Lint for significant drops who may have surprising lifetimes #1
author Preston From <prestonfrom@gmail.com> 1645164142 -0600 committer Preston From <prestonfrom@gmail.com> 1650005351 -0600
This commit is contained in:
Preston From
parent
13e8ace73c
commit
41c7e4d382
@ -3696,6 +3696,7 @@ Released 2018-09-13
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[`skip_while_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#skip_while_next
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[`slow_vector_initialization`]: https://rust-lang.github.io/rust-clippy/master/index.html#slow_vector_initialization
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[`stable_sort_primitive`]: https://rust-lang.github.io/rust-clippy/master/index.html#stable_sort_primitive
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[`significant_drop_in_scrutinee`]: https://rust-lang.github.io/rust-clippy/master/index.html#significant_drop_in_scrutinee
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[`str_to_string`]: https://rust-lang.github.io/rust-clippy/master/index.html#str_to_string
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[`string_add`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add
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[`string_add_assign`]: https://rust-lang.github.io/rust-clippy/master/index.html#string_add_assign
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@ -475,6 +475,7 @@
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size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT,
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slow_vector_initialization::SLOW_VECTOR_INITIALIZATION,
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stable_sort_primitive::STABLE_SORT_PRIMITIVE,
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significant_drop_in_scrutinee::SIGNIFICANT_DROP_IN_SCRUTINEE,
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strings::STRING_ADD,
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strings::STRING_ADD_ASSIGN,
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strings::STRING_FROM_UTF8_AS_BYTES,
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@ -25,6 +25,7 @@
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LintId::of(path_buf_push_overwrite::PATH_BUF_PUSH_OVERWRITE),
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LintId::of(redundant_pub_crate::REDUNDANT_PUB_CRATE),
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LintId::of(regex::TRIVIAL_REGEX),
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LintId::of(significant_drop_in_scrutinee::SIGNIFICANT_DROP_IN_SCRUTINEE),
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LintId::of(strings::STRING_LIT_AS_BYTES),
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LintId::of(suspicious_operation_groupings::SUSPICIOUS_OPERATION_GROUPINGS),
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LintId::of(trailing_empty_array::TRAILING_EMPTY_ARRAY),
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@ -364,6 +364,7 @@ macro_rules! declare_clippy_lint {
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mod semicolon_if_nothing_returned;
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mod serde_api;
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mod shadow;
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mod significant_drop_in_scrutinee;
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mod single_char_lifetime_names;
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mod single_component_path_imports;
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mod size_of_in_element_count;
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@ -874,6 +875,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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store.register_late_pass(move || Box::new(manual_bits::ManualBits::new(msrv)));
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store.register_late_pass(|| Box::new(default_union_representation::DefaultUnionRepresentation));
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store.register_late_pass(|| Box::new(only_used_in_recursion::OnlyUsedInRecursion));
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store.register_late_pass(|| Box::new(significant_drop_in_scrutinee::SignificantDropInScrutinee));
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store.register_late_pass(|| Box::new(dbg_macro::DbgMacro));
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let cargo_ignore_publish = conf.cargo_ignore_publish;
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store.register_late_pass(move || {
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408
clippy_lints/src/significant_drop_in_scrutinee.rs
Normal file
408
clippy_lints/src/significant_drop_in_scrutinee.rs
Normal file
@ -0,0 +1,408 @@
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use crate::FxHashSet;
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::get_attr;
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use clippy_utils::source::{indent_of, snippet};
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use rustc_errors::{Applicability, Diagnostic};
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use rustc_hir::intravisit::{walk_expr, Visitor};
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::ty::subst::GenericArgKind;
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use rustc_middle::ty::{Ty, TypeAndMut};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::Span;
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declare_clippy_lint! {
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/// ### What it does
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/// Check for temporaries returned from function calls in a match scrutinee that have the
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/// `clippy::has_significant_drop` attribute.
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///
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/// ### Why is this bad?
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/// The `clippy::has_significant_drop` attribute can be added to types whose Drop impls have
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/// an important side-effect, such as unlocking a mutex, making it important for users to be
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/// able to accurately understand their lifetimes. When a temporary is returned in a function
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/// call in a match scrutinee, its lifetime lasts until the end of the match block, which may
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/// be surprising.
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///
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/// For `Mutex`es this can lead to a deadlock. This happens when the match scrutinee uses a
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/// function call that returns a `MutexGuard` and then tries to lock again in one of the match
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/// arms. In that case the `MutexGuard` in the scrutinee will not be dropped until the end of
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/// the match block and thus will not unlock.
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///
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/// ### Example
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/// ```rust
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/// # use std::sync::Mutex;
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///
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/// # struct State {}
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///
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/// # impl State {
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/// # fn foo(&self) -> bool {
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/// # true
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/// # }
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///
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/// # fn bar(&self) {}
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/// # }
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///
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///
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/// let mutex = Mutex::new(State {});
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///
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/// match mutex.lock().unwrap().foo() {
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/// true => {
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/// mutex.lock().unwrap().bar(); // Deadlock!
