gen-c: put the brackets after the name in a module array constant - #3458
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Closes #3457 const A : [4]u8 = [1,2,3,4]; static const [4]u8 A = { 1, 2, 3, 4 }; error: brackets are not allowed here; to declare an array, place the brackets after the identifier The MUTABLE TWIN four lines above the site the probe found carried the same defect -- `var A : [4]u8` gives `static [4]u8 A` -- and only a grep for every site that builds a declarator from a type and a name turned it up. A slice constant was broken before either: `const A : []u8` gave `static const []u8 A`, where `T name[] = { ... }` is legal C and takes its size from the list. Fourth position for one rule, built from the field helper rather than a fourth copy of it: parameter T x[static N] #3435 struct field T f[N]; #3446 local T x[N]; #3448 module const T name[N] here MEASURED, whole corpus, -ferror-limit=0: errors 15126 -> 15021 files that compile 301 -> 302 files better 11 `math/e8_lie_algebra` 44 -> 4, `fpga/mac` 101 -> 85, `queen/lotus` 29 -> 16. ONE FILE'S COUNT ROSE AND IT IS NOT A REGRESSION. `isa/registers` goes 34 -> 44 because the declarations now PARSE: the errors that disappear are `brackets are not allowed here` and two `expected ';'`, and what appears behind them is semantic -- `TernaryWord{.raw=0}` is not C, a separate defect the parse cascade had been hiding. A raw error count is not monotone under a repair that fixes a parse error; the per-file split is what makes that visible. MY OWN TEST ASSERTED SOMETHING THAT NEVER EXISTED. It required a slice const to keep "the old pointer lowering", and there was no pointer lowering -- the type went through verbatim. The test was wrong AND the code was wrong, and the test failing is what showed both. A MUTANT SURVIVED AND THE ANSWER WAS TO DELETE. A `has_init` parameter guarded a case neither caller can produce, so the mutant deleting its check changed nothing. A guard nothing can reach is not protection: the parameter is removed rather than annotated. Two other mutants died. Round six of the parity table, the const-initialiser position it had never covered. The previous round found only latent defects; this one found a live one on its first form, so the table does not stop yet. 28 seals refreshed in the same commit. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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September 8, 2026 03:21
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Closes #3457
The mutable twin four lines above the site the probe found had the same
defect (
var A : [4]u8→static [4]u8 A), and only a grep for everydeclarator-building site turned it up. A slice constant was broken before
either:
static const []u8 A, whereT name[] = { … }is legal C.Fourth position for one rule
T x[static N]T f[N];T x[N];T name[N]Built from the field helper, not a fourth copy.
Measured — whole corpus,
-ferror-limit=0math/e8_lie_algebra44 → 4 ·fpga/mac101 → 85 ·queen/lotus29 → 16 ·boards/xc7a100t_minimal11 → 1.One file's count rose and it is not a regression.
isa/registersgoes34 → 44 because the declarations now parse: what disappears is
brackets are not allowed hereand twoexpected ';'; what appears behind them is semantic(
TernaryWord{.raw=0}is not C — a separate defect the cascade was hiding). Araw error count is not monotone under a repair that fixes a parse error.
Two things I got wrong, both caught here
My own test asserted something that never existed — that a slice const must
keep "the old pointer lowering". There was no pointer lowering; the type went
through verbatim. The test was wrong and the code was wrong, and the failing
test showed both.
A mutant survived and the answer was to delete. A
has_initparameterguarded a case neither caller can produce. A guard nothing can reach is not
protection, so it is removed rather than annotated.
has_initcheck removedFull suite: 2630 passed, 0 failed. 28 seals refreshed in the same commit.
The round
Round six of
tools/backend_parity_table.py— the const-initialiser positionit had never covered. Round five found only latent defects; this one found a
live one on its first form, so the table does not stop yet.