update to the rust-PR that unblocks clippy

[rust.git] / clippy_lints / src / mut_mut.rs

diff --git a/clippy_lints/src/mut_mut.rs b/clippy_lints/src/mut_mut.rs
index 0bed45b0b5bbe387671ac07ecf7666449a577763..40bb77871dbc641caaa23351c44474c078261507 100644 (file)
--- a/clippy_lints/src/mut_mut.rs
+++ b/clippy_lints/src/mut_mut.rs
@@ -1,20 +1,25 @@
+use rustc::hir;
+use rustc::hir::intravisit;
 use rustc::lint::*;
 use rustc::ty::{TypeAndMut, TyRef};
-use rustc::hir::*;
-use utils::{in_external_macro, span_lint};
+use utils::{higher, in_external_macro, span_lint};
 
-/// **What it does:** This lint checks for instances of `mut mut` references.
+/// **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.
+/// **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
+/// **Known problems:** None.
 ///
-/// **Example:** `let x = &mut &mut y;`
+/// **Example:**
+/// ```rust
+/// let x = &mut &mut y;
+/// ```
 declare_lint! {
     pub MUT_MUT,
     Allow,
-    "usage of double-mut refs, e.g. `&mut &mut ...` (either copy'n'paste error, \
-     or shows a fundamental misunderstanding of references)"
+    "usage of double-mut refs, e.g. `&mut &mut ...`"
 }
 
 #[derive(Copy,Clone)]
@@ -26,31 +31,60 @@ fn get_lints(&self) -> LintArray {
     }
 }
 
-impl LateLintPass for MutMut {
-    fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
-        if in_external_macro(cx, expr.span) {
+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: cx }, block);
+    }
+
+    fn check_ty(&mut self, cx: &LateContext<'a, 'tcx>, ty: &'tcx hir::Ty) {
+        use rustc::hir::intravisit::Visitor;
+
+        MutVisitor { cx: cx }.visit_ty(ty);
+    }
+}
+
+pub struct MutVisitor<'a, 'tcx: 'a> {
+    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, expr.span) {
             return;
         }
 
-        if let ExprAddrOf(MutMutable, ref e) = expr.node {
-            if let ExprAddrOf(MutMutable, _) = e.node {
-                span_lint(cx, MUT_MUT, expr.span, "generally you want to avoid `&mut &mut _` if possible");
-            } else {
-                if let TyRef(_, TypeAndMut { mutbl: MutMutable, .. }) = cx.tcx.expr_ty(e).sty {
-                    span_lint(cx,
-                              MUT_MUT,
-                              expr.span,
-                              "this expression mutably borrows a mutable reference. Consider reborrowing");
-                }
+        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::ExprAddrOf(hir::MutMutable, ref e) = expr.node {
+            if let hir::ExprAddrOf(hir::MutMutable, _) = e.node {
+                span_lint(self.cx, MUT_MUT, expr.span, "generally you want to avoid `&mut &mut _` if possible");
+            } else if let TyRef(_, TypeAndMut { mutbl: hir::MutMutable, .. }) = self.cx.tcx.tables().expr_ty(e).sty {
+                span_lint(self.cx,
+                          MUT_MUT,
+                          expr.span,
+                          "this expression mutably borrows a mutable reference. Consider reborrowing");
             }
         }
     }
 
-    fn check_ty(&mut self, cx: &LateContext, ty: &Ty) {
-        if let TyRptr(_, MutTy { ty: ref pty, mutbl: MutMutable }) = ty.node {
-            if let TyRptr(_, MutTy { mutbl: MutMutable, .. }) = pty.node {
-                span_lint(cx, MUT_MUT, ty.span, "generally you want to avoid `&mut &mut _` if possible");
+    fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
+        if let hir::TyRptr(_, hir::MutTy { ty: ref pty, mutbl: hir::MutMutable }) = ty.node {
+            if let hir::TyRptr(_, 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::All(&self.cx.tcx.map)
     }
 }