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/// }
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/// false => {}
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/// };
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///
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/// println!("All done!");
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///
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/// ```
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/// Use instead:
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/// ```rust
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/// # use std::sync::Mutex;
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///
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/// # struct State {}
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///
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/// # impl State {
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/// # fn foo(&self) -> bool {
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/// # true
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/// # }
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///
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/// # fn bar(&self) {}
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/// # }
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///
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/// let mutex = Mutex::new(State {});
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///
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/// let is_foo = mutex.lock().unwrap().foo();
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/// match is_foo {
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/// true => {
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/// mutex.lock().unwrap().bar();
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/// }
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/// false => {}
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/// };
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///
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/// println!("All done!");
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/// ```
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#[clippy::version = "1.60.0"]
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pub SIGNIFICANT_DROP_IN_SCRUTINEE,
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nursery,
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"warns when a temporary of a type with a drop with a significant side-effect might have a surprising lifetime"
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}
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declare_lint_pass!(SignificantDropInScrutinee => [SIGNIFICANT_DROP_IN_SCRUTINEE]);
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impl<'tcx> LateLintPass<'tcx> for SignificantDropInScrutinee {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
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if let Some(suggestions) = has_significant_drop_in_scrutinee(cx, expr) {
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for found in suggestions {
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span_lint_and_then(
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cx,
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SIGNIFICANT_DROP_IN_SCRUTINEE,
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found.found_span,
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"temporary with significant drop in match scrutinee",
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|diag| set_diagnostic(diag, cx, expr, found),
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)
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}
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}
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}
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}
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fn set_diagnostic<'tcx>(diag: &mut Diagnostic, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, found: FoundSigDrop) {
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if found.lint_suggestion == LintSuggestion::MoveAndClone {
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// If our suggestion is to move and clone, then we want to leave it to the user to
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// decide how to address this lint, since it may be that cloning is inappropriate.
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// Therefore, we won't to emit a suggestion.
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return;
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}
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let original = snippet(cx, found.found_span, "..");
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let trailing_indent = " ".repeat(indent_of(cx, found.found_span).unwrap_or(0));
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let replacement = if found.lint_suggestion == LintSuggestion::MoveAndDerefToCopy {
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format!("let value = *{};\n{}", original, trailing_indent)
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} else if found.is_unit_return_val {
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// If the return value of the expression to be moved is unit, then we don't need to
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// capture the result in a temporary -- we can just replace it completely with `()`.
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format!("{};\n{}", original, trailing_indent)
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} else {
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format!("let value = {};\n{}", original, trailing_indent)
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};
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let suggestion_message = if found.lint_suggestion == LintSuggestion::MoveOnly {
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"try moving the temporary above the match"
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} else {
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"try moving the temporary above the match and create a copy"
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};
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let scrutinee_replacement = if found.is_unit_return_val {
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"()".to_owned()
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} else {
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"value".to_owned()
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};
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diag.multipart_suggestion(
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suggestion_message,
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vec![
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(expr.span.shrink_to_lo(), replacement),
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(found.found_span, scrutinee_replacement),
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],
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Applicability::MaybeIncorrect,
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);
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}
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/// If the expression is an ExprKind::Match, check if the scrutinee has a significant drop that may
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/// have a surprising lifetime.
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fn has_significant_drop_in_scrutinee<'tcx, 'a>(
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cx: &'a LateContext<'tcx>,
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expr: &'tcx Expr<'tcx>,
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) -> Option<Vec<FoundSigDrop>> {
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let mut helper = SigDropHelper::new(cx);
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match expr.kind {
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ExprKind::Match(match_expr, _, _) => helper.find_sig_drop(match_expr),
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_ => None,
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}
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}
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struct SigDropHelper<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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is_chain_end: bool,
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seen_types: FxHashSet<Ty<'tcx>>,
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has_significant_drop: bool,
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current_sig_drop: Option<FoundSigDrop>,
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sig_drop_spans: Option<Vec<FoundSigDrop>>,
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special_handling_for_binary_op: bool,
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}
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#[derive(Debug, PartialEq, Eq, Clone, Copy)]
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enum LintSuggestion {
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MoveOnly,
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MoveAndDerefToCopy,
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MoveAndClone,
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}
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#[derive(Clone, Copy)]
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struct FoundSigDrop {
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found_span: Span,
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is_unit_return_val: bool,
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lint_suggestion: LintSuggestion,
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}
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impl<'a, 'tcx> SigDropHelper<'a, 'tcx> {
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fn new(cx: &'a LateContext<'tcx>) -> SigDropHelper<'a, 'tcx> {
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SigDropHelper {
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cx,
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is_chain_end: true,
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seen_types: FxHashSet::default(),
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has_significant_drop: false,
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current_sig_drop: None,
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sig_drop_spans: None,
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special_handling_for_binary_op: false,
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}
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}
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fn find_sig_drop(&mut self, match_expr: &'tcx Expr<'_>) -> Option<Vec<FoundSigDrop>> {
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self.visit_expr(match_expr);
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// If sig drop spans is empty but we found a significant drop, it means that we didn't find
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// a type that was trivially copyable as we moved up the chain after finding a significant
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// drop, so move the entire scrutinee.
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if self.has_significant_drop && self.sig_drop_spans.is_none() {
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self.try_setting_current_suggestion(match_expr, true);
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self.move_current_suggestion();
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}
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self.sig_drop_spans.take()
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}
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/// This will try to set the current suggestion (so it can be moved into the suggestions vec
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/// later). If allow_move_and_clone is false, the suggestion *won't* be set -- this gives us
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/// an opportunity to look for another type in the chain that will be trivially copyable.
