b9754f9e7b
Use `const_eval_select!()` macro to enable contract checking only at runtime. The existing contract logic relies on closures, which are not supported in constant functions. This commit also removes one level of indirection for ensures clauses, however, it currently has a spurious warning message when the bottom of the function is unreachable.
56 lines
1.6 KiB
Rust
56 lines
1.6 KiB
Rust
//! Check if we can annotate a constant function with contracts.
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//!
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//! The contract is only checked at runtime, and it will not fail if evaluated statically.
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//! This is an existing limitation due to the existing architecture and the lack of constant
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//! closures.
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//!
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//@ revisions: all_pass runtime_fail_pre runtime_fail_post
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//
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//@ [all_pass] run-pass
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//
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//@ [runtime_fail_pre] run-fail
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//@ [runtime_fail_post] run-fail
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//
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//@ [all_pass] compile-flags: -Zcontract-checks=yes
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//@ [runtime_fail_pre] compile-flags: -Zcontract-checks=yes
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//@ [runtime_fail_post] compile-flags: -Zcontract-checks=yes
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#![feature(contracts)]
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//~^ WARN the feature `contracts` is incomplete and may not be safe to use and/or cause compiler crashes [incomplete_features]
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extern crate core;
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use core::contracts::*;
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#[requires(x < 100)]
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const fn less_than_100(x: u8) -> u8 {
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x
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}
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// This is wrong on purpose.
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#[ensures(|ret| *ret)]
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const fn always_true(b: bool) -> bool {
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b
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}
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const ZERO: u8 = less_than_100(0);
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// This is no-op because the contract cannot be checked at compilation time.
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const TWO_HUNDRED: u8 = less_than_100(200);
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/// Example from <https://github.com/rust-lang/rust/issues/136925>.
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#[ensures(move |ret: &u32| *ret > x)]
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const fn broken_sum(x: u32, y: u32) -> u32 {
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x + y
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}
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fn main() {
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assert_eq!(ZERO, 0);
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assert_eq!(TWO_HUNDRED, 200);
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assert_eq!(broken_sum(0, 1), 1);
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assert_eq!(always_true(true), true);
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#[cfg(runtime_fail_post)]
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let _ok = always_true(false);
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// Runtime check should fail.
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#[cfg(runtime_fail_pre)]
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let _200 = less_than_100(200);
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}
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