Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros. by mejrs · Pull Request #158608 · rust-lang/rust

mejrs · 2026-06-30T10:32:10Z

There are some more places where we can use this, for example

rust/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

Lines 623 to 639 in 3456328

    
           let in_std_macro = 
        
               match obligation.cause.span.ctxt().outer_expn_data().macro_def_id { 
        
                   Some(macro_def_id) => { 
        
                       let crate_name = tcx.crate_name(macro_def_id.krate); 
        
                       STDLIB_STABLE_CRATES.contains(&crate_name) 
        
                   } 
        
                   None => false, 
        
               }; 
        
           if in_std_macro 
        
               && matches!( 
        
                   self.tcx.get_diagnostic_name(leaf_trait_predicate.def_id()), 
        
                   Some(sym::Debug | sym::Display) 
        
               ) 
        
           { 
        
               return err.emit(); 
        
           }

but those turned out to be a little complicated so are left for followup prs.

Tracking issue: #158813

rustbot · 2026-06-30T10:32:14Z

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

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

rustc_errors::emitter was changed

cc @Muscraft

rustbot · 2026-06-30T11:00:14Z

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

rustbot · 2026-07-05T12:37:24Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

estebank · 2026-07-14T15:37:40Z

@bors r+

rust-bors · 2026-07-14T15:37:43Z

📌 Commit 106bb96 has been approved by estebank

It is now in the queue for this repository.

Rollup of 15 pull requests Successful merges: - #159311 (Add 1.97.1 release notes) - #156220 (Implement `VecDeque::truncate_to_range`) - #158608 (Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros.) - #159168 (Fix static_mut_refs lint check logic) - #159242 (resolve: Inherit eager invocation parents) - #159256 (Account for async closures when pointing at lifetime in return type) - #159310 (cleanup: upstream dropped AMX-TF32) - #158348 (Add documentation for the `inline` attribute) - #159181 (add rustc_no_writable to mem::forget and structs it uses) - #159191 (Mark `PrivateItems` with `std_internals` unstable feature.) - #159194 (rustdoc: Fix auto trait normalization env) - #159196 (OnceCell: Improve wording in module docs) - #159289 (Fix Zulip backport command suggestion) - #159294 (renovate: don't update PRs in the merge queue) - #159305 (std: clarify available_parallelism docs for Windows 11 processor groups)

@estebank

Rollup merge of #158608 - mejrs:opaque, r=estebank Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros. r? @estebank There are some more places where we can use this, for example https://github.com/rust-lang/rust/blob/345632878cffcb4c8e90750e943296b43d16c76e/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs#L623-L639 but those turned out to be a little complicated so are left for followup prs. Tracking issue: #158813

Rollup of 15 pull requests Successful merges: - rust-lang/rust#159311 (Add 1.97.1 release notes) - rust-lang/rust#156220 (Implement `VecDeque::truncate_to_range`) - rust-lang/rust#158608 (Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros.) - rust-lang/rust#159168 (Fix static_mut_refs lint check logic) - rust-lang/rust#159242 (resolve: Inherit eager invocation parents) - rust-lang/rust#159256 (Account for async closures when pointing at lifetime in return type) - rust-lang/rust#159310 (cleanup: upstream dropped AMX-TF32) - rust-lang/rust#158348 (Add documentation for the `inline` attribute) - rust-lang/rust#159181 (add rustc_no_writable to mem::forget and structs it uses) - rust-lang/rust#159191 (Mark `PrivateItems` with `std_internals` unstable feature.) - rust-lang/rust#159194 (rustdoc: Fix auto trait normalization env) - rust-lang/rust#159196 (OnceCell: Improve wording in module docs) - rust-lang/rust#159289 (Fix Zulip backport command suggestion) - rust-lang/rust#159294 (renovate: don't update PRs in the merge queue) - rust-lang/rust#159305 (std: clarify available_parallelism docs for Windows 11 processor groups)

@mejrs

…ros, r=mejrs Apply `#[diagnostic::opaque]` to macros expanding to built-in syntax For context, thin wrapper macros expanding to built-in syntax `builtin # SYNTAX(…)` (internal feature `builtin_syntax`) is an alternative to built-in macros (`#[rustc_builtin_macro]`) for introducing new syntax constructs that takes slightly less code to implement in the compiler (since one doesn't need to write boiler-plate expanders, see RUST-122806 for example). However, one disadvantage of that approach is the fact that the thin wrapper macro is a normal macro and is thus considered "interesting" wrt. macro backtraces. The fact that it expands to `builtin # SYNTAX(…)` should be considered an implementation detail and thus these macros should be considered opaque. I've applied `#[diagnostic::opaque]` (rust-lang#158608) to all of these macros which successfully suppresses diagnostic notes of the form `` this error originates in the macro `SYNTAX` (…) ``. Well, it doesn't actually omit the expansion from the macro backtrace when `-Zmacro-backtrace` is passed which was surprising but seems intentional looking at the linked PR. Still, this is better than nothing. r? @mejrs

