From bbadce9ec0a8855ab72852af1a6ed1f68c9ce0c2 Mon Sep 17 00:00:00 2001 From: Quinn Sinclair Date: Wed, 3 Jan 2024 04:03:00 +0200 Subject: [PATCH] Fixed ICE introduced in #12004 Issue: in #12004, we emit a lint for `filter(Option::is_some)`. If the parent expression is a `.map` we don't emit that lint as there exists a more specialized lint for that. The ICE introduced in #12004 is a consequence of the assumption that a parent expression after a filter would be a method call with the filter call being the receiver. However, it is entirely possible to have a closure of the form ``` || { vec![Some(1), None].into_iter().filter(Option::is_some) } ``` The previous implementation looked at the parent expression; namely the closure, and tried to check the parameters by indexing [0] on an empty list. This commit is an overhaul of the lint with significantly more FP tests and checks. Impl details: 1. We verify that the filter method we are in is a proper trait method to avoid FPs. 2. We check that the parent expression is not a map by checking whether it exists; if is a trait method; and then a method call. 3. We check that we don't have comments in the span. 4. We verify that we are in an Iterator of Option and Result. 5. We check the contents of the filter. 1. For closures we peel it. If it is not a single expression, we don't lint. 2. For paths, we do a typecheck to avoid FPs for types that impl functions with the same names. 3. For calls, we verify the type, via the path, and that the param of the closure is the single argument to the call. 4. For method calls we verify that the receiver is the parameter of the closure. Since we handle single, non-block exprs, the parameter can't be shadowed, so no FP. This commit also adds additional FP tests. --- clippy_lints/src/methods/filter_map.rs | 3 +- clippy_lints/src/methods/iter_filter.rs | 206 ++++++++++++++++----- tests/ui/iter_filter_is_ok.fixed | 193 +++++++++++++++++++- tests/ui/iter_filter_is_ok.rs | 193 +++++++++++++++++++- tests/ui/iter_filter_is_ok.stderr | 74 +++++++- tests/ui/iter_filter_is_some.fixed | 231 +++++++++++++++++++++++- tests/ui/iter_filter_is_some.rs | 231 +++++++++++++++++++++++- tests/ui/iter_filter_is_some.stderr | 62 ++++++- 8 files changed, 1092 insertions(+), 101 deletions(-) diff --git a/clippy_lints/src/methods/filter_map.rs b/clippy_lints/src/methods/filter_map.rs index 7cfd3d346b63..e489899c19e3 100644 --- a/clippy_lints/src/methods/filter_map.rs +++ b/clippy_lints/src/methods/filter_map.rs @@ -26,13 +26,14 @@ fn is_method(cx: &LateContext<'_>, expr: &hir::Expr<'_>, method_name: Symbol) -> hir::ExprKind::Closure(&hir::Closure { body, .. }) => { let body = cx.tcx.hir().body(body); let closure_expr = peel_blocks(body.value); - let arg_id = body.params[0].pat.hir_id; match closure_expr.kind { hir::ExprKind::MethodCall(hir::PathSegment { ident, .. }, receiver, ..) => { if ident.name == method_name && let hir::ExprKind::Path(path) = &receiver.kind && let Res::Local(ref local) = cx.qpath_res(path, receiver.hir_id) + && !body.params.is_empty() { + let arg_id = body.params[0].pat.hir_id; return arg_id == *local; } false diff --git a/clippy_lints/src/methods/iter_filter.rs b/clippy_lints/src/methods/iter_filter.rs index ade8e3155fae..9f84321ced4a 100644 --- a/clippy_lints/src/methods/iter_filter.rs +++ b/clippy_lints/src/methods/iter_filter.rs @@ -1,87 +1,197 @@ +use clippy_utils::ty::get_iterator_item_ty; +use hir::ExprKind; use rustc_lint::{LateContext, LintContext}; use super::{ITER_FILTER_IS_OK, ITER_FILTER_IS_SOME}; use clippy_utils::diagnostics::span_lint_and_sugg; use clippy_utils::source::{indent_of, reindent_multiline}; -use clippy_utils::{is_trait_method, peel_blocks, span_contains_comment}; +use clippy_utils::{get_parent_expr, is_trait_method, peel_blocks, span_contains_comment}; use rustc_errors::Applicability; use rustc_hir as hir; -use rustc_hir::def::Res; use rustc_hir::QPath; -use rustc_span::symbol::{sym, Symbol}; +use rustc_span::symbol::{sym, Ident, Symbol}; use rustc_span::Span; use std::borrow::Cow; -fn is_method(cx: &LateContext<'_>, expr: &hir::Expr<'_>, method_name: Symbol) -> bool { - match &expr.kind { - hir::ExprKind::Path(QPath::TypeRelative(_, mname)) => mname.ident.name == method_name, - hir::ExprKind::Path(QPath::Resolved(_, segments)) => { - segments.segments.last().unwrap().ident.name == method_name +/// +/// Returns true if the expression is a method call to `method_name` +/// e.g. `a.method_name()` or `Option::method_name`. +/// +/// The type-checker verifies for us that the method accepts the right kind of items +/// (e.g. `Option::is_some` accepts `Option<_>`), so we don't need to check that. +/// +/// How to capture each case: +/// +/// `.filter(|a| { std::option::Option::is_some(a) })` +/// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <- this is a closure, getting unwrapped and +/// recursively checked. +/// `std::option::Option::is_some(a)` +/// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <- this is a call. It unwraps to a path with +/// `QPath::TypeRelative`. Since this is a type relative path, we need to check the method name, the +/// type, and that the parameter of the closure is passed in the call. This part is the dual of +/// `receiver.method_name()` below. +/// +/// `filter(std::option::Option::is_some);` +/// ^^^^^^^^^^^^^^^^^^^^^^^^^^^ <- this is a type relative path, like above, we check the +/// type and the method name. +/// +/// `filter(|a| a.is_some());` +/// ^^^^^^^^^^^^^^^ <- this is a method call inside a closure, +/// we check that the parameter of the closure is the receiver of the method call and don't allow +/// any other parameters. +fn is_method( + cx: &LateContext<'_>, + expr: &hir::Expr<'_>, + type_symbol: Symbol, + method_name: Symbol, + params: &[&hir::Pat<'_>], +) -> bool { + fn pat_is_recv(ident: Ident, param: &hir::Pat<'_>) -> bool { + match param.kind { + hir::PatKind::Binding(_, _, other, _) => ident == other, + hir::PatKind::Ref(pat, _) => pat_is_recv(ident, pat), + _ => false, + } + } + match expr.kind { + hir::ExprKind::MethodCall(hir::PathSegment { ident, .. }, recv, ..) => { + // compare the identifier of the receiver to the parameter + // we are in a filter => closure has a single parameter and a single, non-block + // expression, this means that the parameter shadows all outside variables with + // the same name => avoid FPs. If the parameter is not the receiver, then this hits + // outside variables => avoid FP + if ident.name == method_name + && let ExprKind::Path(QPath::Resolved(None, path)) = recv.kind + && let &[seg] = path.segments + && params.iter().any(|p| pat_is_recv(seg.ident, p)) + { + return true; + } + false + }, + // This is used to check for complete paths via `|a| std::option::Option::is_some(a)` + // this then unwraps to a path with `QPath::TypeRelative` + // we pass the params as they've been passed to the current call through the closure + hir::ExprKind::Call(expr, [param]) => { + // this will hit the `QPath::TypeRelative` case and check that the method name is correct + if is_method(cx, expr, type_symbol, method_name, params) + // we then check that this is indeed passing the parameter of the closure + && let ExprKind::Path(QPath::Resolved(None, path)) = param.kind + && let &[seg] = path.segments + && params.iter().any(|p| pat_is_recv(seg.ident, p)) + { + return true; + } + false + }, + hir::ExprKind::Path(QPath::TypeRelative(ty, mname)) => { + let ty = cx.typeck_results().node_type(ty.hir_id); + if let Some(did) = cx.tcx.get_diagnostic_item(type_symbol) + && ty.ty_adt_def() == cx.tcx.type_of(did).skip_binder().ty_adt_def() + { + return mname.ident.name == method_name; + } + false }, - hir::ExprKind::MethodCall(segment, _, _, _) => segment.ident.name == method_name, hir::ExprKind::Closure(&hir::Closure { body, .. }) => { let body = cx.tcx.hir().body(body); let closure_expr = peel_blocks(body.value); - let arg_id = body.params[0].pat.hir_id; - match closure_expr.kind { - hir::ExprKind::MethodCall(hir::PathSegment { ident, .. }, receiver, ..) => { - if ident.name == method_name - && let hir::ExprKind::Path(path) = &receiver.kind - && let Res::Local(ref local) = cx.qpath_res(path, receiver.hir_id) - { - return arg_id == *local; - } - false - }, - _ => false, - } + let params = body.params.iter().map(|param| param.pat).collect::>(); + is_method(cx, closure_expr, type_symbol, method_name, params.as_slice()) }, _ => false, } } fn parent_is_map(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool { - if let hir::Node::Expr(parent_expr) = cx.tcx.hir().get_parent(expr.hir_id) { - is_method(cx, parent_expr, rustc_span::sym::map) - } else { - false + if let Some(expr) = get_parent_expr(cx, expr) + && is_trait_method(cx, expr, sym::Iterator) + && let hir::ExprKind::MethodCall(path, _, _, _) = expr.kind + && path.ident.name == rustc_span::sym::map + { + return true; } + false } -#[allow(clippy::too_many_arguments)] -pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, filter_arg: &hir::Expr<'_>, filter_span: Span) { - let is_iterator = is_trait_method(cx, expr, sym::Iterator); - let parent_is_not_map = !parent_is_map(cx, expr); +enum FilterType { + IsSome, + IsOk, +} - if is_iterator - && parent_is_not_map - && is_method(cx, filter_arg, sym!(is_some)) - && !span_contains_comment(cx.sess().source_map(), filter_span.with_hi(expr.span.hi())) +/// Returns the `FilterType` of the expression if it is a filter over an Iter