diff options
Diffstat (limited to 'clippy_lints/src/loops/never_loop.rs')
| -rw-r--r-- | clippy_lints/src/loops/never_loop.rs | 82 |
1 files changed, 51 insertions, 31 deletions
diff --git a/clippy_lints/src/loops/never_loop.rs b/clippy_lints/src/loops/never_loop.rs index 5f1fdf00be8..4f2092492aa 100644 --- a/clippy_lints/src/loops/never_loop.rs +++ b/clippy_lints/src/loops/never_loop.rs @@ -1,22 +1,23 @@ use super::utils::make_iterator_snippet; use super::NEVER_LOOP; -use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::consts::constant; use clippy_utils::higher::ForLoop; use clippy_utils::source::snippet; +use clippy_utils::{consts::Constant, diagnostics::span_lint_and_then}; use rustc_errors::Applicability; use rustc_hir::{Block, Destination, Expr, ExprKind, HirId, InlineAsmOperand, Pat, Stmt, StmtKind}; use rustc_lint::LateContext; use rustc_span::Span; use std::iter::{once, Iterator}; -pub(super) fn check( - cx: &LateContext<'_>, - block: &Block<'_>, +pub(super) fn check<'tcx>( + cx: &LateContext<'tcx>, + block: &Block<'tcx>, loop_id: HirId, span: Span, for_loop: Option<&ForLoop<'_>>, ) { - match never_loop_block(block, &mut Vec::new(), loop_id) { + match never_loop_block(cx, block, &mut Vec::new(), loop_id) { NeverLoopResult::AlwaysBreak => { span_lint_and_then(cx, NEVER_LOOP, span, "this loop never actually loops", |diag| { if let Some(ForLoop { @@ -95,7 +96,12 @@ fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult, ignore_ids: &[HirI } } -fn never_loop_block(block: &Block<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: HirId) -> NeverLoopResult { +fn never_loop_block<'tcx>( + cx: &LateContext<'tcx>, + block: &Block<'tcx>, + ignore_ids: &mut Vec<HirId>, + main_loop_id: HirId, +) -> NeverLoopResult { let iter = block .stmts .iter() @@ -103,10 +109,10 @@ fn never_loop_block(block: &Block<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id .chain(block.expr.map(|expr| (expr, None))); iter.map(|(e, els)| { - let e = never_loop_expr(e, ignore_ids, main_loop_id); + let e = never_loop_expr(cx, 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), ignore_ids) + combine_branches(e, never_loop_block(cx, els, ignore_ids, main_loop_id), ignore_ids) }) }) .fold(NeverLoopResult::Otherwise, combine_seq) @@ -122,7 +128,12 @@ fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<(&'tcx Expr<'tcx>, Option<&'t } #[allow(clippy::too_many_lines)] -fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: HirId) -> NeverLoopResult { +fn never_loop_expr<'tcx>( + cx: &LateContext<'tcx>, + expr: &Expr<'tcx>, + ignore_ids: &mut Vec<HirId>, + main_loop_id: HirId, +) -> NeverLoopResult { match expr.kind { ExprKind::Unary(_, e) | ExprKind::Cast(e, _) @@ -130,45 +141,51 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H | ExprKind::Field(e, _) | ExprKind::AddrOf(_, _, e) | ExprKind::Repeat(e, _) - | ExprKind::DropTemps(e) => never_loop_expr(e, ignore_ids, main_loop_id), - ExprKind::Let(let_expr) => never_loop_expr(let_expr.init, ignore_ids, main_loop_id), - ExprKind::Array(es) | ExprKind::Tup(es) => never_loop_expr_all(&mut es.iter(), ignore_ids, main_loop_id), + | ExprKind::DropTemps(e) => never_loop_expr(cx, e, ignore_ids, main_loop_id), + ExprKind::Let(let_expr) => never_loop_expr(cx, let_expr.init, ignore_ids, main_loop_id), + ExprKind::Array(es) | ExprKind::Tup(es) => never_loop_expr_all(cx, &mut es.iter(), ignore_ids, main_loop_id), ExprKind::MethodCall(_, receiver, es, _) => never_loop_expr_all( + cx, &mut std::iter::once(receiver).chain(es.iter()), ignore_ids, main_loop_id, ), ExprKind::Struct(_, fields, base) => { - let fields = never_loop_expr_all(&mut fields.iter().map(|f| f.expr), ignore_ids, main_loop_id); + let fields = never_loop_expr_all(cx, &mut fields.iter().map(|f| f.expr), ignore_ids, main_loop_id); if let Some(base) = base { - combine_seq(fields, never_loop_expr(base, ignore_ids, main_loop_id)) + combine_seq(fields, never_loop_expr(cx, base, ignore_ids, main_loop_id)) } else { fields } }, - ExprKind::Call(e, es) => never_loop_expr_all(&mut once(e).chain(es.iter()), ignore_ids, main_loop_id), + ExprKind::Call(e, es) => never_loop_expr_all(cx, &mut