mbe: Rework diagnostics for metavariable expressions by tgross35 · Pull Request #142950 · rust-lang/rust

tgross35 · 2025-06-24T07:22:04Z

Make the diagnostics for metavariable expressions more user-friendly. This mostly addresses syntactic errors; I will be following up with improvements to concat(..).

r? @petrochenkov

rustbot · 2025-06-24T07:22:11Z

There are changes to the tidy tool.

cc @jieyouxu

compiler/rustc_expand/src/mbe/metavar_expr.rs

tgross35 · 2025-06-30T14:57:25Z

I split the nonfunctional changes here to a new PR, #143245. I think this should make it a bit more straightforward to do the other changes here.

petrochenkov · 2025-06-30T17:02:00Z

Blocked on #143245.
@rustbot blocked

…ation, r=petrochenkov mbe: Add tests and restructure metavariable expressions Add tests that show better diagnostics, and factor `concat` handling to a separate function. Each commit message has further details. This performs the nonfunctional perparation for further changes such as rust-lang#142950 and rust-lang#142975 .

tgross35 · 2025-07-01T08:04:45Z

@rustbot author
after that merges I’m going to do some cleanup of this and the remaining draft PR

rustbot · 2025-07-01T08:04:50Z

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

Rollup merge of #143245 - tgross35:metavariable-expr-organization, r=petrochenkov mbe: Add tests and restructure metavariable expressions Add tests that show better diagnostics, and factor `concat` handling to a separate function. Each commit message has further details. This performs the nonfunctional perparation for further changes such as #142950 and #142975 .

tgross35 · 2025-07-04T08:59:37Z

I rebased on top of #143245 and dropped the more confusing identifier changes, which makes more sense to bring back as part of #142975.

@rustbot ready

compiler/rustc_expand/src/mbe/metavar_expr.rs

petrochenkov · 2025-07-09T20:26:04Z

r=me with the comments addressed.
@rustbot author

Give a more user-friendly diagnostic about the following: * Trailing tokens within braces, e.g. `${foo() extra}` * Missing parentheses, e.g. `${foo}` * Incorrect number of arguments, with a hint about correct usage.

Change to a structural diagnostic, update the valid list, and move the valid list to a note.

tgross35 · 2025-07-10T01:16:05Z

Applied the suggestions then rebased.

@bors r=petrochenkov rollup

bors · 2025-07-10T01:16:07Z

📌 Commit 87e9819 has been approved by petrochenkov

It is now in the queue for this repository.

… r=petrochenkov mbe: Rework diagnostics for metavariable expressions Make the diagnostics for metavariable expressions more user-friendly. This mostly addresses syntactic errors; I will be following up with improvements to `concat(..)`.

Rollup of 9 pull requests Successful merges: - #141996 (Fix `proc_macro::Ident`'s handling of `$crate`) - #142911 (Remove support for dynamic allocas) - #142950 (mbe: Rework diagnostics for metavariable expressions) - #143270 (tests/codegen/enum/enum-match.rs: accept negative range attribute) - #143298 (`tests/ui`: A New Order [23/N]) - #143398 (tidy: add support for `--extra-checks=auto:` feature) - #143632 (fix: correct parameter names in LLVMRustBuildMinNum and LLVMRustBuildMaxNum FFI declarations) - #143644 (Add triagebot stdarch mention ping) - #143651 (Win: Use exceptions with empty data for SEH panic exception copies instead of a new panic) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 9 pull requests Successful merges: - #141996 (Fix `proc_macro::Ident`'s handling of `$crate`) - #142950 (mbe: Rework diagnostics for metavariable expressions) - #143011 (Make lint `ambiguous_glob_imports` deny-by-default and report-in-deps) - #143265 (Mention as_chunks in the docs for chunks) - #143270 (tests/codegen/enum/enum-match.rs: accept negative range attribute) - #143298 (`tests/ui`: A New Order [23/N]) - #143396 (Move NaN tests to floats/mod.rs) - #143398 (tidy: add support for `--extra-checks=auto:` feature) - #143644 (Add triagebot stdarch mention ping) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #142950 - tgross35:metavariable-expr-rework, r=petrochenkov mbe: Rework diagnostics for metavariable expressions Make the diagnostics for metavariable expressions more user-friendly. This mostly addresses syntactic errors; I will be following up with improvements to `concat(..)`.

