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Changing -O to opt-level=3 #828

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clubby789 opened this issue Jan 14, 2025 · 3 comments
Closed
2 of 3 tasks

Changing -O to opt-level=3 #828

clubby789 opened this issue Jan 14, 2025 · 3 comments
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major-change A proposal to make a major change to rustc major-change-accepted A major change proposal that was accepted T-compiler Add this label so rfcbot knows to poll the compiler team

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@clubby789
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clubby789 commented Jan 14, 2025 •
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Proposal

The -O flag has existed for over 14 years, predating opt-levels entirely. It is somewhat surprising that it means opt-level=2, especially as Cargo's release profile uses level 3.

In C compilers, -O usually means a non-maximum opt level as some optimizations can cause unsoundness; Rust doesn't have this limitation. (Not sure this part is true)

I'd like to propose changing this shorthand flag to a more useful default.

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 merge on either the MCP or the PR.
  • 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.
@clubby789 clubby789 added major-change A proposal to make a major change to rustc T-compiler Add this label so rfcbot knows to poll the compiler team labels Jan 14, 2025
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rustbot commented Jan 14, 2025

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.

Concerns or objections to the proposal should be discussed on Zulip and formally registered here by adding a comment with the following syntax:

@rfcbot concern reason-for-concern 
<description of the concern>

Concerns can be lifted with:

@rfcbot resolve reason-for-concern

See documentation at https://forge.rust-lang.org

cc @rust-lang/compiler

@rustbot rustbot added the to-announce Announce this issue on triage meeting label Jan 14, 2025
@Noratrieb
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@rustbot second

@rustbot rustbot added the final-comment-period The FCP has started, most (if not all) team members are in agreement label Jan 14, 2025
@clubby789 clubby789 mentioned this issue Jan 14, 2025
Merged
@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Jan 23, 2025
@apiraino
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@rustbot label -final-comment-period +major-change-accepted

@rustbot rustbot added major-change-accepted A major change proposal that was accepted to-announce Announce this issue on triage meeting and removed final-comment-period The FCP has started, most (if not all) team members are in agreement labels Jan 27, 2025
@apiraino apiraino removed the to-announce Announce this issue on triage meeting label Jan 30, 2025
workingjubilee added a commit to workingjubilee/rustc that referenced this issue Feb 6, 2025
@workingjubilee
Rollup merge of rust-lang#135439 - clubby789:O3, r=Noratrieb
608990f 
Make `-O` mean `OptLevel::Aggressive`

~~Just out of curiosity to see if anything is relying on this~~
MCP: rust-lang/compiler-team#828

This also renames `OptLevel::Default` to `OptLevel::More`, as `Default` no longer makes sense

r? ghost
workingjubilee added a commit to workingjubilee/rustc that referenced this issue Feb 8, 2025
@workingjubilee
Rollup merge of rust-lang#135439 - clubby789:O3, r=Noratrieb
048a7b0 
Make `-O` mean `OptLevel::Aggressive`

Implementation of this MCP: rust-lang/compiler-team#828, changing the meaning of `-O` from `-Copt-level=2` to `-Copt-level=3`.

This also renames `OptLevel::Default` to `OptLevel::More`, as `Default` no longer makes sense.
workingjubilee added a commit to workingjubilee/rustc that referenced this issue Feb 14, 2025
@workingjubilee
Rollup merge of rust-lang#135439 - clubby789:O3, r=Noratrieb
c3e21a2 
Make `-O` mean `OptLevel::Aggressive`

Implementation of this MCP: rust-lang/compiler-team#828, changing the meaning of `-O` from `-Copt-level=2` to `-Copt-level=3`.

This also renames `OptLevel::Default` to `OptLevel::More`, as `Default` no longer makes sense.
workingjubilee added a commit to workingjubilee/rustc that referenced this issue Feb 14, 2025
@workingjubilee
Rollup merge of rust-lang#135439 - clubby789:O3, r=Noratrieb
e7d9cb3 
Make `-O` mean `OptLevel::Aggressive`

Implementation of this MCP: rust-lang/compiler-team#828, changing the meaning of `-O` from `-Copt-level=2` to `-Copt-level=3`.

This also renames `OptLevel::Default` to `OptLevel::More`, as `Default` no longer makes sense.
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Feb 14, 2025
@rust-timer
Unrolled build for rust-lang#135439
8d07739 
Rollup merge of rust-lang#135439 - clubby789:O3, r=Noratrieb

Make `-O` mean `OptLevel::Aggressive`

Implementation of this MCP: rust-lang/compiler-team#828, changing the meaning of `-O` from `-Copt-level=2` to `-Copt-level=3`.

This also renames `OptLevel::Default` to `OptLevel::More`, as `Default` no longer makes sense.
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