From 3922f1c34e625cc4fd12fed94ddaa142f7d2cd74 Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Sat, 22 Aug 2026 19:28:54 +0900
Subject: [PATCH] fix: ignore hidden named source operands

---
 cmd/ww/main.c                |  60 ++++++
 docs/build-system.md         | 125 +++++++++++++
 docs/spec.md                 |  16 ++
 docs/test-system-v2.md       |  20 ++
 selfhost/cmd/ww/main.ww      |  58 ++++++
 test/package/package_test.ww | 348 +++++++++++++++++++++++++++++++++++
 6 files changed, 627 insertions(+)

diff --git a/cmd/ww/main.c b/cmd/ww/main.c
index f7056faf..6c46e01f 100644
--- a/cmd/ww/main.c
+++ b/cmd/ww/main.c
@@ -7136,6 +7136,38 @@ basename_no_ext(const char *path, char *out, size_t outsz)
 	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
 }
 
+/* Go's named-file package still applies matchFile's unconditional basename
+ * exclusion before UseAllFiles, platform suffixes, source parsing, or test-file
+ * classification.  Keep this predicate on the public operand spelling: a
+ * hidden parent does not hide a visible named file, while a hidden symlink
+ * spelling remains hidden regardless of its non-directory target kind. */
+static int
+source_operand_ignored(const char *path)
+{
+	struct stat st;
+	size_t n = strlen(path);
+	if (n < 3 || strcmp(path + n - 3, ".ww") != 0) return 0;
+	if (stat(path, &st) != 0 || S_ISDIR(st.st_mode)) return 0;
+	const char *base = strrchr(path, '/');
+	base = base ? base + 1 : path;
+	return base[0] == '.' || base[0] == '_';
+}
+
+static void
+source_operand_no_sources(const char *path)
+{
+	const char *slash = strrchr(path, '/');
+	fputs("ww: ", stderr);
+	if (slash == NULL) {
+		fputc('.', stderr);
+	} else if (slash == path) {
+		fputc('/', stderr);
+	} else {
+		(void)fwrite(path, 1, (size_t)(slash - path), stderr);
+	}
+	fputs(": directory contains no WW package sources\n", stderr);
+}
+
 /* Go's build -o directory branch follows an existing destination through
  * stat, and a trailing platform separator declares a directory which the
  * request may need to create.  WW's platform separator is '/'. */
@@ -7442,6 +7474,11 @@ do_build(int argc, char **argv)
 	}
 	struct stat requested;
 	int literal = stat(src, &requested) == 0;
+	if (source_operand_ignored(src)) {
+		source_operand_no_sources(src);
+		free(incs);
+		return 1;
+	}
 	char resolved[PATH_MAX];
 	int is_dir = 0;
 	if (!resolve_module(src, incs, resolved, sizeof resolved, &is_dir)) {
@@ -7988,6 +8025,29 @@ do_test(int argc, char **argv)
 		}
 	}
 	int discard_output = strcmp(outstem, "/dev/null") == 0;
+	if (strstr(target, "...") == NULL && source_operand_ignored(target)) {
+		if (nproducts != 0 && outstem[0]) {
+			fprintf(stderr,
+			    "ww test: package-test products reject -o\n");
+			return 2;
+		}
+		if (nproducts != 0) {
+			fprintf(stderr,
+			    "ww test: package-test variant needs one directory\n");
+			return 2;
+		}
+		if (packageopts) {
+			fprintf(stderr,
+			    "ww test: package options need a directory\n");
+			return 2;
+		}
+		source_operand_no_sources(target);
+		if (src != NULL && !compileonly && !emit_asm)
+			fputs("FAIL\n", stdout);
+		free(products);
+		free(incs);
+		return 1;
+	}
 	if (pattern != NULL) {
 		struct stat first;
 		if (stat(target, &first) != 0 || !S_ISREG(first.st_mode)) {
diff --git a/docs/build-system.md b/docs/build-system.md
index cd58d49b..fd1156fb 100644
--- a/docs/build-system.md
+++ b/docs/build-system.md
@@ -9955,6 +9955,131 @@ artifact-layout, harness-protocol, cache, database, or publication field.
 Build workdir format remains `18`, test workdir format remains `19`, semantic
 storage format remains `3`, and no test-result cache is introduced.
