From dd92647f33e153b7a1feed1afbcd2c658c32b334 Mon Sep 17 00:00:00 2001 From: Nicholas Nethercote Date: Fri, 14 Mar 2025 09:03:23 +1100 Subject: [PATCH] Use `Option` 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 #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. --- .../src/functions/renamed_function_params.rs | 45 ++++++++++--------- clippy_lints/src/lifetimes.rs | 10 ++--- 2 files changed, 29 insertions(+), 26 deletions(-) diff --git a/clippy_lints/src/functions/renamed_function_params.rs b/clippy_lints/src/functions/renamed_function_params.rs index 5ad83f886e2e..041f6228fba2 100644 --- a/clippy_lints/src/functions/renamed_function_params.rs +++ b/clippy_lints/src/functions/renamed_function_params.rs @@ -5,7 +5,7 @@ use rustc_hir::hir_id::OwnerId; use rustc_hir::{Impl, ImplItem, ImplItemKind, ImplItemRef, ItemKind, Node, TraitRef}; use rustc_lint::LateContext; use rustc_span::Span; -use rustc_span::symbol::{Ident, Symbol, kw}; +use rustc_span::symbol::{Ident, kw}; use super::RENAMED_FUNCTION_PARAMS; @@ -51,22 +51,33 @@ struct RenamedFnArgs(Vec<(Span, String)>); impl RenamedFnArgs { /// Comparing between an iterator of default names and one with current names, /// then collect the ones that got renamed. - fn new(default_names: &mut I, current_names: &mut T) -> Self + fn new(default_idents: &mut I1, current_idents: &mut I2) -> Self where - I: Iterator, - T: Iterator, + I1: Iterator>, + I2: Iterator>, { let mut renamed: Vec<(Span, String)> = vec![]; - debug_assert!(default_names.size_hint() == current_names.size_hint()); - while let (Some(def_name), Some(cur_name)) = (default_names.next(), current_names.next()) { - let current_name = cur_name.name; - let default_name = def_name.name; - if is_unused_or_empty_symbol(current_name) || is_unused_or_empty_symbol(default_name) { - continue; - } - if current_name != default_name { - renamed.push((cur_name.span, default_name.to_string())); + debug_assert!(default_idents.size_hint() == current_idents.size_hint()); + while let (Some(default_ident), Some(current_ident)) = + (default_idents.next(), current_idents.next()) + { + let has_name_to_check = |ident: Option| { + if let Some(ident) = ident + && ident.name != kw::Underscore + && !ident.name.as_str().starts_with('_') + { + Some(ident) + } else { + None + } + }; + + if let Some(default_ident) = has_name_to_check(default_ident) + && let Some(current_ident) = has_name_to_check(current_ident) + && default_ident.name != current_ident.name + { + renamed.push((current_ident.span, default_ident.to_string())); } } @@ -83,14 +94,6 @@ impl RenamedFnArgs { } } -fn is_unused_or_empty_symbol(symbol: Symbol) -> bool { - // FIXME: `body_param_names` currently returning empty symbols for `wild` as well, - // so we need to check if the symbol is empty first. - // Therefore the check of whether it's equal to [`kw::Underscore`] has no use for now, - // but it would be nice to keep it here just to be future-proof. - symbol.is_empty() || symbol == kw::Underscore || symbol.as_str().starts_with('_') -} - /// Get the [`trait_item_def_id`](ImplItemRef::trait_item_def_id) of a relevant impl item. fn trait_item_def_id_of_impl(items: &[ImplItemRef], target: OwnerId) -> Option { items.iter().find_map(|item| { diff --git a/clippy_lints/src/lifetimes.rs b/clippy_lints/src/lifetimes.rs index 3dd2de1fafc7..8d47c756fc53 100644 --- a/clippy_lints/src/lifetimes.rs +++ b/clippy_lints/src/lifetimes.rs @@ -189,7 +189,7 @@ fn check_fn_inner<'tcx>( cx: &LateContext<'tcx>, sig: &'tcx FnSig<'_>, body: Option, - trait_sig: Option<&[Ident]>, + trait_sig: Option<&[Option]>, generics: &'tcx Generics<'_>, span: Span, report_extra_lifetimes: bool, @@ -264,7 +264,7 @@ fn could_use_elision<'tcx>( cx: &LateContext<'tcx>, func: &'tcx FnDecl<'_>, body: Option, - trait_sig: Option<&[Ident]>, + trait_sig: Option<&[Option]>, named_generics: &'tcx [GenericParam<'_>], msrv: Msrv, ) -> Option<(Vec, Vec)> { @@ -310,7 +310,7 @@ fn could_use_elision<'tcx>( let body = cx.tcx.hir_body(body_id); let first_ident = body.params.first().and_then(|param| param.pat.simple_ident()); - if non_elidable_self_type(cx, func, first_ident, msrv) { + if non_elidable_self_type(cx, func, Some(first_ident), msrv) { return None; } @@ -384,8 +384,8 @@ fn allowed_lts_from(named_generics: &[GenericParam<'_>]) -> FxIndexSet(cx: &LateContext<'tcx>, func: &FnDecl<'tcx>, ident: Option, msrv: Msrv) -> bool { - if let Some(ident) = ident +fn non_elidable_self_type<'tcx>(cx: &LateContext<'tcx>, func: &FnDecl<'tcx>, ident: Option>, msrv: Msrv) -> bool { + if let Some(Some(ident)) = ident && ident.name == kw::SelfLower && !func.implicit_self.has_implicit_self() && let Some(self_ty) = func.inputs.first()