Split compiler flags to avoid dependency recompilation #4211
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### Context When working on #4211 & #4213, I was initially very confused by all the machinery in [`call_cargo.rs`](https://github.com/model-checking/kani/blob/main/kani-driver/src/call_cargo.rs) and [`call_single_file.rs`](https://github.com/model-checking/kani/blob/main/kani-driver/src/call_single_file.rs) that we used to pass arguments to the different layers of the compiler. The main source of my confusion was that there were many arguments all destined for different places (e.g. cargo, rustc, or kani-compiler) that all had to be encoded in differing ways (e.g. through the `--llvm-args` flag or the `CARGO_ENCODED_RUSTFLAGS` environment variable) but were mixed together sharing the same `String` type and similar-sounding variable names. Although misconfiguration would often be caught at runtime with a section of the compiler complaining about unexpected arguments, this confusion silently bit me a few times where argument names were shared. ### Fix This PR represents an attempt to encode the way arguments target different portions of the compiler into the type system using specific wrapper types for each kind of argument we use. You can convert transparently into these wrapper types, but then can only convert between them or pass them to a cargo command using the proper encoding methods. Although not perfect (you could still convert into the wrong kind of argument wrapper initially), this does seem to add some slight guardrails on the way we call cargo, especially against smaller changes to the existing patterns like the ones I was making in my PRs. It also may make the code easier to parse. By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.
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from the autogenerated : ## What's Changed * Ensure that contract closures are FnOnce by @vonaka in #4151 * Adjust sized hierarchy for Kani's memory predicates by @tautschnig in #4193 * Update to Rust edition 2024 by @tautschnig in #4197 * `ptr_offset_from`: Replace arithmetic over pointers by offset arithmetic by @tautschnig in #4180 * Automatic cargo update to 2025-07-07 by @github-actions[bot] in #4208 * Bump tests/perf/s2n-quic from `b8f8cca` to `8715fdf` by @dependabot[bot] in #4209 * Upgrade Rust toolchain to 2025-07-04 by @tautschnig in #4199 * Upgrade Rust toolchain to 2025-07-10 by @thanhnguyen-aws in #4215 * Update CBMC dependency to 6.7.1 by @tautschnig in #4178 * Split compiler flags to avoid dependency recompilation by @AlexanderPortland in #4211 * Fix the bug that assign clause cannot be inferred for the inner loop of nested loops by @thanhnguyen-aws in #4179 * Upgrade Rust toolchain to 2025-07-11 by @thanhnguyen-aws in #4219 * Automatic toolchain upgrade to nightly-2025-07-12 by @github-actions[bot] in #4222 * Fix bug: `goto-cc` crash when there are two quantifers in one proof by @thanhnguyen-aws in #4221 * Automatic toolchain upgrade to nightly-2025-07-13 by @github-actions[bot] in #4223 * Automatic cargo update to 2025-07-14 by @github-actions[bot] in #4224 * Cleanup links to issues that have been addressed by @tautschnig in #4200 * Selectively enable and fix (slow) Tokio tests by @tautschnig in #4203 * Bump tests/perf/s2n-quic from `32ba87d` to `1cbd879` by @dependabot[bot] in #4227 * Implement support for Cargo.toml's default-members by @tautschnig in #4201 * Do not invoke memset with count of zero by @tautschnig in #4205 * Support bitwuzla, cvc5, z3 as solver attribute values by @tautschnig in #4218 * Use CBMC's shuffle_vector expression by @tautschnig in #4204 * Move tests from slow/kani back to regular suite by @tautschnig in #4202 * Automatic toolchain upgrade to nightly-2025-07-14 by @github-actions[bot] in #4225 * Enable GitHub Linux/Arm runners in CI by @tautschnig in #3841 * Automatic cargo update to 2025-07-21 by @github-actions[bot] in #4231 * Skip codegen for unneeded harnesses