Add `rustc::missing_generic_type_visitable` lint by ada4a · Pull Request #163538 · rust-lang/rust

ada4a · 2026-09-30T11:49:49Z

Best reviewed commit-by-commit.

The CI will probably complain about the TODOs, but I've added them deliberately, as a way to ask questions.

r? @JonathanBrouwer
cc @rust-lang/rust-analyzer

When `TypeVisitable` is implemented but `GenericTypeVisitable` isn't, the lint (which we'll add soon) recommends adding `#[derive(GenericTypeVisitable)]`. However, this suggestion is incorrect for types whose impls ought to be trivial. There, the problem occurs because the type was added to `TrivialTypeTraversalImpls!` in `macros.rs`, which added the `TypeVisitable` impl, but wasn't added to `trivial_impls!` in `generic_visit.rs`, such that the `GenericTypeVisitable` impl wasn't added. Imo, the root cause of this problem is that we have two separate macros for adding trivial impls. So this commit merges them into one, by making `TrivialTypeTraversalImpls!` add a `GenericTypeVisitable` impl as well. RE: `Variance`: its `GenericTypeVisitable` impl is now provided by `TrivialTypeTraversalImpls!`, making the derive unnecessary. RE: `rustc_hash::FxBuildHasher`: its `GenericTypeVisitable` impl ended up being removed, because `TypeVisitable` can't be implemented due to it not implemnting `Debug`. This shouldn't be a problem however, as `{Generic,}TypeVisitable` should always be implemented in pairs anyway. I confirmed this by removing the impl from `ra-ap-rustc_type_ir` and `cargo check`-ing r-a.

The missing impl for arrays was (indirectly) highlighted by the test suite, the rest -- by the `#[deny]`

JonathanBrouwer · 2026-10-07T11:09:39Z

A lot of comments but it's a lot of small things
I like the PR in general :3

ada4a · 2026-10-07T17:30:42Z

Everything should be addressed now:)

@rustbot ready

JonathanBrouwer

@bors r+ rollup

View changes since this review

rust-bors · 2026-10-07T19:10:15Z

📌 Commit 6257faf has been tentatively approved by JonathanBrouwer

It will be put into the queue for this repository once PR CI succeeds.

ada4a · 2026-10-08T07:19:43Z

  warning: unknown lint: `rustc::missing_generic_type_visitable_derive`
  Warning:   --> /checkout/tests/ui-fulldeps/internal-lints/missing-generic-type-visitable-derive.rs:5:9
     |
  LL | #![deny(rustc::missing_generic_type_visitable_derive)]
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: `#[warn(unknown_lints)]` on by default
  
  warning: 1 warning emitted
  ------------------------------------------
  
  ---- [ui] tests/ui-fulldeps/internal-lints/missing-generic-type-visitable-derive.rs stdout end ----
  
  failures:
      [ui] tests/ui-fulldeps/internal-lints/missing-generic-type-visitable-derive.rs
  
  test result: FAILED. 30 passed; 1 failed; 54 ignored; 0 measured; 0 filtered out; finished in 3.57s
  
  Some tests failed in compiletest suite=ui-fulldeps mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
  Bootstrap failed while executing `--stage 1 test --skip src/tools/tidy --skip src/tools/linkchecker`

Well of course it failed – it was running a ui-fulldeps test in stage 1!

Do you have any idea how to fix this?..

JonathanBrouwer · 2026-10-08T07:39:56Z

I think you just have to add //@ ignore-stage1 to the test

ada4a · 2026-10-08T08:11:46Z

Also added a FIXME to remove it again, like it's done in

rust/tests/ui-fulldeps/internal-lints/lint_pass_impl_without_macro.rs

Lines 2 to 3 in 42cfc04

    
           // FIXME(bootstrap): Remove the ignore once we promote the next beta. 
        
           //@ ignore-stage1

Uhh let's see if I can get the syntax right?

