ww driver: zero discovered tests is a loud failure

rundirtests returned rc=0 when it discovered no tests — a typo'd
path or empty corpus read as success. Fail loudly, matching the
cstage driver.

Makefile

@@ -266,6 +266,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_wwdumpgate_run \
 	  $(BIN)/test_datargate_run \
 	  $(BIN)/test_dynentry_run \
+	  $(BIN)/test_zerotest_run \
 	  $(BIN)/test_ampfncollide_run \
 	  $(BIN)/test_trycallcollide_run \
 	  $(BIN)/test_gunsigned_run \
@@ -860,6 +861,16 @@ $(BIN)/test_dynentry_run: test/wcc/989_dynentry_run.c \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+# 989_zerotest_run (#64, F15 c7): `ww test <dir>` over a directory with no
+# *_test.ww files fails loud (rc=1 + "no *_test.ww files in ...") instead of a
+# silent rc=0 false-green. Runs both driver twins (rule-10). See the header.
+$(BIN)/test_zerotest_run: test/wcc/989_zerotest_run.c \
+		$(BIN)/ww $(BIN)/ww_ww \
+		$(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
+		$(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 # 989_ampfncollide_run (#4, c2): `&fn` synthesis (unoptype TK_AMP +
 # assignableaddrfn) prefers the current module's fn when a same-leaf fn is
 # declared in a later module. Builds/rejects on BOTH driver twins (rule-10).

selfhost/cmd/ww/main.combined.ww

@@ -4394,6 +4394,7 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 
 	let pass: i32 = 0;
 	let fail: i32 = 0;
+	let seen: i32 = 0;	// #64: count *_test.ww matches for the zero-test gate
 	let buf: []u8 = alloc([], 8192u64)!;
 	buf.len = 8192;
 	let dirlen: u64 = cstrlen(dir);
@@ -4409,6 +4410,7 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 			let reclen: u64 = blo + (bhi * 256u64);
 			let name: *u8 = buf.ptr + off + 19u64;
 			if (cstrendswithlit(name, "_test.ww")) {
+				seen += 1;
 				let nlen: u64 = cstrlen(name);
 				// path = <dir>/<name>
 				let path: []u8 = alloc([], (os.PATH_MAX: u64))!;
@@ -4458,6 +4460,15 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 		n = os.getdents64(fd, buf.ptr, 8192u64);
 	};
 	os.close(fd);
+	// #64: a directory with no *_test.ww files is a loud failure, not a
+	// silent rc=0 false-green. Mirrors cstage do_test (cmd/ww/main.c:945)
+	// "ww test: no *_test.ww files in %s".
+	if (seen == 0) {
+		cerr("ww test: no *_test.ww files in ");
+		os.write(2, dir, dirlen);
+		cerr("\n");
+		return 1;
+	};
 	if (fail == 0) { return 0; };
 	return 1;
 };

selfhost/cmd/ww/main.ww

@@ -1556,6 +1556,7 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 
 	let pass: i32 = 0;
 	let fail: i32 = 0;
+	let seen: i32 = 0;	// #64: count *_test.ww matches for the zero-test gate
 	let buf: []u8 = alloc([], 8192u64)!;
 	buf.len = 8192;
 	let dirlen: u64 = cstrlen(dir);
@@ -1571,6 +1572,7 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 			let reclen: u64 = blo + (bhi * 256u64);
 			let name: *u8 = buf.ptr + off + 19u64;
 			if (cstrendswithlit(name, "_test.ww")) {
+				seen += 1;
 				let nlen: u64 = cstrlen(name);
 				// path = <dir>/<name>
 				let path: []u8 = alloc([], (os.PATH_MAX: u64))!;
@@ -1620,6 +1622,15 @@ fn rundirtests(selfdir: *u8, dir: *u8) i32 = {
 		n = os.getdents64(fd, buf.ptr, 8192u64);
 	};
 	os.close(fd);
+	// #64: a directory with no *_test.ww files is a loud failure, not a
+	// silent rc=0 false-green. Mirrors cstage do_test (cmd/ww/main.c:945)
+	// "ww test: no *_test.ww files in %s".
+	if (seen == 0) {
+		cerr("ww test: no *_test.ww files in ");
+		os.write(2, dir, dirlen);
+		cerr("\n");
+		return 1;
+	};
 	if (fail == 0) { return 0; };
 	return 1;
 };

