A typed module-level constant whose initializer did not match its
annotation was silently accepted: `N : string : 4` compiled, then
`print(N)` segfaulted (an integer emitted as a `string` const → a bogus
pointer) and `[N]s64` folded `N` to 4 as an integer count. Issue 0088.
Root cause: `registerTypedModuleConst` stored the annotation type but never
validated the initializer literal against it, and
`program_index.moduleConstInt` folded a const into a count by inspecting
the initializer node alone, ignoring `ModuleConstInfo.ty`.
Fix at the declaration (kills both symptoms):
- lower.zig: `registerTypedModuleConst` now validates the initializer via
`typedConstInitFits` (arms mirror `emitModuleConst`'s faithful-emit
precondition: int→int/float, float→float, bool→bool, string→string,
null→pointer/optional, `---`→any). A mismatch emits a `type mismatch`
diagnostic at the initializer span and does not register the const (also
evicting the pass-0 placeholder). Not routed through
`coercionResolver().classify`: that runtime-coercion planner is unsound
here (null's natural type is void → false-rejects `*T`; bool is 1 bit →
false-accepts s64).
- program_index.zig: `moduleConstInt` now takes the `TypeTable` and gates
the fold on `isCountableConstType(ci.ty)` (integer of any width, or a
float), so a non-numeric typed const can never fold into a count off its
initializer node. Callers in lower.zig and type_bridge.zig updated.
Regression:
- examples/1143-diagnostics-typed-module-const-mismatch.sx (negative, exit 1)
- examples/0162-types-typed-module-const-roundtrip.sx (positive)
- program_index.test.zig: gate-on-declared-type unit test
Docs: specs.md §3 Constant Binding + readme.md note the compatibility rule.
