test: port 794_xmod_ident_prefer to collide_test; retire the carrier

The last bug-pinned C carrier. Its header documents both #55 halves;
with the cgen side fixed the STRONGER assertion set it deferred is
expressible: barevalue builds the 794 two-file program FLAT
(file-keyed import — a dir-keyed aa/ compiles aa as its own sep unit
where main.v is invisible and the collision cannot express), runs
exit 7 on BOTH drivers, and asserts the flat __root.s cs==ww
byte-identical (rule 10). defshadow pins the def-vs-fn arm-order
corner (foreign scalar def under a curmod fn: bare read 42, not
141), modqualfnval the qualified fn-value positive twin.

Carrier fleet 16 -> 15: 5 units / 6 bootstrap / 3 platform /
738_module_decl. Zero bug-pins remain.

test/xmod/collide_test.ww

@@ -132,3 +132,148 @@ fn textcount(s: str, sym: str) i32 = {
 	};
 	testenv.clean(td);
 };
+
+// barevalue (#55 cgen-side sibling) — the migrated 794 carrier
+// (test/wcc/794_xmod_ident_prefer.c, retired with this row; its header
+// documents both #55 halves). A bare VALUE ident read inside an
+// imported module must be classified by the checker-stamped type, not
+// a unit-wide leaf table: aa exports `v: i32 = 7` and getv() reads the
+// bare `v`; the root declares a same-leaf `fn v() i64`. FLAT layout
+// (file-keyed import) is REQUIRED — both files fold into one unit so
+// the foreign fn lands in the leaf table; a dir-keyed aa/ compiles aa
+// as its own sep unit where main.v is invisible and the collision
+// cannot express. Pre-fix wwstage cgen took fnretlookup's leaf
+// fallback and emitted `LEAQ aa.v(SB)` (fn address, no load) — the
+// binary exited 0; cstage loads 7 (LEAQ+MOVSXD). Both drivers must
+// build, run 7, and the flat __root.s must be cs==ww byte-identical
+// (rule 10) — the stronger assertion set the carrier deferred while
+// the cgen side was open.
+@test fn barevalue() void = {
+	let td: str = testenv.fresh();
+	testenv.writefile(strings.concat(td, "/aa.ww"), strings.concat(
+		"package aa;\n",
+		"export let v: i32 = 7;\n",
+		"export fn getv() i32 = {\n",
+		"	return v;\n",
+		"};\n"));
+	testenv.writefile(strings.concat(td, "/main.ww"), strings.concat(
+		"package main;\n",
+		"import aa;\n",
+		"fn v() i64 = { return 100; };\n",
+		"export fn main() i32 = {\n",
+		"	return aa.getv();\n",
+		"};\n"));
+	let drvs: []str = ["ww", "ww_ww"];
+	let tags: []str = ["cs", "ww"];
+	let asms: []str = ["", ""];
+	let s: i32 = 0;
+	for (s < 2) {
+		let stem: str = strings.concat(td, "/prog.", tags[s]);
+		let av: []str = [testenv.driver(drvs[s]), "build", "-o", stem,
+			"-I", td, strings.concat(td, "/main.ww")];
+		if (runcode(td, strings.concat("build_", tags[s]), av) != 0) {
+			fail("barevalue", strings.concat(drvs[s], " build failed"));
+		};
+		let rav: []str = [stem];
+		if (runcode(td, strings.concat("run_", tags[s]), rav) != 7) {
+			fail("barevalue", strings.concat(drvs[s], " exit != 7 ",
+				"(bare v in aa.getv must LOAD aa.v, not take the ",
+				"foreign fn's address)"));
+		};
+		asms[s] = testenv.readfile(strings.concat(stem,
+			".sepwork/__root.s"));
+		s += 1;
+	};
+	if (!testenv.same(asms[0], asms[1])) {
+		fail("barevalue", "cs .s != ww .s (rule 10)");
+	};
+	testenv.clean(td);
