ww/test/wcc/842_dup_main_reject.c

/*
 * 841_dup_main_reject — cstage and wwstage LOUD-REJECT a program that
 * declares more than one top-level `main` (F-D; rob ruling 2026-06-14).
 *
 * `main` lowers to ONE bare entry symbol. A second top-level decl named
 * `main` (any kind, any package) collides with the entry at link time:
 * the `let main` DATA symbol and the entry `fn main` TEXT symbol clash.
 * Pre-fix BOTH stages built the program rc=0 and SEGFAULTED at runtime
 * (the w6l silent-dup-symbol latent, task #31); align both UP to a loud
 * compile-time reject. Correct multi-main mangling (entry stays bare,
 * every other `main` module-qualifies) is the deferred root-unit entry
 * detection (task #32) — until then the collision is rejected, never
 * silently miscompiled (rule 7).
 *
 * The reject is program-GLOBAL, name-only, CROSS-MODULE: it counts
 * top-level decls named "main" across the fully-bundled program. The
 * existing duplicate-decl rejects key on (name, MODULE), so they read a
 * cross-package `foo.main` and the bare entry `main` as DISTINCT and
 * miss this clash. The trigger is COUNT("main") > 1, NOT package
 * identity — ww has no package-main convention (examples/cmatrix, lisp,
 * mandelbrot are working entries with `fn main` in a non-main package).
 *
 * Each reject row is a GENUINE cross-module case: a real `import foo;`
 * binds package foo, so decl_mod stamps foo's `main` with module "foo"
 * and the entry `main` with module NULL — DISTINCT keys the existing
 * (name, module) reject reads apart and lets through. Without the
 * import both `main`s collapse to module NULL and the OLD `duplicate fn
 * main` reject already fires, so the import is what exercises THIS
 * check (verified: pre-fix base 7a6b67f builds every row rc=0).
 *
 *   row             | shape                                   | expect
 *   ----------------+-----------------------------------------+--------
 *   let_main        | import foo; foo `let main` + entry main  | REJECT
 *   fn_main         | import foo; foo `fn main`  + entry main  | REJECT
 *   def_main        | import foo; foo `def main` + entry main  | REJECT
 *   type_main       | import foo; foo `type main`+ entry main  | REJECT
 *   single_nonmain  | one `fn main` in a NON-main package      | BUILD,
 *                   | (cmatrix-style) — the corpus-safety      | run 7
 *                   | guard: a lone main must STILL compile.   |
 *
 * DISCRIMINATION (verified against a clean 7a6b67f base): pre-fix the
 * let_main/def_main rows built rc=0 then exited 139 (SIGSEGV) and
 * fn_main/type_main built rc=0 and ran the WRONG entry (two bare `TEXT
 * main` symbols, the w6l silent-dup latent task #31); post-fix every
 * row loud-rejects at compile (build rc!=0, no binary), both stages.
 * The single_nonmain row proves the reject did not eat the working
 * single-`main` corpus.
 */
#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;
}

static int
filehas(const char *path, const char *needle)
{
	char buf[8192];
	FILE *f = fopen(path, "rb");
	if (!f) return 0;
	size_t n = fread(buf, 1, sizeof buf - 1, f);
	fclose(f);
	buf[n] = '\0';
	return strstr(buf, needle) != NULL;
}

/* build_should_fail — a dup-`main` program must error on `driver`
 * (loud reject); returns 0 when the build FAILS *and* emits `diag`.
 * This test drives the full `ww` driver, so a crash inside w6c also
 * surfaces as the driver's "w6c failed" exit 1 — the diagnostic-substring
 * check is the ONLY way to tell a crash from a clean reject here (#20).
 * Intermediates land in tmpdir, never the source tree (rule 14). */
static int
build_should_fail(const char *driver, const char *label, const char *src,
    const char *diag, int i)
{
	char s[128], tmpdir[64], outbin[128], errf[128], rmcmd[160], cmd[1024];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/dupmain_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/dupmain_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/out", tmpdir);
	snprintf(errf, sizeof errf, "%s/err.txt", tmpdir);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);

	FILE *f = fopen(s, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	fputs(src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s build -o %s %s >/dev/null 2>%s",
	    driver, outbin, s, errf);
	int rc = runwait(cmd);
	int hasmsg = filehas(errf, diag);

	runwait(rmcmd);
	if (rc == 0) {
		fprintf(stderr,
		    "dup_main[%s][%s]: built ok, expected a loud reject\n",
		    driver, label);
		return -1;
	}
	if (!hasmsg) {
		fprintf(stderr, "dup_main[%s][%s]: nonzero exit but missing "
		    "diagnostic \"%s\" (a crash, not a clean reject)\n",
		    driver, label, diag);
		return -1;
	}
	return 0;
}

