implement raw-pointer self. Works for traits, including trait objects, but not structs

Author: mikeyhew

src/librustc/traits/object_safety.rs

@@ -59,9 +59,7 @@ impl ObjectSafetyViolation {
             ObjectSafetyViolation::Method(name, MethodViolationCode::Generic) =>
                 format!("method `{}` has generic type parameters", name).into(),
             ObjectSafetyViolation::Method(name, MethodViolationCode::NonStandardSelfType) =>
-                format!("method `{}` has a non-standard `self` type. Only `&self`, \
-                        `&mut self`, and `Box<Self>` are currently supported \
-                        for trait objects", name).into(),
+                format!("method `{}` has a non-standard `self` type", name).into(),
             ObjectSafetyViolation::AssociatedConst(name) =>
                 format!("the trait cannot contain associated consts like `{}`", name).into(),
         }

src/librustc/ty/util.rs

@@ -1191,6 +1191,7 @@ fn needs_drop_raw<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 pub enum ExplicitSelf<'tcx> {
     ByValue,
     ByReference(ty::Region<'tcx>, hir::Mutability),
+    ByRawPointer(hir::Mutability),
     ByBox,
     Other
 }
@@ -1231,10 +1232,15 @@ impl<'tcx> ExplicitSelf<'tcx> {
 
         match self_arg_ty.sty {
             _ if is_self_ty(self_arg_ty) => ByValue,
-            ty::TyRef(region, ty::TypeAndMut { ty, mutbl}) if is_self_ty(ty) => {
+            ty::TyRef(region, ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => {
                 ByReference(region, mutbl)
             }
-            ty::TyAdt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => ByBox,
+            ty::TyRawPtr(ty::TypeAndMut { ty, mutbl }) if is_self_ty(ty) => {
+                ByRawPointer(mutbl)
+            }
+            ty::TyAdt(def, _) if def.is_box() && is_self_ty(self_arg_ty.boxed_ty()) => {
+                ByBox
+            }
             _ => Other
         }
     }

src/librustc_typeck/check/autoderef.rs

@@ -37,6 +37,7 @@ pub struct Autoderef<'a, 'gcx: 'tcx, 'tcx: 'a> {
     cur_ty: Ty<'tcx>,
     obligations: Vec<traits::PredicateObligation<'tcx>>,
     at_start: bool,
+    include_raw_pointers: bool,
     span: Span,
 }
 
@@ -76,12 +77,13 @@ impl<'a, 'gcx, 'tcx> Iterator for Autoderef<'a, 'gcx, 'tcx> {
         }
 
         // Otherwise, deref if type is derefable:
-        let (kind, new_ty) = if let Some(mt) = self.cur_ty.builtin_deref(false, NoPreference) {
-            (AutoderefKind::Builtin, mt.ty)
-        } else {
-            let ty = self.overloaded_deref_ty(self.cur_ty)?;
-            (AutoderefKind::Overloaded, ty)
-        };
+        let (kind, new_ty) =
+            if let Some(mt) = self.cur_ty.builtin_deref(self.include_raw_pointers, NoPreference) {
+                (AutoderefKind::Builtin, mt.ty)
+            } else {
+                let ty = self.overloaded_deref_ty(self.cur_ty)?;
+                (AutoderefKind::Overloaded, ty)
+            };
 
         if new_ty.references_error() {
             return None;
@@ -194,6 +196,15 @@ impl<'a, 'gcx, 'tcx> Autoderef<'a, 'gcx, 'tcx> {
         }
     }
 
+    /// also dereference through raw pointer types
+    /// e.g. assuming ptr_to_Foo is the type `*const Foo`
+    /// fcx.autoderef(span, ptr_to_Foo)  => [*const Foo]
+    /// fcx.autoderef(span, ptr_to_Foo).include_raw_ptrs() => [*const Foo, Foo]
+    pub fn include_raw_pointers(mut self) -> Self {
+        self.include_raw_pointers = true;
+        self
+    }
+
     pub fn finalize(self) {
         let fcx = self.fcx;
         fcx.register_predicates(self.into_obligations());
@@ -212,6 +223,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             cur_ty: self.resolve_type_vars_if_possible(&base_ty),
             obligations: vec![],
             at_start: true,
+            include_raw_pointers: false,
             span,
         }
     }

src/librustc_typeck/check/wfcheck.rs

@@ -503,7 +503,7 @@ impl<'a, 'gcx> CheckTypeWellFormedVisitor<'a, 'gcx> {
             &ty::Binder(self_arg_ty)
         );
 
