rust-lang / rust-lang/rfcs

Should `INT_MIN % -1` return 0 instead of panicking?

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Description

As @bill-myers originally pointed out here INT_MIN % -1 is mathematically well-defined to be 0, but Rust currently unconditionally panics instead, as like INT_MIN / -1 it is technically an overflow according to the two's complement representation. If we're incurring a branch to test for this case anyways, then we might as well return the correct result.

("Forked" from #1237.)

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
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Research direction

Start by reading the linked RFC #146 discussion and the forked issue #1237 to understand the existing decision and rationale. The work is done when the project has a settled specification for whether INT_MIN % -1 returns 0 or panics, including the overflow semantics.

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Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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