diff --git a/clippy_lints/src/collapsible_match.rs b/clippy_lints/src/collapsible_match.rs index a34ba2d00a8c..604ba1020469 100644 --- a/clippy_lints/src/collapsible_match.rs +++ b/clippy_lints/src/collapsible_match.rs @@ -2,7 +2,7 @@ use crate::utils::visitors::LocalUsedVisitor; use crate::utils::{span_lint_and_then, SpanlessEq}; use if_chain::if_chain; use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res}; -use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind, QPath, StmtKind}; +use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind, QPath, StmtKind, UnOp}; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty::{DefIdTree, TyCtxt}; use rustc_session::{declare_lint_pass, declare_tool_lint}; @@ -72,8 +72,7 @@ fn check_arm(arm: &Arm<'_>, wild_outer_arm: &Arm<'_>, cx: &LateContext<'_>) { if arms_inner.iter().all(|arm| arm.guard.is_none()); // match expression must be a local binding // match { .. } - if let ExprKind::Path(QPath::Resolved(None, path)) = expr_in.kind; - if let Res::Local(binding_id) = path.res; + if let Some(binding_id) = addr_adjusted_binding(expr_in, cx); // one of the branches must be "wild-like" if let Some(wild_inner_arm_idx) = arms_inner.iter().rposition(|arm_inner| arm_is_wild_like(arm_inner, cx.tcx)); let (wild_inner_arm, non_wild_inner_arm) = @@ -85,7 +84,12 @@ fn check_arm(arm: &Arm<'_>, wild_outer_arm: &Arm<'_>, cx: &LateContext<'_>) { // the "wild-like" branches must be equal if SpanlessEq::new(cx).eq_expr(wild_inner_arm.body, wild_outer_arm.body); // the binding must not be used in the if guard - if !matches!(arm.guard, Some(Guard::If(guard)) if LocalUsedVisitor::new(binding_id).check_expr(guard)); + if match arm.guard { + None => true, + Some(Guard::If(expr) | Guard::IfLet(_, expr)) => { + !LocalUsedVisitor::new(binding_id).check_expr(expr) + } + }; // ...or anywhere in the inner match if !arms_inner.iter().any(|arm| LocalUsedVisitor::new(binding_id).check_arm(arm)); then { @@ -170,3 +174,20 @@ fn is_none_ctor(res: Res, tcx: TyCtxt<'_>) -> bool { } false } + +/// Retrieves a binding ID with optional `&` and/or `*` operators removed. (e.g. `&**foo`) +/// Returns `None` if a non-reference type is de-referenced. +/// For example, if `Vec` is de-referenced to a slice, `None` is returned. +fn addr_adjusted_binding(mut expr: &Expr<'_>, cx: &LateContext<'_>) -> Option { + loop { + match expr.kind { + ExprKind::AddrOf(_, _, e) => expr = e, + ExprKind::Path(QPath::Resolved(None, path)) => match path.res { + Res::Local(binding_id) => break Some(binding_id), + _ => break None, + }, + ExprKind::Unary(UnOp::UnDeref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e, + _ => break None, + } + } +} diff --git a/clippy_lints/src/main_recursion.rs b/clippy_lints/src/main_recursion.rs index eceae706e4fc..1ed3f3de8390 100644 --- a/clippy_lints/src/main_recursion.rs +++ b/clippy_lints/src/main_recursion.rs @@ -43,8 +43,7 @@ impl LateLintPass<'_> for MainRecursion { if_chain! { if let ExprKind::Call(func, _) = &expr.kind; - if let ExprKind::Path(path) = &func.kind; - if let QPath::Resolved(_, path) = &path; + if let ExprKind::Path(QPath::Resolved(_, path)) = &func.kind; if let Some(def_id) = path.res.opt_def_id(); if is_entrypoint_fn(cx, def_id); then { diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs index c6329a1381c9..b5aa34111402 100644 --- a/clippy_lints/src/ptr.rs +++ b/clippy_lints/src/ptr.rs @@ -263,8 +263,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id: } else if match_type(cx, ty, &paths::COW) { if_chain! { if let TyKind::Rptr(_, MutTy { ref ty, ..