75 lines
2.8 KiB
Rust
75 lines
2.8 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::ty::is_normalizable;
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use clippy_utils::{path_to_local, path_to_local_id};
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use rustc_abi::WrappingRange;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, Node};
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use rustc_lint::LateContext;
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use rustc_middle::ty::Ty;
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use super::EAGER_TRANSMUTE;
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fn peel_parent_unsafe_blocks<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
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for (_, parent) in cx.tcx.hir().parent_iter(expr.hir_id) {
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match parent {
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Node::Block(_) => {},
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Node::Expr(e) if let ExprKind::Block(..) = e.kind => {},
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Node::Expr(e) => return Some(e),
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_ => break,
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}
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}
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None
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}
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fn range_fully_contained(from: WrappingRange, to: WrappingRange) -> bool {
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to.contains(from.start) && to.contains(from.end)
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}
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx Expr<'tcx>,
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transmutable: &'tcx Expr<'tcx>,
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from_ty: Ty<'tcx>,
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to_ty: Ty<'tcx>,
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) -> bool {
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if let Some(then_some_call) = peel_parent_unsafe_blocks(cx, expr)
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&& let ExprKind::MethodCall(path, receiver, [arg], _) = then_some_call.kind
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&& cx.typeck_results().expr_ty(receiver).is_bool()
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&& path.ident.name == sym!(then_some)
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&& let ExprKind::Binary(_, lhs, rhs) = receiver.kind
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&& let Some(local_id) = path_to_local(transmutable)
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&& (path_to_local_id(lhs, local_id) || path_to_local_id(rhs, local_id))
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&& is_normalizable(cx, cx.param_env, from_ty)
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&& is_normalizable(cx, cx.param_env, to_ty)
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// we only want to lint if the target type has a niche that is larger than the one of the source type
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// e.g. `u8` to `NonZeroU8` should lint, but `NonZeroU8` to `u8` should not
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&& let Ok(from_layout) = cx.tcx.layout_of(cx.param_env.and(from_ty))
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&& let Ok(to_layout) = cx.tcx.layout_of(cx.param_env.and(to_ty))
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&& match (from_layout.largest_niche, to_layout.largest_niche) {
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(Some(from_niche), Some(to_niche)) => !range_fully_contained(from_niche.valid_range, to_niche.valid_range),
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(None, Some(_)) => true,
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(_, None) => false,
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}
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{
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span_lint_and_then(
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cx,
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EAGER_TRANSMUTE,
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expr.span,
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"this transmute is always evaluated eagerly, even if the condition is false",
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|diag| {
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diag.multipart_suggestion(
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"consider using `bool::then` to only transmute if the condition holds",
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vec![
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(path.ident.span, "then".into()),
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(arg.span.shrink_to_lo(), "|| ".into()),
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],
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Applicability::MaybeIncorrect,
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);
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},
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);
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true
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} else {
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false
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}
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}
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