reject `...` without pattern post-expansion - #160165

folkertdev · 2026-07-29T16:25:10Z

tracking issue: #44930
fixes #160109

Discussed in today's lang meeting (notes).

We already emit the varargs_without_pattern FCW for ... without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

folkertdev · 2026-07-29T18:51:37Z

cc @traviscross
r? compiler

oli-obk · 2026-07-31T14:45:24Z

So... post-expansion it requires feature gates, and we're only breaking that?

folkertdev · 2026-07-31T14:48:24Z

We're not breaking anything (on stable/beta). Previously, bare ... post-expansion would hit the unstable c_variadic feature. We've now stabilized this feature (but this is not yet on beta). This PR makes the change to actually hard-error on it.

folkertdev · 2026-08-03T10:31:48Z

Is there other information I can provide to make the review easier?

oli-obk · 2026-08-03T10:48:19Z

@bors r+ rollup

rust-bors · 2026-08-03T10:48:22Z

📌 Commit 1d77f8a has been approved by oli-obk

It is now in the queue for this repository.

oli-obk · 2026-08-03T10:48:54Z

Is there other information I can provide to make the review easier?

Nope, just asked my question to double check my understanding

…xpansion, r=oli-obk reject `...` without pattern post-expansion tracking issue: rust-lang#44930 fixes rust-lang#160109 Discussed in today's lang meeting ([notes](https://hackmd.io/TiPFDCs4SD26EKTu12NNsg#C-variadic-function-definitions-stabilization-allows--without-pattern-with-immediate-FCW-rust160109)). We already emit the `varargs_without_pattern` FCW for `...` without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

…uwer Rollup of 21 pull requests Successful merges: - #159844 (Subtree cg_gcc sync (2026-07-24)) - #159326 (Deny multiple EII impls on a single item) - #159535 (Optimize slice::contains for bytewise types) - #159595 (Promote loongarch32-unknown-none* to Tier 2) - #160007 (allow `-Ldependency` search paths for panic runtimes) - #160320 (point at trait definition when it is used as a derive macro) - #160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - #160406 (`DepKind` cleanups) - #160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - #159014 ([rustdoc] Do not take `doc(cfg())` into account when filtering doctests) - #159303 (Fix ICE for direct inline const generic defaults) - #159977 (Add regression test for bool indexing codegen) - #160165 (reject `...` without pattern post-expansion) - #160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - #160305 (Linkify C-SKY targets in `platform-support.md`) - #160314 (fix borrowck ICE for consts with fn pointer type) - #160322 (ElaborateBoxDeref: remove unnecessary projection) - #160338 (Add regression test for supertrait associated type normalization through dyn) - #160340 (Add regression test for unused_parens on contract clauses) - #160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - #160384 (Add PR body notes for Cargo lock file maintenance)

…xpansion, r=oli-obk reject `...` without pattern post-expansion tracking issue: rust-lang#44930 fixes rust-lang#160109 Discussed in today's lang meeting ([notes](https://hackmd.io/TiPFDCs4SD26EKTu12NNsg#C-variadic-function-definitions-stabilization-allows--without-pattern-with-immediate-FCW-rust160109)). We already emit the `varargs_without_pattern` FCW for `...` without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

…uwer Rollup of 23 pull requests Successful merges: - #153749 (Account for ownership mismatch on argument that doesn't meet bound) - #159326 (Deny multiple EII impls on a single item) - #159535 (Optimize slice::contains for bytewise types) - #159595 (Promote loongarch32-unknown-none* to Tier 2) - #160007 (allow `-Ldependency` search paths for panic runtimes) - #160184 (Add -Zinstrument-mcount={fentry-nop-record,fentry-record}) - #160320 (point at trait definition when it is used as a derive macro) - #160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - #160406 (`DepKind` cleanups) - #160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - #159303 (Fix ICE for direct inline const generic defaults) - #159977 (Add regression test for bool indexing codegen) - #160011 (remove InterpError::map_err_info) - #160165 (reject `...` without pattern post-expansion) - #160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - #160305 (Linkify C-SKY targets in `platform-support.md`) - #160314 (fix borrowck ICE for consts with fn pointer type) - #160322 (ElaborateBoxDeref: remove unnecessary projection) - #160338 (Add regression test for supertrait associated type normalization through dyn) - #160340 (Add regression test for unused_parens on contract clauses) - #160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - #160384 (Add PR body notes for Cargo lock file maintenance) - #160435 (bump tracing-tree)

…xpansion, r=oli-obk reject `...` without pattern post-expansion tracking issue: rust-lang#44930 fixes rust-lang#160109 Discussed in today's lang meeting ([notes](https://hackmd.io/TiPFDCs4SD26EKTu12NNsg#C-variadic-function-definitions-stabilization-allows--without-pattern-with-immediate-FCW-rust160109)). We already emit the `varargs_without_pattern` FCW for `...` without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

