Port `#[rustc_as_ptr]` to the new attribute system #142498

GrigorenkoPV · 2025-06-14T10:36:26Z

It might make sense to introduce some new parser analogous to Single, but even more simple: for parsing attributes that take no arguments and may appear only once (such as #[rustc_as_ptr] or #[rustc_const_stable_indirect]). Not sure if this should be a single impl parsing all such attributes, or one impl per attribute. Or how it will play along with the upcoming rework of attribute validation. Or how these argumentless attributes should be called (I've loosely referred to them as markers in the name of the new module in this PR, but not sure how good it is).

This is a part of #131229, so
r? @jdonszelmann

For reference, the #[rustc_as_ptr] attribute was created back in #132732 as a followup to #128985.

@rustbot label +S-blocked
Blocked on #142552.

rustbot · 2025-06-14T10:36:33Z

Some changes occurred in compiler/rustc_attr_data_structures

cc @jdonszelmann

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

mejrs

Or how these argumentless attributes should be called (I've loosely referred to them as markers in the name of the new module in this PR, but not sure how good it is).

"markers" already means quite a lot, see https://doc.rust-lang.org/nightly/nightly-rustc/rustc_attr_parsing/index.html for example.

Anyway, your questions seem to be about code organization - I think it would be better to organize attributes based on what they do rather than how they are parsed.

a single impl parsing all such attributes

The downside of this approach is that updating an attribute to take an argument would get annoying. Say if we had just #[blah] and then changed it to #[blah(alot|maybe| <nothing>)] then that would require moving all the code related to parsing blah, rather than just making changes in it.

compiler/rustc_attr_parsing/src/attributes/markers.rs

compiler/rustc_attr_parsing/src/attributes/mod.rs

jdonszelmann · 2025-06-14T14:25:21Z

compiler/rustc_passes/src/check_attr.rs

@@ -147,6 +147,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                    | AttributeKind::ConstStabilityIndirect
                    | AttributeKind::MacroTransparency(_),
                ) => { /* do nothing  */ }
+                Attribute::Parsed(AttributeKind::AsPtr) => {
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)


this is an ICE, check_applied_to_fn_or_method runs attr.span() which aren't supported on parsed attributes

no it isn't, look

rust/compiler/rustc_passes/src/check_attr.rs

Line 1835 in 86039cc

attr_span: attr.span(),

It still calls attr.span()

no it isn't, look

rust/compiler/rustc_passes/src/check_attr.rs

Line 1835 in 86039cc

attr_span: attr.span(),

It still calls attr.span()

Which works fine, because of
https://github.com/rust-lang/rust/pull/142498/files#diff-67c494d6d292cbe0a96d420fa02cf4589c7fad5a8d9abbdfa317d49a8bdce6daR1305

I kind of want to get rid of that function, the few that are in that list are there because it was too painful to migrate otherwise

could you solve it properly?

could you solve it properly?

Fully getting rid of that function is going to be quite an effort, because it is in impl AttributeExt for Attribute, which is relied on by many parts of the compiler.

I've started the process (#142552) of migrating from Attribute to either AttrItem or AttributeKind in other parts of the compiler, which should help both with getting rid of that impl specifically and with other #131229-related changes in general.

While this PR can technically be fixed independently of #142552, it will cause merge conflicts, so I'm going to wait for that one first instead.

compiler/rustc_attr_parsing/src/attributes/markers.rs

compiler/rustc_attr_parsing/src/attributes/mod.rs

compiler/rustc_attr_data_structures/src/attributes.rs

jdonszelmann · 2025-06-14T14:32:00Z

a single impl parsing all such attributes

I agree with @mejrs here, all attributes should get their own parser. Only if a parsed hir attribute's diagnostics depends on more than one syntactic attribute is it sensible to combine accept functions (see stability, and for example I intend to do this with allow/deny)

jdonszelmann · 2025-06-14T14:33:16Z

I do intend to make a simpler parser for single word attribute parsers just like there's already SingleAttributeParser. That transformation is trivial later, let's keep it as is for now. This change is at least conceptually good @GrigorenkoPV , just needs some minor work

jdonszelmann · 2025-06-14T14:34:51Z

@rustbot author

rustbot · 2025-06-14T14:34:55Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

GrigorenkoPV · 2025-06-14T17:28:59Z

@rustbot ready

jdonszelmann · 2025-06-15T11:04:41Z

@rustbot author

GrigorenkoPV · 2025-06-15T11:29:04Z

@rustbot ready

jdonszelmann · 2025-06-15T14:45:19Z

@rustbot author

rustbot assigned jdonszelmann Jun 14, 2025

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) 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 Jun 14, 2025

mejrs reviewed Jun 14, 2025

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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 Jun 14, 2025

Port #[rustc_as_ptr] to the new attribute system

86039cc

GrigorenkoPV force-pushed the as-ptr-refactor branch from 21f71d7 to 86039cc Compare June 14, 2025 14:57

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 Jun 14, 2025

jdonszelmann mentioned this pull request Jun 15, 2025

Tracking issue: Attribute refactor #131229

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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 Jun 15, 2025

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GrigorenkoPV mentioned this pull request Jun 15, 2025

Port #[may_dangle] to the new attribute system #142539

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GrigorenkoPV mentioned this pull request Jun 15, 2025

Use AttrItem instead of Attribute in more places #142552

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rustbot added the S-blocked Status: Blocked on something else such as an RFC or other implementation work. label Jun 15, 2025

Port #[rustc_as_ptr] to the new attribute system #142498

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Port #[rustc_as_ptr] to the new attribute system #142498

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Port `#[rustc_as_ptr]` to the new attribute system #142498

Port `#[rustc_as_ptr]` to the new attribute system #142498

GrigorenkoPV commented Jun 14, 2025 •

edited by rustbot

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jdonszelmann commented Jun 14, 2025 •

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