w6c+selfhost: same-module preference for bare-leaf lookup

selfhost/cmd/wcc/check.ww

@@ -31,6 +31,10 @@ type checker = struct {
 	errs:        i32,
 	verbose:     i32,	// when non-zero, log each unresolved name
 	fnret:       *node,	// enclosing fn's return type AST (for `?`)
+	curmod:      str,	// importing-module bareword for the decl
+				// currently being walked; "" for primary
+				// compilation unit. Drives same-module
+				// preference in bare-leaf lookups.
 };
 
 // seedprimitives — install the built-in type names so `i32`, `str`,
@@ -129,7 +133,7 @@ fn resolvewalk(c: *checker, n: *node) void = {
 	if (k == nkind.N_IDENT) {
 		let nm: str = n.str;
 		if (nm.len > 0) {
-			let s: *sym = scopelookup(c.cur, nm);
+			let s: *sym = scopelookupprefer(c.cur, c.curmod, nm);
 			if (s == nil) {
 				c.nunresolved += 1;
 				if (c.verbose != 0) {
@@ -144,7 +148,7 @@ fn resolvewalk(c: *checker, n: *node) void = {
 	if (k == nkind.N_TNAME) {
 		let nm: str = n.str;
 		if (nm.len > 0) {
-			let s: *sym = scopelookup(c.cur, nm);
+			let s: *sym = scopelookupprefer(c.cur, c.curmod, nm);
 			// `pkg.Type` — strip the last dot prefix and look up
 			// the leaf with a mod filter so same-leaf-name types
 			// from different imports (`bufio.stream` vs
@@ -943,6 +947,8 @@ export fn checkinit(c: *checker, a: *arena, tc: *tctx) void = {
 	c.errs = 0;
 	c.verbose = 0;
 	c.fnret = nil;
+	let empty: str;
+	c.curmod = empty;
 	seedprimitives(c);
 };
 
@@ -958,8 +964,12 @@ export fn checkfile(c: *checker, file: *node) void = {
 	};
 
 	// Pass 2: walk decl bodies/types and resolve identifiers.
+	// Track the per-decl module bareword so bare-leaf lookups inside
+	// the body prefer same-module entries over alphabetically-earlier
+	// same-leaf imports.
 	d = file.list;
 	for (d != nil) {
+		c.curmod = declmod(file, d);
 		let k: nkind = d.kind;
 		if (k == nkind.N_FNDECL) {
 			if (d.lhs != nil) { resolvewalk(c, d.lhs); };	// return type
@@ -975,5 +985,7 @@ export fn checkfile(c: *checker, file: *node) void = {
 		};};};};
 		d = d.next;
 	};
+	let empty: str;
+	c.curmod = empty;
 
 };