Surface rename of the signed integer family: s1..s64 become i1..i64
(u1..u64, usize, isize unchanged). 'string' keeps the s-prefix arm in
name classification; width parsing moves to the i-prefix arm next to
isize.
Internal TypeId tags follow the surface (.s8/.s16/.s32/.s64 ->
.i8/.i16/.i32/.i64), as do mono-key mangle fragments (ptr_i64,
tu_i64_bool) and all display/diagnostic formatting (i{d}).
Migrated in the same sweep: stdlib + examples + issue repros + FFI C
companions (shared symbol names like ffi_id_i64), expected
stdout/stderr/ir snapshots, specs.md, readme.md, CLAUDE.md/AGENTS.md,
implementation_plan.md, docs/, issue writeups. Vendored stb_image and
historical flow state left untouched.
zig build test: 426/426; examples suite: 595/595.
The reserved/builtin-type-name binding diagnostic was a hand-walked subset
of binding-bearing AST nodes with a silent `else => {}`, so each review
found another syntactic binding form that bypassed it and hit the original
LLVM verifier abort: destructure names (`s2, x := …`), `impl` method
params/locals, and `if` / `while` / `for` / match-arm / `catch` / `onfail`
captures.
Rewrite `checkBindingNames` (src/ir/semantic_diagnostics.zig) as an
EXHAUSTIVE `switch` over every `Node.Data` tag with NO `else` arm — a future
binding-bearing node type now fails to compile until it is handled here, so
coverage is enforced by the compiler instead of a hand-maintained list. The
check stays in the pre-lowering semantic pass rather than moving to the
`Scope.put` scope-registration choke point: lowering is lazy, so an
uncalled function's bindings never reach `Scope.put`, yet they must still be
rejected at their declaration (e.g. the never-called `takes_u8` in 1119).
No lowering special-case; `lower.zig` unchanged.
Regression tests (fail-before: LLVM abort or silent accept → pass-after:
clean diagnostic, exit 1):
- 1121 control-flow: destructure, if/while bindings, for capture+index,
match-arm capture
- 1122 impl-block method: reserved param AND reserved local
- 1123 catch + onfail tag bindings
- 1124 destructure name reserved in an imported module
Existing 0125 / 1119 / 0135 / 1120 tests kept; full suite 368 passed.
