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Move likely/unlikely argument outside of invisible unsafe block #79058

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merged 1 commit into from
Nov 15, 2020

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dtolnay
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@dtolnay dtolnay commented Nov 14, 2020

The previous likely!/unlikely! macros were unsound because it permits the caller's expr to contain arbitrary unsafe code.

pub fn huh() -> bool {
    likely!(std::ptr::read(&() as *const () as *const bool))
}

Before: compiles cleanly.
After:

error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
   |
70 |     likely!(std::ptr::read(&() as *const () as *const bool))
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
   |
   = note: consult the function's documentation for information on how to avoid undefined behavior

The previous `likely!`/`unlikely!` macros were unsound because it
permits the caller's expr to contain arbitrary unsafe code.

    pub fn huh() -> bool {
        likely!(std::ptr::read(&() as *const () as *const bool))
    }

Before: compiles cleanly.
After:

    error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
       |
    70 |     likely!(std::ptr::read(&() as *const () as *const bool))
       |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
       |
       = note: consult the function's documentation for information on how to avoid undefined behavior
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r? @varkor

(rust_highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 14, 2020
@Mark-Simulacrum
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@bors r+ rollup

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bors commented Nov 14, 2020

📌 Commit afb8170 has been approved by Mark-Simulacrum

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 14, 2020
bors added a commit to rust-lang-ci/rust that referenced this pull request Nov 15, 2020
…as-schievink

Rollup of 13 pull requests

Successful merges:

 - rust-lang#77802 (Allow making `RUSTC_BOOTSTRAP` conditional on the crate name)
 - rust-lang#79004 (Add `--color` support to bootstrap)
 - rust-lang#79005 (cleanup: Remove `ParseSess::injected_crate_name`)
 - rust-lang#79016 (Make `_` an expression, to discard values in destructuring assignments)
 - rust-lang#79019 (astconv: extract closures into a separate trait)
 - rust-lang#79026 (Implement BTreeMap::retain and BTreeSet::retain)
 - rust-lang#79031 (Validate that locals have a corresponding `LocalDecl`)
 - rust-lang#79034 (rustc_resolve: Make `macro_rules` scope chain compression lazy)
 - rust-lang#79036 (Move Steal to rustc_data_structures.)
 - rust-lang#79041 (Rename clean::{ItemEnum -> ItemKind}, clean::Item::{inner -> kind})
 - rust-lang#79058 (Move likely/unlikely argument outside of invisible unsafe block)
 - rust-lang#79059 (Print 'checking cranelift artifacts' to easily separate it from other artifacts)
 - rust-lang#79063 (Update rustfmt to v1.4.26)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit ae1916b into rust-lang:master Nov 15, 2020
@rustbot rustbot added this to the 1.50.0 milestone Nov 15, 2020
@dtolnay dtolnay deleted the likelymacro branch November 23, 2020 19:57
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6 participants