once(e).chain(es.iter()), ignore_ids, main_loop_id), ExprKind::Binary(_, e1, e2) | ExprKind::Assign(e1, e2, _) | ExprKind::AssignOp(_, e1, e2) - | ExprKind::Index(e1, e2) => never_loop_expr_all(&mut [e1, e2].iter().copied(), ignore_ids, main_loop_id), + | ExprKind::Index(e1, e2) => never_loop_expr_all(cx, &mut [e1, e2].iter().copied(), ignore_ids, main_loop_id), ExprKind::Loop(b, _, _, _) => { // Break can come from the inner loop so remove them. - absorb_break(never_loop_block(b, ignore_ids, main_loop_id)) + absorb_break(never_loop_block(cx, b, ignore_ids, main_loop_id)) }, ExprKind::If(e, e2, e3) => { - let e1 = never_loop_expr(e, ignore_ids, main_loop_id); - let e2 = never_loop_expr(e2, ignore_ids, main_loop_id); + let e1 = never_loop_expr(cx, e, ignore_ids, main_loop_id); + let e2 = never_loop_expr(cx, e2, ignore_ids, main_loop_id); + // If we know the `if` condition evaluates to `true`, don't check everything past it; it + // should just return whatever's evaluated for `e1` and `e2` since `e3` is unreachable + if let Some(Constant::Bool(true)) = constant(cx, cx.typeck_results(), e) { + return combine_seq(e1, e2); + } let e3 = e3.as_ref().map_or(NeverLoopResult::Otherwise, |e| { - never_loop_expr(e, ignore_ids, main_loop_id) + never_loop_expr(cx, e, ignore_ids, main_loop_id) }); combine_seq(e1, combine_branches(e2, e3, ignore_ids)) }, ExprKind::Match(e, arms, _) => { - let e = never_loop_expr(e, ignore_ids, main_loop_id); + let e = never_loop_expr(cx, e, ignore_ids, main_loop_id); if arms.is_empty() { e } else { - let arms = never_loop_expr_branch(&mut arms.iter().map(|a| a.body), ignore_ids, main_loop_id); + let arms = never_loop_expr_branch(cx, &mut arms.iter().map(|a| a.body), ignore_ids, main_loop_id); combine_seq(e, arms) } }, @@ -176,7 +193,7 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H if l.is_some() { ignore_ids.push(b.hir_id); } - let ret = never_loop_block(b, ignore_ids, main_loop_id); + let ret = never_loop_block(cx, b, ignore_ids, main_loop_id); if l.is_some() { ignore_ids.pop(); } @@ -198,11 +215,11 @@ 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::IgnoreUntilEnd(t), |e| { - never_loop_expr(e, ignore_ids, main_loop_id) + never_loop_expr(cx, e, ignore_ids, main_loop_id) }), ExprKind::Break(_, e) | ExprKind::Ret(e) => e.as_ref().map_or(NeverLoopResult::AlwaysBreak, |e| { combine_seq( - never_loop_expr(e, ignore_ids, main_loop_id), + never_loop_expr(cx, e, ignore_ids, main_loop_id), NeverLoopResult::AlwaysBreak, ) }), @@ -211,12 +228,13 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H .iter() .map(|(o, _)| match o { InlineAsmOperand::In { expr, .. } | InlineAsmOperand::InOut { expr, .. } => { - never_loop_expr(expr, ignore_ids, main_loop_id) + never_loop_expr(cx, expr, ignore_ids, main_loop_id) }, InlineAsmOperand::Out { expr, .. } => { - never_loop_expr_all(&mut expr.iter().copied(), ignore_ids, main_loop_id) + never_loop_expr_all(cx, &mut expr.iter().copied(), ignore_ids, main_loop_id) }, InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => never_loop_expr_all( + cx, &mut once(*in_expr).chain(out_expr.iter().copied()), ignore_ids, main_loop_id, @@ -236,22 +254,24 @@ fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: H } } -fn never_loop_expr_all<'a, T: Iterator<Item = &'a Expr<'a>>>( +fn never_loop_expr_all<'tcx, T: Iterator<Item = &'tcx Expr<'tcx>>>( + cx: &LateContext<'tcx>, es: &mut T, ignore_ids: &mut Vec<HirId>, main_loop_id: HirId, ) -> NeverLoopResult { - es.map(|e| never_loop_expr(e, ignore_ids, main_loop_id)) + es.map(|e| never_loop_expr(cx, e, ignore_ids, main_loop_id)) .fold(NeverLoopResult::Otherwise, combine_seq) } -fn never_loop_expr_branch<'a, T: Iterator<Item = &'a Expr<'a>>>( +fn never_loop_expr_branch<'tcx, T: Iterator<Item = &'tcx Expr<'tcx>>>( + cx: &LateContext<'tcx>, e: &mut T, ignore_ids: &mut Vec<HirId>, main_loop_id: HirId, ) -> NeverLoopResult { e.fold(NeverLoopResult::AlwaysBreak, |a, b| { - combine_branches(a, never_loop_expr(b, ignore_ids, main_loop_id), ignore_ids) + combine_branches(a, never_loop_expr(cx, b, ignore_ids, main_loop_id), ignore_ids) }) } |