ww+wcc: emit and lex // MODULE: <name> directive in combined.ww

cmd/ww/main.c

@@ -113,6 +113,36 @@ locate_import(const char *dirs, const char *name, char *out, size_t outsz)
 	return 0;
 }
 
+/* module_of — pick the source's containing-directory basename.
+ * lib/os/os.ww      -> "os"
+ * selfhost/cmd/wcc/sym.ww -> "wcc"
+ * bare "main.ww"    -> "main"
+ * Writes into dst (size ≥ 1); always NUL-terminates. */
+static void
+module_of(const char *path, char *dst, size_t dstn)
+{
+	if (dstn == 0) return;
+	dst[0] = '\0';
+	const char *last = strrchr(path, '/');
+	if (last == NULL) {
+		/* bare filename — use the stem (path minus .ww). */
+		size_t n = strlen(path);
+		if (n >= 3 && strcmp(path + n - 3, ".ww") == 0) n -= 3;
+		if (n >= dstn) n = dstn - 1;
+		memcpy(dst, path, n);
+		dst[n] = '\0';
+		return;
+	}
+	/* Basename of the parent directory. */
+	const char *prev = last - 1;
+	while (prev >= path && *prev != '/') prev--;
+	prev++;
+	size_t n = (size_t)(last - prev);
+	if (n >= dstn) n = dstn - 1;
+	memcpy(dst, prev, n);
+	dst[n] = '\0';
+}
+
 /* Recursively expand `path`: for each top-level `use IDENT;` we find,
  * resolve the import and expand it first, then append our own bytes.
  * Already-visited paths are skipped. */
@@ -156,6 +186,15 @@ expand(FILE *out, const char *path, struct ImportSet *visited,
 		expand(out, ipath, visited, libdir);
 	}
 
+	/* Prefix a `// MODULE: <name>` directive so the ww-side wcc lexer
+	 * can stamp each top-level decl with its originating module. The
+	 * marker is a comment to every other reader (including the C-side
+	 * wcc), so it's safe to emit unconditionally. */
+	char modname[128];
+	module_of(path, modname, sizeof modname);
+	if (modname[0] != '\0')
+		fprintf(out, "// MODULE: %s\n", modname);
+
 	rewind(in);
 	int ch;
 	while ((ch = fgetc(in)) != EOF) fputc(ch, out);