wcc/cgen: loud-align static-global tagged cast-init (wwstage align to cstage)

A module-global tagged init via cast (`let g: u = true: u;`) silently
emitted tag=0; cstage louds. Route emittaggeddata through flatvariantidx
(the cstage cg_tag_for_variant twin) so an unsupported variant louds while
valid str/slice cast-inits still accept+run. test/wcc/838.

Makefile

@@ -262,6 +262,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_nested_union_int_box \
 	  $(BIN)/test_tagged_assignable_cluster \
 	  $(BIN)/test_idcast_tagged_return \
+	  $(BIN)/test_global_tagged_castinit \
 	  $(BIN)/test_inferred_array_global \
 	  $(BIN)/test_slice_str_global_arg \
 	  $(BIN)/test_slice_str_global_zero \
@@ -751,6 +752,12 @@ $(BIN)/test_idcast_tagged_return: test/wcc/837_idcast_tagged_return.c $(BIN)/ww
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_global_tagged_castinit: test/wcc/838_global_tagged_castinit.c $(BIN)/ww \
+		$(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
+		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 $(BIN)/test_inferred_array_global: test/wcc/833_inferred_array_global.c $(BIN)/ww \
 		$(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
 		$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \

selfhost/cmd/w6c/main.combined.ww

@@ -41336,7 +41336,22 @@ fn emittaggeddata(c: *cgen, name: str, module: str, tt: *node, rhs: *node, sz: i
 	let r: *node = rhs;
 	for (r != nil && r.kind == nkind.N_CAST) { r = r.lhs; };
 	if (r == nil) { return false; };
-	let tag: i32 = taggedvariantindex(c, tt, r);
+	// E8/#35: select the variant via flatvariantidx — the EXACT twin of
+	// cstage emit_tagged_data's cg_tag_for_variant (cmd/w6c/cgen.c:15472).
+	// taggedvariantindex adds a str/slice SHAPE fallback (cgenutil.ww:3054)
+	// that cstage does NOT run at this site: a same-type/subset CAST init
+	// (`let g: u = true: u;`) stamps the peeled literal's type_ as the
+	// union itself, so flatvariantidx finds no variant and returns -1,
+	// matching cstage's loud (caller emits "unsupported variant init",
+	// cgen.ww:2818). The shape fallback instead picked the first scalar
+	// variant (tag 0) -> SILENT miscompile (ran the int arm on a bool
+	// value, the S1 coincidence trap). A bare-literal init (`= true` / `=
+	// 7`) keeps its concrete/untyped type and still resolves via
+	// flatvariantidx pass 1 (byte-id with cstage); a str-literal CAST
+	// (`"hi": u`) keeps its str type and resolves to the str variant too.
+	// Faithful tag-remap for a cast-init static global = the deferred
+	// #23/#40 nominal widen feature.
+	let tag: i32 = flatvariantidx(c, tt, r);
 	if (tag < 0) { return false; };
 	let wide: bool = nodeisstr(c, r) || nodeisslice(c, r);
 	let i: i32 = 0;

selfhost/cmd/wcc/cgen.ww

@@ -2473,7 +2473,22 @@ fn emittaggeddata(c: *cgen, name: str, module: str, tt: *node, rhs: *node, sz: i
 	let r: *node = rhs;
 	for (r != nil && r.kind == nkind.N_CAST) { r = r.lhs; };
 	if (r == nil) { return false; };
-	let tag: i32 = taggedvariantindex(c, tt, r);
+	// E8/#35: select the variant via flatvariantidx — the EXACT twin of
+	// cstage emit_tagged_data's cg_tag_for_variant (cmd/w6c/cgen.c:15472).
+	// taggedvariantindex adds a str/slice SHAPE fallback (cgenutil.ww:3054)
+	// that cstage does NOT run at this site: a same-type/subset CAST init
+	// (`let g: u = true: u;`) stamps the peeled literal's type_ as the
+	// union itself, so flatvariantidx finds no variant and returns -1,
+	// matching cstage's loud (caller emits "unsupported variant init",
+	// cgen.ww:2818). The shape fallback instead picked the first scalar
+	// variant (tag 0) -> SILENT miscompile (ran the int arm on a bool
+	// value, the S1 coincidence trap). A bare-literal init (`= true` / `=
+	// 7`) keeps its concrete/untyped type and still resolves via
+	// flatvariantidx pass 1 (byte-id with cstage); a str-literal CAST
+	// (`"hi": u`) keeps its str type and resolves to the str variant too.
+	// Faithful tag-remap for a cast-init static global = the deferred
+	// #23/#40 nominal widen feature.
+	let tag: i32 = flatvariantidx(c, tt, r);
 	if (tag < 0) { return false; };
 	let wide: bool = nodeisstr(c, r) || nodeisslice(c, r);
 	let i: i32 = 0;