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/// However, if we are at the the end of the chain, we want to accept whatever is there. (The
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/// suggestion won't actually be output, but the diagnostic message will be output, so the user
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/// can determine the best way to handle the lint.)
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fn try_setting_current_suggestion(&mut self, expr: &'tcx Expr<'_>, allow_move_and_clone: bool) {
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if self.current_sig_drop.is_some() {
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return;
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}
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let ty = self.get_type(expr);
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if ty.is_ref() {
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// We checked that the type was ref, so builtin_deref will return Some TypeAndMut,
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// but let's avoid any chance of an ICE
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if let Some(TypeAndMut { ty, .. }) = ty.builtin_deref(true) {
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if ty.is_trivially_pure_clone_copy() {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveAndDerefToCopy,
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});
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} else if allow_move_and_clone {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveAndClone,
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});
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}
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}
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} else if ty.is_trivially_pure_clone_copy() {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: expr.span,
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is_unit_return_val: false,
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lint_suggestion: LintSuggestion::MoveOnly,
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});
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}
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}
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fn move_current_suggestion(&mut self) {
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if let Some(current) = self.current_sig_drop.take() {
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self.sig_drop_spans.get_or_insert_with(Vec::new).push(current);
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}
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}
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fn get_type(&self, ex: &'tcx Expr<'_>) -> Ty<'tcx> {
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self.cx.typeck_results().expr_ty(ex)
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}
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fn has_seen_type(&mut self, ty: Ty<'tcx>) -> bool {
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!self.seen_types.insert(ty)
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}
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fn visit_exprs_for_binary_ops(
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&mut self,
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left: &'tcx Expr<'_>,
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right: &'tcx Expr<'_>,
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is_unit_return_val: bool,
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span: Span,
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) {
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self.special_handling_for_binary_op = true;
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self.visit_expr(left);
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self.visit_expr(right);
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// If either side had a significant drop, suggest moving the entire scrutinee to avoid
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// unnecessary copies and to simplify cases where both sides have significant drops.
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if self.has_significant_drop {
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self.current_sig_drop.replace(FoundSigDrop {
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found_span: span,
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is_unit_return_val,
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lint_suggestion: LintSuggestion::MoveOnly,
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});
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}
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self.special_handling_for_binary_op = false;
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}
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fn has_sig_drop_attr(&mut self, cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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if let Some(adt) = ty.ty_adt_def() {
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if get_attr(cx.sess(), cx.tcx.get_attrs(adt.did()), "has_significant_drop").count() > 0 {
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return true;
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}
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}
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match ty.kind() {
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rustc_middle::ty::Adt(a, b) => {
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for f in a.all_fields() {
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let ty = f.ty(cx.tcx, b);
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if !self.has_seen_type(ty) && self.has_sig_drop_attr(cx, ty) {
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return true;
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}
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}
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for generic_arg in b.iter() {
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if let GenericArgKind::Type(ty) = generic_arg.unpack() {
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if self.has_sig_drop_attr(cx, ty) {
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return true;
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}
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}
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}
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false
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},
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rustc_middle::ty::Array(ty, _) => self.has_sig_drop_attr(cx, *ty),
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rustc_middle::ty::RawPtr(TypeAndMut { ty, .. }) => self.has_sig_drop_attr(cx, *ty),
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rustc_middle::ty::Ref(_, ty, _) => self.has_sig_drop_attr(cx, *ty),
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rustc_middle::ty::Slice(ty) => self.has_sig_drop_attr(cx, *ty),
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_ => false,
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}
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}
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}
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impl<'a, 'tcx> Visitor<'tcx> for SigDropHelper<'a, 'tcx> {
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fn visit_expr(&mut self, ex: &'tcx Expr<'_>) {
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if !self.is_chain_end && self.has_sig_drop_attr(self.cx, self.get_type(ex)) {
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self.has_significant_drop = true;
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return;
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}
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self.is_chain_end = false;
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match ex.kind {
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ExprKind::MethodCall(_, [ref expr, ..], _) => {
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self.visit_expr(expr)
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}
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ExprKind::Binary(_, left, right) => {
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self.visit_exprs_for_binary_ops(left, right, false, ex.span);
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}
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ExprKind::Assign(left, right, _) => {
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self.visit_exprs_for_binary_ops(left, right, true, ex.span);
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}
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ExprKind::AssignOp(_, left, right) => {
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self.visit_exprs_for_binary_ops(left, right, true, ex.span);
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}
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ExprKind::Tup(exprs) => {
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for expr in exprs {
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self.visit_expr(expr);
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if self.has_significant_drop {
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// We may have not have set current_sig_drop if all the suggestions were
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// MoveAndClone, so add this tuple item's full expression in that case.
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if self.current_sig_drop.is_none() {
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self.try_setting_current_suggestion(expr, true);
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}
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// Now we are guaranteed to have something, so add it to the final vec.
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self.move_current_suggestion();
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}
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// Reset `has_significant_drop` after each tuple expression so we can look for
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// additional cases.
