rustc: replace autoderefs' use of MethodCallee with OverloadedDeref.

Author: eddyb

src/librustc/ich/impls_ty.rs

@@ -110,7 +110,7 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a, 'tcx>> for ty::adjustment::Ad
 }
 
 impl_stable_hash_for!(struct ty::adjustment::Adjustment<'tcx> { kind, target });
-impl_stable_hash_for!(struct ty::MethodCallee<'tcx> { def_id, substs, sig });
+impl_stable_hash_for!(struct ty::adjustment::OverloadedDeref<'tcx> { region, mutbl, target });
 impl_stable_hash_for!(struct ty::UpvarId { var_id, closure_expr_id });
 impl_stable_hash_for!(struct ty::UpvarBorrow<'tcx> { kind, region });
 

src/librustc/middle/expr_use_visitor.rs

@@ -745,23 +745,16 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
     fn walk_autoderefs(&mut self,
                        expr: &hir::Expr,
                        mut cmt: mc::cmt<'tcx>,
-                       autoderefs: &[Option<ty::MethodCallee<'tcx>>])
+                       autoderefs: &[Option<adjustment::OverloadedDeref<'tcx>>])
                        -> mc::McResult<mc::cmt<'tcx>> {
         debug!("walk_autoderefs expr={:?} autoderefs={:?}", expr, autoderefs);
 
         for &overloaded in autoderefs {
-            if let Some(method) = overloaded {
-                let self_ty = method.sig.inputs()[0];
-                let self_ty = self.mc.infcx.resolve_type_vars_if_possible(&self_ty);
-
-                let (m, r) = match self_ty.sty {
-                    ty::TyRef(r, ref m) => (m.mutbl, r),
-                    _ => span_bug!(expr.span, "bad overloaded deref type {:?}", self_ty)
-                };
-                let bk = ty::BorrowKind::from_mutbl(m);
+            if let Some(deref) = overloaded {
+                let bk = ty::BorrowKind::from_mutbl(deref.mutbl);
                 self.delegate.borrow(expr.id, expr.span, cmt.clone(),
-                                     r, bk, AutoRef);
-                cmt = self.mc.cat_overloaded_autoderef(expr, method)?;
+                                     deref.region, bk, AutoRef);
+                cmt = self.mc.cat_overloaded_autoderef(expr, deref)?;
             } else {
                 cmt = self.mc.cat_deref(expr, cmt, false)?;
             }

src/librustc/middle/mem_categorization.rs

@@ -485,8 +485,8 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
                         debug!("cat_expr: autoderefs={:?}, cmt={:?}",
                                autoderefs, cmt);
                         for &overloaded in autoderefs {
-                            if let Some(method) = overloaded {
-                                cmt = self.cat_overloaded_autoderef(expr, method)?;
+                            if let Some(deref) = overloaded {
+                                cmt = self.cat_overloaded_autoderef(expr, deref)?;
                             } else {
                                 cmt = self.cat_deref(expr, cmt, false)?;
                             }
@@ -936,12 +936,15 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
 
     pub fn cat_overloaded_autoderef(&self,
                                     expr: &hir::Expr,
-                                    method: ty::MethodCallee<'tcx>)
+                                    deref: adjustment::OverloadedDeref<'tcx>)
                                     -> McResult<cmt<'tcx>> {
-        debug!("cat_overloaded_autoderef: method={:?}", method);
+        debug!("cat_overloaded_autoderef: deref={:?}", deref);
 
-        let ref_ty = method.sig.output();
-        let ref_ty = self.infcx.resolve_type_vars_if_possible(&ref_ty);
+        let target = self.infcx.resolve_type_vars_if_possible(&deref.target);
+        let ref_ty = self.tcx().mk_ref(deref.region, ty::TypeAndMut {
+            ty: target,
+            mutbl: deref.mutbl,
+        });
         let base_cmt = self.cat_rvalue_node(expr.id, expr.span, ref_ty);
         self.cat_deref(expr, base_cmt, false)
     }

src/librustc/ty/adjustment.rs

@@ -8,9 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use ty::{self, Ty, TyCtxt, TypeAndMut};
-
 use hir;
+use hir::def_id::DefId;
+use ty::{self, Ty, TyCtxt, TypeAndMut};
+use ty::subst::Substs;
 