 
+### 11.50 Implemented named-source leading-dot/underscore eligibility
+
+An explicitly named raw `.ww` source now observes the same unconditional
+basename exclusion as a named `.go` source in Go 1.26.5. This closes the gap in
+WW's existing single-source command route: a final requested basename beginning
+`.` or `_` is not a package source, even though named sources otherwise bypass
+directory-only target-suffix selection. Directory selection already enforced
+this rule and remains unchanged.
+
+#### Pinned Go evidence and applicability
+
+The reference is official Go 1.26.5 at commit
+`c19862e5f8415b4f24b189d065ed739517c548ba`:
+
+- `PackagesAndErrors` recognizes an existing `.go` operand and routes the
+  complete named list to `GoFilesPackage`
+  ([`cmd/go/internal/load/pkg.go`, lines 2903–2918](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/load/pkg.go#L2903-L2918)).
+  `GoFilesPackage` enables `UseAllFiles`, presents only the named `FileInfo`
+  entries through a synthetic directory, and loads one command-line package
+  ([lines 3244–3315](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/load/pkg.go#L3244-L3315)).
+- `go/build.Import` passes each synthetic entry through `Context.matchFile`
+  ([`go/build/build.go`, lines 886–914](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/go/build/build.go#L886-L914)).
+  `matchFile` rejects a name beginning `_` or `.` before extension, target
+  suffix, open, imports, or build constraints; that branch precedes the
+  `UseAllFiles` condition
+  ([lines 1438–1509](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/go/build/build.go#L1438-L1509)).
+  A package with no remaining source category returns `NoGoError`
+  ([lines 1076–1082](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/go/build/build.go#L1076-L1082));
+  the command loader presents the case as `no Go files`
+  ([`cmd/go/internal/load/pkg.go`, lines 250–270](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/load/pkg.go#L250-L270)).
+- Build reports load errors before installation/action construction
+  ([`cmd/go/internal/work/build.go`, lines 697–728](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/work/build.go#L697-L728)).
+  Test uses the same loader
+  ([`cmd/go/internal/test/test.go`, lines 703–719](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/test/test.go#L703-L719))
+  and turns its error into package setup failure before constructing a runnable
+  ([lines 1015–1050](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/test/test.go#L1015-L1050)).
+- Official command testdata explicitly records that `_cgo_yy.go` named on the
+  command line is ignored and permits the exact `no Go files` result
+  ([`cgo_bad_directives.txt`, lines 11–23](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/testdata/script/cgo_bad_directives.txt#L11-L23)).
+  `import_ignore.txt` independently proves a dot file contributes no import
+  ([lines 1–11](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/testdata/script/import_ignore.txt#L1-L11)).
+
+The rule honestly applies to WW's local literal `.ww` operand. It adds no
+module, manifest, registry, network, generalized import, or build-expression
+surface. This section is deliberately bounded to the existing single raw
+source target. Multiple named sources as one package and visible
+`*_test.ww` exclusion from `ww build` remain separate open semantics; when a
+future source-set loader admits multiple names, it must apply this same rule to
+each requested basename.
+
+#### Source, package, and import ownership
+
+The twin public drivers own one allocation-free operand predicate after
+existing CLI-shape checks and a successful requested-path `Stat`, but before
+logical resolution or graph entry. It requires an original spelling ending
+exactly `.ww`, then examines only the final requested basename. A hidden parent
+containing visible `main.ww` does not
+exclude the named source. A requested hidden symlink spelling is excluded even
+when its target is visible or non-regular, while a visible requested spelling
+remains eligible even when its target basename is hidden. This follows the
+`FileInfo.Name` seen
+by Go's synthetic named-file directory: Unix `Stat` follows the target but
+fills `Name` from the requested path
+([`os/stat_unix.go`, lines 28–38](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/os/stat_unix.go#L28-L38),
+[`os/stat_linux.go`, lines 13–30](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/os/stat_linux.go#L13-L30)).
+Physical target paths do not become identity.
+
+Prefix exclusion precedes every later classifier. `_main_test.ww` and
+`.main_test.ww` are absent before production/test partitioning. A hidden
+`_main_windows.ww` is absent, but a visible `main_windows.ww` named directly
+remains eligible because the named-file analogue uses `UseAllFiles`; directory
+platform filtering is unchanged. Logical operands without a `.ww` suffix,
+directory and recursive requests, imports, and `ww run` retain their existing
+routes.