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self.has_significant_drop = false;
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}
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if self.sig_drop_spans.is_some() {
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self.has_significant_drop = true;
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}
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}
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ExprKind::Box(..) |
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ExprKind::Array(..) |
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ExprKind::Call(..) |
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ExprKind::Unary(..) |
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ExprKind::If(..) |
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ExprKind::Match(..) |
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||||
ExprKind::Field(..) |
|
||||
ExprKind::Index(..) |
|
||||
ExprKind::Ret(..) |
|
||||
ExprKind::Repeat(..) |
|
||||
ExprKind::Yield(..) |
|
||||
ExprKind::MethodCall(..) => walk_expr(self, ex),
|
||||
ExprKind::AddrOf(_, _, _) |
|
||||
ExprKind::Block(_, _) |
|
||||
ExprKind::Break(_, _) |
|
||||
ExprKind::Cast(_, _) |
|
||||
// Don't want to check the closure itself, only invocation, which is covered by MethodCall
|
||||
ExprKind::Closure(_, _, _, _, _) |
|
||||
ExprKind::ConstBlock(_) |
|
||||
ExprKind::Continue(_) |
|
||||
ExprKind::DropTemps(_) |
|
||||
ExprKind::Err |
|
||||
ExprKind::InlineAsm(_) |
|
||||
ExprKind::Let(_) |
|
||||
ExprKind::Lit(_) |
|
||||
ExprKind::Loop(_, _, _, _) |
|
||||
ExprKind::Path(_) |
|
||||
ExprKind::Struct(_, _, _) |
|
||||
ExprKind::Type(_, _) => {
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
// Once a significant temporary has been found, we need to go back up at least 1 level to
|
||||
// find the span to extract for replacement, so the temporary gets dropped. However, for
|
||||
// binary ops, we want to move the whole scrutinee so we avoid unnecessary copies and to
|
||||
// simplify cases where both sides have significant drops.
|
||||
if self.has_significant_drop && !self.special_handling_for_binary_op {
|
||||
self.try_setting_current_suggestion(ex, false);
|
||||
}
|
||||
}
|
||||
}
|
||||
@ -22,6 +22,7 @@ pub enum DeprecationStatus {
|
||||
("cyclomatic_complexity", DeprecationStatus::Replaced("cognitive_complexity")),
|
||||
("dump", DeprecationStatus::None),
|
||||
("msrv", DeprecationStatus::None),
|
||||
("has_significant_drop", DeprecationStatus::None),
|
||||
];
|
||||
|
||||
pub struct LimitStack {
|
||||
|
||||
526
tests/ui/significant_drop_in_scrutinee.rs
Normal file
526
tests/ui/significant_drop_in_scrutinee.rs
Normal file
@ -0,0 +1,526 @@
|
||||
// FIXME: Ideally these suggestions would be fixed via rustfix. Blocked by rust-lang/rust#53934
|
||||
// // run-rustfix
|
||||
|
||||
#![warn(clippy::significant_drop_in_scrutinee)]
|
||||
#![allow(clippy::single_match)]
|
||||
#![allow(clippy::match_single_binding)]
|
||||
#![allow(unused_assignments)]
|
||||
#![allow(dead_code)]
|
||||
|
||||
use std::ops::Deref;
|
||||
use std::sync::atomic::{AtomicU64, Ordering};
|
||||
use std::sync::{Mutex, MutexGuard};
|
||||
|
||||
struct State {}
|
||||
|
||||
impl State {
|
||||
fn foo(&self) -> bool {
|
||||
true
|
||||
}
|
||||
|
||||
fn bar(&self) {}
|
||||
}
|
||||
|
||||
fn should_not_trigger_lint_with_mutex_guard_outside_match() {
|
||||
let mutex = Mutex::new(State {});
|
||||
|
||||
// Should not trigger lint because the temporary should drop at the `;` on line before the match
|
||||
let is_foo = mutex.lock().unwrap().foo();
|
||||
match is_foo {
|
||||
true => {
|
||||
mutex.lock().unwrap().bar();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_not_trigger_lint_with_mutex_guard_when_taking_ownership_in_match() {
|
||||
let mutex = Mutex::new(State {});
|
||||
|
||||
// Should not trigger lint because the scrutinee is explicitly returning the MutexGuard,
|
||||
// so its lifetime should not be surprising.
|
||||
match mutex.lock() {
|
||||
Ok(guard) => {
|
||||
guard.foo();
|
||||
mutex.lock().unwrap().bar();
|
||||
}
|
||||
_ => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_trigger_lint_with_mutex_guard_in_match_scrutinee() {
|
||||
let mutex = Mutex::new(State {});
|
||||
|
||||
// Should trigger lint because the lifetime of the temporary MutexGuard is surprising because it
|
||||
// is preserved until the end of the match, but there is no clear indication that this is the
|
||||
// case.
|
||||
match mutex.lock().unwrap().foo() {
|
||||
true => {
|
||||
mutex.lock().unwrap().bar();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_not_trigger_lint_for_insignificant_drop() {
|
||||
// Should not trigger lint because there are no temporaries whose drops have a significant
|
||||
// side effect.
