);
 		if(x->prefix == nil) {
 			x->prefix = prefix;
 			x->def = def;
 			x->file = file;
-			x->export = export;
-		} else {
-			if(strcmp(x->prefix, prefix) != 0) {
+		} else if(strcmp(x->prefix, prefix) != 0) {
 			fprint(2, "ar: conflicting definitions for %s\n", name);
 			fprint(2, "%s:\t%s %s ...\n", x->file, x->prefix, name);
 			fprint(2, "%s:\t%s %s ...\n", file, prefix, name);
 			errors++;
-			}
-			else if(strcmp(x->def, def) != 0) {
+		} else if(strcmp(x->def, def) == 0) {
+			// fine
+		} else if((ndef = forwardfix(x->def, def)) != nil) {
+			x->def = ndef;
+		} else {
 			fprint(2, "ar: conflicting definitions for %s\n", name);
 			fprint(2, "%s:\t%s %s %s\n", x->file, x->prefix, name, x->def);
 			fprint(2, "%s:\t%s %s %s\n", file, prefix, name, def);
 			errors++;
 		}
-
-			// okay if some .6 say export/package and others don't.
-			// all it takes is one.  not okay if some say export
-			// and others say package.
-			if(export) {
-				if(x->export == nil)
-					x->export = export;
-				else if(strcmp(x->export, export) != 0) {
-					fprint(2, "ar: conflicting scopes for %s\n", name);
-					fprint(2, "%s:\t%s\n", x->file, x->export);
-					fprint(2, "%s:\t%s\n", file, export);
-					errors++;
-				}
-			}
-		}
 	}
 }
 
 int
-parsepkgdata(char **pp, char *ep, char **exportp, char **prefixp, char **namep, char **defp)
+parsepkgdata(char **pp, char *ep, char **prefixp, char **namep, char **defp)
 {
 	char *p, *prefix, *name, *def, *edef, *meth;
 	int n;
@@ -1548,16 +1554,6 @@ parsepkgdata(char **pp, char *ep, char **exportp, char **prefixp, char **namep,
 	if(p == ep)
 		return 0;
 
-	// [export|package ]
-	*exportp = 0;
-	if(p + 7 <= ep && strncmp(p, "export ", 7) == 0) {
-		*exportp = "export";
-		p += 7;
-	} else if(p + 8 <= ep && strncmp(p, "package ", 8) == 0) {
-		*exportp = "package";
-		p += 8;
-	}
-
 	// prefix: (var|type|func|const)
 	prefix = p;
 
@@ -1710,8 +1706,6 @@ getpkgdef(char **datap, int *lenp)
 			len += strlen(x->prefix) + 1
 				+ strlen(x->name) + 1
 				+ strlen(x->def) + 1;
-			if(x->export)
-				len += strlen(x->export) + 1;
 		}
 	}
 	if(j != nimport) {
@@ -1735,11 +1729,7 @@ getpkgdef(char **datap, int *lenp)
 	p = strappend(p, "\n");
 	for(i=0; i<nimport; i++) {
 		x = all[i];
-		// [export|package] prefix name def\n
-		if(x->export) {
-			p = strappend(p, x->export);
-			p = strappend(p, " ");
-		}
+		// prefix name def\n
 		p = strappend(p, x->prefix);
 		p = strappend(p, " ");
 		p = strappend(p, x->name);

src/cmd/gc/dcl.c

@@ -93,12 +93,13 @@ updatetype(Type *n, Type *t)
 {
 	Sym *s;
 	int local;
-	int maplineno, lno;
+	int maplineno, lno, etype;
 
 	s = n->sym;
 	if(s == S || s->def == N || s->def->op != OTYPE || s->def->type != n)
 		fatal("updatetype %T = %T", n, t);
 
+	etype = n->etype;
 	switch(n->etype) {
 	case TFORW:
 		break;
@@ -316,13 +317,7 @@ addmethod(Node *n, Type *t, int local)
 	if(f == T)
 		goto bad;
 
-	if(local && !f->local) {
-		yyerror("cannot define methods on non-local type %T", f);
-		return;
-	}
-
 	pa = f;
-
 	if(pkgimportname != S && !exportname(sf->name))
 		sf = pkglookup(sf->name, pkgimportname->name);
 