@bors try test-x86_64-gnu-llvm-22-3

rust-bors · 2026-10-08T08:11:49Z

Unknown argument "test-x86_64-gnu-llvm-22-3". Did you mean to use @bors jobs=<jobs>|parent=<parent>? Run @bors help or go to https://bors.rust-lang.org/help to see available commands.

ada4a · 2026-10-08T08:13:34Z

Ugh, does it not pick up message edits.

Okay let's try again.

@bors try jobs=test-x86_64-gnu-llvm-22-3

Add `rustc::missing_generic_type_visitable` lint try-job: test-x86_64-gnu-llvm-22-3

rust-bors · 2026-10-08T10:07:20Z

☀️ Try build successful (CI)
Build commit: 823963c (823963c46578469b01249c580a2345861e73cbb5)
Base parent: 42cfc04 (42cfc04deaa723bc21611f3f9d7c8651be6300df)

JonathanBrouwer · 2026-10-08T10:09:57Z

@bors r+

rust-bors · 2026-10-08T10:10:00Z

📌 Commit 19735e0 has been approved by JonathanBrouwer

It is now in the queue for this repository.

@JonathanBrouwer

…le, r=JonathanBrouwer Add `rustc::missing_generic_type_visitable` lint Best reviewed commit-by-commit. The CI will probably complain about the TODOs, but I've added them deliberately, as a way to ask questions. r? @JonathanBrouwer cc @rust-lang/rust-analyzer

@JonathanBrouwer

…le, r=JonathanBrouwer Add `rustc::missing_generic_type_visitable` lint Best reviewed commit-by-commit. The CI will probably complain about the TODOs, but I've added them deliberately, as a way to ask questions. r? @JonathanBrouwer cc @rust-lang/rust-analyzer

…uwer Rollup of 9 pull requests Successful merges: - #163462 (Fix COFF renaming of decorated (stdcall/fastcall/vectorcall) exports) - #163855 (Include enclosing item's context on const errors) - #163861 (Run LLDB debuginfo tests on `x86_64-mingw`) - #163538 (Add `rustc::missing_generic_type_visitable` lint) - #163617 (mips: make `Complex<T>` ABI match GCC) - #163832 (reject non-async coroutine closures as async callables) - #163958 (only make `RustaceansAreAwesome` satisfy trait clauses) - #163974 (Condense AdtDef lang item checks into one match) - #163979 (Add `bf16` to arm features) Failed merges: - #163972 (const-eval: ICE when we hit a non-const fn)

@JonathanBrouwer

…le, r=JonathanBrouwer Add `rustc::missing_generic_type_visitable` lint Best reviewed commit-by-commit. The CI will probably complain about the TODOs, but I've added them deliberately, as a way to ask questions. r? @JonathanBrouwer cc @rust-lang/rust-analyzer

…uwer Rollup of 12 pull requests Successful merges: - #163462 (Fix COFF renaming of decorated (stdcall/fastcall/vectorcall) exports) - #163855 (Include enclosing item's context on const errors) - #163861 (Run LLDB debuginfo tests on `x86_64-mingw`) - #161201 (Speed up tidy again) - #163538 (Add `rustc::missing_generic_type_visitable` lint) - #163617 (mips: make `Complex<T>` ABI match GCC) - #163772 (comptime fn error: suggest wrapping in const block) - #163832 (reject non-async coroutine closures as async callables) - #163958 (only make `RustaceansAreAwesome` satisfy trait clauses) - #163974 (Condense AdtDef lang item checks into one match) - #163979 (Add `bf16` to arm features) - #163989 (Revert "compiletest: stream output of executor process when --no-capture is set") Failed merges: - #163972 (const-eval: ICE when we hit a non-const fn)