|
||||
match 1u64.to_string().is_empty() {
|
||||
true => {
|
||||
println!("It was empty")
|
||||
}
|
||||
false => {
|
||||
println!("It was not empty")
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
struct StateWithMutex {
|
||||
m: Mutex<u64>,
|
||||
}
|
||||
|
||||
struct MutexGuardWrapper<'a> {
|
||||
mg: MutexGuard<'a, u64>,
|
||||
}
|
||||
|
||||
impl<'a> MutexGuardWrapper<'a> {
|
||||
fn get_the_value(&self) -> u64 {
|
||||
*self.mg.deref()
|
||||
}
|
||||
}
|
||||
|
||||
struct MutexGuardWrapperWrapper<'a> {
|
||||
mg: MutexGuardWrapper<'a>,
|
||||
}
|
||||
|
||||
impl<'a> MutexGuardWrapperWrapper<'a> {
|
||||
fn get_the_value(&self) -> u64 {
|
||||
*self.mg.mg.deref()
|
||||
}
|
||||
}
|
||||
|
||||
impl StateWithMutex {
|
||||
fn lock_m(&self) -> MutexGuardWrapper<'_> {
|
||||
MutexGuardWrapper {
|
||||
mg: self.m.lock().unwrap(),
|
||||
}
|
||||
}
|
||||
|
||||
fn lock_m_m(&self) -> MutexGuardWrapperWrapper<'_> {
|
||||
MutexGuardWrapperWrapper {
|
||||
mg: MutexGuardWrapper {
|
||||
mg: self.m.lock().unwrap(),
|
||||
},
|
||||
}
|
||||
}
|
||||
|
||||
fn foo(&self) -> bool {
|
||||
true
|
||||
}
|
||||
|
||||
fn bar(&self) {}
|
||||
}
|
||||
|
||||
fn should_trigger_lint_with_wrapped_mutex() {
|
||||
let s = StateWithMutex { m: Mutex::new(1) };
|
||||
|
||||
// Should trigger lint because a temporary contains a type with a significant drop and its
|
||||
// lifetime is not obvious. Additionally, it is not obvious from looking at the scrutinee that
|
||||
// the temporary contains such a type, making it potentially even more surprising.
|
||||
match s.lock_m().get_the_value() {
|
||||
1 => {
|
||||
println!("Got 1. Is it still 1?");
|
||||
println!("{}", s.lock_m().get_the_value());
|
||||
}
|
||||
2 => {
|
||||
println!("Got 2. Is it still 2?");
|
||||
println!("{}", s.lock_m().get_the_value());
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
println!("All done!");
|
||||
}
|
||||
|
||||
fn should_trigger_lint_with_double_wrapped_mutex() {
|
||||
let s = StateWithMutex { m: Mutex::new(1) };
|
||||
|
||||
// Should trigger lint because a temporary contains a type which further contains a type with a
|
||||
// significant drop and its lifetime is not obvious. Additionally, it is not obvious from
|
||||
// looking at the scrutinee that the temporary contains such a type, making it potentially even
|
||||
// more surprising.
|
||||
match s.lock_m_m().get_the_value() {
|
||||
1 => {
|
||||
println!("Got 1. Is it still 1?");
|
||||
println!("{}", s.lock_m().get_the_value());
|
||||
}
|
||||
2 => {
|
||||
println!("Got 2. Is it still 2?");
|
||||
println!("{}", s.lock_m().get_the_value());
|
||||
}
|
||||
_ => {}
|
||||
}
|
||||
println!("All done!");
|
||||
}
|
||||
|
||||
struct Counter {
|
||||
i: AtomicU64,
|
||||
}
|
||||
|
||||
#[clippy::has_significant_drop]
|
||||
struct CounterWrapper<'a> {
|
||||
counter: &'a Counter,
|
||||
}
|
||||
|
||||
impl<'a> CounterWrapper<'a> {
|
||||
fn new(counter: &Counter) -> CounterWrapper {
|
||||
counter.i.fetch_add(1, Ordering::Relaxed);
|
||||
CounterWrapper { counter }
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a> Drop for CounterWrapper<'a> {
|
||||
fn drop(&mut self) {
|
||||
self.counter.i.fetch_sub(1, Ordering::Relaxed);
|
||||
}
|
||||
}
|
||||
|
||||
impl Counter {
|
||||
fn temp_increment(&self) -> Vec<CounterWrapper> {
|
||||
vec![CounterWrapper::new(self), CounterWrapper::new(self)]
|
||||
}
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_vec() {
|
||||
let counter = Counter { i: AtomicU64::new(0) };
|
||||
|
||||
// Should trigger lint because the temporary in the scrutinee returns a collection of types
|
||||
// which have significant drops. The types with significant drops are also non-obvious when
|
||||
// reading the expression in the scrutinee.
|
||||
match counter.temp_increment().len() {
|
||||
2 => {
|
||||
let current_count = counter.i.load(Ordering::Relaxed);
|
||||
println!("Current count {}", current_count);
|
||||
assert_eq!(current_count, 0);
|
||||
}
|
||||
1 => {}
|
||||
3 => {}
|
||||
_ => {}
|
||||
};
|
||||
}
|
||||
|
||||
struct StateWithField {
|
||||
s: String,
|
||||
}
|
||||
|
||||
// Should trigger lint only on the type in the tuple which is created using a temporary
|
||||
// with a significant drop. Additionally, this test ensures that the format of the tuple
|
||||
// is preserved correctly in the suggestion.
