Auto merge of #49799 - hdhoang:46205_deny_incoherent_fundamental_impls, r=nikomatsakis

[rust.git] / src / libstd / error.rs

diff --git a/src/libstd/error.rs b/src/libstd/error.rs
index 3eb289501cb0fd080ccea3d7f3df479ede4ef8eb..62282006a40248df320c8eedc5c99c37b5b4683c 100644 (file)
--- a/src/libstd/error.rs
+++ b/src/libstd/error.rs
@@ -84,7 +84,7 @@ fn description(&self) -> &str {
     /// }
     ///
     /// impl fmt::Display for SuperError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "SuperError is here!")
     ///     }
     /// }
@@ -103,7 +103,7 @@ fn description(&self) -> &str {
     /// struct SuperErrorSideKick;
     ///
     /// impl fmt::Display for SuperErrorSideKick {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "SuperErrorSideKick is here!")
     ///     }
     /// }
@@ -149,7 +149,7 @@ fn cause(&self) -> Option<&dyn Error> {
     /// }
     ///
     /// impl fmt::Display for SuperError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "SuperError is here!")
     ///     }
     /// }
@@ -168,7 +168,7 @@ fn cause(&self) -> Option<&dyn Error> {
     /// struct SuperErrorSideKick;
     ///
     /// impl fmt::Display for SuperErrorSideKick {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "SuperErrorSideKick is here!")
     ///     }
     /// }
@@ -198,12 +198,22 @@ fn source(&self) -> Option<&(dyn Error + 'static)> { None }
 
     /// Gets the `TypeId` of `self`
     #[doc(hidden)]
-    #[stable(feature = "error_type_id", since = "1.34.0")]
-    fn type_id(&self) -> TypeId where Self: 'static {
+    #[unstable(feature = "error_type_id",
+               reason = "this is memory unsafe to override in user code",
+               issue = "60784")]
+    fn type_id(&self, _: private::Internal) -> TypeId where Self: 'static {
         TypeId::of::<Self>()
     }
 }
 
+mod private {
+    // This is a hack to prevent `type_id` from being overridden by `Error`
+    // implementations, since that can enable unsound downcasting.
+    #[unstable(feature = "error_type_id", issue = "60784")]
+    #[derive(Debug)]
+    pub struct Internal;
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
     /// Converts a type of [`Error`] into a box of dyn [`Error`].
@@ -219,7 +229,7 @@ impl<'a, E: Error + 'a> From<E> for Box<dyn Error + 'a> {
     /// struct AnError;
     ///
     /// impl fmt::Display for AnError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f , "An error")
     ///     }
     /// }
@@ -256,7 +266,7 @@ impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<dyn Error + Send + Sync +
     /// struct AnError;
     ///
     /// impl fmt::Display for AnError {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f , "An error")
     ///     }
     /// }
@@ -306,7 +316,7 @@ fn description(&self) -> &str { &self.0 }
         }
 
         impl Display for StringError {
-            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 Display::fmt(&self.0, f)
             }
         }
@@ -573,7 +583,7 @@ pub fn is<T: Error + 'static>(&self) -> bool {
         let t = TypeId::of::<T>();
 
         // Get TypeId of the type in the trait object
-        let boxed = self.type_id();
+        let boxed = self.type_id(private::Internal);
 
         // Compare both TypeIds on equality
         t == boxed
@@ -686,13 +696,13 @@ pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn E
     /// struct B(Option<Box<dyn Error + 'static>>);
     ///
     /// impl fmt::Display for A {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "A")
     ///     }
     /// }
     ///
     /// impl fmt::Display for B {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "B")
     ///     }
     /// }
@@ -721,7 +731,7 @@ pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn E
     /// [`source`]: trait.Error.html#method.source
     #[unstable(feature = "error_iter", issue = "58520")]
     #[inline]
-    pub fn iter_chain(&self) -> ErrorIter {
+    pub fn iter_chain(&self) -> ErrorIter<'_> {
         ErrorIter {
             current: Some(self),
         }
@@ -747,19 +757,19 @@ pub fn iter_chain(&self) -> ErrorIter {
     /// struct C(Option<Box<dyn Error + 'static>>);
     ///
     /// impl fmt::Display for A {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "A")
     ///     }
     /// }
     ///
     /// impl fmt::Display for B {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "B")
     ///     }
     /// }
     ///
     /// impl fmt::Display for C {
-    ///     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    ///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
     ///         write!(f, "C")
     ///     }
     /// }
@@ -795,7 +805,7 @@ pub fn iter_chain(&self) -> ErrorIter {
     /// [`source`]: trait.Error.html#method.source
     #[inline]
     #[unstable(feature = "error_iter", issue = "58520")]
-    pub fn iter_sources(&self) -> ErrorIter {
+    pub fn iter_sources(&self) -> ErrorIter<'_> {
         ErrorIter {
             current: self.source(),
         }
@@ -861,12 +871,12 @@ mod tests {
     struct B;
 
     impl fmt::Display for A {
-        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
             write!(f, "A")
         }
     }
     impl fmt::Display for B {
-        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
             write!(f, "B")
         }
     }