+
+An excluded operand creates no package clause, declaration, production/test
+variant, or top-level state. Its bytes are not decoded or parsed: malformed
+UTF-8, NUL, BOM, missing/invalid package clauses, late imports, missing imports,
+unused imports, cycles, `internal`/vendor rules, and checker diagnostics cannot
+resurrect it or outrank selection. It contributes no qualifier, import-use
+obligation, edge, canonical dotted identity, initializer, or link closure. The
+lexical parent printed by the diagnostic is presentation metadata only and is
+never package, import, graph, action, symbol, `.wwi`, artifact, publication, or
+persistence identity.
+
+#### Observable command and lifecycle behavior
+
+`ww build HIDDEN.ww` exits 1 with empty standard output and
+`ww: PARENT: directory contains no WW package sources` on standard error.
+An ordinary explicit running `ww test HIDDEN.ww` adds its established exact
+command-owned `FAIL` line on standard output; compile-only and assembly-only
+test requests do not. With no slash, `PARENT` is `.`, a root child uses `/`,
+and otherwise it is the requested lexical bytes before the final slash. CLI
+flag/path-length errors and the existing raw-test directory-only package-option
+shape keep their precedence. A failed requested-path `Stat` retains ordinary
+target/logical resolution; for an existing non-directory raw operand,
+no-source selection precedes logical resolution, output-destination preflight,
+and all source, producer, publication, and runtime diagnostics. Exact
+`/dev/null` does not suppress the load failure.
+
+No root/dependency action, test support, generated main, compiler, assembler,
+archiver, linker, harness, test child, or program process starts. Cold rejection
+creates no default or explicit output, workdir, adjacent `.sepwork`, unit,
+`.wwi`, assembly, object, archive, init artifact, binary, status, stage, capture,
+result, transaction, or private temporary directory. Warm rejection starts no
+transaction and preserves every prior work-artifact and public/retained byte.
+It leaves no `.new`, `.install`, `.wwtxn.*`, or recovery residue. Producer,
+runtime, publication-only, cleanup-only, signal, timeout, and descendant
+semantics for visible inputs are unchanged.
+
+The predicate is request-local and creates no shared state, process group,
+lock, or interruption owner, so overlapping hidden and visible requests remain
+isolated. Cstage and WWstage must agree byte-for-byte on status, stdout, stderr,
+and complete artifact absence; representative visible named sources retain
+binary and semantic-artifact identity. The focused native
+`named_source_prefixes_are_ignored` observer owns both prefixes, build/test and
+compile-only paths, prefix-before-test/platform precedence, requested symlink
+spelling, hidden-parent/visible-basename and wrong-platform controls, unread
+malformed/import bytes, cold cleanup, warm preservation/restoration, residue,
+and stage parity.
+
+No serialized format changes. Build workdir format remains `18`, test workdir
+format remains `19`, semantic storage format remains `3`, and there is no test
+result cache.
+
 ## 12. Candidate architectures and hard-gate decision
 
 Five candidates were developed as coherent systems, not as feature bins.
diff --git a/docs/spec.md b/docs/spec.md
index cdd5de7b..7cb7b7ec 100644
--- a/docs/spec.md
+++ b/docs/spec.md
@@ -319,6 +319,22 @@ ImportPath    = ident { "." ident } .
   delegated graph-import scan or tools. An ordinary build compares production
   names only; one test product compares its production, same-package test, and
   external-test selections without merging their units.
+- A single existing raw `.ww` operand is also subject to the unconditional
+  leading-name rule: if its final requested basename begins `.` or `_`, it is
+  ignored before the source is opened. Named raw sources otherwise retain their
+  existing all-files behavior, so a visible wrong-platform suffix remains
+  eligible. Only the requested basename participates: a hidden parent does not
+  hide visible `main.ww`, a hidden symlink spelling stays hidden for any
+  existing non-directory target, and a visible symlink spelling stays eligible.
+  The excluded operand creates no package, declaration, import binding/edge,
+  action, artifact, initialization, test,
+  publication, or persistent state. `ww build` reports the existing
+  `directory contains no WW package sources` condition; an explicit running
+  raw `ww test` also emits its command-owned `FAIL`, while `-c` and `-S` do not.
+  This rule does not add multiple named-source package support, does not change
+  visible `*_test.ww` handling, and does not apply to logical operands,
+  directory/recursive requests, imports, or `ww run`. The diagnostic parent is
+  presentation metadata and never canonical identity.
