6g:

	new type equality restrictions
	better handling of renamed packages
	"sys" is no longer available to programs

R=ken
OCL=28553
CL=28578

11 files changed, 172 insertions, 88 deletions

diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 8f8fe7273..0e7db2c06 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -384,7 +384,7 @@ agen(Node *n, Node *res)
 		break;
 
 	case OCONV:
-		if(!eqtype(n->type, nl->type))
+		if(!cvttype(n->type, nl->type))
 			fatal("agen: non-trivial OCONV");
 		agen(nl, res);
 		return;
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index b29cab304..f63d1c352 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -1105,8 +1105,8 @@ naddr(Node *n, Addr *a)
 		if(n->method) {
 			if(n->type != T)
 			if(n->type->sym != S)
-			if(n->type->sym->opackage != nil)
-				a->sym = pkglookup(a->sym->name, n->type->sym->opackage);
+			if(n->type->sym->package != nil)
+				a->sym = pkglookup(a->sym->name, n->type->sym->package);
 		}
 
 		switch(n->class) {
diff --git a/src/cmd/6g/obj.c b/src/cmd/6g/obj.c
index 1970d1fab..25416a936 100644
--- a/src/cmd/6g/obj.c
+++ b/src/cmd/6g/obj.c
@@ -40,7 +40,7 @@ zname(Biobuf *b, Sym *s, int t)
 	Bputc(b, t);		/* type */
 	Bputc(b, s->sym);	/* sym */
 
-	for(n=s->opackage; *n; n++)
+	for(n=s->package; *n; n++)
 		Bputc(b, *n);
 	Bputdot(b);
 	for(n=s->name; *n; n++)
diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index 59a591ccc..50b582394 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -80,7 +80,7 @@ convlit1(Node *n, Type *t, int explicit)
 	}
 
 	// avoided repeated calculations, errors
-	if(eqtype(n->type, t)) {
+	if(cvttype(n->type, t)) {
 		n->type = t;
 		return;
 	}
@@ -99,8 +99,19 @@ convlit1(Node *n, Type *t, int explicit)
 	}
 
 	// if already has non-ideal type, cannot change implicitly
-	if(n->type->etype != TIDEAL && n->type->etype != TNIL && !explicit)
-		goto bad;
+	if(!explicit) {
+		switch(n->type->etype) {
+		case TIDEAL:
+		case TNIL:
+			break;
+		case TSTRING:
+			if(n->type == idealstring)
+				break;
+			// fall through
+		default:
+			goto bad;
+		}
+	}
 
 	switch(ct) {
 	default:
@@ -532,7 +543,7 @@ unary:
 
 	switch(TUP(n->op, v.ctype)) {
 	default:
-		yyerror("illegal constant expression %O %T %d", n->op, nl->type, v.ctype);
+		yyerror("illegal constant expression %O %T", n->op, nl->type);
 		return;
 
 	case TUP(OPLUS, CTINT):
@@ -588,12 +599,6 @@ ret:
 	*n = *nl;
 	n->val = v;
 
-	// lose type name if any:
-	//	type T int
-	//	const A T = 1;
-	// A+0 has type int, not T.
-	n->type = types[n->type->etype];
-
 	// check range.
 	lno = lineno;
 	lineno = n->lineno;
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index bf9afee2f..3e6f76092 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -250,7 +250,7 @@ methodsym(Sym *nsym, Type *t0)
 
 	snprint(buf, sizeof(buf), "%#hT·%s", t0, nsym->name);
 //print("methodname %s\n", buf);
-	return pkglookup(buf, s->opackage);
+	return pkglookup(buf, s->package);
 