|
||||
fn should_trigger_lint_for_tuple_in_scrutinee() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
|
||||
|
||||
{
|
||||
match (mutex1.lock().unwrap().s.len(), true) {
|
||||
(3, _) => {
|
||||
println!("started");
|
||||
mutex1.lock().unwrap().s.len();
|
||||
println!("done");
|
||||
}
|
||||
(_, _) => {}
|
||||
};
|
||||
|
||||
match (true, mutex1.lock().unwrap().s.len(), true) {
|
||||
(_, 3, _) => {
|
||||
println!("started");
|
||||
mutex1.lock().unwrap().s.len();
|
||||
println!("done");
|
||||
}
|
||||
(_, _, _) => {}
|
||||
};
|
||||
|
||||
let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
|
||||
match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
|
||||
(3, _, 3) => {
|
||||
println!("started");
|
||||
mutex1.lock().unwrap().s.len();
|
||||
mutex2.lock().unwrap().s.len();
|
||||
println!("done");
|
||||
}
|
||||
(_, _, _) => {}
|
||||
};
|
||||
|
||||
let mutex3 = Mutex::new(StateWithField { s: "three".to_owned() });
|
||||
match mutex3.lock().unwrap().s.as_str() {
|
||||
"three" => {
|
||||
println!("started");
|
||||
mutex1.lock().unwrap().s.len();
|
||||
mutex2.lock().unwrap().s.len();
|
||||
println!("done");
|
||||
}
|
||||
_ => {}
|
||||
};
|
||||
|
||||
|
||||
match (true, mutex3.lock().unwrap().s.as_str()) {
|
||||
(_, "three") => {
|
||||
println!("started");
|
||||
mutex1.lock().unwrap().s.len();
|
||||
mutex2.lock().unwrap().s.len();
|
||||
println!("done");
|
||||
}
|
||||
(_, _) => {}
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
// Should trigger lint when either side of a binary operation creates a temporary with a
|
||||
// significant drop.
|
||||
// To avoid potential unnecessary copies or creating references that would trigger the significant
|
||||
// drop problem, the lint recommends moving the entire binary operation.
|
||||
fn should_trigger_lint_for_accessing_field_in_mutex_in_one_side_of_binary_op() {
|
||||
let mutex = Mutex::new(StateWithField { s: "state".to_owned() });
|
||||
|
||||
match mutex.lock().unwrap().s.len() > 1 {
|
||||
true => {
|
||||
mutex.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
|
||||
match 1 < mutex.lock().unwrap().s.len() {
|
||||
true => {
|
||||
mutex.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
// Should trigger lint when both sides of a binary operation creates a temporary with a
|
||||
// significant drop.
|
||||
// To avoid potential unnecessary copies or creating references that would trigger the significant
|
||||
// drop problem, the lint recommends moving the entire binary operation.
|
||||
fn should_trigger_lint_for_accessing_fields_in_mutex_in_both_sides_of_binary_op() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "state".to_owned() });
|
||||
let mutex2 = Mutex::new(StateWithField { s: "statewithfield".to_owned() });
|
||||
|
||||
match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
|
||||
true => {
|
||||
println!("{} < {}", mutex1.lock().unwrap().s.len(), mutex2.lock().unwrap().s.len());
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
|
||||
match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
|
||||
true => {
|
||||
println!("{} >= {}", mutex1.lock().unwrap().s.len(), mutex2.lock().unwrap().s.len());
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_not_trigger_lint_for_closure_in_scrutinee() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
|
||||
|
||||
let get_mutex_guard = || mutex1.lock().unwrap().s.len();
|
||||
|
||||
// Should not trigger lint because the temporary with a significant drop will be dropped
|
||||
// at the end of the closure, so the MutexGuard will be unlocked and not have a potentially
|
||||
// surprising lifetime.
|
||||
match get_mutex_guard() > 1 {
|
||||
true => {
|
||||
mutex1.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_return_from_closure_in_scrutinee() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
|
||||
|
||||
let get_mutex_guard = || mutex1.lock().unwrap();
|
||||
|
||||
// Should trigger lint because the temporary with a significant drop is returned from the
|
||||
// closure but not used directly in any match arms, so it has a potentially surprising lifetime.
|
||||
match get_mutex_guard().s.len() > 1 {
|
||||
true => {
|
||||
mutex1.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_return_from_match_in_scrutinee() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
|
||||
let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
|
||||
|
||||
let i = 100;
|
||||
|
||||
// Should trigger lint because the nested match within the scrutinee returns a temporary with a
|
||||
// significant drop is but not used directly in any match arms, so it has a potentially
|
||||
// surprising lifetime.
|
||||
match match i { 100 => mutex1.lock().unwrap(), _ => mutex2.lock().unwrap() }.s.len() > 1 {
|
||||
true => {
|
||||
mutex1.lock().unwrap().s.len();
|
||||
}
|
||||
false => {
|
||||
println!("nothing to do here");
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_return_from_if_in_scrutinee() {
|
||||
let mutex1 = Mutex::new(StateWithField { s: "one".to_owned() });
|
||||
let mutex2 = Mutex::new(StateWithField { s: "two".to_owned() });
|
||||
|
||||
let i = 100;
|
||||
|
||||
// Should trigger lint because the nested if-expression within the scrutinee returns a temporary
|
||||
// with a significant drop is but not used directly in any match arms, so it has a potentially
|
||||
// surprising lifetime.