+};
+
+// defshadow — corner (c) of the same class: a foreign scalar `def`
+// leaf colliding with a curmod fn. The def arm ran BEFORE
+// fn-classification in wwstage cgident (cstage checks TY_FN first),
+// so the bare `MSG` fn value read `MOVQ main.MSG(SB)` data where
+// cstage takes the fn address; the qualified `p5aa.MSG` data read hit
+// the mirror corner (d) in cgdot. Runtime pre-fix: 141, want 42.
+@test fn defshadow() void = {
+	let td: str = testenv.fresh();
+	testenv.writefile(strings.concat(td, "/p5aa.ww"), strings.concat(
+		"package p5aa;\n",
+		"export def MSG: i32 = 3;\n"));
+	testenv.writefile(strings.concat(td, "/main.ww"), strings.concat(
+		"package main;\n",
+		"import p5aa;\n",
+		"fn MSG(x: i32) i32 = { return x + 40; };\n",
+		"export fn main() i32 = {\n",
+		"	let f = MSG;\n",
+		"	return f(2) + p5aa.MSG - 3;\n",
+		"};\n"));
+	let drvs: []str = ["ww", "ww_ww"];
+	let tags: []str = ["cs", "ww"];
+	let asms: []str = ["", ""];
+	let s: i32 = 0;
+	for (s < 2) {
+		let stem: str = strings.concat(td, "/prog.", tags[s]);
+		let av: []str = [testenv.driver(drvs[s]), "build", "-o", stem,
+			"-I", td, strings.concat(td, "/main.ww")];
+		if (runcode(td, strings.concat("build_", tags[s]), av) != 0) {
+			fail("defshadow", strings.concat(drvs[s], " build failed"));
+		};
+		let rav: []str = [stem];
+		if (runcode(td, strings.concat("run_", tags[s]), rav) != 42) {
+			fail("defshadow", strings.concat(drvs[s], " exit != 42 ",
+				"(bare MSG is the curmod fn; p5aa.MSG is the ",
+				"foreign data def)"));
+		};
+		asms[s] = testenv.readfile(strings.concat(stem,
+			".sepwork/__root.s"));
+		s += 1;
+	};
+	if (!testenv.same(asms[0], asms[1])) {
+		fail("defshadow", "cs .s != ww .s (rule 10)");
+	};
+	testenv.clean(td);
+};
+
+// modqualfnval — corner (d) positive twin: a module-QUALIFIED fn used
+// as a value must still take the address arm under the stamped-type
+// gate (proves the checker stamps the N_DOT fn rvalue as TY_FN).
+@test fn modqualfnval() void = {
+	let td: str = testenv.fresh();
+	testenv.writefile(strings.concat(td, "/p6aa.ww"), strings.concat(
+		"package p6aa;\n",
+		"export fn hit(x: i32) i32 = { return x + 40; };\n"));
+	testenv.writefile(strings.concat(td, "/main.ww"), strings.concat(
+		"package main;\n",
+		"import p6aa;\n",
+		"export fn main() i32 = {\n",
+		"	let f = p6aa.hit;\n",
+		"	return f(2);\n",
+		"};\n"));
+	let drvs: []str = ["ww", "ww_ww"];
+	let tags: []str = ["cs", "ww"];
+	let asms: []str = ["", ""];
+	let s: i32 = 0;
+	for (s < 2) {
+		let stem: str = strings.concat(td, "/prog.", tags[s]);
+		let av: []str = [testenv.driver(drvs[s]), "build", "-o", stem,
+			"-I", td, strings.concat(td, "/main.ww")];
+		if (runcode(td, strings.concat("build_", tags[s]), av) != 0) {
+			fail("modqualfnval", strings.concat(drvs[s],
+				" build failed"));
+		};
+		let rav: []str = [stem];
+		if (runcode(td, strings.concat("run_", tags[s]), rav) != 42) {
+			fail("modqualfnval", strings.concat(drvs[s],
+				" exit != 42"));
+		};
+		asms[s] = testenv.readfile(strings.concat(stem,
+			".sepwork/__root.s"));
+		s += 1;
+	};
+	if (!testenv.same(asms[0], asms[1])) {
+		fail("modqualfnval", "cs .s != ww .s (rule 10)");
+	};
+	testenv.clean(td);
+};