 - `import acme.codec;` loads the canonical package `acme.codec`. If that
   package declares `package wire;`, the importing file sees its exported names
   as `wire.Name`; `codec.Name` is not an additional binding. An explicit alias
diff --git a/docs/test-system-v2.md b/docs/test-system-v2.md
index 91051c6d..17b59a11 100644
--- a/docs/test-system-v2.md
+++ b/docs/test-system-v2.md
@@ -219,6 +219,26 @@ every `-j` level, and `-j 1` — the default — matches the former sequential
 run loop exactly. Measured on the 31-package `lib/...` walk:
 7.0s sequential, 2.4s at `-j 4`.
 
+The raw single-source compatibility route applies package-source eligibility
+before it invokes the compiler or harness. An existing operand ending `.ww`
+whose final requested basename begins `.` or `_` is ignored exactly as it is by
+directory discovery, even when the name also ends `_test.ww`; the file is not
+opened and cannot contribute a test descriptor, package declaration, import,
+variant, graph action, diagnostic, artifact, retained binary, or persistent
+state. A normal explicit running request exits 1 with exact `FAIL\n` stdout and
+the driver's `directory contains no WW package sources` stderr; `-c` and `-S`
+omit the final marker. Visible wrong-platform raw names remain eligible, and
+only the requested basename matters for symlinks (including non-regular
+targets) and hidden parent directories.
+CLI/target and the existing raw package-option shape retain precedence. Cold
+rejection creates no work or temporary product; warm rejection preserves prior
+work and public bytes without transaction residue. The focused
+`named_source_prefixes_are_ignored` package observer proves these rules in both
+driver stages, including malformed/import precedence, prefix-before-test and
+platform classification, symlink spelling, output rollback, residue, and
+diagnostic/artifact parity. Directory package coordination and test process,
+filter, timeout, signal, and descendant topology are unchanged.
+
 List mode uses that same product process and initialization boundary but starts
 no per-test child. The shared language harness emits only selected qualified
 test names, one per line in descriptor order. A valid filter selecting no tests
diff --git a/selfhost/cmd/ww/main.ww b/selfhost/cmd/ww/main.ww
index a82642e4..08e31d2b 100644
--- a/selfhost/cmd/ww/main.ww
+++ b/selfhost/cmd/ww/main.ww
@@ -8564,6 +8564,40 @@ fn basenameoff(p: *u8, plen: u64) u64 = {
 	return start;
 };
 
+// A named Go source still passes through matchFile's leading-dot/underscore
+// exclusion even when UseAllFiles bypasses platform suffixes and build tags.
+// Inspect the public operand spelling so a hidden parent is not source identity
+// and a hidden symlink spelling cannot be resurrected by a non-directory
+// target's name or file kind.
+fn sourceoperandignored(path: *u8) bool = {
+	if (!cstrendswithlit(path, ".ww")) { return false; };
+	let fi: os.filestat;
+	match (os.stat(&fi, pathstr(path))) {
+	case void => {
+		let typ: u32 = (fi.mode: u32) & 61440u32;
+		if (typ == os.mode.DIR: u32) { return false; };
+	};
+	case let e: os.oserror => return false;
+	};
+	let n: u64 = cstrlen(path);
+	let base: u64 = basenameoff(path, n);
+	return path[base] == '.' || path[base] == '_';
+};
+
+fn sourceoperandnosources(path: *u8) void = {
+	let n: u64 = cstrlen(path);
+	let base: u64 = basenameoff(path, n);
+	cerr("ww: ");
+	if (base == 0u64) {
+		cerr(".");
+	} else { if (base == 1u64) {
+		cerr("/");
+	} else {
+		os.write(os.STDERR_FILENO, path, base - 1u64);
+	}; };
+	cerr(": directory contains no WW package sources\n");
+};
+
 fn arenadupcstr(src: *u8, plen: u64) *u8 = {
 	let buf: []u8 = alloc([], plen + 1u64)!;
 	let i: u64 = 0u64;
@@ -8914,6 +8948,10 @@ fn dobuild(selfdir: *u8, argv: **u8, argc: i32, start: i32) i32 = {
 	case void => requestedliteral = true;
 	case let e: os.oserror => void;
 	};
+	if (sourceoperandignored(src)) {
+		sourceoperandnosources(src);
+		return 1;
+	};
 	let isdir: i32 = 0;
 	let resolved: *u8 = resolvemodule(selfdir, src, incs.ptr, &isdir);
 	if (resolved == nil) {
@@ -9792,6 +9830,26 @@ fn dotest(selfdir: *u8, argv: **u8, argc: i32, start: i32) i32 = {
 			producti += 1;
 		};
 	};
+	if (!strings.contains(pathstr(target), "...")
