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Allow raw pointers in SIMD types - #85919

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workingjubilee:simd-ptrs-are-valid
Jun 5, 2021
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Allow raw pointers in SIMD types#85919
bors merged 3 commits into
rust-lang:masterfrom
workingjubilee:simd-ptrs-are-valid

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@workingjubilee

@workingjubilee workingjubilee commented Jun 2, 2021

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Closes #85915 by loosening the strictness in typechecking and adding a test to guarantee it passes.

This still might be too strict, as references currently do pass monomorphization, but my understanding is that they are not guaranteed to be "scalar" in the same way.

@rust-highfive

rust-highfive commented Jun 2, 2021

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r? @petrochenkov

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@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 2, 2021
@programmerjake

programmerjake commented Jun 2, 2021

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what happens when you try to use struct Simd([*mut str; 4])? does it error properly?

@workingjubilee

workingjubilee commented Jun 2, 2021 •
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That likely will produce a monomorphization-time error, which is already reachable via the open-ended Param(_) case. If you can provide test cases for them, I would be happy to follow up and close more issues.

@programmerjake

programmerjake commented Jun 2, 2021

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afaict references have exactly the same "scalarness" guarantees as raw pointers -- both of them can be fat pointers (e.g. *const dyn Trait) or thin pointers.

@programmerjake programmerjake mentioned this pull request Jun 2, 2021
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@programmerjake

programmerjake commented Jun 2, 2021

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That likely will produce a monomorphization-time error, which is already reachable via the open-ended Param(_) case. If you can provide test cases for them, I would be happy to follow up and close more issues.

submitted a pull request adding the requested test case: workingjubilee#1

@workingjubilee

workingjubilee commented Jun 2, 2021

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Ah, I meant if you could find something that does pass and doesn't error... a monomorphization time error (which is currently what happens) is the expected result. It's ugly and undesirable but the status quo, and improving on that is left for later work.

@programmerjake

programmerjake commented Jun 2, 2021

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force pushed my pull request since github's working again. added passing test as requested.

petrochenkov
petrochenkov reviewed Jun 2, 2021
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Comment thread compiler/rustc_middle/src/ty/sty.rs Outdated
@petrochenkov

petrochenkov commented Jun 2, 2021

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@workingjubilee
Could you add a test case for a fat raw pointer - #85919 (comment) ?

@petrochenkov petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 2, 2021
@programmerjake

programmerjake commented Jun 2, 2021

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Could you add a test case for a fat raw pointer - #85919 (comment) ?

Is this good? workingjubilee@c0ca382

@petrochenkov

petrochenkov commented Jun 2, 2021

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@programmerjake
I'd add one more case where *mut [u8] is used directly rather than through a type parameter.

@programmerjake

programmerjake commented Jun 2, 2021

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@programmerjake
I'd add one more case where *mut [u8] is used directly rather than through a type parameter.

added: workingjubilee@4dbe392

@programmerjake
test for more SIMD monomorphization errors
d9a5df6 
build-fail test for simd type with an element type that's a wide pointer
test for SIMD element type of optional nonnull ptr to extern type
test that wide ptr simd element type of *mut [u8] fails
@workingjubilee workingjubilee added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 2, 2021
@workingjubilee

workingjubilee commented Jun 2, 2021

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Updated appropriately~ And looks like CI passes!

@petrochenkov

petrochenkov commented Jun 3, 2021

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@bors r+

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bors commented Jun 3, 2021

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📌 Commit d9a5df6 has been approved by petrochenkov

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 3, 2021
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bors commented Jun 5, 2021

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⌛ Testing commit d9a5df6 with merge 4e20754...

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bors commented Jun 5, 2021

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☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 4e20754 to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Jun 5, 2021
@bors
bors merged commit 4e20754 into rust-lang:master Jun 5, 2021
@rustbot rustbot added this to the 1.54.0 milestone Jun 5, 2021
@workingjubilee
workingjubilee deleted the simd-ptrs-are-valid branch October 4, 2021 20:43
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