by @AlexanderPortland in #4213 * Strongly type differing compiler args for clarity by @AlexanderPortland in #4220 * Remove StableMIR ICE workaround by @carolynzech in #4235 * Fix bug: Kani unwinds loops with contract in generic function (with -Z loop-contracts) by @thanhnguyen-aws in #4232 * Automatic cargo update to 2025-07-28 by @github-actions[bot] in #4238 * Bump tests/perf/s2n-quic from `1cbd879` to `4938450` by @dependabot[bot] in #4242 * Upgrade Rust toolchain to 2025-07-21 by @tautschnig in #4241 * Remove `pretty_ty` and use rustc_public's formatter instead by @tautschnig in #4243 * Upgrade Rust toolchain to 2025-07-24 by @tautschnig in #4244 * Documentation cleanup of UB detected by Kani by @tautschnig in #4245 * Upgrade Rust toolchain to 2025-07-29 by @tautschnig in #4247 * Automatic toolchain upgrade to nightly-2025-07-30 by @github-actions[bot] in #4253 * Add unstable option prove-safety-only by @tautschnig in #4239 * Set bits_per_byte in byte_extract expressions by @tautschnig in #4255 * `KaniAttributes` Path Resolution Refactor by @carolynzech in #4249 * Automatic toolchain upgrade to nightly-2025-07-31 by @github-actions[bot] in #4256 * Support contracts & stubs in trait implementations (partial fix) by @carolynzech in #4250 * [Breaking Changes] Remove unstable list feature and default memory checks by @carolynzech in #4258 * Upgrade Rust toolchain to 2025-08-01 by @tautschnig in #4261 * Autoharness: add support for references by @tautschnig in #4234 * Turn off debug assertions under `--prove-safety-only` by @tautschnig in #4262 * Automatic toolchain upgrade to nightly-2025-08-02 by @github-actions[bot] in #4264 * Automatic toolchain upgrade to nightly-2025-08-03 by @github-actions[bot] in #4265 * Automatic cargo update to 2025-08-04 by @github-actions[bot] in #4267 * Automatic toolchain upgrade to nightly-2025-08-04 by @github-actions[bot] in #4266 * Introduce thread pool for writing goto binaries in parallel by @AlexanderPortland in #4236 * Major-version update cargo dependencies by @tautschnig in #4240 * Bump tests/perf/s2n-quic from `4938450` to `8f510f0` by @dependabot[bot] in #4270 * Automatic toolchain upgrade to nightly-2025-08-05 by @github-actions[bot] in #4271 * Automatic toolchain upgrade to nightly-2025-08-06 by @github-actions[bot] in #4272 * Avoid updating irrelevant symbols when handling quantifiers by @AlexanderPortland in #4268 * Lazily evaluate debug info by @AlexanderPortland in #4269 * Clone a template `BodyTransformer` to avoid re-initialization by @AlexanderPortland in #4259 * Ensuring that MIR constants are marked as static consts by @vonaka in #4233 * Fix release job dependencies by @tautschnig in #4273 ## New Contributors * @vonaka made their first contribution in #4151 **Full Changelog**: kani-0.64.0...kani-0.65.0 --------- Co-authored-by: Zyad Hassan <[email protected]>
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We currently pass all Kani options to
rustcfor use by thekani-compiler. This means that the Cargo build cache will detect a compilation fingerprint change whenever these options change and have to fully recompile the project (including all dependencies). However, for the majority of options, this is wholly unnecessary, as they only affect our codegen of the target crate once it’s already been lowered to MIR.This PR now passes most of
kani-compiler’s options only to the target crate so that they don’t change how dependencies are built and we can avoid their recompilation.There are two exceptions:
--ignore-global-assembly: this is needed even in dependencies because the check we do to detect global assembly happens even if we are skipping codegen.--check-version: this ensures we recompile everything when the user upgrades Kani versions. While not strictly necessary, existing comments understandably seem to want this behavior, and upgrades are rare enough I don’t see it being a real issue.Resolves #2230
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.