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add known-bug tests for derive failure to detect packed repr #121025

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merged 1 commit into from
Mar 8, 2024
Merged

add known-bug tests for derive failure to detect packed repr #121025

merged 1 commit into from
Mar 8, 2024

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oli-obk
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@oli-obk oli-obk commented Feb 13, 2024 •
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We only taint if it was a normal item. Modules and imports are untouched. Tainting them needs to be done differently, and it's unclear if that would be useful or desirable. If we just taint them into Res::Err, we end up losing some duplicate name messages in the presence of other resolution errors.

r? @petrochenkov

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 13, 2024
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What will happen in a case like this? Will it still ICE?

#[derive(PartialEq)]
#[proc_macro_attribute_that_generates_repr_packed]
struct Dealigned<T>(u8, T);

Built-in macros are still macros, they still see their input as tokens (well, maybe as AST, but that is supposed to be an unobservable optimization).
I'm not sure we should make assumptions about their output that are strong enough to produce ICEs when something goes wrong.
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@rustbot rustbot 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 Mar 4, 2024
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oli-obk commented Mar 5, 2024

oh wow this has been an issue since the repr(packed) special casing in derives was added: https://github.com/rust-lang/rust/pull/44884/files#diff-b4f496d9af443165c646c4418ab441725f3f46770121cec0b9c2fab246f64724R412

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oli-obk commented Mar 5, 2024

I'm not sure we should make assumptions about their output that are strong enough to produce ICEs when something goes wrong.

I don't see any way around that (well we could error), but the fundamental limitation is there as long as we don't expand proc macros attributes before we run the derive.

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oli-obk commented Mar 5, 2024

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I added a known-bug ICE test and marked this PR as not fixing the issue anymore.

I think the diagnostic changes are still an improvement, so we may want to land it regardless?

@rustbot rustbot 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 Mar 5, 2024
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petrochenkov commented Mar 5, 2024 •
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Yeah, the diagnostics are improved, but I'm not sure what are the full implications of updating the resolution here.
Resolutions for items are "definite" and not expected to change once set (unlike e.g. glob imports).

So the old resolution may stuck in some places, and the new resolution in other places, and the mismatches could cause ICEs in places like import validation.
See for example #57185, that fixed one such mismatch.

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oli-obk commented Mar 5, 2024

Yea, makes sense. Do you have any ideas what we could do to taint anything in case there are name collisions? If not, let's just close this and address the ICE separately

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I need to think.

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Let's just not do this, the improvements are probably not worth the effort.
(But keep the added tests.)
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@rustbot rustbot 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 Mar 7, 2024
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Add known-bug tests for derive(PartialEq) mismatches with `#[repr(p…
bed9d1f 
…acked)]` attributes that are not visible before macro expansion
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oli-obk commented Mar 7, 2024

Makes sense, thanks for checking.

Kept the tests, removed the rest.

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@rustbot rustbot 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 Mar 7, 2024
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@bors r+

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bors commented Mar 8, 2024

📌 Commit bed9d1f has been approved by petrochenkov

It is now in the queue for this repository.

@bors bors removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Mar 8, 2024
@bors bors added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Mar 8, 2024
@oli-obk oli-obk changed the title Taint resolution if there were multiple items of the same name add known-bug tests for derive failure to detect packed repr Mar 8, 2024
@matthiaskrgr matthiaskrgr mentioned this pull request Mar 8, 2024
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bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 8, 2024
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Auto merge of rust-lang#122190 - matthiaskrgr:rollup-9ol4y30, r=matth…
28e8274 
…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#121025 (add known-bug tests for derive failure to detect packed repr)
 - rust-lang#121194 (Refactor pre-getopts command line argument handling)
 - rust-lang#121563 (Use `ControlFlow` in visitors.)
 - rust-lang#122173 (Don't ICE in CTFE if raw/fn-ptr types differ)
 - rust-lang#122175 (Bless tidy issues order)
 - rust-lang#122179 (rustc: Fix typo)
 - rust-lang#122181 (Fix crash in internal late lint checking)
 - rust-lang#122183 (interpret: update comment about read_discriminant on uninhabited variants)

Failed merges:

 - rust-lang#122076 (Tweak the way we protect in-place function arguments in interpreters)
 - rust-lang#122132 (Diagnostic renaming 3)

r? `@ghost`
`@rustbot` modify labels: rollup
bors added a commit to rust-lang-ci/rust that referenced this pull request Mar 8, 2024
@bors
Auto merge of rust-lang#122190 - matthiaskrgr:rollup-9ol4y30, r=matth…
a655e64 
…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#121025 (add known-bug tests for derive failure to detect packed repr)
 - rust-lang#121194 (Refactor pre-getopts command line argument handling)
 - rust-lang#121563 (Use `ControlFlow` in visitors.)
 - rust-lang#122173 (Don't ICE in CTFE if raw/fn-ptr types differ)
 - rust-lang#122175 (Bless tidy issues order)
 - rust-lang#122179 (rustc: Fix typo)
 - rust-lang#122181 (Fix crash in internal late lint checking)
 - rust-lang#122183 (interpret: update comment about read_discriminant on uninhabited variants)

Failed merges:

 - rust-lang#122076 (Tweak the way we protect in-place function arguments in interpreters)
 - rust-lang#122132 (Diagnostic renaming 3)

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 075f1c3 into rust-lang:master Mar 8, 2024
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@rustbot rustbot added this to the 1.78.0 milestone Mar 8, 2024
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Mar 8, 2024
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Unrolled build for rust-lang#121025
3e513c4 
Rollup merge of rust-lang#121025 - oli-obk:taint_after_errors, r=petrochenkov

add known-bug tests for derive failure to detect packed repr

We only taint if it was a normal item. Modules and imports are untouched. Tainting them needs to be done differently, and it's unclear if that would be useful or desirable. If we just taint them into `Res::Err`, we end up losing some duplicate name messages *in the presence of other resolution errors*.

r? `@petrochenkov`
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