2015-05-18 02:02:24 -05:00
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use syntax::ptr::P;
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use syntax::ast::*;
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2015-05-18 03:41:15 -05:00
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use rustc::lint::{Context, LintPass, LintArray, Lint};
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use rustc::middle::ty::{expr_ty, sty, ty_ptr, ty_rptr, mt};
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2015-05-18 02:02:24 -05:00
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declare_lint!(pub MUT_MUT, Warn,
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"Warn on usage of double-mut refs, e.g. '&mut &mut ...'");
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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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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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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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2015-05-18 03:41:15 -05:00
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unwrap_addr(expr).map(|e| {
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2015-05-21 08:59:38 -05:00
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unwrap_addr(e).map(|_| {
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2015-05-18 03:41:15 -05:00
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cx.span_lint(MUT_MUT, expr.span,
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2015-05-18 03:52:43 -05:00
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"Generally you want to avoid &mut &mut _ if possible.")
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2015-05-21 08:59:38 -05:00
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}).unwrap_or_else(|| {
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if let ty_rptr(_, mt{ty: _, mutbl: MutMutable}) =
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expr_ty(cx.tcx, e).sty {
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2015-05-18 04:36:56 -05:00
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cx.span_lint(MUT_MUT, expr.span,
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2015-05-21 08:59:38 -05:00
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"This expression mutably borrows a mutable reference. \
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Consider reborrowing")
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2015-05-18 03:41:15 -05:00
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}
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2015-05-21 08:59:38 -05:00
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})
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}).unwrap_or(())
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2015-05-18 02:02:24 -05:00
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}
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fn check_ty(&mut self, cx: &Context, ty: &Ty) {
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2015-05-21 08:59:38 -05:00
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unwrap_mut(ty).and_then(unwrap_mut).map(|_| cx.span_lint(MUT_MUT,
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ty.span, "Generally you want to avoid &mut &mut _ if possible.")).
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unwrap_or(())
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2015-05-18 02:02:24 -05:00
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}
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}
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2015-05-18 03:41:15 -05:00
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fn unwrap_mut(ty : &Ty) -> Option<&Ty> {
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match ty.node {
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TyPtr(MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
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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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