+		&& sourceoperandignored(target)) {
+		if (products.len != 0 && outstem != nil) {
+			cerr("ww test: package-test products reject -o\n");
+			return 2;
+		};
+		if (products.len != 0) {
+			cerr("ww test: package-test variant needs one directory\n");
+			return 2;
+		};
+		if (packageopts) {
+			cerr("ww test: package options need a directory\n");
+			return 2;
+		};
+		sourceoperandnosources(target);
+		if (targetindex >= 0 && compileonly == 0 && emitasm == 0) {
+			os.write(1, "FAIL\n".ptr, 5u64);
+		};
+		return 1;
+	};
 	if (patarg != nil) {
 		let first: os.filestat;
 		let firstregular: bool = false;
diff --git a/test/package/package_test.ww b/test/package/package_test.ww
index 7c43d7e3..0cee0c38 100644
--- a/test/package/package_test.ww
+++ b/test/package/package_test.ww
@@ -987,6 +987,354 @@ fn cwdwritedata(dir: str, label: str) void = {
 	clean(root);
 };
 
+@test fn named_source_prefixes_are_ignored() void = {
+	let root: str = fresh();
+	let source: str = strings.concat(root, "/source");
+	let hiddenparent: str = strings.concat(source, "/.parent");
+	let symlinks: str = strings.concat(source, "/symlinks");
+	let warm: str = strings.concat(source, "/warm");
+	mkdirall(source); mkdirall(hiddenparent); mkdirall(symlinks); mkdirall(warm);
+
+	let maintext: str =
+		"package main;\nfn main() i32 = { return 0; };\n";
+	let testtext: str = strings.concat(
+		"package raw_windows_test;\n",
+		"@test fn selected() void = { assert(true); };\n");
+	let missingmain: str = strings.concat(
+		"package main;\nimport absent.pkg;\n",
+		"fn main() i32 = { return pkg.value(); };\n");
+	let missingtest: str = strings.concat(
+		"package missing_test;\nimport absent.pkg;\n",
+		"@test fn never() void = { abort(); };\n");
+	let malformed: str = "this source must never be opened {\n";
+	let hiddenbuild: str = strings.concat(source, "/_broken_windows_test.ww");
+	let dotbuild: str = strings.concat(source, "/.missing.ww");
+	let hiddentest: str = strings.concat(source,
+		"/_broken_windows_test.ww");
+	let dottest: str = strings.concat(source, "/.missing_test.ww");
+	let visiblewrong: str = strings.concat(source, "/visible_windows.ww");
+	let visiblewrongtest: str = strings.concat(source,
+		"/visible_windows_test.ww");
+	let hiddenparentmain: str = strings.concat(hiddenparent, "/main.ww");
+	let visibletarget: str = strings.concat(symlinks, "/target.ww");
+	let hiddentarget: str = strings.concat(symlinks, "/.target.ww");
+	let hiddenlink: str = strings.concat(symlinks, "/_link.ww");
+	let hiddendevice: str = strings.concat(symlinks, "/_device.ww");
+	let visiblelink: str = strings.concat(symlinks, "/visible-link.ww");
+	let warmvisible: str = strings.concat(warm, "/warm.ww");
+	let warmhidden: str = strings.concat(warm, "/_warm.ww");
+	writefile(hiddenbuild, malformed);
+	writefile(dotbuild, missingmain);
+	writefile(dottest, missingtest);
+	writefile(visiblewrong, maintext);
+	writefile(visiblewrongtest, testtext);
+	writefile(hiddenparentmain, maintext);
+	writefile(visibletarget, maintext);
+	writefile(hiddentarget, maintext);
+	assert(os.symlink(visibletarget, hiddenlink) == 0);
+	assert(os.symlink("/dev/null", hiddendevice) == 0);
+	assert(os.symlink(hiddentarget, visiblelink) == 0);
+	writefile(warmvisible, maintext);
+
+	let stages: []str = ["ww", "ww_ww"];
+	let tags: []str = ["c", "ww"];
+	let rootartifacts: []str = ["/__root.unit.ww", "/__root.wwi",
+		"/__root.s", "/__root.o", "/__root.a",
+		"/__root.init.unit.ww", "/__root.init.s", "/__root.init.o"];
+	let visiblebuildbin: str = "";
+	let visiblebuildartifacts: []str = alloc([], rootartifacts.len: u64)!;
+	let visibletestbin: str = "";
+	let visibletestartifacts: []str = alloc([], rootartifacts.len: u64)!;
+	let visibleteststdout: str = "";
+	let hiddendiagnostics: []str = alloc([], 20u64)!;
+	let si: i32 = 0;
+	for (si < stages.len) {
+		let prefix: str = strings.concat(tags[si], "-");
+		let coldwork: str = strings.concat(root, "/cold-work-", tags[si]);
+		let coldout: str = strings.concat(root, "/cold-output-", tags[si]);
+		let out: commandout;
+
+		// A final requested basename, rather than any parent component, owns
+		// Go's unconditional editor-temporary exclusion.