Rollup of 9 pull requests Successful merges: - rust-lang#141996 (Fix `proc_macro::Ident`'s handling of `$crate`) - rust-lang#142950 (mbe: Rework diagnostics for metavariable expressions) - rust-lang#143011 (Make lint `ambiguous_glob_imports` deny-by-default and report-in-deps) - rust-lang#143265 (Mention as_chunks in the docs for chunks) - rust-lang#143270 (tests/codegen/enum/enum-match.rs: accept negative range attribute) - rust-lang#143298 (`tests/ui`: A New Order [23/N]) - rust-lang#143396 (Move NaN tests to floats/mod.rs) - rust-lang#143398 (tidy: add support for `--extra-checks=auto:` feature) - rust-lang#143644 (Add triagebot stdarch mention ping) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 9 pull requests Successful merges: - rust-lang/rust#141996 (Fix `proc_macro::Ident`'s handling of `$crate`) - rust-lang/rust#142950 (mbe: Rework diagnostics for metavariable expressions) - rust-lang/rust#143011 (Make lint `ambiguous_glob_imports` deny-by-default and report-in-deps) - rust-lang/rust#143265 (Mention as_chunks in the docs for chunks) - rust-lang/rust#143270 (tests/codegen/enum/enum-match.rs: accept negative range attribute) - rust-lang/rust#143298 (`tests/ui`: A New Order [23/N]) - rust-lang/rust#143396 (Move NaN tests to floats/mod.rs) - rust-lang/rust#143398 (tidy: add support for `--extra-checks=auto:` feature) - rust-lang/rust#143644 (Add triagebot stdarch mention ping) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned petrochenkov Jun 24, 2025

tgross35 added the F-macro_metavar_expr `#![feature(macro_metavar_expr)]` label Jun 24, 2025

petrochenkov reviewed Jun 24, 2025

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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 24, 2025

tgross35 mentioned this pull request Jun 26, 2025

mbe: Rework the concat metavariable expression #142975

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tgross35 changed the title ~~mbe: Rework diagnostics for metavariable expressions.~~ mbe: Rework diagnostics for metavariable expressions Jun 30, 2025

tgross35 mentioned this pull request Jun 30, 2025

mbe: Add tests and restructure metavariable expressions #143245

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tgross35 force-pushed the metavariable-expr-rework branch 2 times, most recently from 51693ef to 1146773 Compare July 4, 2025 06:37

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tgross35 force-pushed the metavariable-expr-rework branch 3 times, most recently from 13a7e49 to 7e5760b Compare July 4, 2025 08:55

tgross35 force-pushed the metavariable-expr-rework branch from 7e5760b to 5366b37 Compare July 4, 2025 08:58

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 Jul 4, 2025

tgross35 force-pushed the metavariable-expr-rework branch from 5366b37 to b276ff8 Compare July 4, 2025 09:28

petrochenkov reviewed Jul 9, 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 Jul 9, 2025

tgross35 force-pushed the metavariable-expr-rework branch from b276ff8 to dff37db Compare July 10, 2025 01:10

tgross35 added 2 commits July 9, 2025 21:11

mbe: Refactor diagnostics for invalid metavar expression syntax

e7ef31d

Give a more user-friendly diagnostic about the following: * Trailing tokens within braces, e.g. `${foo() extra}` * Missing parentheses, e.g. `${foo}` * Incorrect number of arguments, with a hint about correct usage.

mbe: Refactor the diagnostic for unrecognized metavariable expressions

87e9819

Change to a structural diagnostic, update the valid list, and move the valid list to a note.

tgross35 force-pushed the metavariable-expr-rework branch from dff37db to 87e9819 Compare July 10, 2025 01:15

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 10, 2025

tgross35 mentioned this pull request Jul 10, 2025

Rollup of 9 pull requests #143715

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tgross35 mentioned this pull request Jul 10, 2025

Rollup of 9 pull requests #143721

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bors merged commit 643efda into rust-lang:master Jul 10, 2025
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rustbot added this to the 1.90.0 milestone Jul 10, 2025

tgross35 deleted the metavariable-expr-rework branch July 10, 2025 18:41

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mbe: Rework diagnostics for metavariable expressions#142950

mbe: Rework diagnostics for metavariable expressions#142950
bors merged 2 commits intorust-lang:masterfrom
tgross35:metavariable-expr-rework

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