ZSTD_estimateCCtxSize_internal() evaluates four fixed source-size tiers and
must retain every C-owned parameter and sizing call, including raw error-shaped
size_t results. Store those four results in C, then delegate only the final
unsigned maximum comparison to a scalar Rust ABI helper. The outer monotonic
compression-level budget and the separate CStream estimation path remain
unchanged.
The Rust unit tests cover zero, ordinary, equal, SIZE_MAX, and encoded error
values to document that the helper compares raw size_t values without arithmetic
or error interpretation.
Test Plan:
- `cargo clippy --manifest-path rust/Cargo.toml --no-default-features --features compression` -- passed before and after formatting
- Same clippy command with `--benches` -- passed before and after formatting
- Same clippy command with `--tests` -- passed before and after formatting
- `cargo +nightly fmt --manifest-path rust/Cargo.toml` -- passed
- `cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression` -- 328 passed
- `make -B -C lib -j2 lib` -- passed
- `make -C tests test-rust-lib-smoke` -- passed
- `tests/fuzzer -s4560 -t56 -i57 -v` -- passed
- `make -C tests -j2 test-zstream` -- 84 named plus 5,923 and 9,247 randomized cases passed
- `git diff --check` and `git diff --cached --check` -- passed
The zstream build retains the pre-existing initializer-string warning at
tests/zstreamtest.c:1899.
ddidderr
c0038a8aaa