Implement core::error::Error for ParsingError

Cargo.toml

@@ -21,3 +21,4 @@ name = "elf"
 default = ["std", "to_str"]
 std = []
 to_str = []
+nightly = []

src/lib.rs

@@ -133,6 +133,7 @@
 //! ```
 
 #![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(all(feature = "nightly", not(feature = "std")), feature(error_in_core))]
 
 pub mod abi;
 

src/parse.rs

@@ -78,12 +78,34 @@ impl std::error::Error for ParseError {
             ParseError::Utf8Error(ref err) => Some(err),
             ParseError::TryFromSliceError(ref err) => Some(err),
             ParseError::TryFromIntError(ref err) => Some(err),
-            #[cfg(feature = "std")]
             ParseError::IOError(ref err) => Some(err),
         }
     }
 }
 
+#[cfg(all(feature = "nightly", not(feature = "std")))]
+impl core::error::Error for ParseError {
+    fn source(&self) -> Option<&(dyn core::error::Error + 'static)> {
+        match *self {
+            ParseError::BadMagic(_) => None,
+            ParseError::UnsupportedElfClass(_) => None,
+            ParseError::UnsupportedElfEndianness(_) => None,
+            ParseError::UnsupportedVersion(_) => None,
+            ParseError::BadOffset(_) => None,
+            ParseError::StringTableMissingNul(_) => None,
+            ParseError::BadEntsize(_) => None,
+            ParseError::UnexpectedSectionType(_) => None,
+            ParseError::UnexpectedSegmentType(_) => None,
+            ParseError::UnexpectedAlignment(_) => None,
+            ParseError::SliceReadError(_) => None,
+            ParseError::IntegerOverflow => None,
+            ParseError::Utf8Error(ref err) => Some(err),
+            ParseError::TryFromSliceError(ref err) => Some(err),
+            ParseError::TryFromIntError(ref err) => Some(err),
+        }
+    }
+}
+
 impl core::fmt::Display for ParseError {
     fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
         match *self {