int, uint, float and double reach rustc verbatim: the Rust mapper never learned the generic spellings #5570

Re-filed from #3333. An attempt claimed that issue on 2026-09-27 and left an empty branch, and a dispatch row that has spent its retry ceiling keeps its issue for good - so no bee could take it again, however much the brief improved. The work below is carried over unchanged.

Every neighbour answers them and t27_type_to_rust does not.

t27_array_type_to_zig (compiler.rs:8349) carries "float" => "f64", "double" => "f64", "int" => "i32", "uint" => "u32" with a comment naming the same defect one backend over:

W591: float is not a Zig type. Same family as the f32/f64 gap W583 found on the C side — a scalar the corpus spells and the mapper never learned, so it passed through the other arm and reached the backend verbatim.

The C emitter matches on "f16" | "f32" | "f64" | "float" | "double" in three places. The Rust mapper knows u8..u128, i8..i128, f32, f64, gf16, bool, str, string, literal, void — and nothing else, so int and float fell to the default and reached rustc as themselves.

Measured on two pinned binaries of distinct hashes, 651 specs: 336 OK both sides, zero regressions — the column does not move. What moves is the emission: 5 specs change their generated Rust (pub step_id: int → pub step_id: i32), and cannot find type int/float was the FIRST rustc error on 3 of them and is now the first error on none.

Deliberately narrow: Int and Float capitalised are NOT mapped. No neighbour answers those, so mapping them would be a decision rather than a transfer.

Boundary

• bootstrap/src/compiler.rs

The instruments

Every one of these reads and prints; none of them writes. Run them from the repository root, with <spec> replaced by the file in ## Boundary:

.t27 is not Rust and not Zig, and a bee fluent in either writes one by
accident. Measured 2026-09-20: a bee filled eight bodies in
specs/file/watcher.t27 with return Ok(());, Err(FileError::WatcherNotFound)
and for i in 0..watchers.length. The parse ratchet refused the whole file --
Unexpected token in expression: RParen, line 123 -- and a spec that does not
parse generates nothing, so every test it already carried stopped running.

At the top level the parser accepts exactly these eight forms, with an optional
pub, and no others:

const   var   fn   enum   struct   test   invariant   bench

There is no trait, no impl, no type X = ..., no generics, no macro. What
a bee reaches for from another language, and what happens:

• Rust's result sugar (Ok(()), Err(E::V), ?) is not a construct here.
• Rust macros (println!, format!, vec!) are not constructs here.
• A range loop (for i in 0..n) is Rust and Zig, not this language.
• Zig builtins (catch unreachable, @intCast, @constCast) are not constructs here.
• Cross-module reuse (use other::fn;) parses and then generates a comment and an unqualified call, so the Zig fails with use of undeclared identifier (use a::b; generates no import, so no spec can reuse a function from another spec #4298). It does not work yet.

t27c parse <spec> answers in one line whether what you wrote is the language.
Run it before you report, every time.

• t27c spec-status <spec> - the compiler's one-word verdict: IMPLEMENTED, PARTIAL, UNWRITTEN, NOPARSE, NOFN. Exit code is 0 whatever it says, so read the word.
• t27c symbols <spec> - every name the file declares, with its kind. Answers "does this already exist here?" before you add it.
• t27c outline <spec> - per function: its locals, what it calls, what it returns. The contract you are implementing against.
• t27c coverage <spec> - which functions have a test and which do not. The issue asks for tests; this is how you check you wrote them.
• t27c lint <spec> - style and shape warnings. It OVER-REPORTS has no test or invariant: measured 2026-09-20 over 60 specs it printed 677 of those where coverage found 190 untested functions, disagreeing on 59 of the 60 - it warns about bit_to_trit_pair in specs/base/ternary_encoding.t27, which test bit_to_trit_pair_zero calls on line 249. Read it as a hint; coverage is the answer.
• t27c typecheck <spec> - types, before generation. Prints Typecheck OK (0 errors, 0 warnings) or the errors.
• t27c test-report <spec> - builds this spec and runs its own tests, which is what the oracle does. BLOCKED means the generated Zig does not compile, with the error beside it.
• python3 tools/dupe_scan.py --name <function> - where that function already lives, if it does. 576 of 4021 bodies here are byte-identical copies.

The rest of the toolbelt is in docs/BEE_TOOLBELT.md.