Make Send and Sync traits unsafe

src/test/run-pass/const-block.rs

@@ -18,7 +18,7 @@ struct Foo {
     b: *const ()
 }
 
-impl Sync for Foo {}
+unsafe impl Sync for Foo {}
 
 fn foo<T>(a: T) -> T {
     a

src/test/run-pass/const-cast-ptr-int.rs

@@ -14,7 +14,7 @@ struct TestStruct {
     x: *const u8
 }
 
-impl Sync for TestStruct {}
+unsafe impl Sync for TestStruct {}
 
 static a: TestStruct = TestStruct{x: 0 as *const u8};
 

src/test/run-pass/const-cast.rs

@@ -14,7 +14,7 @@ struct TestStruct {
     x: *const libc::c_void
 }
 
-impl Sync for TestStruct {}
+unsafe impl Sync for TestStruct {}
 
 extern fn foo() {}
 const x: extern "C" fn() = foo;

src/test/run-pass/issue-13837.rs

@@ -12,7 +12,7 @@ struct TestStruct {
     x: *const [int; 2]
 }
 
-impl Sync for TestStruct {}
+unsafe impl Sync for TestStruct {}
 
 static TEST_VALUE : TestStruct = TestStruct{x: 0x1234 as *const [int; 2]};
 

src/test/run-pass/issue-17718-static-unsafe-interior.rs

@@ -36,7 +36,7 @@ struct Wrap<T> {
     value: T
 }
 
-impl<T: Send> Sync for Wrap<T> {}
+unsafe impl<T: Send> Sync for Wrap<T> {}
 
 static UNSAFE: RacyCell<int> = RacyCell(UnsafeCell{value: 1});
 static WRAPPED_UNSAFE: Wrap<&'static RacyCell<int>> = Wrap { value: &UNSAFE };

src/test/run-pass/issue-2718.rs

@@ -46,7 +46,7 @@ pub mod pipes {
         payload: Option<T>
     }
 
-    impl<T:Send> Send for packet<T> {}
+    unsafe impl<T:Send> Send for packet<T> {}
 
     pub fn packet<T:Send>() -> *const packet<T> {
         unsafe {

src/test/run-pass/typeck_type_placeholder_1.rs

@@ -15,7 +15,7 @@ struct TestStruct {
     x: *const int
 }
 
-impl Sync for TestStruct {}
+unsafe impl Sync for TestStruct {}
 
 static CONSTEXPR: TestStruct = TestStruct{x: &413 as *const _};