@@ -331,13 +326,11 @@ addmethod(Node *n, Type *t, int local)
 
 	d = T;	// last found
 	for(f=pa->method; f!=T; f=f->down) {
+		d = f;
 		if(f->etype != TFIELD)
 			fatal("addmethod: not TFIELD: %N", f);
-
-		if(strcmp(sf->name, f->sym->name) != 0) {
-			d = f;
+		if(strcmp(sf->name, f->sym->name) != 0)
 			continue;
-		}
 		if(!eqtype(t, f->type)) {
 			yyerror("method redeclared: %T.%S", pa, sf);
 			print("\t%T\n\t%T\n", f->type, t);
@@ -345,6 +338,14 @@ addmethod(Node *n, Type *t, int local)
 		return;
 	}
 
+	if(local && !pa->local) {
+		// defining method on non-local type.
+		// method must have been forward declared
+		// elsewhere, i.e. where the type was.
+		yyerror("cannot define new methods on non-local type %T", pa);
+		return;
+	}
+
 	if(d == T)
 		stotype(n, 0, &pa->method);
 	else

src/cmd/gc/export.c

@@ -168,9 +168,13 @@ dumpexporttype(Sym *s)
 	Bprint(bout, "\t");
 	switch (t->etype) {
 	case TFORW:
+		yyerror("export of incomplete type %T", t);
+		return;
 	case TFORWSTRUCT:
+		Bprint(bout, "type %#T struct\n", t);
+		return;
 	case TFORWINTER:
-		yyerror("export of incomplete type %T", t);
+		Bprint(bout, "type %#T interface\n", t);
 		return;
 	}
 	Bprint(bout, "type %#T %l#T\n",  t, t);
@@ -276,11 +280,15 @@ importsym(Sym *s, int op)
 		else
 			yyerror("redeclaration of %lS during import", s, s->def->op, op);
 	}
+
+	// mark the symbol so it is not reexported
+	if(s->def == N) {
 		if(exportname(s->name))
 			s->export = 1;
 		else
 			s->export = 2;	// package scope
 		s->imported = 1;
+	}
 	return s;
 }
 
@@ -359,9 +367,12 @@ importtype(Sym *s, Type *t)
 	if(n != N && n->op == OTYPE) {
 		if(cvttype(t, n->type))
 			return;
-		if(n->type->etype != TFORW) {
-			warn("redeclare import type %S from %lT to %lT",
-				s, n->type, t);
+		if(t->etype == TFORWSTRUCT && n->type->etype == TSTRUCT)
+			return;
+		if(t->etype == TFORWINTER && n->type->etype == TINTER)
+			return;
+		if(n->type->etype != TFORW && n->type->etype != TFORWSTRUCT && n->type->etype != TFORWINTER) {
+			yyerror("redeclare import type %S from %lT to %lT", s, n->type, t);
 			n = s->def = typenod(typ(0));
 		}
 	}
@@ -376,7 +387,16 @@ importtype(Sym *s, Type *t)
 	*n->type = *t;
 	n->type->sym = s;
 	n->type->nod = n;
+	switch(n->type->etype) {
+	case TFORWINTER:
+	case TFORWSTRUCT:
+		// allow re-export in case it gets defined
+		s->export = 0;
+		s->imported = 0;
+		break;
+	default:
 		checkwidth(n->type);
+	}
 
 	if(debug['E'])
 		print("import type %S %lT\n", s, t);

src/cmd/gc/go.y

@@ -1700,6 +1700,14 @@ hidden_import:
 	{
 		importtype($2, $3);
 	}
+|	LTYPE hidden_pkg_importsym LSTRUCT
+	{
+		importtype($2, typ(TFORWSTRUCT));
+	}
+|	LTYPE hidden_pkg_importsym LINTERFACE
+	{
+		importtype($2, typ(TFORWINTER));
+	}
 |	LFUNC hidden_pkg_importsym '(' ohidden_funarg_list ')' ohidden_funres
 	{
 		importvar($2, functype(N, $4, $6), PFUNC);

