62 lines
1.8 KiB
Rust
62 lines
1.8 KiB
Rust
use rustc::lint::*;
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use rustc_front::hir::*;
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use rustc::middle::ty::{TypeAndMut, TyRef};
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use utils::{in_external_macro, span_lint};
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declare_lint!(pub MUT_MUT, Allow,
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"usage of double-mut refs, e.g. `&mut &mut ...` (either copy'n'paste error, \
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or shows a fundamental misunderstanding of references)");
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#[derive(Copy,Clone)]
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pub struct MutMut;
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impl LintPass for MutMut {
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fn get_lints(&self) -> LintArray {
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lint_array!(MUT_MUT)
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}
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}
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impl LateLintPass for MutMut {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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check_expr_mut(cx, expr)
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}
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fn check_ty(&mut self, cx: &LateContext, ty: &Ty) {
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unwrap_mut(ty).and_then(unwrap_mut).map_or((), |_| span_lint(cx, MUT_MUT,
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ty.span, "generally you want to avoid `&mut &mut _` if possible"))
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}
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}
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fn check_expr_mut(cx: &LateContext, expr: &Expr) {
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if in_external_macro(cx, expr.span) { return; }
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fn unwrap_addr(expr : &Expr) -> Option<&Expr> {
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match expr.node {
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ExprAddrOf(MutMutable, ref e) => Option::Some(e),
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_ => Option::None
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}
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}
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unwrap_addr(expr).map_or((), |e| {
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unwrap_addr(e).map(|_| {
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span_lint(cx, MUT_MUT, expr.span,
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"generally you want to avoid `&mut &mut _` if possible")
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}).unwrap_or_else(|| {
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if let TyRef(_, TypeAndMut{ty: _, mutbl: MutMutable}) =
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cx.tcx.expr_ty(e).sty {
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span_lint(cx, MUT_MUT, expr.span,
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"this expression mutably borrows a mutable reference. \
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Consider reborrowing")
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}
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})
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})
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}
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fn unwrap_mut(ty : &Ty) -> Option<&Ty> {
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match ty.node {
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TyRptr(_, MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
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_ => Option::None
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}
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}
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