test: port the xmod collide observers to ww; birth test/xmod

test/xmod/collide_test.ww replaces 989_fnptrcollide_run.c and
989_barefn_collide_run.c with every assertion preserved (build-reject
both stages; run-exit 9 + exactly-one TEXT main.run/aa.run + cs==ww).
Makefile grows the XMOD_WW_TESTS block mirroring SEP_WW_TESTS, wired
into test-compiler.

test/xmod/collide_test.ww

@@ -0,0 +1,134 @@
+package collide_test;
+
+// Cross-module leaf-name collision observers on both driver stages.
+// Ports of the retired native carriers test/wcc/989_fnptrcollide_run.c
+// and 989_barefn_collide_run.c; every assertion preserved.
+//
+// fnptrcollide (#14 F7-c7) — a data global `slot: i64` whose LEAF
+// collides with the imported fn bar.slot must FAIL to build on BOTH
+// stages: type-keyed nodefnptr refuses to fold `&slot` into the fn's
+// TEXT reloc. Pre-fix wwstage was name-keyed and silently BUILT it
+// (a DATAR to the fn symbol — cat-A: cs loud-fails, ww builds). The
+// collision REQUIRES the import path (imported fn leaf vs local data
+// global), so a single-file fixture cannot express it.
+//
+// barefn (#84/#24a) — a `package main;` root `fn run` coexists with
+// imported aa.run: build+run exit 9 on BOTH stages (the user's
+// main.run wins, never aa.run=5); the concatenated
+// __root.s+aa.s (fixed #93 sep order) carries EXACTLY ONE
+// `TEXT main.run,` and EXACTLY ONE `TEXT aa.run,` (distinct symbols,
+// no #31-class w6l-tolerated duplicate, no silently-dead bare fn);
+// cs==ww byte-for-byte (rule 10).
+//
+// Dropped C machinery, not assertions: the ww_ww-absent skip gate
+// (the Make target declares both drivers), the shell `timeout 240`
+// (runcommand's deadline carries it), and the unlink/rmdir accounting
+// (testenv.clean asserts the removal).
+
+import os;
+import os.exec;
+import strings;
+import testenv;
+import time;
+
+fn fail(label: str, why: str) void = {
+	let m: str = strings.concat("collide FAIL: ", label, " -- ", why,
+		"\n");
+	os.write(2, m.ptr, m.len: u64);
+	assert(false);
+};
+
+fn tmo() time.duration = {
+	return (240i64 * (time.second: i64)): time.duration;
+};
+
+// -1 encodes an abnormal (non-EXIT) termination, never a valid code.
+fn runcode(dir: str, name: str, argv: []str) i32 = {
+	let co: testenv.commandout;
+	testenv.runcommand(dir, dir, name, argv, tmo(), &co);
+	if (co.termination != exec.termination.EXIT) { return -1; };
+	return co.code;
+};
+
+@test fn fnptrcollide() void = {
+	let drvs: []str = ["ww", "ww_ww"];
+	let i: i32 = 0;
+	for (i < 2) {
+		let td: str = testenv.fresh();
+		assert(os.mkdir(strings.concat(td, "/bar"), 493) == 0);
+		testenv.writefile(strings.concat(td, "/bar/bar.ww"),
+			strings.concat(
+			"package bar;\n",
+			"export fn slot() i64 = { return 99; };\n"));
+		testenv.writefile(strings.concat(td, "/main.ww"), strings.concat(
+			"package main;\n",
+			"import bar;\n",
+			"let slot: i64 = 7;\n",
+			"let fp: *i64 = &slot;\n",
+			"export fn main() int = { return (*fp): int; };\n"));
+		let av: []str = [testenv.driver(drvs[i]), "build", "-I", "bar",
+			"main.ww"];
+		if (runcode(td, strings.concat("build_", drvs[i]), av) == 0) {
+			fail("fnptrcollide", strings.concat(drvs[i], " built ok, ",
+				"expected the leaf-name collision to be rejected (#14 -- ",
+				"&slot mis-folded to the fn TEXT reloc)"));
+		};
+		testenv.clean(td);
+		i += 1;
+	};
+};
+
+// __root.s then aa.s: the carrier's fixed #93 sep concat order.
+fn catfixed(stem: str) str = {
+	return strings.concat(
+		testenv.readfile(strings.concat(stem, ".sepwork/__root.s")),
+		testenv.readfile(strings.concat(stem, ".sepwork/aa.s")));
+};
+
+// column-0 anchored label lines; the '\n' prepend counts a file-leading
+// label too.
+fn textcount(s: str, sym: str) i32 = {
+	return testenv.occurrences(strings.concat("\n", s),
+		strings.concat("\nTEXT ", sym, ","));
+};
+
+@test fn barefn() void = {
+	let td: str = testenv.fresh();
+	assert(os.mkdir(strings.concat(td, "/aa"), 493) == 0);
+	testenv.writefile(strings.concat(td, "/aa/aa.ww"), strings.concat(
+		"package aa;\n",
+		"export fn run() i32 = { return 5; };\n"));
+	testenv.writefile(strings.concat(td, "/root.ww"), strings.concat(
+		"package main;\n",
+		"import aa;\n",
+		"fn run() i32 = { return 9; };\n",
+		"export fn main() i32 = { return run(); };\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, "/root.ww")];
+		if (runcode(td, strings.concat("build_", tags[s]), av) != 0) {
+			fail("barefn", strings.concat(drvs[s], " build failed"));
+		};
+		let rav: []str = [stem];
+		if (runcode(td, strings.concat("run_", tags[s]), rav) != 9) {
+			fail("barefn", strings.concat(drvs[s], " exit != 9 ",
+				"(user main.run must win, not aa.run=5)"));
+		};
+		asms[s] = catfixed(stem);
+		if (textcount(asms[s], "main.run") != 1
+			|| textcount(asms[s], "aa.run") != 1) {
+			fail("barefn", strings.concat(drvs[s], " TEXT label counts ",
+				"!= 1/1 (user main.run distinct from import, no dup)"));
+		};
+		s += 1;
+	};
+	if (!testenv.same(asms[0], asms[1])) {
+		fail("barefn", "cs .s != ww .s (rule 10)");
+	};
+	testenv.clean(td);
+};