Make ParseIntError and IntErrorKind fully public

src/libcore/num/mod.rs

@@ -4768,14 +4768,30 @@ fn from_str_radix<T: FromStrRadixHelper>(src: &str, radix: u32) -> Result<T, Par
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct ParseIntError {
-    kind: IntErrorKind,
+    /// Stores the cause of parsing an integer failing
+    pub kind: IntErrorKind,
 }
 
+/// Enum to store the various types of errors that can cause parsing an integer to fail.
+#[unstable(feature = "int_error_matching",
+           reason = "it can be useful to match errors when making error messages \
+                     for integer parsing",
+           issue = "22639")]
 #[derive(Debug, Clone, PartialEq, Eq)]
-enum IntErrorKind {
+#[non_exhaustive]
+pub enum IntErrorKind {
+    /// Value being parsed is empty.
+    ///
+    /// Among other causes, this variant will be constructed when parsing an empty string.
     Empty,
+    /// Contains an invalid digit.
+    ///
+    /// Among other causes, this variant will be constructed when parsing a string that
+    /// contains a letter.
     InvalidDigit,
+    /// Integer is too small to store in target integer type.
     Overflow,
+    /// Integer is too large to store in target integer type.
     Underflow,
 }