} ) = arg.kind; - if let TyKind::Path(ref path) = ty.kind; - if let QPath::Resolved(None, ref pp) = *path; + if let TyKind::Path(QPath::Resolved(None, ref pp)) = ty.kind; if let [ref bx] = *pp.segments; if let Some(ref params) = bx.args; if !params.parenthesized; diff --git a/clippy_lints/src/utils/higher.rs b/clippy_lints/src/utils/higher.rs index 9b3585865da3..bb71d95a7e2b 100644 --- a/clippy_lints/src/utils/higher.rs +++ b/clippy_lints/src/utils/higher.rs @@ -158,8 +158,7 @@ pub fn for_loop<'tcx>( /// `while cond { body }` becomes `(cond, body)`. pub fn while_loop<'tcx>(expr: &'tcx hir::Expr<'tcx>) -> Option<(&'tcx hir::Expr<'tcx>, &'tcx hir::Expr<'tcx>)> { if_chain! { - if let hir::ExprKind::Loop(block, _, hir::LoopSource::While) = &expr.kind; - if let hir::Block { expr: Some(expr), .. } = &**block; + if let hir::ExprKind::Loop(hir::Block { expr: Some(expr), .. }, _, hir::LoopSource::While) = &expr.kind; if let hir::ExprKind::Match(cond, arms, hir::MatchSource::WhileDesugar) = &expr.kind; if let hir::ExprKind::DropTemps(cond) = &cond.kind; if let [hir::Arm { body, .. }, ..] = &arms[..]; diff --git a/clippy_lints/src/utils/mod.rs b/clippy_lints/src/utils/mod.rs index 8698a618f90c..991fae6b1aaa 100644 --- a/clippy_lints/src/utils/mod.rs +++ b/clippy_lints/src/utils/mod.rs @@ -1126,8 +1126,7 @@ pub fn is_self(slf: &Param<'_>) -> bool { pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool { if_chain! { - if let TyKind::Path(ref qp) = slf.kind; - if let QPath::Resolved(None, ref path) = *qp; + if let TyKind::Path(QPath::Resolved(None, ref path)) = slf.kind; if let Res::SelfTy(..) = path.res; then { return true diff --git a/tests/ui/collapsible_match2.rs b/tests/ui/collapsible_match2.rs index d571ac4ab693..8372a2124773 100644 --- a/tests/ui/collapsible_match2.rs +++ b/tests/ui/collapsible_match2.rs @@ -40,6 +40,35 @@ fn lint_cases(opt_opt: Option>, res_opt: Result, String> // there is still a better way to write this. mac!(res_opt => Ok(val), val => Some(n), foo(n)); } + + // deref reference value + match Some(&[1]) { + Some(s) => match *s { + [n] => foo(n), + _ => (), + }, + _ => (), + } + + // ref pattern and deref + match Some(&[1]) { + Some(ref s) => match &*s { + [n] => foo(n), + _ => (), + }, + _ => (), + } +} + +fn no_lint() { + // deref inner value (cannot pattern match with Vec) + match Some(vec![1]) { + Some(s) => match *s { + [n] => foo(n), + _ => (), + }, + _ => (), + } } fn make() -> T { diff --git a/tests/ui/collapsible_match2.stderr b/tests/ui/collapsible_match2.stderr index 490d82d12cd5..b2eb457d1732 100644 --- a/tests/ui/collapsible_match2.stderr +++ b/tests/ui/collapsible_match2.stderr @@ -57,5 +57,41 @@ LL | mac!(res_opt => Ok(val), val => Some(n), foo(n)); | Replace this binding = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info) -error: aborting due to 3 previous errors +error: Unnecessary nested match + --> $DIR/collapsible_match2.rs:46:20 + | +LL | Some(s) => match *s { + | ____________________^ +LL | | [n] => foo(n), +LL | | _ => (), +LL | | }, + | |_________^ + | +help: The outer pattern can be modified to include the inner pattern. + --> $DIR/collapsible_match2.rs:46:14 + | +LL | Some(s) => match *s { + | ^ Replace this binding +LL | [n] => foo(n), + | ^^^ with this pattern + +error: Unnecessary nested match + --> $DIR/collapsible_match2.rs:55:24 + | +LL | Some(ref s) => match &*s { + | ________________________^ +LL | | [n] => foo(n), +LL | | _ => (), +LL | | }, + | |_________^ + | +help: The outer pattern can be modified to include the inner pattern. + --> $DIR/collapsible_match2.rs:55:14 + | +LL | Some(ref s) => match &*s { + | ^^^^^ Replace this binding +LL | [n] => foo(n), + | ^^^ with this pattern + +error: aborting due to 5 previous errors