…uwer Rollup of 26 pull requests Successful merges: - #153749 (Account for ownership mismatch on argument that doesn't meet bound) - #158727 (std: use `readdir` on nearly all UNIX platforms) - #159130 (a bit optimize four-digit chunks in integer formatting) - #159326 (Deny multiple EII impls on a single item) - #159535 (Optimize slice::contains for bytewise types) - #159595 (Promote loongarch32-unknown-none* to Tier 2) - #160184 (Add -Zinstrument-mcount={fentry-nop-record,fentry-record}) - #160320 (point at trait definition when it is used as a derive macro) - #160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - #160406 (`DepKind` cleanups) - #160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - #159303 (Fix ICE for direct inline const generic defaults) - #159977 (Add regression test for bool indexing codegen) - #160011 (remove InterpError::map_err_info) - #160165 (reject `...` without pattern post-expansion) - #160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - #160305 (Linkify C-SKY targets in `platform-support.md`) - #160314 (fix borrowck ICE for consts with fn pointer type) - #160322 (ElaborateBoxDeref: remove unnecessary projection) - #160338 (Add regression test for supertrait associated type normalization through dyn) - #160340 (Add regression test for unused_parens on contract clauses) - #160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - #160384 (Add PR body notes for Cargo lock file maintenance) - #160412 (Move duplicate-names check for #[rustc_must_implement_one_of] to attribute parser) - #160435 (bump tracing-tree) - #160449 (Fix lookup of object files)

…xpansion, r=oli-obk reject `...` without pattern post-expansion tracking issue: rust-lang#44930 fixes rust-lang#160109 Discussed in today's lang meeting ([notes](https://hackmd.io/TiPFDCs4SD26EKTu12NNsg#C-variadic-function-definitions-stabilization-allows--without-pattern-with-immediate-FCW-rust160109)). We already emit the `varargs_without_pattern` FCW for `...` without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

Rollup of 28 pull requests Successful merges: - #153749 (Account for ownership mismatch on argument that doesn't meet bound) - #159130 (a bit optimize four-digit chunks in integer formatting) - #159326 (Deny multiple EII impls on a single item) - #159535 (Optimize slice::contains for bytewise types) - #159595 (Promote loongarch32-unknown-none* to Tier 2) - #160184 (Add -Zinstrument-mcount={fentry-nop-record,fentry-record}) - #160320 (point at trait definition when it is used as a derive macro) - #160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - #160406 (`DepKind` cleanups) - #160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - #159303 (Fix ICE for direct inline const generic defaults) - #159977 (Add regression test for bool indexing codegen) - #160011 (remove InterpError::map_err_info) - #160165 (reject `...` without pattern post-expansion) - #160172 (tests: Enable `feature(stmt_expr_attributes)` in `2229_closure_analysis` tests) - #160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - #160305 (Linkify C-SKY targets in `platform-support.md`) - #160314 (fix borrowck ICE for consts with fn pointer type) - #160322 (ElaborateBoxDeref: remove unnecessary projection) - #160338 (Add regression test for supertrait associated type normalization through dyn) - #160340 (Add regression test for unused_parens on contract clauses) - #160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - #160384 (Add PR body notes for Cargo lock file maintenance) - #160412 (Move duplicate-names check for #[rustc_must_implement_one_of] to attribute parser) - #160427 (Run try builds on EC2 by default) - #160435 (bump tracing-tree) - #160449 (Fix lookup of object files) - #160477 (Update the tracking issue for `borrowed_buf_init`)

Rollup of 29 pull requests Successful merges: - #153749 (Account for ownership mismatch on argument that doesn't meet bound) - #159130 (a bit optimize four-digit chunks in integer formatting) - #159326 (Deny multiple EII impls on a single item) - #159535 (Optimize slice::contains for bytewise types) - #159595 (Promote loongarch32-unknown-none* to Tier 2) - #160184 (Add -Zinstrument-mcount={fentry-nop-record,fentry-record}) - #160320 (point at trait definition when it is used as a derive macro) - #160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - #160406 (`DepKind` cleanups) - #160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - #160434 (Avoid Docker push when the image did not change) - #159303 (Fix ICE for direct inline const generic defaults) - #159977 (Add regression test for bool indexing codegen) - #160011 (remove InterpError::map_err_info) - #160165 (reject `...` without pattern post-expansion) - #160172 (tests: Enable `feature(stmt_expr_attributes)` in `2229_closure_analysis` tests) - #160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - #160305 (Linkify C-SKY targets in `platform-support.md`) - #160314 (fix borrowck ICE for consts with fn pointer type) - #160322 (ElaborateBoxDeref: remove unnecessary projection) - #160338 (Add regression test for supertrait associated type normalization through dyn) - #160340 (Add regression test for unused_parens on contract clauses) - #160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - #160384 (Add PR body notes for Cargo lock file maintenance) - #160412 (Move duplicate-names check for #[rustc_must_implement_one_of] to attribute parser) - #160427 (Run try builds on EC2 by default) - #160435 (bump tracing-tree) - #160449 (Fix lookup of object files) - #160477 (Update the tracking issue for `borrowed_buf_init`)

