RFC: Demote i686-pc-windows-gnu to Tier 2 by Noratrieb · Pull Request #3771 · rust-lang/rfcs

Noratrieb · 2025-02-11T20:07:14Z

Rendered

Co-authored-by: Jubilee Young <workingjubilee@gmail.com>

text/3771-demote-i686-pc-windows-gnu.md

jieyouxu

I'm in favor of this, left some remarks / additional context which are not meant to be requested changes.

jieyouxu · 2025-02-11T20:15:57Z

text/3771-demote-i686-pc-windows-gnu.md

+While some of these issues apply to all GNU-based targets, 32-bit x86 seems to be especially affected.
+And when a 32-bit Windows GNU issue comes up, contributors rarely actually investigate it, because it is such a complex and nonstandard environment compared to 64-bit Windows GNU, which is a lot easier to set up and work with.


Remark: one such example: rust-lang/rust#136795

text/3771-demote-i686-pc-windows-gnu.md

jieyouxu · 2025-02-11T20:24:56Z

text/3771-demote-i686-pc-windows-gnu.md

+> The target maintainer team must include at least 3 developers.
+
+This is not the case at all. There is currently no maintainer team.
+Though we should note that this is currently also true for many other Tier 1 targets, as this is a new rule not upheld everywhere yet.
+But experience tells that it is highly unlikely that 3 maintainers for 32 bit Windows GNU will be found.


Remark: and I think it's arguably misleading to say (or "promise", for that matter) i686-pc-windows-gnu is a Tier 1 target when it does not really receive Tier 1 maintenance support IMHO.

jieyouxu · 2025-02-11T20:29:22Z

text/3771-demote-i686-pc-windows-gnu.md

+
+## Conclusion
+
+Given the usage count and lack of maintenance leading to more than one requirement not being fulfilled, it becomes clear that `i686-pc-windows-gnu` is not worthy of being a Tier 1 target and is already getting much worse support than expected from a Tier 1 target.


Remark: arguably, it also imposes a maintenance burden on compiler contributors because if a test fails on just i686-mingw (32-bit windows-gnu) but not 64-bit windows-{msvc,gnu} it's very annoying to bless that.

jieyouxu · 2025-02-11T20:30:58Z

text/3771-demote-i686-pc-windows-gnu.md

+`x86_64-pc-windows-gnu` will remain a Tier 1 target after this RFC.
+While its popularity is more aligned with Tier 1, it suffers from the same lack of maintenance (but to a lesser degree) as its 32-bit cousin.
+It may be demoted as well in the future.


Remark: at least the 64-bit windows-gnu is more accessible as a host target, unlike the 32-bit windows-gnu.

if you want to cross-compile from linux to windows, the 64-bit windows-gnu (or gnullvm) target is the best way to do that, so I expect it to stay around a lot longer. we'd probably want to add an arm gnu target too at some point.

I expect that we would have an aarch64-pc-windows-gnullvm or whatever target instead (though that's functionally equivalent for practical use-cases).

This discussion is drifting away from the culprit, but I don't see value in ARM targets (32-bit).

AArch64 is already there as a cross compilation target (gnullvm only until GNU catches up), and once LLVM 20 goes live, I'll try to start MCP for promoting 64-bit gnullvm targets to hosts.

AArch64 is already there as a cross compilation target (gnullvm only until GNU catches up), and once LLVM 20 goes live, I'll try to start MCP for promoting 64-bit gnullvm targets to hosts.

nice! I had meant aarch64, but iirc windows doesn't call it that for some reason...

Noratrieb · 2025-02-15T15:55:29Z

I addressed some of the feedback I thought was worth putting into the RFC text itself.

The target tier policy says

A proposed new tier 1 target must be reviewed and approved by the compiler team based on these requirements. In addition, the release team must approve the viability and value of supporting the target. For a tier 1 target, this will typically take place via a full RFC proposing the target, to be jointly reviewed and approved by the compiler team and release team.

It does not say what teams should be involved in the demotion of a tier 1 target, but I leaned on the side of caution and chose to include compiler and release. I guess release can judge the non-viability and lack of value of supporting the target :D

I don't expect this to be controversial, so
@rfcbot fcp merge

rfcbot · 2025-02-15T15:55:31Z

text/3771-demote-i686-pc-windows-gnu.md

Noratrieb · 2025-02-26T17:57:53Z

ping @Mark-Simulacrum @SparrowLii @cjgillot @estebank @petrochenkov @spastorino

joshtriplett · 2025-02-26T23:39:45Z

text/3771-demote-i686-pc-windows-gnu.md

+That demotion will not need an RFC.
+
+The `*-windows-gnullvm` targets, which are based on LLVM instead of GNU tools, may see increased maintenance and popularity in the future, replacing the `*-windows-gnu` targets.
+But it seems unlikely that `i686-pc-windows-gnullvm` would ever acquire Tier 1 status.


Suggested change

But it seems unlikely that `i686-pc-windows-gnullvm` would ever acquire Tier 1 status.

(However, the 32-bit `i686-pc-windows-gnullvm` will not attain Tier 1 status either, for multiple reasons including the inability to link large binaries such as `rustc`.)

I can resolve the uncertainty; it is outright impossible.
LLVM uses memory mapping for many I/O operations. On 32-bit Windows, it cannot even host itself due to insufficient address space.

@mati865 Is that an issue with the compiler or with the linker? (Would it work if linked with a different linker?)