selfhost/cmd/wwdump/main.combined.ww

@@ -41336,7 +41336,22 @@ fn emittaggeddata(c: *cgen, name: str, module: str, tt: *node, rhs: *node, sz: i
 	let r: *node = rhs;
 	for (r != nil && r.kind == nkind.N_CAST) { r = r.lhs; };
 	if (r == nil) { return false; };
-	let tag: i32 = taggedvariantindex(c, tt, r);
+	// E8/#35: select the variant via flatvariantidx — the EXACT twin of
+	// cstage emit_tagged_data's cg_tag_for_variant (cmd/w6c/cgen.c:15472).
+	// taggedvariantindex adds a str/slice SHAPE fallback (cgenutil.ww:3054)
+	// that cstage does NOT run at this site: a same-type/subset CAST init
+	// (`let g: u = true: u;`) stamps the peeled literal's type_ as the
+	// union itself, so flatvariantidx finds no variant and returns -1,
+	// matching cstage's loud (caller emits "unsupported variant init",
+	// cgen.ww:2818). The shape fallback instead picked the first scalar
+	// variant (tag 0) -> SILENT miscompile (ran the int arm on a bool
+	// value, the S1 coincidence trap). A bare-literal init (`= true` / `=
+	// 7`) keeps its concrete/untyped type and still resolves via
+	// flatvariantidx pass 1 (byte-id with cstage); a str-literal CAST
+	// (`"hi": u`) keeps its str type and resolves to the str variant too.
+	// Faithful tag-remap for a cast-init static global = the deferred
+	// #23/#40 nominal widen feature.
+	let tag: i32 = flatvariantidx(c, tt, r);
 	if (tag < 0) { return false; };
 	let wide: bool = nodeisstr(c, r) || nodeisslice(c, r);
 	let i: i32 = 0;

