Description
Proposal
Rustc emits two traps when one would do, when TrapUnreachable is enabled (Godbolt) for most targets.
After some semi-related investigation (rust-lang/rust#102132), I came to the conclusion that using LLVM's NoTrapAfterNoreturn TargetOption would mostly solve this (for x86 and arm, but not wasm).
On @nikic's advice, I'm filing an MCP to make sure no-one has any concerns about this.
I propose to set this in the llvm wrapper, whenever TrapUnreachable is set:
majaha/rust@6fa99de
Apparently, NoTrapAfterNoreturn is undesireable on some targets like Playstation consoles. LLVM will override us in that case.
Mentors or Reviewers
Process
The main points of the Major Change Process are as follows:
- File an issue describing the proposal.
- A compiler team member or contributor who is knowledgeable in the area can second by writing
@rustbot second.- Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a
-C flag, then full team check-off is required. - Compiler team members can initiate a check-off via
@rfcbot fcp mergeon either the MCP or the PR.
- Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a
- Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.
You can read more about Major Change Proposals on forge.
Comments
This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.