12552e125d
Two silent-miscompile codegen fixes:
0083 — named-const array dimension. `TypeResolver.resolveCompound`'s array
arm resolved the dimension with `if int_literal ... else 0`, so a named const
(`N :: 16; [N]T`) hit the silent `else 0`: the array became 0-length / 0-byte
and element access ran out of bounds (garbage for scalars, bus error for
slice/pointer/struct elements). The arm now delegates the dimension to
`inner.resolveArrayLen` (symmetric with `inner.resolveInner` for the element).
The stateful `Lowering.resolveArrayLen` evaluates it as a compile-time integer
across the comptime-constant / generic-value / module-global const tables and
emits a diagnostic — no fabricated length — when it isn't one.
0084 — `.[...]` literal passed directly as a call arg. `lowerArrayLiteral`
always yields an aggregate array value; the array→slice conversion is the
caller's job. The local-bound var-decl path did it, but the call-arg coercion
path had no array→slice arm, so `classify([N]T, []T)` returned `.none` and the
raw array was passed where a slice was expected (callee read its {ptr,len}
header off the wrong bytes → 0 / garbage / segfault). `classify` now returns a
new `.array_to_slice` plan for same-element `[N]T → []T`, and `coerceToType`
emits the existing `array_to_slice` op — identical to the local-bound path.
Regressions (fail-before/pass-after demonstrated on the pre-fix compiler):
examples/0140-types-named-const-array-dim.sx (s64 + string + struct elems)
examples/0141-types-slice-literal-direct-call-arg.sx (string + []s64)
Gate: zig build, zig build test, bash tests/run_examples.sh (387 passed).
Issues 0083 and 0084 marked RESOLVED.
44 lines
2.5 KiB
Markdown
44 lines
2.5 KiB
Markdown
# 0084 — array/slice literal passed directly as a call argument miscompiles
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> **RESOLVED.** Root cause: `lowerArrayLiteral` always produces an aggregate
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> ARRAY value; the array→slice conversion is the caller's job. The local-bound
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> var-decl path did it (emits `array_to_slice`), but the call-argument coercion
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> path (`coerceCallArgs` → `coerceToType` → `CoercionResolver.classify`) had no
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> array→slice arm, so `classify([N]T, []T)` returned `.none` and the raw array
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> value was passed where a slice was expected — the callee read its {ptr,len}
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> header off the wrong bytes (returned 0 / garbage, segfaulted for `[]s64`). Fix:
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> `classify` now returns a new `.array_to_slice` plan for `[N]T → []T` (same
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> element type), and `coerceToType` emits the existing `array_to_slice` op, which
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> materializes the array into addressable storage and builds the slice header —
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> identical to the local-bound path. Files: `src/ir/conversions.zig`,
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> `src/ir/lower.zig`. Regression: `examples/0141-types-slice-literal-direct-call-arg.sx`
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> (string + numeric `[]s64`, direct vs local-bound).
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## Symptom
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A `.[...]` array/slice literal passed DIRECTLY as a call argument yields a slice
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whose element CONTENTS are not reliably readable in the callee (silent — reads
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garbage, wrong results). Binding the same literal to a typed local first and
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passing the local is correct.
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## Reproduction
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```sx
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#import "modules/std.sx";
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show :: (xs: []string) -> s64 { n:=0; i:=0; while i<xs.len { if xs[i]=="nope" {n+=1;} i+=1; } return n; }
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main :: () {
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print("direct={}\n", show(.["a","nope","b","nope"])); // prints 0 (WRONG)
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local : []string = .["a","nope","b","nope"]; print("local={}\n", show(local)); // prints 2 (correct)
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}
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```
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Want both `2`. Direct-literal-arg returns `0`.
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## Investigation prompt
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Passing a `.[...]` literal directly as a call arg builds a slice/array temporary
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whose backing storage is not correctly materialized/kept alive for the callee —
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the slice header may point at a stack temp that is clobbered, or the elements are
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not stored before the call. Binding to a typed local first works (the local's
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storage backs the slice). Look at how a literal aggregate argument is lowered at a
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call site (materialize the literal into addressable storage whose lifetime spans
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the call, then pass a slice/pointer to it) vs the local-bound path. Fix so a
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directly-passed literal arg behaves identically to a local-bound one. Verify with
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the repro (both `2`) + a numeric `[]s64` case, gate green.
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