Fix repeated input evaluation in bitflags_match! #499

Merged

christophacham merged 1 commit from fix/bitflags-match-evaluate-once into main

2026-09-18 01:59:49 -05:00

christophacham commented

2026-09-16 03:57:09 -05:00

(Migrated from github.com)

bitflags_match! could evaluate its input repeatedly—once per attempted match—instead of once overall.

So bitflags_match!(next_flags(), …) could call next_flags() several times and match against different values. With only a default arm, it never called it.

The fix evaluates the input once and reuses it without moving it. Four regression tests cover this.

Evaluate the input once without moving it. Add regression tests for later-arm matches, fallback matches, default-only invocations, and non-Copy inputs. Verified with cargo test --all-features and cargo fmt --all -- --check. `bitflags_match!` could evaluate its input repeatedly—once per attempted match—instead of once overall. So `bitflags_match!(next_flags(), …)` could call `next_flags()` several times and match against different values. With only a default arm, it never called it. The fix evaluates the input once and reuses it without moving it. Four regression tests cover this.

KodrAus (Migrated from github.com) approved these changes

2026-09-16 15:29:40 -05:00

KodrAus (Migrated from github.com) left a comment