From d63aeceaa1f4f175ad63456e691395912460ef41 Mon Sep 17 00:00:00 2001 From: Yotam Ofek Date: Mon, 19 Sep 2022 10:02:17 +0000 Subject: [PATCH] [`never_loop`]: Fix FP with let..else statements. --- clippy_lints/src/loops/never_loop.rs | 31 +++++++++++++++++--------- tests/ui/never_loop.rs | 27 +++++++++++++++++++++++ tests/ui/never_loop.stderr | 33 +++++++++++++++++++--------- 3 files changed, 71 insertions(+), 20 deletions(-) diff --git a/clippy_lints/src/loops/never_loop.rs b/clippy_lints/src/loops/never_loop.rs index 116e589cad6..2386f4f4f4e 100644 --- a/clippy_lints/src/loops/never_loop.rs +++ b/clippy_lints/src/loops/never_loop.rs @@ -42,6 +42,7 @@ pub(super) fn check( } } +#[derive(Copy, Clone)] enum NeverLoopResult { // A break/return always get triggered but not necessarily for the main loop. AlwaysBreak, @@ -51,8 +52,8 @@ enum NeverLoopResult { } #[must_use] -fn absorb_break(arg: &NeverLoopResult) -> NeverLoopResult { - match *arg { +fn absorb_break(arg: NeverLoopResult) -> NeverLoopResult { + match arg { NeverLoopResult::AlwaysBreak | NeverLoopResult::Otherwise => NeverLoopResult::Otherwise, NeverLoopResult::MayContinueMainLoop => NeverLoopResult::MayContinueMainLoop, } @@ -92,19 +93,29 @@ fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult) -> NeverLoopResult } fn never_loop_block(block: &Block<'_>, main_loop_id: HirId) -> NeverLoopResult { - let mut iter = block.stmts.iter().filter_map(stmt_to_expr).chain(block.expr); + let mut iter = block + .stmts + .iter() + .filter_map(stmt_to_expr) + .chain(block.expr.map(|expr| (expr, None))); never_loop_expr_seq(&mut iter, main_loop_id) } -fn never_loop_expr_seq<'a, T: Iterator>>(es: &mut T, main_loop_id: HirId) -> NeverLoopResult { - es.map(|e| never_loop_expr(e, main_loop_id)) - .fold(NeverLoopResult::Otherwise, combine_seq) +fn never_loop_expr_seq<'a, T: Iterator, Option<&'a Block<'a>>)>>( + es: &mut T, + main_loop_id: HirId, +) -> NeverLoopResult { + es.map(|(e, els)| { + let e = never_loop_expr(e, main_loop_id); + els.map_or(e, |els| combine_branches(e, never_loop_block(els, main_loop_id))) + }) + .fold(NeverLoopResult::Otherwise, combine_seq) } -fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<&'tcx Expr<'tcx>> { +fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<(&'tcx Expr<'tcx>, Option<&'tcx Block<'tcx>>)> { match stmt.kind { - StmtKind::Semi(e, ..) | StmtKind::Expr(e, ..) => Some(e), - StmtKind::Local(local) => local.init, + StmtKind::Semi(e, ..) | StmtKind::Expr(e, ..) => Some((e, None)), + StmtKind::Local(local) => local.init.map(|init| (init, local.els)), StmtKind::Item(..) => None, } } @@ -139,7 +150,7 @@ fn never_loop_expr(expr: &Expr<'_>, main_loop_id: HirId) -> NeverLoopResult { | ExprKind::Index(e1, e2) => never_loop_expr_all(&mut [e1, e2].iter().copied(), main_loop_id), ExprKind::Loop(b, _, _, _) => { // Break can come from the inner loop so remove them. - absorb_break(&never_loop_block(b, main_loop_id)) + absorb_break(never_loop_block(b, main_loop_id)) }, ExprKind::If(e, e2, e3) => { let e1 = never_loop_expr(e, main_loop_id); diff --git a/tests/ui/never_loop.rs b/tests/ui/never_loop.rs index 0a21589dd0d..fc60b440766 100644 --- a/tests/ui/never_loop.rs +++ b/tests/ui/never_loop.rs @@ -1,3 +1,4 @@ +#![feature(let_else)] #![allow( clippy::single_match, unused_assignments, @@ -203,6 +204,32 @@ pub fn test17() { }; } +// Issue #9356: `continue` in else branch of let..else +pub fn test18() { + let x = Some(0); + let y = 0; + // might loop + let _ = loop { + let Some(x) = x else { + if y > 0 { + continue; + } else { + return; + } + }; + + break x; + }; + // never loops + let _ = loop { + let Some(x) = x else { + return; + }; + + break x; + }; +} + fn main() { test1(); test2(); diff --git a/tests/ui/never_loop.stderr b/tests/ui/never_loop.stderr index f49b23924ef..1709e7512eb 100644 --- a/tests/ui/never_loop.stderr +++ b/tests/ui/never_loop.stderr @@ -1,5 +1,5 @@ error: this loop never actually loops - --> $DIR/never_loop.rs:10:5 + --> $DIR/never_loop.rs:11:5 | LL | / loop { LL | | // clippy::never_loop @@ -13,7 +13,7 @@ LL | | } = note: `#[deny(clippy::never_loop)]` on by default error: this loop never actually loops - --> $DIR/never_loop.rs:32:5 + --> $DIR/never_loop.rs:33:5 | LL | / loop { LL | | // never loops @@ -23,7 +23,7 @@ LL | | } | |_____^ error: this loop never actually loops - --> $DIR/never_loop.rs:52:5 + --> $DIR/never_loop.rs:53:5 | LL | / loop { LL | | // never loops @@ -35,7 +35,7 @@ LL | | } | |_____^ error: this loop never actually loops - --> $DIR/never_loop.rs:54:9 + --> $DIR/never_loop.rs:55:9 | LL | / while i == 0 { LL | | // never loops @@ -44,7 +44,7 @@ LL | | } | |_________^ error: this loop never actually loops - --> $DIR/never_loop.rs:66:9 + --> $DIR/never_loop.rs:67:9 | LL | / loop { LL | | // never loops @@ -56,7 +56,7 @@ LL | | } | |_________^ error: this loop never actually loops - --> $DIR/never_loop.rs:102:5 + --> $DIR/never_loop.rs:103:5 | LL | / while let Some(y) = x { LL | | // never loops @@ -65,7 +65,7 @@ LL | | } | |_____^ error: this loop never actually loops - --> $DIR/never_loop.rs:109:5 + --> $DIR/never_loop.rs:110:5 | LL | / for x in 0..10 { LL | | // never loops @@ -82,7 +82,7 @@ LL | if let Some(x) = (0..10).next() { | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: this loop never actually loops - --> $DIR/never_loop.rs:157:5 + --> $DIR/never_loop.rs:158:5 | LL | / 'outer: while a { LL | | // never loops @@ -94,12 +94,25 @@ LL | | } | |_____^ error: this loop never actually loops - --> $DIR/never_loop.rs:172:9 + --> $DIR/never_loop.rs:173:9 | LL | / while false { LL | | break 'label; LL | | } | |_________^ -error: aborting due to 9 previous errors +error: this loop never actually loops + --> $DIR/never_loop.rs:224:13 + | +LL | let _ = loop { + | _____________^ +LL | | let Some(x) = x else { +LL | | return; +LL | | }; +LL | | +LL | | break x; +LL | | }; + | |_____^ + +error: aborting due to 10 previous errors