|
||||
match if i > 1 { mutex1.lock().unwrap() } else { mutex2.lock().unwrap() }.s.len() > 1 {
|
||||
true => {
|
||||
mutex1.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
fn should_not_trigger_lint_for_if_in_scrutinee() {
|
||||
let mutex = Mutex::new(StateWithField { s: "state".to_owned() });
|
||||
|
||||
let i = 100;
|
||||
|
||||
// Should not trigger the lint because the temporary with a significant drop *is* dropped within
|
||||
// the body of the if-expression nested within the match scrutinee, and therefore does not have
|
||||
// a potentially surprising lifetime.
|
||||
match if i > 1 { mutex.lock().unwrap().s.len() > 1 } else { false } {
|
||||
true => {
|
||||
mutex.lock().unwrap().s.len();
|
||||
}
|
||||
false => {}
|
||||
};
|
||||
}
|
||||
|
||||
struct StateWithBoxedMutexGuard {
|
||||
u: Mutex<u64>,
|
||||
}
|
||||
|
||||
impl StateWithBoxedMutexGuard {
|
||||
fn new() -> StateWithBoxedMutexGuard {
|
||||
StateWithBoxedMutexGuard { u: Mutex::new(42) }
|
||||
}
|
||||
fn lock(&self) -> Box<MutexGuard<u64>> {
|
||||
Box::new(self.u.lock().unwrap())
|
||||
}
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_boxed_mutex_guard() {
|
||||
let s = StateWithBoxedMutexGuard::new();
|
||||
|
||||
// Should trigger lint because a temporary Box holding a type with a significant drop in a match
|
||||
// scrutinee may have a potentially surprising lifetime.
|
||||
match s.lock().deref().deref() {
|
||||
0 | 1 => println!("Value was less than 2"),
|
||||
_ => println!("Value is {}", s.lock().deref()),
|
||||
};
|
||||
}
|
||||
|
||||
struct StateStringWithBoxedMutexGuard {
|
||||
s: Mutex<String>,
|
||||
}
|
||||
|
||||
impl StateStringWithBoxedMutexGuard {
|
||||
fn new() -> StateStringWithBoxedMutexGuard {
|
||||
StateStringWithBoxedMutexGuard { s: Mutex::new("A String".to_owned()) }
|
||||
}
|
||||
fn lock(&self) -> Box<MutexGuard<String>> {
|
||||
Box::new(self.s.lock().unwrap())
|
||||
}
|
||||
}
|
||||
|
||||
fn should_trigger_lint_for_boxed_mutex_guard_holding_string() {
|
||||
let s = StateStringWithBoxedMutexGuard::new();
|
||||
|
||||
let matcher = String::from("A String");
|
||||
|
||||
// Should trigger lint because a temporary Box holding a type with a significant drop in a match
|
||||
// scrutinee may have a potentially surprising lifetime.
|
||||
match s.lock().deref().deref() {
|
||||
matcher => println!("Value is {}", s.lock().deref()),
|
||||
_ => println!("Value was not a match"),
|
||||
};
|
||||
}
|
||||
|
||||
|
||||
struct StateWithIntField {
|
||||
i: u64,
|
||||
}
|
||||
|
||||
// Should trigger lint when either side of an assign expression contains a temporary with a
|
||||
// significant drop, because the temporary's lifetime will be extended to the end of the match.
|
||||
// To avoid potential unnecessary copies or creating references that would trigger the significant
|
||||
// drop problem, the lint recommends moving the entire binary operation.
|
||||
fn should_trigger_lint_in_assign_expr() {
|
||||
let mutex = Mutex::new(StateWithIntField { i: 10 });
|
||||
|
||||
let mut i = 100;
|
||||
|
||||
match mutex.lock().unwrap().i = i {
|
||||
_ => {
|
||||
println!("{}", mutex.lock().unwrap().i);
|
||||
}
|
||||
};
|
||||
|
||||
match i = mutex.lock().unwrap().i {
|
||||
_ => {
|
||||
println!("{}", mutex.lock().unwrap().i);
|
||||
}
|
||||
};
|
||||
|
||||
match mutex.lock().unwrap().i += 1 {
|
||||
_ => {
|
||||
println!("{}", mutex.lock().unwrap().i);
|
||||
}
|
||||
};
|
||||
|
||||
match i += mutex.lock().unwrap().i {
|
||||
_ => {
|
||||
println!("{}", mutex.lock().unwrap().i);
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
enum RecursiveEnum {
|
||||
Foo(Option<Box<RecursiveEnum>>)
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
enum GenericRecursiveEnum<T> {
|
||||
Foo(T, Option<Box<GenericRecursiveEnum<T>>>)
|
||||
}
|
||||
|
||||
fn should_not_cause_stack_overflow() {
|
||||
// Test that when a type recursively contains itself, a stack overflow does not occur when
|
||||
// checking sub-types for significant drops.
