lib+test: fmt rename fprint→fdprint; add io.stream fprint sink

test/wcc/970_fmt_run.c

@@ -0,0 +1,52 @@
+/*
+ * 970_fmt_run — execute the lib/fmt @test fixture under the C-side
+ * `ww run` driver and assert exit 0.
+ *
+ * fmt sits below io conceptually (sinks formatted bytes into an
+ * io.stream); slotting at 970 keeps it ahead of the 980-989
+ * stdlib-run sub-band that depends on it. fmttest.ww carries its
+ * own `export fn main()` that drives the @test fns and signals
+ * which case failed via the exit code, so this file is a thin
+ * wrapper — no @test scanning, no synthetic main generation.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.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;
+}
+
+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 cwd[1024];
+	if (getcwd(cwd, sizeof cwd) == NULL) return 1;
+
+	const char *src = "lib/fmt/fmttest.ww";
+	char path[1024], cmd[2048];
+	snprintf(path, sizeof path, "%s/%s", cwd, src);
+	snprintf(cmd, sizeof cmd, "%s/ww run %s", bin, path);
+	int rc = runwait(cmd);
+	if (rc != 0) {
+		fprintf(stderr, "fmt_run FAIL: %s exited %d\n", src, rc);
+		return 1;
+	}
+	printf("fmt_run: %s ok\n", src);
+	return 0;
+}