+		let av: []str = [driver(stages[si]), "build", "-w", coldwork,
+			"-o", coldout, "_broken_windows_test.ww"];
+		runcommanddir(root, strings.concat(prefix, "relative-hidden-build"),
+			source, av, (30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		let relativebuilddiag: str =
+			"ww: .: directory contains no WW package sources\n";
+		assert(out.stdout.len == 0 && same(out.stderr, relativebuilddiag)
+			&& !os.exists(coldwork) && !os.exists(coldout)
+			&& !os.exists(strings.concat(coldout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let dotbuildav: []str = [driver(stages[si]), "build", "-o",
+			strings.concat(root, "/dot-output-", tags[si]), dotbuild];
+		runcommand(root, strings.concat(prefix, "dot-missing-build"), dotbuildav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		let sourcediag: str = strings.concat("ww: ", source,
+			": directory contains no WW package sources\n");
+		assert(out.stdout.len == 0 && same(out.stderr, sourcediag)
+			&& !has(out.stderr, "absent.pkg")
+			&& !os.exists(strings.concat(root, "/dot-output-", tags[si]))
+			&& !os.exists(strings.concat(root, "/dot-output-", tags[si],
+				".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let testcoldwork: str = strings.concat(root, "/cold-test-work-",
+			tags[si]);
+		let testcoldout: str = strings.concat(root, "/cold-test-output-",
+			tags[si]);
+		let hiddentestrunav: []str = [driver(stages[si]), "test", "-w",
+			testcoldwork, "-o",
+			testcoldout, hiddentest];
+		runcommand(root, strings.concat(prefix, "hidden-test-run"),
+			hiddentestrunav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(same(out.stdout, "FAIL\n") && same(out.stderr, sourcediag)
+			&& !has(out.stderr, "invalid or missing package clause")
+			&& !os.exists(testcoldwork) && !os.exists(testcoldout)
+			&& !os.exists(strings.concat(testcoldout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let compiled: str = strings.concat(root, "/hidden-compiled-", tags[si]);
+		let hiddencompileav: []str = [driver(stages[si]), "test", "-c", "-o",
+			compiled,
+			hiddentest];
+		runcommand(root, strings.concat(prefix, "hidden-test-compile"),
+			hiddencompileav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(out.stdout.len == 0 && same(out.stderr, sourcediag)
+			&& !os.exists(compiled)
+			&& !os.exists(strings.concat(compiled, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let assembly: str = strings.concat(root, "/hidden-assembly-", tags[si]);
+		let hiddenasmav: []str = [driver(stages[si]), "test", "-S", "-o",
+			assembly,
+			hiddentest];
+		runcommand(root, strings.concat(prefix, "hidden-test-assembly"),
+			hiddenasmav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(out.stdout.len == 0 && same(out.stderr, sourcediag)
+			&& !os.exists(assembly)
+			&& !os.exists(strings.concat(assembly, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let dottestav: []str = [driver(stages[si]), "test", dottest];
+		runcommand(root, strings.concat(prefix, "dot-missing-test"), dottestav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(same(out.stdout, "FAIL\n") && same(out.stderr, sourcediag)
+			&& !has(out.stderr, "absent.pkg"));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let visiblework: str = strings.concat(root, "/visible-work-", tags[si]);
+		let visibleout: str = strings.concat(root, "/visible-output-", tags[si]);
+		mkdirall(visiblework);
+		let visiblebuildav: []str = [driver(stages[si]), "build", "-w",
+			visiblework, "-o",
+			visibleout, visiblewrong];
+		runcommand(root, strings.concat(prefix, "visible-wrong-platform-build"),
+			visiblebuildav, (60i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0
+			&& os.exists(visibleout));
+		let runav: []str = [visibleout];
+		runcommand(root, strings.concat(prefix, "visible-wrong-platform-run"),
