Use `Option<Ident>` for lowered param names. #138685

nnethercote · 2025-03-19T03:53:19Z

Parameter patterns are lowered to an Ident by lower_fn_params_to_names, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty Ident.

If the incoming pattern is an empty Ident. This occurs if the parameter is anonymous, e.g. in a bare function type.
If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the span_delayed_bug), but lowering still occurs.

This commit replaces these empty Ident results with None, which eliminates a number of kw::Empty uses, and makes it impossible to fail to check for these exceptional cases.

Note: the FIXME comment in is_unwrap_or_empty_symbol is removed. It actually should have been removed in #138482, the precursor to this PR. That PR changed the lowering of wild patterns to _ symbols instead of empty symbols, which made the mentioned underscore check load-bearing.

r? @compiler-errors

rustbot · 2025-03-19T03:53:25Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

HIR ty lowering was modified

cc @fmease

nnethercote · 2025-03-19T03:54:06Z

@compiler-errors: I requested your review because this is closely related to #138482, which you reviewed. Please re-roll for a different reviewer if you don't want to do it. Thanks.

Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing.

compiler-errors · 2025-03-19T15:27:24Z

@bors r+ rollup

bors · 2025-03-19T15:27:27Z

📌 Commit f27cab8 has been approved by compiler-errors

It is now in the queue for this repository.

…owered-param-names, r=compiler-errors Use `Option<Ident>` for lowered param names. Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing. r? `@compiler-errors`

Rollup of 15 pull requests Successful merges: - rust-lang#138321 ([bootstrap] Distribute split debuginfo if present) - rust-lang#138364 (ports the compiler test cases to new rust_intrinsic format) - rust-lang#138410 (Couple mir building cleanups) - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138536 (stable_mir: Add `MutMirVisitor`) - rust-lang#138623 ([bootstrap] Use llvm_runtimes for compiler-rt) - rust-lang#138650 (Optimize `io::Write::write_fmt` for constant strings) - rust-lang#138652 (Reintroduce remote-test support in run-make tests) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138694 (Fix: add ohos target notes) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138709 (Update GCC submodule) - rust-lang#138724 (Check attrs: Don't try to retrieve the name of list stems) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) r? `@ghost` `@rustbot` modify labels: rollup

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

…owered-param-names, r=compiler-errors Use `Option<Ident>` for lowered param names. Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing. r? ```@compiler-errors```

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#138685 - nnethercote:use-Option-Ident-for-lowered-param-names, r=compiler-errors Use `Option<Ident>` for lowered param names. Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing. r? ``@compiler-errors``

…owered-param-names, r=compiler-errors Use `Option<Ident>` for lowered param names. Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing. r? ``@compiler-errors``

…owered-param-names, r=compiler-errors Use `Option<Ident>` for lowered param names. Parameter patterns are lowered to an `Ident` by `lower_fn_params_to_names`, which is used when lowering bare function types, trait methods, and foreign functions. Currently, there are two exceptional cases where the lowered param can become an empty `Ident`. - If the incoming pattern is an empty `Ident`. This occurs if the parameter is anonymous, e.g. in a bare function type. - If the incoming pattern is neither an ident nor an underscore. Any such parameter will have triggered a compile error (hence the `span_delayed_bug`), but lowering still occurs. This commit replaces these empty `Ident` results with `None`, which eliminates a number of `kw::Empty` uses, and makes it impossible to fail to check for these exceptional cases. Note: the `FIXME` comment in `is_unwrap_or_empty_symbol` is removed. It actually should have been removed in rust-lang#138482, the precursor to this PR. That PR changed the lowering of wild patterns to `_` symbols instead of empty symbols, which made the mentioned underscore check load-bearing. r? ```@compiler-errors```

…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#138435 (Add support for postfix yield expressions) - rust-lang#138685 (Use `Option<Ident>` for lowered param names.) - rust-lang#138700 (Suggest `-Whelp` when pass `--print lints` to rustc) - rust-lang#138727 (Do not rely on `type_var_origin` in `OrphanCheckErr::NonLocalInputType`) - rust-lang#138729 (Clean up `FnCtxt::resolve_coroutine_interiors`) - rust-lang#138731 (coverage: Add LLVM plumbing for expansion regions) - rust-lang#138732 (Use `def_path_str` for def id arg in `UnsupportedOpInfo`) - rust-lang#138735 (Remove `llvm` and `llvms` triagebot ping aliases for `icebreakers-llvm` ping group) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned compiler-errors Mar 19, 2025

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-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Mar 19, 2025

nnethercote force-pushed the use-Option-Ident-for-lowered-param-names branch from 621118b to f27cab8 Compare March 19, 2025 09:54

compiler-errors approved these changes Mar 19, 2025

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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-review Status: Awaiting review from the assignee but also interested parties. labels Mar 19, 2025

nnethercote mentioned this pull request Mar 19, 2025

Too much kw::Empty usage #137978

Closed

jieyouxu mentioned this pull request Mar 20, 2025

Rollup of 15 pull requests #138733

Closed

matthiaskrgr mentioned this pull request Mar 20, 2025

Rollup of 8 pull requests #138747

Merged

matthiaskrgr mentioned this pull request Mar 20, 2025

Rollup of 8 pull requests #138760

Merged

bors merged commit 9155769 into rust-lang:master Mar 21, 2025
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rustbot added this to the 1.87.0 milestone Mar 21, 2025

nnethercote deleted the use-Option-Ident-for-lowered-param-names branch March 21, 2025 02:05

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Use `Option<Ident>` for lowered param names. #138685

Use `Option<Ident>` for lowered param names. #138685

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Use Option<Ident> for lowered param names. #138685

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Use `Option<Ident>` for lowered param names. #138685

Use `Option<Ident>` for lowered param names. #138685