-        let mut autoderef = fcx.autoderef(span, self_arg_ty);
+        let mut autoderef = fcx.autoderef(span, self_arg_ty).include_raw_pointers();
 
         loop {
             if let Some((potential_self_ty, _)) = autoderef.next() {
@@ -532,12 +532,25 @@ impl<'a, 'gcx> CheckTypeWellFormedVisitor<'a, 'gcx> {
         let is_self_ty = |ty| fcx.infcx.can_eq(fcx.param_env, self_ty, ty).is_ok();
         let self_kind = ExplicitSelf::determine(self_arg_ty, is_self_ty);
 
-        if let ExplicitSelf::Other = self_kind {
-            if !fcx.tcx.sess.features.borrow().arbitrary_self_types {
-                feature_gate::feature_err(&fcx.tcx.sess.parse_sess, "arbitrary_self_types", span,
-                    GateIssue::Language, "arbitrary `self` types are unstable")
-                .help("consider changing to `self`, `&self`, `&mut self`, or `self: Box<Self>`")
-                .emit();
+        if !fcx.tcx.sess.features.borrow().arbitrary_self_types {
+            match self_kind {
+                ExplicitSelf::ByValue |
+                ExplicitSelf::ByReference(_, _) |
+                ExplicitSelf::ByBox => (),
+
+                ExplicitSelf::ByRawPointer(_) => {
+                    feature_gate::feature_err(&fcx.tcx.sess.parse_sess, "arbitrary_self_types", span,
+                        GateIssue::Language, "raw pointer `self` is unstable")
+                    .help("consider changing to `self`, `&self`, `&mut self`, or `self: Box<Self>`")
+                    .emit();
+                }
+
+                ExplicitSelf::Other => {
+                    feature_gate::feature_err(&fcx.tcx.sess.parse_sess, "arbitrary_self_types", span,
+                        GateIssue::Language, "arbitrary `self` types are unstable")
+                    .help("consider changing to `self`, `&self`, `&mut self`, or `self: Box<Self>`")
+                    .emit();
+                }
             }
         }
     }

src/test/run-pass/arbitrary_self_types_raw_pointer_struct.rs

@@ -0,0 +1,24 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(arbitrary_self_types)]
+
+struct Foo(String);
+
+impl Foo {
+    unsafe fn foo(self: *const Self) -> *const str {
+        (*self).0.as_ref()
+    }
+}
+
+fn main() {
+    let foo = Foo("abc123".into());
+    assert_eq!("abc123", unsafe { &*(&foo as *const Foo).foo() });
+}

src/test/run-pass/arbitrary_self_types_raw_pointer_trait.rs

@@ -0,0 +1,59 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(arbitrary_self_types)]
+
+use std::ptr;
+
+trait Foo {
+    fn foo(self: *const Self) -> &'static str;
+
+    unsafe fn bar(self: *const Self) -> i64;
+}
+
+impl Foo for i32 {
+    fn foo(self: *const Self) -> &'static str {
+        "I'm an i32!"
+    }
+
+    unsafe fn bar(self: *const Self) -> i64 {
+        *self as i64
+    }
+}
+
+impl Foo for u32 {
+    fn foo(self: *const Self) -> &'static str {
+        "I'm a u32!"
+    }
+
+    unsafe fn bar(self: *const Self) -> i64 {
+        *self as i64
+    }
+}
+
+fn main() {
+    let foo_i32 = ptr::null::<i32>() as *const Foo;
+    let foo_u32 = ptr::null::<u32>() as *const Foo;
+
+    assert_eq!("I'm an i32!", foo_i32.foo());
+    assert_eq!("I'm a u32!", foo_u32.foo());
+
+    let bar_i32 = 5i32;
+    let bar_i32_thin = &bar_i32 as *const i32;
+    assert_eq!(5, unsafe { bar_i32_thin.bar() });
+    let bar_i32_fat = bar_i32_thin as *const Foo;
+    assert_eq!(5, unsafe { bar_i32_fat.bar() });
+
+    let bar_u32 = 18u32;
+    let bar_u32_thin = &bar_u32 as *const u32;
+    assert_eq!(18, unsafe { bar_u32_thin.bar() });
+    let bar_u32_fat = bar_u32_thin as *const Foo;
+    assert_eq!(18, unsafe { bar_u32_fat.bar() });
+}