+			runav, (10i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0);
+		let visiblebytes: str = strings.dup(readfile(visibleout));
+		let ai: i32 = 0;
+		if (si == 0) { visiblebuildbin = strings.dup(visiblebytes); } else {
+			assert(same(visiblebuildbin, visiblebytes));
+		};
+		for (ai < rootartifacts.len) {
+			let bytes: str = strings.dup(readfile(strings.concat(visiblework,
+				rootartifacts[ai])));
+			if (si == 0) { append(visiblebuildartifacts, bytes); }
+			else { assert(same(visiblebuildartifacts[ai], bytes)); };
+			ai += 1;
+		};
+
+		let testwork: str = strings.concat(root, "/visible-test-work-", tags[si]);
+		mkdirall(testwork);
+		let visibletestav: []str = [driver(stages[si]), "test", "-w", testwork,
+			visiblewrongtest];
+		runcommand(root, strings.concat(prefix, "visible-wrong-platform-test"),
+			visibletestav, (60i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stderr.len == 0
+			&& occurrences(out.stdout, "selected ... ok\n") == 1
+			&& occurrences(out.stdout,
+				"1 passed, 0 failed, 0 skipped, 0 harness errors\n") == 1);
+		let testbytes: str = strings.dup(readfile(strings.concat(testwork,
+			"/main")));
+		if (si == 0) {
+			visibletestbin = strings.dup(testbytes);
+			visibleteststdout = strings.dup(out.stdout);
+		} else {
+			assert(same(visibletestbin, testbytes)
+				&& same(visibleteststdout, out.stdout));
+		};
+		ai = 0;
+		for (ai < rootartifacts.len) {
+			let bytes: str = strings.dup(readfile(strings.concat(testwork,
+				rootartifacts[ai])));
+			if (si == 0) { append(visibletestartifacts, bytes); }
+			else { assert(same(visibletestartifacts[ai], bytes)); };
+			ai += 1;
+		};
+
+		let parentout: str = strings.concat(root, "/hidden-parent-", tags[si]);
+		let parentwork: str = strings.concat(root, "/hidden-parent-work-",
+			tags[si]);
+		mkdirall(parentwork);
+		let parentav: []str = [driver(stages[si]), "build", "-w", parentwork,
+			"-o", parentout, hiddenparentmain];
+		runcommand(root, strings.concat(prefix, "hidden-parent-visible-base"),
+			parentav, (30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0
+			&& same(visiblebuildbin, readfile(parentout)));
+
+		let hiddenlinkout: str = strings.concat(root, "/hidden-link-", tags[si]);
+		let hiddenlinkav: []str = [driver(stages[si]), "build", "-o",
+			hiddenlinkout, hiddenlink];
+		runcommand(root, strings.concat(prefix, "hidden-request-symlink"),
+			hiddenlinkav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		let symlinkdiag: str = strings.concat("ww: ", symlinks,
+			": directory contains no WW package sources\n");
+		assert(out.stdout.len == 0 && same(out.stderr, symlinkdiag)
+			&& !os.exists(hiddenlinkout)
+			&& !os.exists(strings.concat(hiddenlinkout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let deviceout: str = strings.concat(root, "/hidden-device-", tags[si]);
+		let devicework: str = strings.concat(root, "/hidden-device-work-",
+			tags[si]);
+		let deviceav: []str = [driver(stages[si]), "build", "-w", devicework,
+			"-o", deviceout, hiddendevice];
+		runcommand(root, strings.concat(prefix, "hidden-device-build"), deviceav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(out.stdout.len == 0 && same(out.stderr, symlinkdiag)
+			&& !os.exists(devicework) && !os.exists(deviceout)
+			&& !os.exists(strings.concat(deviceout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let devicetestwork: str = strings.concat(root,
+			"/hidden-device-test-work-", tags[si]);
+		let devicetestout: str = strings.concat(root,
+			"/hidden-device-test-output-", tags[si]);
+		let devicetestav: []str = [driver(stages[si]), "test", "-w",
+			devicetestwork, "-o", devicetestout, hiddendevice, "selected"];
+		runcommand(root, strings.concat(prefix, "hidden-device-test"),
+			devicetestav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		assert(same(out.stdout, "FAIL\n") && same(out.stderr, symlinkdiag)