/* run_build — build a program that MUST compile, run it, return its
 * exit code (the corpus-safety guard). */
static int
run_build(const char *driver, const char *label, const char *src, int i)
{
	char s[128], tmpdir[64], outbin[128], rmcmd[160], cmd[1024];
	snprintf(tmpdir, sizeof tmpdir, "/tmp/dupmain_ok_%d_d_%d", getpid(), i);
	mkdir(tmpdir, 0755);
	snprintf(s, sizeof s, "%s/dupmain_ok_%d_%d.ww", tmpdir, getpid(), i);
	snprintf(outbin, sizeof outbin, "%s/dupmain_ok_%d_%d", tmpdir, getpid(), i);
	snprintf(rmcmd, sizeof rmcmd, "rm -rf %s", tmpdir);

	FILE *f = fopen(s, "wb");
	if (!f) { runwait(rmcmd); return -1; }
	fputs(src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s build -o %s %s 2>/dev/null",
	    driver, outbin, s);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "dup_main[%s][%s]: build failed (corpus "
		    "regression — a lone main must compile)\n", driver, label);
		runwait(rmcmd);
		return -1;
	}
	int got = runwait(outbin);
	runwait(rmcmd);
	return got;
}

struct rejrow { const char *label; const char *src; const char *diag; };

/* Each program declares a second top-level `main` (in package foo)
 * alongside the entry `fn main` (in package main), bound by a REAL
 * `import foo;` — so decl_mod stamps the two `main`s with DISTINCT
 * modules ("foo" vs NULL) and the existing (name, module) reject reads
 * them apart and misses the clash; only THIS program-global name-only
 * reject fires. The driver bundles both packages into one unit; foo
 * also exports `anchor` so the import is used and foo resolves. */
static const struct rejrow reject_rows[] = {
	{ "let_main",
	  "package foo;\n"
	  "export let main: i32 = 99;\n"
	  "export fn anchor() i32 = { return main; };\n"
	  "package main;\n"
	  "import foo;\n"
	  "fn main() i32 = { return foo.anchor(); };\n",
	  "duplicate entry main" },

	{ "fn_main",
	  "package foo;\n"
	  "export fn main() i32 = { return 1; };\n"
	  "export fn anchor() i32 = { return 2; };\n"
	  "package main;\n"
	  "import foo;\n"
	  "fn main() i32 = { return foo.anchor(); };\n",
	  "duplicate entry main" },

	{ "def_main",
	  "package foo;\n"
	  "export def main: i32 = 5;\n"
	  "export fn anchor() i32 = { return main; };\n"
	  "package main;\n"
	  "import foo;\n"
	  "fn main() i32 = { return foo.anchor(); };\n",
	  "duplicate entry main" },

	{ "type_main",
	  "package foo;\n"
	  "export type main = i32;\n"
	  "export fn anchor() i32 = { return 3; };\n"
	  "package main;\n"
	  "import foo;\n"
	  "fn main() i32 = { return foo.anchor(); };\n",
	  "duplicate entry main" },
};

struct okrow { const char *label; const char *src; int want; };

/* The corpus-safety guard: a SINGLE `fn main` in a NON-main package
 * (cmatrix/lisp/mandelbrot style) MUST still compile and run. */
static const struct okrow ok_rows[] = {
	{ "single_nonmain",
	  "package cmatrix;\n"
	  "fn main() i32 = { return 7; };\n",
	  7 },
};

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);

	struct { const char *name; const char *path; int gated; } drivers[] = {
		{ "cstage",  cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

	int nrej = (int)(sizeof reject_rows / sizeof reject_rows[0]);
	int nok = (int)(sizeof ok_rows / sizeof ok_rows[0]);
	int total = 0, fail = 0;

	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "dup_main: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < nrej; i++) {
			total++;
			if (build_should_fail(drivers[d].path,
			    reject_rows[i].label, reject_rows[i].src,
			    reject_rows[i].diag, d * 100 + i) != 0)
				fail++;
		}
		for (int i = 0; i < nok; i++) {
			total++;
			int got = run_build(drivers[d].path, ok_rows[i].label,
			    ok_rows[i].src, d * 100 + i);
			if (got != ok_rows[i].want) {
				fprintf(stderr,
				    "dup_main[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, ok_rows[i].label,
				    got, ok_rows[i].want);
				fail++;
			}
		}
	}

	if (fail) {
		fprintf(stderr, "dup_main: %d/%d fixtures failed\n",
		    fail, total);
		return 1;
	}
	printf("dup_main: %d/%d ok\n", total, total);
	return 0;
}