 bad:
 	yyerror("illegal <this> type: %T", t);
@@ -797,7 +797,6 @@ dcopy(Sym *a, Sym *b)
 	a->otype = b->otype;
 	a->oconst = b->oconst;
 	a->package = b->package;
-	a->opackage = b->opackage;
 	a->lexical = b->lexical;
 	a->undef = b->undef;
 	a->vargen = b->vargen;
@@ -1632,7 +1631,7 @@ unsafenmagic(Node *l, Node *r)
 	s = l->sym;
 	if(s == S)
 		goto no;
-	if(strcmp(s->opackage, "unsafe") != 0)
+	if(strcmp(s->package, "unsafe") != 0)
 		goto no;
 
 	if(strcmp(s->name, "Sizeof") == 0) {
diff --git a/src/cmd/gc/export.c b/src/cmd/gc/export.c
index 07c7411e4..001cabde1 100644
--- a/src/cmd/gc/export.c
+++ b/src/cmd/gc/export.c
@@ -288,14 +288,11 @@ importsym(Node *ss, int lexical)
 {
 	Sym *s;
 
-	renamepkg(ss);
-
 	if(ss->op != OIMPORT)
 		fatal("importsym: oops1 %N", ss);
 
 	s = pkgsym(ss->sym->name, ss->psym->name, lexical);
 	/* TODO botch - need some diagnostic checking for the following assignment */
-	s->opackage = ss->osym->name;
 	if(exportname(ss->sym->name))
 		s->export = 1;
 	else
@@ -319,8 +316,6 @@ pkgtype(char *name, char *pkg)
 	n = nod(OIMPORT, N, N);
 	n->sym = lookup(name);
 	n->psym = lookup(pkg);
-	n->osym = n->psym;
-	renamepkg(n);
 	s = importsym(n, LATYPE);
 
 	if(s->otype == T) {
@@ -371,7 +366,7 @@ importvar(Node *ss, Type *t, int ctxt)
 
 	s = importsym(ss, LNAME);
 	if(s->oname != N) {
-		if(eqtype(t, s->oname->type))
+		if(cvttype(t, s->oname->type))
 			return;
 		warn("redeclare import var %S from %T to %T",
 			s, s->oname->type, t);
@@ -390,10 +385,10 @@ importtype(Node *ss, Type *t)
 
 	s = importsym(ss, LATYPE);
 	if(s->otype != T) {
-		if(eqtype(t, s->otype))
+		if(cvttype(t, s->otype))
 			return;
 		if(s->otype->etype != TFORW) {
-			warn("redeclare import type %S from %T to %T",
+			warn("redeclare import type %S from %lT to %lT",
 				s, s->otype, t);
 			s->otype = typ(0);
 		}
@@ -464,12 +459,3 @@ return;
 	}
 }
 
-
-
-void
-renamepkg(Node *n)
-{
-	if(n->psym == pkgimportname)
-		if(pkgmyname != S)
-			n->psym = pkgmyname;
-}
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 29e2fd64b..657c582f5 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -223,7 +223,6 @@ struct	Node
 	Node*	outer;	// outer PPARAMREF in nested closure
 	Node*	closure;	// ONAME/PHEAP <-> ONAME/PPARAMREF
 
-	Sym*	osym;		// import
 	Sym*	psym;		// import
 	Sym*	sym;		// various
 	int32	vargen;		// unique name for OTYPE/ONAME
@@ -245,12 +244,12 @@ struct	Sym
 	uchar	uniq;		// imbedded field name first found
 	uchar	siggen;		// signature generated
 
-	char*	opackage;	// original package name
 	char*	package;	// package name
 	char*	name;		// variable name
 	Node*	oname;		// ONAME node if a var
 	Type*	otype;		// TYPE node if a type
 	Node*	oconst;		// OLITERAL node if a const
+	char*	opack;		// package reference if lexical == LPACK
 	vlong	offset;		// stack location if automatic
 	int32	lexical;
 	int32	vargen;		// unique variable number
@@ -555,6 +554,7 @@ EXTERN	uchar	issimple[NTYPE];
 EXTERN	uchar	okforeq[NTYPE];
 EXTERN	uchar	okforadd[NTYPE];
 EXTERN	uchar	okforand[NTYPE];
+EXTERN	Type*	idealstring;
 
