110 lines
3.4 KiB
Rust
110 lines
3.4 KiB
Rust
use crate::utils::{higher, span_lint};
|
|
use rustc::hir;
|
|
use rustc::hir::intravisit;
|
|
use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
|
|
use rustc::ty;
|
|
use rustc::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for instances of `mut mut` references.
|
|
///
|
|
/// **Why is this bad?** Multiple `mut`s don't add anything meaningful to the
|
|
/// source. This is either a copy'n'paste error, or it shows a fundamental
|
|
/// misunderstanding of references.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// # let mut y = 1;
|
|
/// let x = &mut &mut y;
|
|
/// ```
|
|
pub MUT_MUT,
|
|
pedantic,
|
|
"usage of double-mut refs, e.g., `&mut &mut ...`"
|
|
}
|
|
|
|
declare_lint_pass!(MutMut => [MUT_MUT]);
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutMut {
|
|
fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx hir::Block) {
|
|
intravisit::walk_block(&mut MutVisitor { cx }, block);
|
|
}
|
|
|
|
fn check_ty(&mut self, cx: &LateContext<'a, 'tcx>, ty: &'tcx hir::Ty) {
|
|
use rustc::hir::intravisit::Visitor;
|
|
|
|
MutVisitor { cx }.visit_ty(ty);
|
|
}
|
|
}
|
|
|
|
pub struct MutVisitor<'a, 'tcx> {
|
|
cx: &'a LateContext<'a, 'tcx>,
|
|
}
|
|
|
|
impl<'a, 'tcx> intravisit::Visitor<'tcx> for MutVisitor<'a, 'tcx> {
|
|
fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
|
|
if in_external_macro(self.cx.sess(), expr.span) {
|
|
return;
|
|
}
|
|
|
|
if let Some((_, arg, body)) = higher::for_loop(expr) {
|
|
// A `for` loop lowers to:
|
|
// ```rust
|
|
// match ::std::iter::Iterator::next(&mut iter) {
|
|
// // ^^^^
|
|
// ```
|
|
// Let's ignore the generated code.
|
|
intravisit::walk_expr(self, arg);
|
|
intravisit::walk_expr(self, body);
|
|
} else if let hir::ExprKind::AddrOf(hir::MutMutable, ref e) = expr.node {
|
|
if let hir::ExprKind::AddrOf(hir::MutMutable, _) = e.node {
|
|
span_lint(
|
|
self.cx,
|
|
MUT_MUT,
|
|
expr.span,
|
|
"generally you want to avoid `&mut &mut _` if possible",
|
|
);
|
|
} else if let ty::Ref(_, _, hir::MutMutable) = self.cx.tables.expr_ty(e).kind {
|
|
span_lint(
|
|
self.cx,
|
|
MUT_MUT,
|
|
expr.span,
|
|
"this expression mutably borrows a mutable reference. Consider reborrowing",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
|
|
if let hir::TyKind::Rptr(
|
|
_,
|
|
hir::MutTy {
|
|
ty: ref pty,
|
|
mutbl: hir::MutMutable,
|
|
},
|
|
) = ty.node
|
|
{
|
|
if let hir::TyKind::Rptr(
|
|
_,
|
|
hir::MutTy {
|
|
mutbl: hir::MutMutable, ..
|
|
},
|
|
) = pty.node
|
|
{
|
|
span_lint(
|
|
self.cx,
|
|
MUT_MUT,
|
|
ty.span,
|
|
"generally you want to avoid `&mut &mut _` if possible",
|
|
);
|
|
}
|
|
}
|
|
|
|
intravisit::walk_ty(self, ty);
|
|
}
|
|
fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
|
|
intravisit::NestedVisitorMap::None
|
|
}
|
|
}
|