ww/test/wcc/759_check_enum_fold.c

/*
 * 759_check_enum_fold — table-driven sentinel for #22 / A.6.2.1a.
 *
 * check-side enum fold (selfhost/cmd/wcc/check.ww enumvalfold) now
 * mirrors cstage cmd/wcc/check.c:210-284 eval_enum_value: literals
 * (INTLIT/RUNELIT), unary +/-/~, binary arithmetic (+ - * / %),
 * bitwise (& | ^), shifts (<< >>), and sibling backref via
 * N_IDENT. The N_DOT fold mutates the AST to N_INTLIT in place, so
 * a wrong fold value leaks into cgen as the wrong literal and the
 * exit code reflects it. Each row is a self-contained ww program
 * whose `return EnumT.MEMBER: i32` carries the expected fold.
 *
 * Pre-#22 the check-side fold bailed on every shape but bare
 * N_INTLIT and auto-increment; cgen's enumevalmember
 * (selfhost/cmd/wcc/cgen.ww:158-227) absorbed the slack at codegen
 * time. Post-#22 check.ww does the fold itself so A.6.2.1e's
 * post-checker e.type_ assertion no longer fires on `EnumT.MEMBER`
 * references whose body is a backref or arithmetic expression.
 *
 * Each row runs through the cstage `ww` driver and through `ww_ww`
 * when present; the asm-byte-id diff between w6c and w6c_ww pins
 * the symmetric-emit contract (CLAUDE.md rule 10) so a future
 * drift between the two enumvalfold copies fails loud.
 */
#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;
}

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

static const struct row rows[] = {
	/* Baseline N_INTLIT — regression: the literal-only path was the
	 * pre-#22 fold contract and must still resolve. */
	{ "intlit",
	  "type e = enum i32 { A = 7 };\n"
	  "fn main() i32 = { return e.A: i32; };\n",
	  7 },

	/* N_RUNELIT — rune literals carry their codepoint in n.uval
	 * exactly like N_INTLIT (cmd/wcc/check.c:191). */
	{ "runelit",
	  "type e = enum i32 { A = 'A' };\n"
	  "fn main() i32 = { return e.A: i32; };\n",
	  65 },

	/* Bare sibling backref (no op): B = A. Tests the N_IDENT arm
	 * without a wrapping N_BIN/N_UN. */
	{ "sibling_backref",
	  "type e = enum i32 { A = 7, B = A };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	/* N_UN TK_MINUS over literal, fed through a sibling backref. The
	 * NEG member exercises N_UN; the R member exercises the IDENT
	 * lookup that must resolve NEG's already-folded value. */
	{ "unary_minus",
	  "type e = enum i32 { NEG = -7, R = NEG + 14 };\n"
	  "fn main() i32 = { return e.R: i32; };\n",
	  7 },

	/* Nested unary: ~(-8) folds to 7. Tests N_UN recursion (TK_TILDE
	 * over TK_MINUS over N_INTLIT). */
	{ "unary_tilde_nested",
	  "type e = enum i32 { A = ~(-8) };\n"
	  "fn main() i32 = { return e.A: i32; };\n",
	  7 },

	/* N_UN TK_PLUS — noop wrapper; completes the unary whitelist. */
	{ "unary_plus",
	  "type e = enum i32 { A = +7 };\n"
	  "fn main() i32 = { return e.A: i32; };\n",
	  7 },

	/* N_BIN TK_PLUS with sibling backref — the headline RW=R|W
	 * shape's relative. */
	{ "bin_plus",
	  "type e = enum i32 { A = 3, B = A + 4 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_minus",
	  "type e = enum i32 { A = 10, B = A - 3 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_star",
	  "type e = enum i32 { A = 2, B = A * 4 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  8 },

	{ "bin_slash",
	  "type e = enum i32 { A = 14, B = A / 2 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_percent",
	  "type e = enum i32 { A = 17, B = A % 10 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_amp",
	  "type e = enum i32 { A = 15, B = A & 7 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	/* N_BIN TK_PIPE — overlaps with 700_e2e's `RW = R | W` row, kept
	 * here for symmetry with the rest of the binop set. */
	{ "bin_pipe",
	  "type e = enum i32 { A = 4, B = A | 3 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_caret",
	  "type e = enum i32 { A = 5, B = A ^ 2 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	{ "bin_lshift",
	  "type e = enum i32 { A = 1, B = A << 3 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  8 },

	{ "bin_rshift",
	  "type e = enum i32 { A = 28, B = A >> 2 };\n"
	  "fn main() i32 = { return e.B: i32; };\n",
	  7 },

	/* Chained sibling backref — pins the O(N²) walker contract.
	 * Each member's lhs ident lookup re-walks the prefix; if the
	 * `until` bound were >= instead of > (off-by-one) the lookup
	 * of D would walk past C and the fold would diverge or loop. */
	{ "chained_backref",
	  "type e = enum i32 { A = 1, B = A + 1, C = B + 1, D = C + 4 };\n"
	  "fn main() i32 = { return e.D: i32; };\n",
	  7 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/cef_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/cef_%d_d_%d", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s 2>/dev/null",
	    tmpdir, driver, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[128];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

/* asm_byte_identical — diff w6c against w6c_ww for the same source.
 * Pins the symmetric-emit contract: a future drift between cstage's
 * eval_enum_value and wwstage's enumvalfold would show up here as a
 * byte diff even if both stages produce semantically-correct
 * constants. */
static int
asm_byte_identical(const char *bin, const struct row *r, int i)
{
	char src[64], cs[64], ws[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/cef_asm_%d_%d.ww", getpid(), i);
	snprintf(cs,  sizeof cs,  "/tmp/cef_asm_%d_%d_c.s", getpid(), i);
	snprintf(ws,  sizeof ws,  "/tmp/cef_asm_%d_%d_w.s", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s 2>/dev/null", bin, cs, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c errored\n", r->label);
		unlink(src);
		return -1;
	}
	snprintf(cmd, sizeof cmd, "%s/w6c_ww -o %s %s 2>/dev/null",
	    bin, ws, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label);
		unlink(src); unlink(cs);
		return -1;
	}

	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	int rc = 0;
	if (!fc || !fw) {
		rc = -1;
	} else {
		for (;;) {
			int a = fgetc(fc);
			int b = fgetc(fw);
			if (a != b) { rc = -1; break; }
			if (a == EOF) break;
		}
	}
	if (fc) fclose(fc);
	if (fw) fclose(fw);
	if (rc != 0)
		fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n",
		    r->label);
	unlink(src); unlink(cs); unlink(ws);
	return rc;
}

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];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[1024];
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

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

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;

	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated_on_existence
		    && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "check_enum_fold: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			int got = run_driver(drivers[d].path, &rows[i], i);
			total++;
			if (got != rows[i].want) {
				fprintf(stderr,
				    "check_enum_fold[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	/* Asm byte-identity diff, only when wwstage is built. */
	if (access(wdrv, X_OK) == 0) {
		for (int i = 0; i < n; i++) {
			total++;
			if (asm_byte_identical(bin, &rows[i], i) != 0)
				fail++;
		}
	}

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