@mejrs

Rollup merge of #159522 - fmease:opaquify-builtin-syntax-macros, r=mejrs Apply `#[diagnostic::opaque]` to macros expanding to built-in syntax For context, thin wrapper macros expanding to built-in syntax `builtin # SYNTAX(…)` (internal feature `builtin_syntax`) is an alternative to built-in macros (`#[rustc_builtin_macro]`) for introducing new syntax constructs that takes slightly less code to implement in the compiler (since one doesn't need to write boiler-plate expanders, see RUST-122806 for example). However, one disadvantage of that approach is the fact that the thin wrapper macro is a normal macro and is thus considered "interesting" wrt. macro backtraces. The fact that it expands to `builtin # SYNTAX(…)` should be considered an implementation detail and thus these macros should be considered opaque. I've applied `#[diagnostic::opaque]` (#158608) to all of these macros which successfully suppresses diagnostic notes of the form `` this error originates in the macro `SYNTAX` (…) ``. Well, it doesn't actually omit the expansion from the macro backtrace when `-Zmacro-backtrace` is passed which was surprising but seems intentional looking at the linked PR. Still, this is better than nothing. r? @mejrs

@mejrs

Apply `#[diagnostic::opaque]` to macros expanding to built-in syntax For context, thin wrapper macros expanding to built-in syntax `builtin # SYNTAX(…)` (internal feature `builtin_syntax`) is an alternative to built-in macros (`#[rustc_builtin_macro]`) for introducing new syntax constructs that takes slightly less code to implement in the compiler (since one doesn't need to write boiler-plate expanders, see RUST-122806 for example). However, one disadvantage of that approach is the fact that the thin wrapper macro is a normal macro and is thus considered "interesting" wrt. macro backtraces. The fact that it expands to `builtin # SYNTAX(…)` should be considered an implementation detail and thus these macros should be considered opaque. I've applied `#[diagnostic::opaque]` (rust-lang/rust#158608) to all of these macros which successfully suppresses diagnostic notes of the form `` this error originates in the macro `SYNTAX` (…) ``. Well, it doesn't actually omit the expansion from the macro backtrace when `-Zmacro-backtrace` is passed which was surprising but seems intentional looking at the linked PR. Still, this is better than nothing. r? @mejrs

mejrs · 2026-07-24T08:56:19Z

@lcnr this is unstable, I thought we only do relnotes for stuff that's getting stabilized?

rustbot added the A-attributes Area: Attributes (`#[…]`, `#![…]`) label Jun 30, 2026

rustbot assigned estebank Jun 30, 2026

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. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 30, 2026

JonathanBrouwer reviewed Jun 30, 2026

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Comment thread compiler/rustc_attr_parsing/src/attributes/diagnostic/opaque.rs

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rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 30, 2026

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Comment thread library/core/src/macros/mod.rs

mejrs force-pushed the opaque branch from 7569887 to af6d983 Compare July 5, 2026 12:03

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mejrs force-pushed the opaque branch from af6d983 to 4bb55d1 Compare July 5, 2026 12:37

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mejrs force-pushed the opaque branch from 4bb55d1 to 64cb4db Compare July 5, 2026 12:47

mejrs mentioned this pull request Jul 5, 2026

Tracking Issue for #[diagnostic::opaque] #158813

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mejrs added 2 commits July 5, 2026 15:11

Implement diagnostic::opaque attribute

7f3569b

Remove hide_backtrace

6a17b79

mejrs force-pushed the opaque branch from 64cb4db to b6604ca Compare July 5, 2026 13:11

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Remove rustc_diagnostic_item hack

106bb96

mejrs force-pushed the opaque branch from b6604ca to 106bb96 Compare July 5, 2026 15:34

rust-bors Bot 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 14, 2026

jhpratt mentioned this pull request Jul 15, 2026

Rollup of 15 pull requests #159316

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rust-bors Bot merged commit 2d4ae66 into rust-lang:main Jul 15, 2026
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rustbot added this to the 1.99.0 milestone Jul 15, 2026

fmease mentioned this pull request Jul 18, 2026

Apply #[diagnostic::opaque] to macros expanding to built-in syntax #159522

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lcnr added the relnotes Marks issues that should be documented in the release notes of the next release. label Jul 24, 2026

rustbot mentioned this pull request Jul 24, 2026

Tracking issue for release notes of #158608: Implement #[diagnostic::opaque] attribute to hide backtraces of macros. #159824

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mejrs removed the relnotes Marks issues that should be documented in the release notes of the next release. label Jul 31, 2026

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Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros. - #158608

Implement `#[diagnostic::opaque]` attribute to hide backtraces of macros.#158608
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mejrs:opaque

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	let in_std_macro =
	match obligation.cause.span.ctxt().outer_expn_data().macro_def_id {
	Some(macro_def_id) => {
	let crate_name = tcx.crate_name(macro_def_id.krate);
	STDLIB_STABLE_CRATES.contains(&crate_name)
	}
	None => false,
	};

	if in_std_macro
	&& matches!(
	self.tcx.get_diagnostic_name(leaf_trait_predicate.def_id()),
	Some(sym::Debug \| sym::Display)
	)
	{
	return err.emit();
	}

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mejrs commented Jun 30, 2026 •

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