diff options
| -rw-r--r-- | clippy_lints/src/manual_let_else.rs | 71 | ||||
| -rw-r--r-- | tests/ui/manual_let_else.rs | 32 | ||||
| -rw-r--r-- | tests/ui/manual_let_else.stderr | 22 |
3 files changed, 119 insertions, 6 deletions
diff --git a/clippy_lints/src/manual_let_else.rs b/clippy_lints/src/manual_let_else.rs index d6ac6e106b4..0b3bec714c0 100644 --- a/clippy_lints/src/manual_let_else.rs +++ b/clippy_lints/src/manual_let_else.rs @@ -4,11 +4,14 @@ use clippy_utils::diagnostics::span_lint_and_then; use clippy_utils::higher::IfLetOrMatch; use clippy_utils::source::snippet_with_context; use clippy_utils::ty::is_type_diagnostic_item; -use clippy_utils::{is_lint_allowed, is_never_expr, msrvs, pat_and_expr_can_be_question_mark, peel_blocks}; +use clippy_utils::{ + MaybePath, is_lint_allowed, is_never_expr, is_wild, msrvs, pat_and_expr_can_be_question_mark, path_res, peel_blocks, +}; use rustc_ast::BindingMode; use rustc_data_structures::fx::FxHashMap; use rustc_errors::Applicability; -use rustc_hir::{Expr, ExprKind, MatchSource, Pat, PatExpr, PatExprKind, PatKind, QPath, Stmt, StmtKind}; +use rustc_hir::def::{CtorOf, DefKind, Res}; +use rustc_hir::{Arm, Expr, ExprKind, HirId, MatchSource, Pat, PatExpr, PatExprKind, PatKind, QPath, Stmt, StmtKind}; use rustc_lint::{LateContext, LintContext}; use rustc_span::Span; @@ -91,14 +94,15 @@ impl<'tcx> QuestionMark { let Some((idx, diverging_arm)) = diverging_arm_opt else { return; }; + + let pat_arm = &arms[1 - idx]; // If the non-diverging arm is the first one, its pattern can be reused in a let/else statement. // However, if it arrives in second position, its pattern may cover some cases already covered // by the diverging one. - // TODO: accept the non-diverging arm as a second position if patterns are disjointed. - if idx == 0 { + if idx == 0 && !is_arms_disjointed(cx, diverging_arm, pat_arm) { return; } - let pat_arm = &arms[1 - idx]; + let Some(ident_map) = expr_simple_identity_map(local.pat, pat_arm.pat, pat_arm.body) else { return; }; @@ -110,6 +114,63 @@ impl<'tcx> QuestionMark { } } +/// Checks if the patterns of the arms are disjointed. Currently, we only support patterns of simple +/// enum variants without nested patterns or bindings. +/// +/// TODO: Support more complex patterns. +fn is_arms_disjointed(cx: &LateContext<'_>, arm1: &Arm<'_>, arm2: &Arm<'_>) -> bool { + if arm1.guard.is_some() || arm2.guard.is_some() { + return false; + } + + if !is_enum_variant(cx, arm1.pat) || !is_enum_variant(cx, arm2.pat) { + return false; + } + + true +} + +/// Returns `true` if the given pattern is a variant of an enum. +pub fn is_enum_variant(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool { + struct Pat<'hir>(&'hir rustc_hir::Pat<'hir>); + + impl<'hir> MaybePath<'hir> for Pat<'hir> { + fn qpath_opt(&self) -> Option<&QPath<'hir>> { + match self.0.kind { + PatKind::Struct(ref qpath, fields, _) + if fields + .iter() + .all(|field| is_wild(field.pat) || matches!(field.pat.kind, PatKind::Binding(..))) => + { + Some(qpath) + }, + PatKind::TupleStruct(ref qpath, pats, _) + if pats + .iter() + .all(|pat| is_wild(pat) || matches!(pat.kind, PatKind::Binding(..))) => + { + Some(qpath) + }, + PatKind::Expr(&PatExpr { + kind: PatExprKind::Path(ref qpath), + .. + }) => Some(qpath), + _ => None, + } + } + + fn hir_id(&self) -> HirId { + self.0.hir_id + } + } + + let res = path_res(cx, &Pat(pat)); + matches!( + res, + Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(CtorOf::Variant, _), _) + ) +} + fn emit_manual_let_else( cx: &LateContext<'_>, span: Span, diff --git a/tests/ui/manual_let_else.rs b/tests/ui/manual_let_else.rs index a753566b34c..3781ba1676f 100644 --- a/tests/ui/manual_let_else.rs +++ b/tests/ui/manual_let_else.rs @@ -514,3 +514,35 @@ mod issue13768 { }; } } + +mod issue14598 { + fn bar() -> Result<bool, &'static str> { + let value = match foo() { + //~^ manual_let_else + Err(_) => return Err("abc"), + Ok(value) => value, + }; + + let w = Some(0); + let v = match w { + //~^ manual_let_else + None => return Err("abc"), + Some(x) => x, + }; + + enum Foo<T> { + Foo(T), + } + + let v = match Foo::Foo(Some(())) { + Foo::Foo(Some(_)) => return Err("abc"), + Foo::Foo(v) => v, + }; + + Ok(value == 42) + } + + fn foo() -> Result<u32, &'static str> { + todo!() + } +} diff --git a/tests/ui/manual_let_else.stderr b/tests/ui/manual_let_else.stderr index ef042192114..a1eea041929 100644 --- a/tests/ui/manual_let_else.stderr +++ b/tests/ui/manual_let_else.stderr @@ -529,5 +529,25 @@ LL + return; LL + }; | -error: aborting due to 33 previous errors +error: this could be rewritten as `let...else` + --> tests/ui/manual_let_else.rs:520:9 + | +LL | / let value = match foo() { +LL | | +LL | | Err(_) => return Err("abc"), +LL | | Ok(value) => value, +LL | | }; + | |__________^ help: consider writing: `let Ok(value) = foo() else { return Err("abc") };` + +error: this could be rewritten as `let...else` + --> tests/ui/manual_let_else.rs:527:9 + | +LL | / let v = match w { +LL | | +LL | | None => return Err("abc"), +LL | | Some(x) => x, +LL | | }; + | |__________^ help: consider writing: `let Some(v) = w else { return Err("abc") };` + +error: aborting due to 35 previous errors |