In any case, thanks for the clarification. I'll edit the suggestion.

@joshtriplett LLD hit a 32-bit mmap issue long ago, and upstream added a workaround using non-memory-mapped I/O on 32-bits. IIRC this time it was LLVM that encountered this problem while handling archives, but my memory may be faulty.

After reconsidering, I would say it is impossible without (possibly significant) changes to LLVM.

Edit: also see rust-lang/rust#131786

rfcbot · 2025-03-01T19:49:51Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rfcbot · 2025-03-11T19:55:47Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

Noratrieb · 2025-03-12T19:12:49Z

Thanks everyone! I have created rust-lang/rust#138422 to track the necessary steps.

…he_destroyer_of_i686-pc-windows-gnu, r=workingjubilee Demote i686-pc-windows-gnu to Tier 2 In accordance with [RFC 3771](rust-lang/rfcs#3771). FCP has been completed. tracking issue rust-lang#138422 I also added a stub doc page for the target and renamed the windows-gnullvm page for consistency.

…_destroyer_of_i686-pc-windows-gnu, r=workingjubilee Demote i686-pc-windows-gnu to Tier 2 In accordance with [RFC 3771](rust-lang/rfcs#3771). FCP has been completed. tracking issue rust-lang#138422 I also added a stub doc page for the target and renamed the windows-gnullvm page for consistency.

…r_of_i686-pc-windows-gnu, r=workingjubilee Demote i686-pc-windows-gnu to Tier 2 In accordance with [RFC 3771](rust-lang/rfcs#3771). FCP has been completed. tracking issue #138422 I also added a stub doc page for the target and renamed the windows-gnullvm page for consistency.

RFC: Demote i686-pc-windows-gnu to Tier 2

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Co-authored-by: Jubilee Young <workingjubilee@gmail.com>

Noratrieb force-pushed the i686-pc-windows-gnu branch from f8dfc48 to 00b04e1 Compare February 11, 2025 20:07

Noratrieb added T-compiler Relevant to the compiler team, which will review and decide on the RFC. T-release Relevant to the release team, which will review and decide on the RFC. labels Feb 11, 2025

Noratrieb mentioned this pull request Feb 11, 2025

Demote i686-pc-windows-gnu rust-lang/compiler-team#822

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ChrisDenton reviewed Feb 11, 2025

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jieyouxu reviewed Feb 11, 2025

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Noratrieb added 3 commits February 15, 2025 16:46

Sure Chris, I did indeed not fact check this part.

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Of course you're also *officially* our maintainer for gnullvm ❤️

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Expand on ignored tests

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rfcbot added proposed-final-comment-period Currently awaiting signoff of all team members in order to enter the final comment period. disposition-merge This RFC is in PFCP or FCP with a disposition to merge it. labels Feb 15, 2025

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jieyouxu mentioned this pull request Feb 18, 2025

rewrite compiler team documentation rust-lang/rust-forge#804

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joshtriplett reviewed Feb 26, 2025

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rfcbot added final-comment-period Will be merged/postponed/closed in ~10 calendar days unless new substational objections are raised. and removed proposed-final-comment-period Currently awaiting signoff of all team members in order to enter the final comment period. labels Mar 1, 2025

Noratrieb mentioned this pull request Mar 1, 2025

Demote i686-pc-windows-gnu to Tier 2 rust-lang/rust#137869

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rfcbot added finished-final-comment-period The final comment period is finished for this RFC. and removed final-comment-period Will be merged/postponed/closed in ~10 calendar days unless new substational objections are raised. labels Mar 11, 2025

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Noratrieb mentioned this pull request Mar 12, 2025

Tracking Issue for the demotion of i686-pc-windows-gnu rust-lang/rust#138422

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Noratrieb merged commit ceca0a0 into rust-lang:master Mar 12, 2025

Noratrieb deleted the i686-pc-windows-gnu branch March 12, 2025 19:12

ognevny mentioned this pull request Mar 13, 2025

drop 32-bit for some librsvg rdeps msys2/MINGW-packages#23561

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RalfJung mentioned this pull request Apr 5, 2025

mitigate MSVC alignment issue on x86-32 rust-lang/rust#139261

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jieyouxu mentioned this pull request May 24, 2025

document reqd. approvals for target changes rust-lang/rust-forge#834

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mati865 mentioned this pull request May 27, 2025

announce new compiler team members rust-lang/blog.rust-lang.org#1623

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jieyouxu mentioned this pull request Jul 25, 2025

Clarify required approvals for target promotion and demotion/removal between different target tiers rust-lang/rust-forge#921

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		While some of these issues apply to all GNU-based targets, 32-bit x86 seems to be especially affected.
		And when a 32-bit Windows GNU issue comes up, contributors rarely actually investigate it, because it is such a complex and nonstandard environment compared to 64-bit Windows GNU, which is a lot easier to set up and work with.


		## Conclusion

		Given the usage count and lack of maintenance leading to more than one requirement not being fulfilled, it becomes clear that `i686-pc-windows-gnu` is not worthy of being a Tier 1 target and is already getting much worse support than expected from a Tier 1 target.

	But it seems unlikely that `i686-pc-windows-gnullvm` would ever acquire Tier 1 status.
	(However, the 32-bit `i686-pc-windows-gnullvm` will not attain Tier 1 status either, for multiple reasons including the inability to link large binaries such as `rustc`.)

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