 EXTERN	Mpint*	minintval[NTYPE];
 EXTERN	Mpint*	maxintval[NTYPE];
@@ -699,6 +699,8 @@ void	errorexit(void);
 uint32	stringhash(char*);
 Sym*	lookup(char*);
 Sym*	pkglookup(char*, char*);
+Sym*	opkglookup(char*, char*);
+void	importdot(Sym*);
 void	yyerror(char*, ...);
 void	warn(char*, ...);
 void	fatal(char*, ...);
@@ -728,6 +730,7 @@ Type*	maptype(Type*, Type*);
 Type*	methtype(Type*);
 Sym*	signame(Type*);
 int	eqtype(Type*, Type*);
+int	cvttype(Type*, Type*);
 int	eqtypenoname(Type*, Type*);
 void	argtype(Node*, Type*);
 int	eqargs(Type*, Type*);
@@ -847,7 +850,7 @@ Node*	unsafenmagic(Node*, Node*);
 /*
  *	export.c
  */
-void	renamepkg(Node*);
+void	renameimports(void);
 void	autoexport(Sym*);
 int	exportname(char*);
 void	exportsym(Sym*);
diff --git a/src/cmd/gc/go.y b/src/cmd/gc/go.y
index db78c4dc9..7dc635252 100644
--- a/src/cmd/gc/go.y
+++ b/src/cmd/gc/go.y
@@ -115,7 +115,10 @@
 
 %%
 file:
-	package import_there imports oxdcl_list
+	loadsys
+	package
+	imports
+	oxdcl_list
 	{
 		if(debug['f'])
 			frame(1);
@@ -128,13 +131,26 @@ package:
 	{
 		yyerror("package statement must be first");
 		mkpackage("main");
-		cannedimports("sys.6", sysimport);
 	}
 |	LPACKAGE sym
 	{
 		mkpackage($2->name);
+	}
+
+/*
+ * this loads the definitions for the sys functions,
+ * so that the compiler can generate calls to them,
+ * but does not make the name "sys" visible as a package.
+ */
+loadsys:
+	{
 		cannedimports("sys.6", sysimport);
 	}
+	import_package
+	import_there
+	{
+		pkgimportname = S;
+	}
 
 imports:
 |	imports import
@@ -145,26 +161,27 @@ import:
 |	LIMPORT '(' ')'
 
 import_stmt:
-	import_here import_package import_there
+	import_here import_package import_there import_done
 
 import_here:
 	LLITERAL
 	{
 		// import with original name
+		pkgimportname = S;
 		pkgmyname = S;
 		importfile(&$1);
 	}
 |	sym LLITERAL
 	{
 		// import with given name
+		pkgimportname = S;
 		pkgmyname = $1;
-		pkgmyname->lexical = LPACK;
 		importfile(&$2);
 	}
 |	'.' LLITERAL
 	{
-		// import with my name
-		pkgmyname = lookup(package);
+		// import into my name space
+		pkgmyname = lookup(".");
 		importfile(&$2);
 	}
 
@@ -172,14 +189,8 @@ import_package:
 	LPACKAGE sym
 	{
 		pkgimportname = $2;
-
 		if(strcmp($2->name, "main") == 0)
 			yyerror("cannot import package main");
-
-		// if we are not remapping the package name
-		// then the imported package name is LPACK
-		if(pkgmyname == S)
-			pkgimportname->lexical = LPACK;
 	}
 
 import_there:
@@ -187,13 +198,51 @@ import_there:
 	{
 		checkimports();
 		unimportfile();
-		pkgimportname = S;
 	}
 |	LIMPORT '$' '$' hidden_import_list '$' '$'
 	{
 		checkimports();
 	}
 