+			&& !os.exists(devicetestwork) && !os.exists(devicetestout)
+			&& !os.exists(strings.concat(devicetestout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+
+		let visiblelinkout: str = strings.concat(root, "/visible-link-", tags[si]);
+		let visiblelinkwork: str = strings.concat(root, "/visible-link-work-",
+			tags[si]);
+		mkdirall(visiblelinkwork);
+		let visiblelinkav: []str = [driver(stages[si]), "build", "-w",
+			visiblelinkwork, "-o", visiblelinkout, visiblelink];
+		runcommand(root, strings.concat(prefix, "visible-request-symlink"),
+			visiblelinkav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0
+			&& same(visiblebuildbin, readfile(visiblelinkout)));
+
+		let warmwork: str = strings.concat(root, "/warm-work-", tags[si]);
+		let warmout: str = strings.concat(root, "/warm-output-", tags[si]);
+		mkdirall(warmwork);
+		let warmvalidav: []str = [driver(stages[si]), "build", "-w",
+			warmwork, "-o",
+			warmout, warmvisible];
+		runcommand(root, strings.concat(prefix, "warm-visible"), warmvalidav,
+			(60i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0
+			&& os.exists(warmout));
+		let warmbin: str = strings.dup(readfile(warmout));
+		let warmsnapshots: []str = alloc([], rootartifacts.len: u64)!;
+		ai = 0;
+		for (ai < rootartifacts.len) {
+			append(warmsnapshots, strings.dup(readfile(strings.concat(warmwork,
+				rootartifacts[ai]))));
+			ai += 1;
+		};
+		assert(os.rename(warmvisible, warmhidden) == 0);
+		let warmhiddenav: []str = [driver(stages[si]), "build", "-w",
+			warmwork, "-o",
+			warmout, warmhidden];
+		runcommand(root, strings.concat(prefix, "warm-hidden"), warmhiddenav,
+			(30i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 1);
+		let warmdiag: str = strings.concat("ww: ", warm,
+			": directory contains no WW package sources\n");
+		assert(out.stdout.len == 0 && same(out.stderr, warmdiag)
+			&& same(warmbin, readfile(warmout))
+			&& !os.exists(strings.concat(warmout, ".new"))
+			&& !os.exists(strings.concat(warmout, ".sepwork")));
+		append(hiddendiagnostics, strings.dup(out.stderr));
+		ai = 0;
+		for (ai < rootartifacts.len) {
+			assert(same(warmsnapshots[ai], readfile(strings.concat(warmwork,
+				rootartifacts[ai]))));
+			ai += 1;
+		};
+		assert(!directoryhasnew(warmwork)
+			&& !directoryhasfragment(warmwork, ".wwtxn.")
+			&& !directoryhasfragment(warmwork, ".install")
+			&& !directoryhasfragment(warmwork, ".sepwork"));
+		assert(os.rename(warmhidden, warmvisible) == 0);
+		runcommand(root, strings.concat(prefix, "warm-restored"), warmvalidav,
+			(60i64 * (time.second: i64)): time.duration, &out);
+		expectexit(&out, 0);
+		assert(out.stdout.len == 0 && out.stderr.len == 0
+			&& same(warmbin, readfile(warmout)));
+		ai = 0;
+		for (ai < rootartifacts.len) {
+			assert(same(warmsnapshots[ai], readfile(strings.concat(warmwork,
+				rootartifacts[ai]))));
+			ai += 1;
+		};
+		assert(!directoryhasnew(warmwork)
+			&& !directoryhasfragment(warmwork, ".wwtxn.")
+			&& !directoryhasfragment(warmwork, ".install")
+			&& !directoryhasfragment(warmwork, ".sepwork"));
+		si += 1;
+	};
+	let half: i32 = hiddendiagnostics.len / 2;
+	let di: i32 = 0;
+	for (di < half) {
+		assert(same(hiddendiagnostics[di], hiddendiagnostics[di + half]));
+		di += 1;
+	};
+	assert(!directoryhasnew(root)
+		&& !directoryhasfragment(root, ".wwtxn.")
+		&& !directoryhasfragment(root, ".install")
+		&& !directoryhasfragment(root, ".sepwork")
+		&& !directoryhasfragment(root, ".capture")
+		&& !directoryhasfragment(root, ".result")
+		&& !directoryhasfragment(root, ".request"));
+	clean(root);
+};
+
 // A source file has one contiguous import section immediately after its
 // package clause.  The parser may continue after a late import for recovery,
 // but the imports-only loader and the full compiler parser both reject it.