test/wcc/838_global_tagged_castinit.c

@@ -0,0 +1,222 @@
+/*
+ * 838_global_tagged_castinit — E8: a module-level tagged global initialised
+ * by a same-type/subset CAST (`let g: u = true: u;`). ken2 spec
+ * .ai/ken2-family-spec.md (E8 section). Category A, SILENT-in-ww / cstage-
+ * LOUD, aligned DOWN to cstage's loud.
+ *
+ * ww's emittaggeddata selected the variant via taggedvariantindex, whose
+ * str/slice SHAPE fallback (cgenutil.ww) returns the first scalar variant
+ * (tag 0) when no variant typeeq's the source. For a CAST init the checker
+ * stamps the peeled literal's type as the union itself, so no variant matches
+ * and the fallback synthesised tag 0 in the DATA word — SILENT (a bool/int
+ * cast ran the int arm, payload mis-tagged). cstage's emit_tagged_data calls
+ * cg_tag_for_variant (NO shape fallback, cgen.c:15472) which returns -1 ->
+ * the caller loud-stops ("unsupported variant init"). The fix routes ww's
+ * emittaggeddata through flatvariantidx — the EXACT cg_tag_for_variant twin —
+ * so a cast-init that resolves to no variant louds, while every shape cstage
+ * accepts (bare literal, str-literal cast) still resolves via pass 1.
+ *
+ *   neg row      | shape                          | gate
+ *   -------------+--------------------------------+------
+ *   E8_boolcast  | let g: u = true: u;            | FAIL
+ *   E8_intcast   | let g: u = 7: u;               | FAIL
+ *
+ *   pos row      | shape                          | want
+ *   -------------+--------------------------------+------
+ *   E8_barebool  | let g: u = true; match bool    | 11
+ *   E8_bareint   | let g: u = 7;    match int -> n | 7
+ *   E8_barestr   | let g: u = "hi"; match str      | 22
+ *   E8_strcast   | let g: u = "hi": u; (str keeps  | 22
+ *                |   str type -> str variant)      |
+ *
+ * The bare-literal forms are clean on both stages (byte-id with cstage); the
+ * str-literal CAST keeps its concrete str type and resolves to the str
+ * variant, so it must NOT be over-rejected (a naive "N_CAST onto tagged ->
+ * loud" predicate would wrongly reject it). u = (int | bool | str): int is
+ * variant 0, so bare-int landing on tag 0 is correct (and pins the payload).
+ *
+ * BYTE-ID: NEUTRAL. A new ww loud emits no asm; cstage already louds; the
+ * bootstrap cannot contain a shape cstage refuses. The accept-path tags are
+ * unchanged (flatvariantidx returns the same index as the old pass 1). 990-
+ * 997 untouched.
+ */
+#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 char *PROLOGUE =
+	"package main;\n"
+	"type u = (int | bool | str);\n";
+
+static const char *EPILOGUE =
+	"export fn main() i32 = {\n"
+	"\tmatch (g) {\n"
+	"\tcase let n: int => return n: i32;\n"
+	"\tcase let b: bool => return 11;\n"
+	"\tcase let s: str => return 22;\n"
+	"\t};\n"
+	"\treturn 99;\n"
+	"};\n";
+
+static const struct row rows[] = {
+	{ "E8_barebool", "let g: u = true;\n",  11 },
+	{ "E8_bareint",  "let g: u = 7;\n",      7 },
+	{ "E8_barestr",  "let g: u = \"hi\";\n", 22 },
+	{ "E8_strcast",  "let g: u = \"hi\": u;\n", 22 },
+};
+
+static const char *neg[] = {
+	"let g: u = true: u;\n",
+	"let g: u = 7: u;\n",
+};
+
+static void
+write_src(const char *path, const char *mid)
+{
+	FILE *f = fopen(path, "wb");
+	if (!f) return;
+	fputs(PROLOGUE, f);
+	fputs(mid, f);
+	fputs(EPILOGUE, f);
+	fclose(f);
+}
+
+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/gtc_%d_%d.ww", getpid(), i);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/gtc_%d_d_%d", getpid(), i);
+
+	write_src(src, r->src);
+
+	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;
+}
+
+static int
+build_should_fail(const char *driver, const char *mid, int i)
+{
+	char s[64], tmpdir[64], cmd[1024];
+	snprintf(s, sizeof s, "/tmp/gtcn_%d_%d.ww", getpid(), i);
+	snprintf(tmpdir, sizeof tmpdir, "/tmp/gtcn_%d_d_%d", getpid(), i);
+
+	write_src(s, mid);
+
+	mkdir(tmpdir, 0755);
+	snprintf(cmd, sizeof cmd, "cd %s && %s build %s 2>/dev/null",
+	    tmpdir, driver, s);
+	int rc = runwait(cmd);
+	unlink(s);
+	const char *base = strrchr(s, '/');
+	base = base ? base + 1 : s;
+	char outbin[128];
+	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
+	char *dot = strrchr(outbin, '.');
+	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
+	unlink(outbin);
+	rmdir(tmpdir);
+	return rc == 0 ? -1 : 0;	/* build must NOT succeed */
+}
+
+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 nn = (int)(sizeof neg / sizeof neg[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, "global_tagged_castinit: 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,
+				    "global_tagged_castinit[%s][%s]: exit=%d want=%d\n",
+				    drivers[d].name, rows[i].label,
+				    got, rows[i].want);
+				fail++;
+			}
+		}
+		for (int i = 0; i < nn; i++) {
+			total++;
+			if (build_should_fail(drivers[d].path, neg[i],
+			    100 + i) != 0) {
+				fprintf(stderr,
+				    "global_tagged_castinit[%s][neg%d]: built ok, "
+				    "expected a loud reject\n",
+				    drivers[d].name, i);
+				fail++;
+			}
+		}
+	}
+
+	if (fail) {
+		fprintf(stderr,
+		    "global_tagged_castinit: %d/%d fixtures failed\n",
+		    fail, total);
+		return 1;
+	}
+	printf("global_tagged_castinit: %d/%d ok\n", total, total);
+	return 0;
+}