+import_done:
+	{
+		Sym *import, *my;
+
+		import = pkgimportname;
+		my = pkgmyname;
+		pkgmyname = S;
+		pkgimportname = S;
+
+		if(import == S)
+			break;
+		if(my == S)
+			my = import;
+		if(my->name[0] == '.') {
+			importdot(import);
+			break;
+		}
+
+		// In order to allow multifile packages to use type names
+		// that are the same as the package name (i.e. go/parser
+		// is package parser and has a type called parser), we have
+		// to not bother trying to declare the package if it is our package.
+		// TODO(rsc): Is there a better way to tell if the package is ours?
+		if(my == import && strcmp(import->name, package) == 0)
+			break;
+
+		if(my->lexical != LNAME || my->oname != N || my->otype != T) {
+			// TODO(rsc): this line is only needed because of the
+			//	package net
+			//	import "net"
+			// convention; if we get rid of it, the check can go away
+			// and we can just always print the error
+			if(my->lexical != LPACK || strcmp(my->opack, import->name) != 0)
+				yyerror("redeclaration of %S by import", my);
+		}
+		my->lexical = LPACK;
+		my->opack = import->name;
+	}
+
 hidden_import_list:
 	{
 		defercheckwidth();
@@ -963,8 +1012,16 @@ pexpr:
 lpack:
 	LPACK
 	{
-		context = $1->name;
+		context = $1->opack;
+	}
+/*
+ * adding this would enable gri's nested package idea
+ *
+|	lpack '.' LPACK
+	{
+		context = $3->opack;
 	}
+ */
 
 laconst:
 	LACONST
@@ -2028,7 +2085,6 @@ hidden_importsym:
 	sym1 '.' sym2
 	{
 		$$ = nod(OIMPORT, N, N);
-		$$->osym = $1;
 		$$->psym = $1;
 		$$->sym = $3;
 	}
diff --git a/src/cmd/gc/lex.c b/src/cmd/gc/lex.c
index e5edf5051..43cd2f6f8 100644
--- a/src/cmd/gc/lex.c
+++ b/src/cmd/gc/lex.c
@@ -773,7 +773,7 @@ talph:
 		s = pkglookup(s->name, context);
 		if(s->lexical == LIGNORE)
 			goto l0;
-		if(!exportname(s->name) && strcmp(package, s->opackage) != 0)
+		if(!exportname(s->name) && strcmp(package, s->package) != 0)
 			s = pkglookup(s->name, ".private");
 	}
 
@@ -1134,7 +1134,6 @@ static	struct
 	"string",	LBASETYPE,	TSTRING,
 
 	"any",		LBASETYPE,	TANY,
-	"sys",		LPACK,		Txxx,
 
 	"break",	LBREAK,		Txxx,
 	"case",		LCASE,		Txxx,
@@ -1200,6 +1199,7 @@ lexinit(void)
 		lex = syms[i].lexical;
 		s = lookup(syms[i].name);
 		s->lexical = lex;
+		s->package = package;
 
 		if(lex != LBASETYPE)
 			continue;
@@ -1220,6 +1220,14 @@ lexinit(void)
 		types[etype] = t;
 		s->otype = t;
 	}
+
+	// logically, the type of a string literal.
+	// types[TSTRING] is the named type string
+	// (the type of x in var x string or var x = "hello").
+	// this is the ideal form
+	// (the type of x in const x = "hello").
+	// TODO(rsc): this may need some more thought.
+	idealstring = typ(TSTRING);
 }
 
 struct
@@ -1304,15 +1312,16 @@ mkpackage(char* pkg)
 	}
 
 	// redefine all names to be this package
-	package = pkg;
 	for(h=0; h<NHASH; h++)
-		for(s = hash[h]; s != S; s = s->link) {
-			s->package = package;
-			s->opackage = package;
-		}
+		for(s = hash[h]; s != S; s = s->link)
+			if(s->package == package)
+				s->package = pkg;
+	package = pkg;
 