Rollup merge of #160165 - folkertdev:reject-dotdotdot-post-expansion, r=oli-obk reject `...` without pattern post-expansion tracking issue: #44930 fixes #160109 Discussed in today's lang meeting ([notes](https://hackmd.io/TiPFDCs4SD26EKTu12NNsg#C-variadic-function-definitions-stabilization-allows--without-pattern-with-immediate-FCW-rust160109)). We already emit the `varargs_without_pattern` FCW for `...` without a pattern in function definitions and trait method declarations. This PR adds a hard error if this makes it past macro expansion.

Rollup of 29 pull requests Successful merges: - rust-lang/rust#153749 (Account for ownership mismatch on argument that doesn't meet bound) - rust-lang/rust#159130 (a bit optimize four-digit chunks in integer formatting) - rust-lang/rust#159326 (Deny multiple EII impls on a single item) - rust-lang/rust#159535 (Optimize slice::contains for bytewise types) - rust-lang/rust#159595 (Promote loongarch32-unknown-none* to Tier 2) - rust-lang/rust#160184 (Add -Zinstrument-mcount={fentry-nop-record,fentry-record}) - rust-lang/rust#160320 (point at trait definition when it is used as a derive macro) - rust-lang/rust#160369 (When suggesting method names, prefer *exact* doc aliases over similar names) - rust-lang/rust#160406 (`DepKind` cleanups) - rust-lang/rust#160424 (Use `thread::available_parallelism` as the default limit for backend parallelism) - rust-lang/rust#160434 (Avoid Docker push when the image did not change) - rust-lang/rust#159303 (Fix ICE for direct inline const generic defaults) - rust-lang/rust#159977 (Add regression test for bool indexing codegen) - rust-lang/rust#160011 (remove InterpError::map_err_info) - rust-lang/rust#160165 (reject `...` without pattern post-expansion) - rust-lang/rust#160172 (tests: Enable `feature(stmt_expr_attributes)` in `2229_closure_analysis` tests) - rust-lang/rust#160295 (Fix rustdoc ICE when checking if a generic arg can be elided) - rust-lang/rust#160305 (Linkify C-SKY targets in `platform-support.md`) - rust-lang/rust#160314 (fix borrowck ICE for consts with fn pointer type) - rust-lang/rust#160322 (ElaborateBoxDeref: remove unnecessary projection) - rust-lang/rust#160338 (Add regression test for supertrait associated type normalization through dyn) - rust-lang/rust#160340 (Add regression test for unused_parens on contract clauses) - rust-lang/rust#160371 (Add doc aliases for transpositions `read_exact_buf` and `read_exact_buf_at`) - rust-lang/rust#160384 (Add PR body notes for Cargo lock file maintenance) - rust-lang/rust#160412 (Move duplicate-names check for #[rustc_must_implement_one_of] to attribute parser) - rust-lang/rust#160427 (Run try builds on EC2 by default) - rust-lang/rust#160435 (bump tracing-tree) - rust-lang/rust#160449 (Fix lookup of object files) - rust-lang/rust#160477 (Update the tracking issue for `borrowed_buf_init`)

reject varargs without pattern post-expansion

1d77f8a

folkertdev added the F-c_variadic `#![feature(c_variadic)]` label Jul 29, 2026

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jul 29, 2026

folkertdev mentioned this pull request Jul 29, 2026

add c-variadic function definitions rust-lang/reference#2177

Merged

rustbot assigned oli-obk Jul 29, 2026

folkertdev marked this pull request as ready for review July 29, 2026 18:51

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 29, 2026

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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 3, 2026

JonathanBrouwer mentioned this pull request Aug 3, 2026

Rollup of 21 pull requests #160437

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JonathanBrouwer mentioned this pull request Aug 3, 2026

Rollup of 23 pull requests #160455

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JonathanBrouwer mentioned this pull request Aug 3, 2026

Rollup of 26 pull requests #160469

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jhpratt mentioned this pull request Aug 4, 2026

Rollup of 29 pull requests #160481

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jhpratt mentioned this pull request Aug 4, 2026

Rollup of 28 pull requests #160482

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Kobzol mentioned this pull request Aug 4, 2026

Rollup of 29 pull requests #160493

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rust-bors Bot merged commit cf0abb9 into rust-lang:main Aug 4, 2026
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rustbot added this to the 1.99.0 milestone Aug 4, 2026

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reject `...` without pattern post-expansion - #160165