diff options
| -rw-r--r-- | clippy_lints/src/loops/never_loop.rs | 35 | ||||
| -rw-r--r-- | tests/ui/never_loop.rs | 38 | ||||
| -rw-r--r-- | tests/ui/never_loop.stderr | 15 |
3 files changed, 78 insertions, 10 deletions
diff --git a/clippy_lints/src/loops/never_loop.rs b/clippy_lints/src/loops/never_loop.rs index 3cb5b1ffc7b..ea7630ce56d 100644 --- a/clippy_lints/src/loops/never_loop.rs +++ b/clippy_lints/src/loops/never_loop.rs @@ -39,6 +39,7 @@ pub(super) fn check( }); }, NeverLoopResult::MayContinueMainLoop | NeverLoopResult::Otherwise => (), + NeverLoopResult::IgnoreUntilEnd(_) => unreachable!(), } } @@ -48,6 +49,8 @@ enum NeverLoopResult { AlwaysBreak, // A continue may occur for the main loop. MayContinueMainLoop, + // Ignore everything until the end of the block with this id + IgnoreUntilEnd(HirId), Otherwise, } @@ -56,6 +59,7 @@ fn absorb_break(arg: NeverLoopResult) -> NeverLoopResult { match arg { NeverLoopResult::AlwaysBreak | NeverLoopResult::Otherwise => NeverLoopResult::Otherwise, NeverLoopResult::MayContinueMainLoop => NeverLoopResult::MayContinueMainLoop, + NeverLoopResult::IgnoreUntilEnd(id) => NeverLoopResult::IgnoreUntilEnd(id), } } @@ -63,15 +67,26 @@ fn absorb_break(arg: NeverLoopResult) -> NeverLoopResult { #[must_use] fn combine_seq(first: NeverLoopResult, second: NeverLoopResult) -> NeverLoopResult { match first { - NeverLoopResult::AlwaysBreak | NeverLoopResult::MayContinueMainLoop => first, + NeverLoopResult::AlwaysBreak | NeverLoopResult::MayContinueMainLoop | NeverLoopResult::IgnoreUntilEnd(_) => { + first + }, NeverLoopResult::Otherwise => second, } } // Combine two results where only one of the part may have been executed. #[must_use] -fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult) -> NeverLoopResult { +fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult, ignore_ids: &[HirId]) -> NeverLoopResult { match (b1, b2) { + (NeverLoopResult::IgnoreUntilEnd(a), NeverLoopResult::IgnoreUntilEnd(b)) => { + if ignore_ids.iter().find(|&e| e == &a || e == &b).unwrap() == &a { + NeverLoopResult::IgnoreUntilEnd(b) + } else { + NeverLoopResult::IgnoreUntilEnd(a) + } + }, + (i @ NeverLoopResult::IgnoreUntilEnd(_), NeverLoopResult::AlwaysBreak) + | (NeverLoopResult::AlwaysBreak, i @ NeverLoopResult::IgnoreUntilEnd(_)) => i, (NeverLoopResult::AlwaysBreak, NeverLoopResult::AlwaysBreak) => NeverLoopResult::AlwaysBreak, (NeverLoopResult::MayContinueMainLoop, _) | (_, NeverLoopResult::MayContinueMainLoop) => { NeverLoopResult::MayContinueMainLoop @@ -91,7 +106,7 @@ fn never_loop_block(block: &Block<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id let e = never_loop_expr(e, ignore_ids, main_loop_id); // els is an else block in a let...else binding els.map_or(e, |els| { - combine_branches(e, never_loop_block(els, ignore_ids, main_loop_id)) + combine_branches(e, never_loop_block(els, ignore_ids, main_loop_id), ignore_ids) }) }) .fold(NeverLoopResult::Otherwise, combine_seq) @@ -147,7 +162,7 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H let e3 = e3.as_ref().map_or(NeverLoopResult::Otherwise, |e| { never_loop_expr(e, ignore_ids, main_loop_id) }); - combine_seq(e1, combine_branches(e2, e3)) + combine_seq(e1, combine_branches(e2, e3, ignore_ids)) }, ExprKind::Match(e, arms, _) => { let e = never_loop_expr(e, ignore_ids, main_loop_id); @@ -166,7 +181,10 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H if l.is_some() { ignore_ids.pop(); } - ret + match ret { + NeverLoopResult::IgnoreUntilEnd(a) if a == b.hir_id => NeverLoopResult::Otherwise, + _ => ret, + } }, ExprKind::Continue(d) => { let id = d @@ -180,7 +198,7 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H }, // checks if break targets a block instead of a loop ExprKind::Break(Destination { target_id: Ok(t), .. }, e) if ignore_ids.contains(&t) => e - .map_or(NeverLoopResult::Otherwise, |e| { + .map_or(NeverLoopResult::IgnoreUntilEnd(t), |e| { never_loop_expr(e, ignore_ids, main_loop_id) }), ExprKind::Break(_, e) | ExprKind::Ret(e) => e.as_ref().map_or(NeverLoopResult::AlwaysBreak, |e| { @@ -232,8 +250,9 @@ fn never_loop_expr_branch<'a, T: Iterator<Item = &'a Expr<'a>>>( ignore_ids: &mut Vec<HirId>, main_loop_id: HirId, ) -> NeverLoopResult { - e.map(|e| never_loop_expr(e, ignore_ids, main_loop_id)) - .fold(NeverLoopResult::AlwaysBreak, combine_branches) + e.fold(NeverLoopResult::AlwaysBreak, |a, b| { + combine_branches(a, never_loop_expr(b, ignore_ids, main_loop_id), ignore_ids) + }) } fn for_to_if_let_sugg(cx: &LateContext<'_>, iterator: &Expr<'_>, pat: &Pat<'_>) -> String { diff --git a/tests/ui/never_loop.rs b/tests/ui/never_loop.rs index a177d5e06aa..29821ff96fc 100644 --- a/tests/ui/never_loop.rs +++ b/tests/ui/never_loop.rs @@ -253,12 +253,48 @@ pub fn test20() { pub fn test21() { loop { 'a: { - { } + {} break 'a; } } } +// Issue 10304: code after break from block was not considered +// unreachable code and was considered for further analysis of +// whether the loop would ever be executed or not. +pub fn test22() { + for _ in 0..10 { + 'block: { + break 'block; + return; + } + println!("looped"); + } +} + +pub fn test23() { + for _ in 0..10 { + 'block: { + for _ in 0..20 { + break 'block; + } + } + println!("looped"); + } +} + +pub fn test24() { + 'a: for _ in 0..10 { + 'b: { + let x = Some(1); + match x { + None => break 'a, + Some(_) => break 'b, + } + } + } +} + fn main() { test1(); test2(); diff --git a/tests/ui/never_loop.stderr b/tests/ui/never_loop.stderr index b7029bf8bed..704d448644e 100644 --- a/tests/ui/never_loop.stderr +++ b/tests/ui/never_loop.stderr @@ -126,5 +126,18 @@ LL | | } LL | | } | |_____^ -error: aborting due to 11 previous errors +error: this loop never actually loops + --> $DIR/never_loop.rs:278:13 + | +LL | / for _ in 0..20 { +LL | | break 'block; +LL | | } + | |_____________^ + | +help: if you need the first element of the iterator, try writing + | +LL | if let Some(_) = (0..20).next() { + | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +error: aborting due to 12 previous errors |