 	// declare this name as a package
-	lookup(package)->lexical = LPACK;
+	s = lookup(package);
+	s->lexical = LPACK;
+	s->opack = s->name;
 
 	if(outfile == nil) {
 		p = strrchr(infile, '/');
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 50f526981..6a5ee5dc7 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -151,14 +151,13 @@ lookup(char *p)
 		if(s->name[0] != c)
 			continue;
 		if(strcmp(s->name, p) == 0)
-			if(strcmp(s->package, package) == 0)
+			if(s->package && strcmp(s->package, package) == 0)
 				return s;
 	}
 
 	s = mal(sizeof(*s));
 	s->lexical = LNAME;
 	s->name = mal(strlen(p)+1);
-	s->opackage = package;
 	s->package = package;
 
 	strcpy(s->name, p);
@@ -182,7 +181,7 @@ pkglookup(char *p, char *k)
 		if(s->name[0] != c)
 			continue;
 		if(strcmp(s->name, p) == 0)
-			if(strcmp(s->package, k) == 0)
+			if(s->package && strcmp(s->package, k) == 0)
 				return s;
 	}
 
@@ -193,7 +192,6 @@ pkglookup(char *p, char *k)
 
 	// botch - should probably try to reuse the pkg string
 	s->package = mal(strlen(k)+1);
-	s->opackage = s->package;
 	strcpy(s->package, k);
 
 	s->link = hash[h];
@@ -202,6 +200,37 @@ pkglookup(char *p, char *k)
 	return s;
 }
 
+// find all the symbols in package opkg
+// and make them available in the current package
+void
+importdot(Sym *opkg)
+{
+	Sym *s, *s1;
+	uint32 h;
+	int c;
+
+	if(strcmp(opkg->name, package) == 0)
+		return;
+
+	c = opkg->name[0];
+	for(h=0; h<NHASH; h++) {
+		for(s = hash[h]; s != S; s = s->link) {
+			if(s->package[0] != c)
+				continue;
+			if(strcmp(s->package, opkg->name) != 0)
+				continue;
+			s1 = lookup(s->name);
+			if(s1->oname != N || s1->otype != T) {
+				yyerror("redeclaration of %S during import", s1);
+				continue;
+			}
+			s1->lexical = s->lexical;
+			s1->oname = s->oname;
+			s1->otype = s->otype;
+		}
+	}
+}
+
 void
 gethunk(void)
 {
@@ -942,7 +971,7 @@ int
 Sconv(Fmt *fp)
 {
 	Sym *s;
-	char *opk, *pkg, *nam;
+	char *pkg, *nam;
 
 	s = va_arg(fp->args, Sym*);
 	if(s == S) {
@@ -952,18 +981,15 @@ Sconv(Fmt *fp)
 
 	pkg = "<nil>";
 	nam = pkg;
-	opk = pkg;
 
-	if(s->opackage != nil)
-		opk = s->opackage;
 	if(s->package != nil)
 		pkg = s->package;
 	if(s->name != nil)
 		nam = s->name;
 
 	if(!(fp->flags & FmtShort))
-	if(strcmp(opk, package) != 0 || (fp->flags & FmtLong)) {
-		fmtprint(fp, "%s.%s", opk, nam);
+	if(strcmp(pkg, package) != 0 || (fp->flags & FmtLong)) {
+		fmtprint(fp, "%s.%s", pkg, nam);
 		return 0;
 	}
 	fmtstrcpy(fp, nam);
@@ -1013,7 +1039,7 @@ Tpretty(Fmt *fp, Type *t)
 				fmtprint(fp, "%hS", s);
 			else
 				fmtprint(fp, "%lS", s);
-			if(strcmp(s->opackage, package) == 0)
+			if(strcmp(s->package, package) == 0)
 			if(s->otype != t || (!s->export && !s->imported)) {
 				fmtprint(fp, "·%s", filename);
 				if(t->vargen)
@@ -1607,7 +1633,7 @@ bad:
 }
 
