rust-clippy/clippy_lints/src/mutable_debug_assertion.rs

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use crate::utils::{is_direct_expn_of, span_lint};
use if_chain::if_chain;
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use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc_hir::{BorrowKind, Expr, ExprKind, MatchSource, Mutability, StmtKind, UnOp};
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use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::Map;
use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::Span;
declare_clippy_lint! {
/// **What it does:** Checks for function/method calls with a mutable
/// parameter in `debug_assert!`, `debug_assert_eq!` and `debug_assert_ne!` macros.
///
/// **Why is this bad?** In release builds `debug_assert!` macros are optimized out by the
/// compiler.
/// Therefore mutating something in a `debug_assert!` macro results in different behaviour
/// between a release and debug build.
///
/// **Known problems:** None
///
/// **Example:**
/// ```rust,ignore
/// debug_assert_eq!(vec![3].pop(), Some(3));
/// // or
/// fn take_a_mut_parameter(_: &mut u32) -> bool { unimplemented!() }
/// debug_assert!(take_a_mut_parameter(&mut 5));
/// ```
pub DEBUG_ASSERT_WITH_MUT_CALL,
nursery,
"mutable arguments in `debug_assert{,_ne,_eq}!`"
}
declare_lint_pass!(DebugAssertWithMutCall => [DEBUG_ASSERT_WITH_MUT_CALL]);
const DEBUG_MACRO_NAMES: [&str; 3] = ["debug_assert", "debug_assert_eq", "debug_assert_ne"];
impl<'tcx> LateLintPass<'tcx> for DebugAssertWithMutCall {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
for dmn in &DEBUG_MACRO_NAMES {
if is_direct_expn_of(e.span, dmn).is_some() {
if let Some(span) = extract_call(cx, e) {
span_lint(
cx,
DEBUG_ASSERT_WITH_MUT_CALL,
span,
&format!("do not call a function with mutable arguments inside of `{}!`", dmn),
);
}
}
}
}
}
//HACK(hellow554): remove this when #4694 is implemented
fn extract_call<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<Span> {
if_chain! {
if let ExprKind::Block(ref block, _) = e.kind;
if block.stmts.len() == 1;
if let StmtKind::Semi(ref matchexpr) = block.stmts[0].kind;
then {
// debug_assert
if_chain! {
if let ExprKind::Match(ref ifclause, _, _) = matchexpr.kind;
if let ExprKind::DropTemps(ref droptmp) = ifclause.kind;
if let ExprKind::Unary(UnOp::UnNot, ref condition) = droptmp.kind;
then {
let mut visitor = MutArgVisitor::new(cx);
visitor.visit_expr(condition);
return visitor.expr_span();
}
}
// debug_assert_{eq,ne}
if_chain! {
if let ExprKind::Block(ref matchblock, _) = matchexpr.kind;
if let Some(ref matchheader) = matchblock.expr;
if let ExprKind::Match(ref headerexpr, _, _) = matchheader.kind;
if let ExprKind::Tup(ref conditions) = headerexpr.kind;
if conditions.len() == 2;
then {
if let ExprKind::AddrOf(BorrowKind::Ref, _, ref lhs) = conditions[0].kind {
let mut visitor = MutArgVisitor::new(cx);
visitor.visit_expr(lhs);
if let Some(span) = visitor.expr_span() {
return Some(span);
}
}
if let ExprKind::AddrOf(BorrowKind::Ref, _, ref rhs) = conditions[1].kind {
let mut visitor = MutArgVisitor::new(cx);
visitor.visit_expr(rhs);
if let Some(span) = visitor.expr_span() {
return Some(span);
}
}
}
}
}
}
None
}
struct MutArgVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
expr_span: Option<Span>,
found: bool,
}
impl<'a, 'tcx> MutArgVisitor<'a, 'tcx> {
fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
expr_span: None,
found: false,
}
}
fn expr_span(&self) -> Option<Span> {
if self.found {
self.expr_span
} else {
None
}
}
}
impl<'a, 'tcx> Visitor<'tcx> for MutArgVisitor<'a, 'tcx> {
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type Map = Map<'tcx>;
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fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
match expr.kind {
ExprKind::AddrOf(BorrowKind::Ref, Mutability::Mut, _) => {
self.found = true;
return;
},
ExprKind::Path(_) => {
if let Some(adj) = self.cx.tables().adjustments().get(expr.hir_id) {
if adj
.iter()
.any(|a| matches!(a.target.kind, ty::Ref(_, _, Mutability::Mut)))
{
self.found = true;
return;
}
}
},
// Don't check await desugars
ExprKind::Match(_, _, MatchSource::AwaitDesugar) => return,
_ if !self.found => self.expr_span = Some(expr.span),
_ => return,
}
walk_expr(self, expr)
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::OnlyBodies(self.cx.tcx.hir())
}
}