test/wcc: retire 990_selfhost; its live assertions move to their owners

Every probe's assertion is owned by a current gate: the compile and
link probes by make all and the bootstrap fixed point; build/run and
cs/ww byte identity by the fixture corpus, test-data-byteid, and
989_lib_byteid; wwstage driver and toolchain parity by 993/995;
checker-diagnostic parity by the corpus' both-stage //ww:error rows.
The wwdump -t/-a dump-parity probes gated the frontend port's
convergence, which the compiler-output identity gates now own end to
end; carrier ran green at retirement.

What was still uniquely alive migrates: smoke.ww becomes corpus
fixture selfhost_smoke (upgraded from a cstage-only build to both
frontends, byte-identical, exit 42 on both toolchains; corpus pins
move to 1,225/763/2,450 with the new identity hash in the same
commit), and sym_link.ww's scope/sym behavior rows become in-language
lib/ww/syntax/symtest.ww under LIBRARY_TESTS. uses.ww (parser-stub-era
-a fixture) and the already-orphaned tagged_ptr_ret.ww/trypromote.ww
retire with the probe corpus. Bootstrap native gates drop to six;
frontend numeric-sync comments now cite the rule-6 mirror instead of
the retired diff probe.

lib/ww/syntax/ast.ww

@@ -14,13 +14,12 @@ import strconv;
 
 // ---- Nkind ------------------------------------------------------------
 //
-// Mirror of cmd/wcc/ww.h Nkind. Values must stay numerically equal so
-// the AST diff probe in 990_selfhost works.
+// Mirror of cmd/wcc/ww.h Nkind. Values must stay numerically equal
+// to the C side (rule-6 data-shape mirror).
 
 // Mirror of the C `Nkind` enum in cmd/wcc/ww.h. Numeric values are
-// explicit and must stay in sync — the 990_selfhost test diffs
-// astprint against the C side byte-for-byte. Tail-appended entries
-// (TYPETEST onward) preserve every prior N_* value.
+// explicit and must stay in sync with the C side. Tail-appended
+// entries (TYPETEST onward) preserve every prior N_* value.
 export type nkind = enum i32 {
 	N_NONE     = 0,
 

lib/ww/syntax/lex.ww

@@ -1,9 +1,8 @@
 // lib/ww/syntax/lex.ww — port of cmd/wcc/lex.c.
 //
 // The DFA, the helpers, and the order of decisions all mirror the C
-// version exactly. The 990_selfhost test diffs the resulting token
-// stream against the C-side wwdump byte-for-byte; any divergence is
-// a port bug.
+// version exactly; any divergence surfaces as a cs/ww byte split in
+// the compiler-output identity gates and is a port bug.
 //
 // Calling-convention note: w6c can't yet pass or return structs >16
 // bytes by value, so `tok` and `pos` are passed by pointer (out

lib/ww/syntax/symtest.ww

@@ -0,0 +1,47 @@
+// symtest — behavior pin for [[newscope]]/[[scopedefine]]/[[scopelookup]]
+// (hashtable scope semantics: define, same-scope duplicate reject,
+// kind-preserving lookup, not-found nil). Run with
+// `ww test -I lib/ww lib/ww/syntax/symtest.ww`.
+//
+// Migrated from selfhost/test/sym_link.ww (the 990_selfhost link
+// probe): the toolchain-link half of that probe is owned by the
+// fixture corpus' ww-stage cells, so only the scope behavior rows
+// survive, as in-language rows. `package main` + bare `import syntax`
+// mirrors toktest/asttest.
+
+package main;
+
+import syntax;
+
+@test fn scope_define_lookup() void = {
+	let s: *scope = newscope(nil);
+	assert(!(s == nil));
+
+	let r1: *sym = scopedefine(s, "foo", skind.SK_VAR, nil, nil);
+	assert(!(r1 == nil));
+	let r2: *sym = scopedefine(s, "bar", skind.SK_TYPE, nil, nil);
+	assert(!(r2 == nil));
+
+	let l1: *sym = scopelookup(s, "foo");
+	assert(!(l1 == nil));
+	assert(!(l1.skind != skind.SK_VAR));
+	let l2: *sym = scopelookup(s, "bar");
+	assert(!(l2 == nil));
+	assert(!(l2.skind != skind.SK_TYPE));
+};
+
+@test fn scope_duplicate_reject() void = {
+	let s: *scope = newscope(nil);
+	assert(!(s == nil));
+	let r1: *sym = scopedefine(s, "foo", skind.SK_VAR, nil, nil);
+	assert(!(r1 == nil));
+	let r3: *sym = scopedefine(s, "foo", skind.SK_VAR, nil, nil);
+	assert(!(r3 != nil));
+};
+
+@test fn scope_notfound_nil() void = {
+	let s: *scope = newscope(nil);
+	assert(!(s == nil));
+	let l3: *sym = scopelookup(s, "baz");
+	assert(!(l3 != nil));
+};

lib/ww/syntax/tok.ww

@@ -1,10 +1,9 @@
 // lib/ww/syntax/tok.ww — port of cmd/wcc/tok.c plus the Tkind /
 // Tok / Pos shapes from cmd/wcc/ww.h.
 //
-// Token kind values must stay numerically equal to the C side: the
-// 990_selfhost test diffs ww-side wwdump output against C-side
-// wwdump output, byte-for-byte. Reordering this list shifts the
-// integers and breaks the diff.
+// Token kind values must stay numerically equal to the C side
+// (rule-6 data-shape mirror of cmd/wcc/ww.h). Reordering this list
+// shifts the integers and splits the two frontends.
 //
 // Bottom of file: tokprint, which emits one token per line in a
 // format identical to cmd/wcc/tok.c:tokprint().
@@ -17,8 +16,7 @@ import strings;
 
 // ---- tkind ------------------------------------------------------------
 // Mirror of the C `Tkind` enum in cmd/wcc/ww.h. Numeric values are
-// explicit and must stay in sync — the 990_selfhost test diffs wwdump
-// output against the C side, byte for byte.
+// explicit and must stay in sync with the C side.
 
 export type tkind = enum i32 {
 	TK_NONE     = 0,
@@ -112,7 +110,7 @@ export type tkind = enum i32 {
 	TK_FATARROW = 81,
 
 	// Tail-appended values — keeps every prior TK_* numeric value
-	// stable for the 990_selfhost byte-diff against the C side.
+	// stable against the C side.
 	TK_IS     = 82,
 	TK_VOID   = 83,
 	TK_YIELD  = 84,

lib/ww/syntax/toktest.ww

@@ -11,8 +11,8 @@
 // switch (STR/IDENT/ERR vs INT/RUNE vs the value-less default) and,
 // through the STR text, fputq's full escape switch (\\, ", \n, \t,
 // \r, the c<0x20 and c==0x7f \xNN arms, and the printable tail) —
-// branches the 990_selfhost corpus does not exercise (source tokens
-// hold raw `\`+`n`, never a literal control byte).
+// branches ordinary source tokens do not exercise (they hold raw
+// `\`+`n`, never a literal control byte).
 // A failing row aborts via the assert/abort builtin (task #5 @test
 // conversion); per-row exit-code pinpoint is intentionally dropped (the
 // abort reports the file, not the row; drew-t2-conversion-spec sec.5).