test/wcc/989_zerotest_run.c

@@ -0,0 +1,145 @@
+/*
+ * 989_zerotest_run (#64, F15 c7) — `ww test <dir>` over a directory with no
+ * *_test.ww files must fail loud, not return rc=0 with a silent false-green.
+ *
+ * THE BUG (wwstage driver only, cat-A silent false-green under rc=0):
+ * rundirtests had no zero-count check — a directory with no *_test.ww files
+ * yielded pass=0 fail=0 → `return 0` with no output at all. A typo'd or empty
+ * test dir got a silent green from the wwstage driver, while cstage do_test
+ * errors "ww test: no *_test.ww files in %s" rc=1 (cmd/ww/main.c:945). THE FIX:
+ * count *_test.ww matches and loud-fail (rc=1 + the same message) when zero.
+ *
+ *   row     | dir contents              | result (cs==ww)
+ *   --------+---------------------------+----------------------------
+ *   empty   | no files                  | rc != 0 (loud "no *_test.ww")
+ *   nomatch | foo.ww (not *_test.ww)    | rc != 0 (loud)
+ *   healthy | foo_test.ww (1 @test)     | rc == 0 (control)
+ *
+ * empty / nomatch were RED pre-c7 on wwstage (rc=0, no output, false-green).
+ * healthy pins the real-test path: both stages run it and exit 0.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+static int
+runwait(const char *cmd)
+{
+	int rc = system(cmd);
+	if (rc == -1) return -1;
+	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
+	return -1;
+}
+
+/* Set up a fresh dir; optionally drop a file with `body` named `fname`.
+ * Returns the dir path in `dir`. */
+static void
+make_dir(char *dir, size_t dsz, const char *tag, const char *fname,
+    const char *body)
+{
+	char cmd[256], fp[256];
+	snprintf(dir, dsz, "/tmp/zt_%d_%s", getpid(), tag);
+	snprintf(cmd, sizeof cmd, "rm -rf %s && mkdir -p %s", dir, dir);
+	system(cmd);
+	if (fname) {
+		snprintf(fp, sizeof fp, "%s/%s", dir, fname);
+		FILE *f = fopen(fp, "wb");
+		if (f) { fputs(body, f); fclose(f); }
+	}
+}
+
+/* `<driver> test <dir>` rc. */
+static int
+run_test(const char *driver, const char *dir)
+{
+	char cmd[1024];
+	snprintf(cmd, sizeof cmd, "%s test %s >/dev/null 2>&1", driver, dir);
+	return runwait(cmd);
+}
+
+int
+main(void)
+{
+	const char *bin = getenv("BIN");
+	if (!bin) bin = "out/bin";
+	char absbin[1024];
+	if (bin[0] != '/') {
+		char cwd[1024];
+		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
+		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
+		bin = absbin;
+	}
+	char cdrv[1024], wdrv[1024];
+	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
+	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);
+	int have_ww = (access(wdrv, X_OK) == 0);
+	if (!have_ww)
+		fprintf(stderr, "zerotest: skip wwstage (no %s)\n", wdrv);
+
+	struct row { const char *tag; const char *fname; const char *body;
+	    int want_loud; };
+	struct row rows[] = {
+		{ "empty",   NULL, NULL, 1 },
+		{ "nomatch", "foo.ww",
+		  "package main;\nexport fn main() i32 = { return 0; };\n", 1 },
+		{ "healthy", "foo_test.ww",
+		  "package zt_test;\n@test fn t_ok() void = { };\n", 0 },
+	};
+
+	int n = (int)(sizeof rows / sizeof rows[0]);
+	int fail = 0, total = 0;
+	for (int i = 0; i < n; i++) {
+		total++;
+		char dir[128];
+		make_dir(dir, sizeof dir, rows[i].tag, rows[i].fname, rows[i].body);
+
+		int crc = run_test(cdrv, dir);
+		if (rows[i].want_loud) {
+			if (crc == 0) {
+				fprintf(stderr, "zerotest[cstage][%s]: rc=0, expected loud "
+				    "no-tests failure\n", rows[i].tag);
+				fail++;
+			}
+		} else if (crc != 0) {
+			fprintf(stderr, "zerotest[cstage][%s]: rc=%d, expected 0\n",
+			    rows[i].tag, crc);
+			fail++;
+		}
+
+		if (have_ww) {
+			int wrc = run_test(wdrv, dir);
+			if (rows[i].want_loud) {
+				if (wrc == 0) {
+					fprintf(stderr, "zerotest[wwstage][%s]: rc=0 on a dir with "
+					    "no *_test.ww (silent false-green — #64)\n", rows[i].tag);
+					fail++;
+				}
+				if ((crc == 0) != (wrc == 0)) {
+					fprintf(stderr, "zerotest[%s]: loud divergence cs_rc=%d "
+					    "ww_rc=%d (#64)\n", rows[i].tag, crc, wrc);
+					fail++;
+				}
+			} else {
+				if (wrc != 0) {
+					fprintf(stderr, "zerotest[wwstage][%s]: rc=%d, expected 0\n",
+					    rows[i].tag, wrc);
+					fail++;
+				}
+			}
+		}
+
+		char cmd[160];
+		snprintf(cmd, sizeof cmd, "rm -rf %s", dir);
+		system(cmd);
+	}
+
+	if (fail) {
+		fprintf(stderr, "zerotest_run: %d/%d check(s) failed\n", fail, total);
+		return 1;
+	}
+	printf("zerotest_run: %d/%d ok\n", total, total);
+	return 0;
+}