|
||||
let f = RecursiveEnum::Foo(Some(Box::new(RecursiveEnum::Foo(None))));
|
||||
match f {
|
||||
RecursiveEnum::Foo(Some(f)) => {
|
||||
println!("{:?}", f)
|
||||
}
|
||||
RecursiveEnum::Foo(f) => {
|
||||
println!("{:?}", f)
|
||||
}
|
||||
}
|
||||
|
||||
let f = GenericRecursiveEnum::Foo(1u64, Some(Box::new(GenericRecursiveEnum::Foo(2u64, None))));
|
||||
match f {
|
||||
GenericRecursiveEnum::Foo(i, Some(f)) => {
|
||||
println!("{} {:?}", i, f)
|
||||
}
|
||||
GenericRecursiveEnum::Foo(i, f) => {
|
||||
println!("{} {:?}", i, f)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {}
|
||||
261
tests/ui/significant_drop_in_scrutinee.stderr
Normal file
261
tests/ui/significant_drop_in_scrutinee.stderr
Normal file
@ -0,0 +1,261 @@
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:57:11
|
||||
|
|
||||
LL | match mutex.lock().unwrap().foo() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
= note: `-D clippy::significant-drop-in-scrutinee` implied by `-D warnings`
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex.lock().unwrap().foo();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:130:11
|
||||
|
|
||||
LL | match s.lock_m().get_the_value() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = s.lock_m().get_the_value();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:151:11
|
||||
|
|
||||
LL | match s.lock_m_m().get_the_value() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = s.lock_m_m().get_the_value();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:199:11
|
||||
|
|
||||
LL | match counter.temp_increment().len() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = counter.temp_increment().len();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:222:16
|
||||
|
|
||||
LL | match (mutex1.lock().unwrap().s.len(), true) {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex1.lock().unwrap().s.len();
|
||||
LL ~ match (value, true) {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:231:22
|
||||
|
|
||||
LL | match (true, mutex1.lock().unwrap().s.len(), true) {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex1.lock().unwrap().s.len();
|
||||
LL ~ match (true, value, true) {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:241:16
|
||||
|
|
||||
LL | match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex1.lock().unwrap().s.len();
|
||||
LL ~ match (value, true, mutex2.lock().unwrap().s.len()) {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:241:54
|
||||
|
|
||||
LL | match (mutex1.lock().unwrap().s.len(), true, mutex2.lock().unwrap().s.len()) {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex2.lock().unwrap().s.len();
|
||||
LL ~ match (mutex1.lock().unwrap().s.len(), true, value) {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:252:15
|
||||
|
|
||||
LL | match mutex3.lock().unwrap().s.as_str() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:263:22
|
||||
|
|
||||
LL | match (true, mutex3.lock().unwrap().s.as_str()) {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:282:11
|
||||
|
|
||||
LL | match mutex.lock().unwrap().s.len() > 1 {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex.lock().unwrap().s.len() > 1;
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:289:11
|
||||
|
|
||||
LL | match 1 < mutex.lock().unwrap().s.len() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = 1 < mutex.lock().unwrap().s.len();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:305:11
|
||||
|
|
||||
LL | match mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex1.lock().unwrap().s.len() < mutex2.lock().unwrap().s.len();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:312:11
|
||||
|
|
||||
LL | match mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = mutex1.lock().unwrap().s.len() >= mutex2.lock().unwrap().s.len();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:343:11
|
||||
|
|
||||
LL | match get_mutex_guard().s.len() > 1 {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = get_mutex_guard().s.len() > 1;
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:360:11
|
||||
|
|
||||
LL | match match i { 100 => mutex1.lock().unwrap(), _ => mutex2.lock().unwrap() }.s.len() > 1 {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = match i { 100 => mutex1.lock().unwrap(), _ => mutex2.lock().unwrap() }.s.len() > 1;
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:379:11
|
||||
|
|
||||
LL | match if i > 1 { mutex1.lock().unwrap() } else { mutex2.lock().unwrap() }.s.len() > 1 {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ let value = if i > 1 { mutex1.lock().unwrap() } else { mutex2.lock().unwrap() }.s.len() > 1;
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:421:11
|
||||
|
|
||||
LL | match s.lock().deref().deref() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match and create a copy
|
||||
|
|
||||
LL ~ let value = *s.lock().deref().deref();
|
||||
LL ~ match value {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:447:11
|
||||
|
|
||||
LL | match s.lock().deref().deref() {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:467:11
|
||||
|
|
||||
LL | match mutex.lock().unwrap().i = i {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ mutex.lock().unwrap().i = i;
|
||||
LL ~ match () {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:473:11
|
||||
|
|
||||
LL | match i = mutex.lock().unwrap().i {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ i = mutex.lock().unwrap().i;
|
||||
LL ~ match () {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:479:11
|
||||
|
|
||||
LL | match mutex.lock().unwrap().i += 1 {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ mutex.lock().unwrap().i += 1;
|
||||
LL ~ match () {
|
||||
|
|
||||
|
||||
error: temporary with significant drop in match scrutinee
|
||||
--> $DIR/significant_drop_in_scrutinee.rs:485:11
|
||||
|
|
||||
LL | match i += mutex.lock().unwrap().i {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
|
|
||||
help: try moving the temporary above the match
|
||||
|
|
||||
LL ~ i += mutex.lock().unwrap().i;
|
||||
LL ~ match () {
|
||||
|
|
||||
|
||||
error: aborting due to 23 previous errors
|
||||
|
||||
Loading…
Reference in New Issue
Block a user