src/cmd/ld/go.c

@@ -22,7 +22,6 @@ typedef struct Import Import;
 struct Import
 {
 	Import *hash;	// next in hash table
-	int export;	// marked as export?
 	char *prefix;	// "type", "var", "func", "const"
 	char *name;
 	char *def;
@@ -89,7 +88,7 @@ gotypefor(char *name)
 
 static void loadpkgdata(char*, char*, int);
 static int parsemethod(char**, char*, char**);
-static int parsepkgdata(char*, char**, char*, int*, char**, char**, char**);
+static int parsepkgdata(char*, char**, char*, char**, char**, char**);
 
 void
 ldpkg(Biobuf *f, int64 len, char *filename)
@@ -154,47 +153,63 @@ ldpkg(Biobuf *f, int64 len, char *filename)
 	loadpkgdata(filename, p0, p1 - p0);
 }
 
+/*
+ * a and b don't match.
+ * is one a forward declaration and the other a valid completion?
+ * if so, return the one to keep.
+ */
+char*
+forwardfix(char *a, char *b)
+{
+	char *t;
+
+	if(strlen(a) > strlen(b)) {
+		t = a;
+		a = b;
+		b = t;
+	}
+	if(strcmp(a, "struct") == 0 && strncmp(b, "struct ", 7) == 0)
+		return b;
+	if(strcmp(a, "interface") == 0 && strncmp(b, "interface ", 10) == 0)
+		return b;
+	return nil;
+}
+
 static void
 loadpkgdata(char *file, char *data, int len)
 {
-	int export;
-	char *p, *ep, *prefix, *name, *def;
+	char *p, *ep, *prefix, *name, *def, *ndef;
 	Import *x;
 
 	file = strdup(file);
 	p = data;
 	ep = data + len;
-	while(parsepkgdata(file, &p, ep, &export, &prefix, &name, &def) > 0) {
+	while(parsepkgdata(file, &p, ep, &prefix, &name, &def) > 0) {
 		x = ilookup(name);
 		if(x->prefix == nil) {
 			x->prefix = prefix;
 			x->def = def;
 			x->file = file;
-			x->export = export;
-		} else {
-			if(strcmp(x->prefix, prefix) != 0) {
+		} else if(strcmp(x->prefix, prefix) != 0) {
 			fprint(2, "%s: conflicting definitions for %s\n", argv0, name);
 			fprint(2, "%s:\t%s %s ...\n", x->file, x->prefix, name);
 			fprint(2, "%s:\t%s %s ...\n", file, prefix, name);
 			nerrors++;
-			}
-			else if(strcmp(x->def, def) != 0) {
-				fprint(2, "%s: conflicting definitions for %s\n", argv0, name);
+		} else if(strcmp(x->def, def) == 0) {
+			// fine
+		} else if((ndef = forwardfix(x->def, def)) != nil) {
+			x->def = ndef;
+		} else {
+			fprint(2, "%d: conflicting definitions for %s\n", argv0, name);
 			fprint(2, "%s:\t%s %s %s\n", x->file, x->prefix, name, x->def);
 			fprint(2, "%s:\t%s %s %s\n", file, prefix, name, def);
 			nerrors++;
 		}
-
-			// okay if some .6 say export and others don't.
-			// all it takes is one.
-			if(export)
-				x->export = 1;
-		}
 	}
 }
 
 static int
-parsepkgdata(char *file, char **pp, char *ep, int *exportp, char **prefixp, char **namep, char **defp)
+parsepkgdata(char *file, char **pp, char *ep, char **prefixp, char **namep, char **defp)
 {
 	char *p, *prefix, *name, *def, *edef, *meth;
 	int n;
@@ -206,17 +221,6 @@ parsepkgdata(char *file, char **pp, char *ep, int *exportp, char **prefixp, char
 	if(p == ep || strncmp(p, "$$\n", 3) == 0)
 		return 0;
 
-	// [export|package ]
-	*exportp = 0;
-	if(p + 7 <= ep && strncmp(p, "export ", 7) == 0) {
-		*exportp = 1;
-		p += 7;
-	}
-	else if(p + 8 <= ep && strncmp(p, "package ", 8) == 0) {
-		*exportp = 2;
-		p += 8;
-	}
-
 	// prefix: (var|type|func|const)
 	prefix = p;