 int
-eqtype1(Type *t1, Type *t2, int d)
+eqtype1(Type *t1, Type *t2, int d, int names)
 {
 	if(d >= 10)
 		return 1;
@@ -1617,13 +1643,15 @@ eqtype1(Type *t1, Type *t2, int d)
 		return 0;
 	if(t1->etype != t2->etype)
 		return 0;
+	if(names && t1->etype != TFIELD && t1->sym && t2->sym && t1 != t2)
+		return 0;
 	switch(t1->etype) {
 	case TINTER:
 	case TSTRUCT:
 		t1 = t1->type;
 		t2 = t2->type;
 		for(;;) {
-			if(!eqtype1(t1, t2, d+1))
+			if(!eqtype1(t1, t2, d+1, names))
 				return 0;
 			if(t1 == T)
 				return 1;
@@ -1659,7 +1687,7 @@ eqtype1(Type *t1, Type *t2, int d)
 					return 0;
 				if(ta->etype != TFIELD || tb->etype != TFIELD)
 					return 0;
-				if(!eqtype1(ta->type, tb->type, d+1))
+				if(!eqtype1(ta->type, tb->type, d+1, names))
 					return 0;
 				ta = ta->down;
 				tb = tb->down;
@@ -1675,13 +1703,19 @@ eqtype1(Type *t1, Type *t2, int d)
 			break;
 		return 0;
 	}
-	return eqtype1(t1->type, t2->type, d+1);
+	return eqtype1(t1->type, t2->type, d+1, names);
 }
 
 int
 eqtype(Type *t1, Type *t2)
 {
-	return eqtype1(t1, t2, 0);
+	return eqtype1(t1, t2, 0, 1);
+}
+
+int
+cvttype(Type *t1, Type *t2)
+{
+	return eqtype1(t1, t2, 0, 0);
 }
 
 int
@@ -1690,7 +1724,6 @@ eqtypenoname(Type *t1, Type *t2)
 	if(t1 == T || t2 == T || t1->etype != TSTRUCT || t2->etype != TSTRUCT)
 		return eqtype(t1, t2);
 
-
 	t1 = t1->type;
 	t2 = t2->type;
 	for(;;) {
@@ -2576,7 +2609,7 @@ expand0(Type *t, int followptr)
 
 	if(u->etype == TINTER) {
 		for(f=u->type; f!=T; f=f->down) {
-			if(!exportname(f->sym->name) && strcmp(f->sym->opackage, package) != 0)
+			if(!exportname(f->sym->name) && strcmp(f->sym->package, package) != 0)
 				continue;
 			if(f->sym->uniq)
 				continue;
@@ -2593,7 +2626,7 @@ expand0(Type *t, int followptr)
 	u = methtype(t);
 	if(u != T) {
 		for(f=u->method; f!=T; f=f->down) {
-			if(!exportname(f->sym->name) && strcmp(f->sym->opackage, package) != 0)
+			if(!exportname(f->sym->name) && strcmp(f->sym->package, package) != 0)
 				continue;
 			if(f->sym->uniq)
 				continue;
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index f5d390203..c2beb3cae 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1107,15 +1107,8 @@ loop:
 		break;
 	}
 
-	if(t == T) {
+	if(t == T)
 		t = n->left->type;
-		// throw away name:
-		//	type MyInt int
-		//	var x MyInt = 0;
-		// -x has type int, not MyInt.
-		if(t != T)
-			t = types[t->etype];
-	}
 	n->type = t;
 	goto ret;
 
@@ -1210,7 +1203,7 @@ walkconv(Node *n)
 		return;
 
 	// nil conversion
-	if(eqtype(t, l->type)) {
+	if(cvttype(t, l->type)) {
 		if(l->op != ONAME) {
 			indir(n, l);
 			n->type = t;