 #[derive(Clone, RustcEncodable, RustcDecodable)]
 pub struct Adjustment<'tcx> {
@@ -105,7 +106,7 @@ pub enum Adjust<'tcx> {
     /// ```
     DerefRef {
         /// Step 1. Apply a number of dereferences, producing an lvalue.
-        autoderefs: Vec<Option<ty::MethodCallee<'tcx>>>,
+        autoderefs: Vec<Option<OverloadedDeref<'tcx>>>,
 
         /// Step 2. Optionally produce a pointer/reference from the value.
         autoref: Option<AutoBorrow<'tcx>>,
@@ -136,6 +137,30 @@ impl<'tcx> Adjustment<'tcx> {
     }
 }
 
+/// An overloaded autoderef step, representing a `Deref(Mut)::deref(_mut)`
+/// call, with the signature `&'a T -> &'a U` or `&'a mut T -> &'a mut U`.
+/// The target type is `U` in both cases, with the region and mutability
+/// being those shared by both the receiver and the returned reference.
+#[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
+pub struct OverloadedDeref<'tcx> {
+    pub region: ty::Region<'tcx>,
+    pub mutbl: hir::Mutability,
+    pub target: Ty<'tcx>,
+}
+
+impl<'a, 'gcx, 'tcx> OverloadedDeref<'tcx> {
+    pub fn method_call(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, source: Ty<'tcx>)
+                       -> (DefId, &'tcx Substs<'tcx>) {
+        let trait_def_id = match self.mutbl {
+            hir::MutImmutable => tcx.lang_items.deref_trait(),
+            hir::MutMutable => tcx.lang_items.deref_mut_trait()
+        };
+        let method_def_id = tcx.associated_items(trait_def_id.unwrap())
+            .find(|m| m.kind == ty::AssociatedKind::Method).unwrap().def_id;
+        (method_def_id, tcx.mk_substs_trait(source, &[]))
+    }
+}
+
 #[derive(Copy, Clone, PartialEq, Debug, RustcEncodable, RustcDecodable)]
 pub enum AutoBorrow<'tcx> {
     /// Convert from T to &T.

src/librustc/ty/mod.rs

@@ -390,18 +390,6 @@ impl Variance {
     }
 }
 
-#[derive(Clone, Copy, Debug, RustcDecodable, RustcEncodable)]
-pub struct MethodCallee<'tcx> {
-    /// Impl method ID, for inherent methods, or trait method ID, otherwise.
-    pub def_id: DefId,
-    pub substs: &'tcx Substs<'tcx>,
-
-    /// Instantiated method signature, i.e. it has been substituted,
-    /// normalized, and has had late-bound lifetimes replaced
-    /// (with inference variables, during type-checking).
-    pub sig: FnSig<'tcx>,
-}
-
 // Contains information needed to resolve types and (in the future) look up
 // the types of AST nodes.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]

src/librustc/ty/structural_impls.rs

@@ -220,6 +220,55 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
     }
 }
 
+impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
+    type Lifted = ty::adjustment::Adjustment<'tcx>;
+    fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(&self.kind).and_then(|kind| {
+            tcx.lift(&self.target).map(|target| {
+                ty::adjustment::Adjustment { kind, target }
+            })
+        })
+    }
+}
+
+impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
+    type Lifted = ty::adjustment::Adjust<'tcx>;
+    fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
+        match *self {
+            ty::adjustment::Adjust::NeverToAny =>
+                Some(ty::adjustment::Adjust::NeverToAny),
+            ty::adjustment::Adjust::ReifyFnPointer =>
+                Some(ty::adjustment::Adjust::ReifyFnPointer),
+            ty::adjustment::Adjust::UnsafeFnPointer =>
+                Some(ty::adjustment::Adjust::UnsafeFnPointer),
+            ty::adjustment::Adjust::ClosureFnPointer =>
+                Some(ty::adjustment::Adjust::ClosureFnPointer),
+            ty::adjustment::Adjust::MutToConstPointer =>
+                Some(ty::adjustment::Adjust::MutToConstPointer),
+            ty::adjustment::Adjust::DerefRef { ref autoderefs, ref autoref, unsize } => {
+                tcx.lift(autoderefs).and_then(|autoderefs| {
+                    tcx.lift(autoref).map(|autoref| {
+                        ty::adjustment::Adjust::DerefRef { autoderefs, autoref, unsize }
+                    })
+                })
+            }
+        }
+    }
+}
+
+impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
+    type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
+    fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(&(self.region, self.target)).map(|(region, target)| {
+            ty::adjustment::OverloadedDeref {
+                region,
+                mutbl: self.mutbl,
+                target,
+            }
+        })
+    }
+}
+
 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
@@ -631,6 +680,65 @@ impl<'tcx> TypeFoldable<'tcx> for ty::ClosureSubsts<'tcx> {
     }
 }
 
+impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::Adjustment<'tcx> {
+    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
+        ty::adjustment::Adjustment {
+            kind: self.kind.fold_with(folder),
+            target: self.target.fold_with(folder),
+        }
+    }
+
+    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
+        self.kind.visit_with(visitor) || self.target.visit_with(visitor)
+    }
+}
+
+impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::Adjust<'tcx> {
+    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
+        match *self {
+            ty::adjustment::Adjust::NeverToAny |
+            ty::adjustment::Adjust::ReifyFnPointer |
+            ty::adjustment::Adjust::UnsafeFnPointer |
+            ty::adjustment::Adjust::ClosureFnPointer |
+            ty::adjustment::Adjust::MutToConstPointer => self.clone(),
+            ty::adjustment::Adjust::DerefRef { ref autoderefs, ref autoref, unsize } => {
+                ty::adjustment::Adjust::DerefRef {
+                    autoderefs: autoderefs.fold_with(folder),
+                    autoref: autoref.fold_with(folder),
+                    unsize,
+                }
+            }
+        }
+    }
+
+    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
+        match *self {
+            ty::adjustment::Adjust::NeverToAny |
+            ty::adjustment::Adjust::ReifyFnPointer |
+            ty::adjustment::Adjust::UnsafeFnPointer |
+            ty::adjustment::Adjust::ClosureFnPointer |
+            ty::adjustment::Adjust::MutToConstPointer => false,
+            ty::adjustment::Adjust::DerefRef { ref autoderefs, ref autoref, unsize: _ } => {
+                autoderefs.visit_with(visitor) || autoref.visit_with(visitor)
+            }
+        }
+    }
+}
+
+impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::OverloadedDeref<'tcx> {
+    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
+        ty::adjustment::OverloadedDeref {
+            region: self.region.fold_with(folder),
+            mutbl: self.mutbl,
+            target: self.target.fold_with(folder),
+        }
+    }
+
+    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
+        self.region.visit_with(visitor) || self.target.visit_with(visitor)
+    }
+}
+
 impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::AutoBorrow<'tcx> {
     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
         match *self {

src/librustc_lint/builtin.rs

@@ -892,11 +892,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnconditionalRecursion {
             if let Some(&Adjustment {
                 kind: Adjust::DerefRef { ref autoderefs, .. }, ..
             }) = cx.tables.adjustments.get(&id) {
+                let mut source = cx.tables.expr_ty(expr);
                 for &overloaded in autoderefs {
-                    if let Some(m) = overloaded {
-                        if method_call_refers_to_method(cx.tcx, method, m.def_id, m.substs, id) {
+                    if let Some(deref) = overloaded {
+                        let (def_id, substs) = deref.method_call(cx.tcx, source);
+                        if method_call_refers_to_method(cx.tcx, method, def_id, substs, id) {
                             return true;
                         }
+                        source = deref.target;
+                    } else {
+                        source = source.builtin_deref(true,
+                            ty::LvaluePreference::NoPreference).unwrap().ty;
                     }
                 }
             }