ww: implement local vendor package semantics

cmd/w6c/main.c

@@ -41,6 +41,19 @@ struct importin {
 	u64 len;
 };
 
+struct importmap {
+	const char *source;
+	const char *path;
+	int seen;
+};
+
+static const char *
+importleaf(const char *path)
+{
+	const char *dot = strrchr(path, '.');
+	return dot != NULL ? dot + 1 : path;
+}
+
 static Node *
 parseinput(Arena *a, const char *file, char *buf, u64 len,
     const char *mod, const char *testsupport, int commandpackage, int *bad)
@@ -85,11 +98,15 @@ main(int argc, char **argv)
 				 * only codegen (emit imported==0 decls
 				 * only; treat `.wwi` deps as external) */
 	struct importin *imports = calloc((size_t)argc, sizeof *imports);
-	if (imports == NULL) {
+	struct importmap *maps = calloc((size_t)argc, sizeof *maps);
+	if (imports == NULL || maps == NULL) {
 		fputs("w6c: out of memory\n", stderr);
+		free(maps);
+		free(imports);
 		return 1;
 	}
 	int nimports = 0;
+	int nmaps = 0;
 	for (int i = 1; i < argc; i++) {
 		const char *a = argv[i];
 		if (strcmp(a, "-o") == 0 && i + 1 < argc) {
@@ -120,6 +137,14 @@ main(int argc, char **argv)
 			imports[nimports].path = argv[++i];
 			imports[nimports].file = argv[++i];
 			nimports++;
+		} else if (strcmp(a, "--import-map") == 0) {
+			if (i + 2 >= argc) {
+				fputs("w6c: --import-map requires source and path\n", stderr);
+				return 2;
+			}
+			maps[nmaps].source = argv[++i];
+			maps[nmaps].path = argv[++i];
+			nmaps++;
 		} else if (a[0] == '-') {
 			fprintf(stderr, "w6c: unknown flag %s\n", a);
 			return 2;
@@ -132,13 +157,17 @@ main(int argc, char **argv)
 	}
 	if (src == NULL) {
 		fputs("usage: w6c [-T|--test-package] [--command-package] [--entry] [-c] [-I out.wwi] "
-		    "[--import path dep.wwi]... [-o out.s] file.ww\n", stderr);
+		    "[--import path dep.wwi]... [--import-map source path]... [-o out.s] file.ww\n", stderr);
 		return 2;
 	}
 	if (nimports > 0 && !sepmode) {
 		fputs("w6c: --import requires -c\n", stderr);
 		return 2;
 	}
+	if (nmaps > 0 && !sepmode) {
+		fputs("w6c: --import-map requires -c\n", stderr);
+		return 2;
+	}
 	if ((entrymode || testpackage || commandpackage) && !sepmode) {
 		fputs("w6c: --entry, --test-package, and --command-package require -c\n", stderr);
 		return 2;
@@ -157,6 +186,33 @@ main(int argc, char **argv)
 			return 2;
 		}
 	}
+	for (int i = 0; i < nmaps; i++) {
+		if (maps[i].source[0] == '\0' || maps[i].path[0] == '\0') {
+			fputs("w6c: --import-map path is empty\n", stderr);
+			return 2;
+		}
+		if (i > 0 && strcmp(maps[i-1].source, maps[i].source) >= 0) {
+			fputs("w6c: --import-map sources must be sorted and unique\n",
+			    stderr);
+			return 2;
+		}
+		if (strcmp(importleaf(maps[i].source),
+		    importleaf(maps[i].path)) != 0) {
+			fputs("w6c: --import-map must preserve import leaf\n", stderr);
+			return 2;
+		}
+		int direct = 0;
+		for (int j = 0; j < nimports; j++)
+			if (strcmp(maps[i].path, imports[j].path) == 0) {
+				direct = 1;
+				break;
+			}
+		if (!direct) {
+			fputs("w6c: --import-map target is not a direct import\n",
+			    stderr);
+			return 2;
+		}
+	}
 	if (testsupport != NULL && (!sepmode
 	    || (strcmp(testsupport, "test") != 0
 		&& strcmp(testsupport, "__wwtest") != 0))) {
@@ -203,6 +259,23 @@ main(int argc, char **argv)
 	Node *file = parseinput(a, src, buf, len, NULL, testsupport,
 	    commandpackage || entrymode, &bad);
 	if (bad) return 1;
+	/* Source keeps its effective spelling and leaf alias, while package
+	 * resolution supplies the expanded canonical owner. Rewrite only the
+	 * primary import key before imported interface nodes are prepended. */
+	for (Node *u = file->list; u; u = u->next) {
+		if (u->kind != N_USE || u->usepath == NULL) continue;
+		for (int i = 0; i < nmaps; i++)
+			if (strcmp(u->usepath, maps[i].source) == 0) {
+				u->usepath = maps[i].path;
+				maps[i].seen = 1;
+				break;
+			}
+	}
+	for (int i = 0; i < nmaps; i++) {
+		if (maps[i].seen) continue;
+		fputs("w6c: --import-map source is not in primary input\n", stderr);
+		return 2;
+	}
 	if (head != NULL) {
 		tail->next = file->list;
 		file->list = head;
@@ -250,6 +323,7 @@ main(int argc, char **argv)
 	freearena(a);
 	for (int i = 0; i < nimports; i++) free(imports[i].buf);
 	free(imports);
+	free(maps);
 	free(buf);
 	return 0;
 }