…uwer Rollup of 19 pull requests Successful merges: - #156112 (Distinguish `repr(C)` ZSTs from others in ABI computation) - #157941 (Deny partial `-Z stack-protector` by default in all editions) - #163462 (Fix COFF renaming of decorated (stdcall/fastcall/vectorcall) exports) - #163855 (Include enclosing item's context on const errors) - #163861 (Run LLDB debuginfo tests on `x86_64-mingw`) - #163913 ( Silence redundant failed obligations on the same statement) - #161201 (Speed up tidy again) - #163380 (Tweak "name not found" resolution error when it happens from within a derive expansion) - #163538 (Add `rustc::missing_generic_type_visitable` lint) - #163617 (mips: make `Complex<T>` ABI match GCC) - #163772 (comptime fn error: suggest wrapping in const block) - #163813 (use pre-borrowck typing env for early MIR validation) - #163924 (replace instances of NonNull::new(&mut x).expect("...") with NonNull::from_mut) - #163958 (only make `RustaceansAreAwesome` satisfy trait clauses) - #163960 (vexos: clear .bss from assembly) - #163974 (Condense AdtDef lang item checks into one match) - #163979 (Add `bf16` to arm features) - #163989 (Revert "compiletest: stream output of executor process when --no-capture is set") - #163995 (m68k-unknown-none-elf: Remove code model) Failed merges: - #163832 (reject non-async coroutine closures as async callables) - #163972 (const-eval: ICE when we hit a non-const fn)

@JonathanBrouwer

Rollup merge of #163538 - ada4a:missing-generic-type-visitable, r=JonathanBrouwer Add `rustc::missing_generic_type_visitable` lint Best reviewed commit-by-commit. The CI will probably complain about the TODOs, but I've added them deliberately, as a way to ask questions. r? @JonathanBrouwer cc @rust-lang/rust-analyzer

…uwer Rollup of 19 pull requests Successful merges: - rust-lang/rust#156112 (Distinguish `repr(C)` ZSTs from others in ABI computation) - rust-lang/rust#157941 (Deny partial `-Z stack-protector` by default in all editions) - rust-lang/rust#163462 (Fix COFF renaming of decorated (stdcall/fastcall/vectorcall) exports) - rust-lang/rust#163855 (Include enclosing item's context on const errors) - rust-lang/rust#163861 (Run LLDB debuginfo tests on `x86_64-mingw`) - rust-lang/rust#163913 ( Silence redundant failed obligations on the same statement) - rust-lang/rust#161201 (Speed up tidy again) - rust-lang/rust#163380 (Tweak "name not found" resolution error when it happens from within a derive expansion) - rust-lang/rust#163538 (Add `rustc::missing_generic_type_visitable` lint) - rust-lang/rust#163617 (mips: make `Complex<T>` ABI match GCC) - rust-lang/rust#163772 (comptime fn error: suggest wrapping in const block) - rust-lang/rust#163813 (use pre-borrowck typing env for early MIR validation) - rust-lang/rust#163924 (replace instances of NonNull::new(&mut x).expect("...") with NonNull::from_mut) - rust-lang/rust#163958 (only make `RustaceansAreAwesome` satisfy trait clauses) - rust-lang/rust#163960 (vexos: clear .bss from assembly) - rust-lang/rust#163974 (Condense AdtDef lang item checks into one match) - rust-lang/rust#163979 (Add `bf16` to arm features) - rust-lang/rust#163989 (Revert "compiletest: stream output of executor process when --no-capture is set") - rust-lang/rust#163995 (m68k-unknown-none-elf: Remove code model) Failed merges: - rust-lang/rust#163832 (reject non-async coroutine closures as async callables) - rust-lang/rust#163972 (const-eval: ICE when we hit a non-const fn)

ada4a added 2 commits September 30, 2026 13:41

dogfood: add missing GenericTypeVisitable impls

e394051

The missing impl for arrays was (indirectly) highlighted by the test suite, the rest -- by the `#[deny]`

rustbot assigned JonathanBrouwer Sep 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. labels Sep 30, 2026