Add information about the syntax used in ranges

... or ..=

src/libsyntax/ast.rs

@@ -538,10 +538,16 @@ pub enum BindingMode {
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum RangeEnd {
-    Included,
+    Included(RangeSyntax),
     Excluded,
 }
 
+#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
+pub enum RangeSyntax {
+    DotDotDot,
+    DotDotEq,
+}
+
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum PatKind {
     /// Represents a wildcard pattern (`_`)
@@ -578,7 +584,7 @@ pub enum PatKind {
     Ref(P<Pat>, Mutability),
     /// A literal
     Lit(P<Expr>),
-    /// A range pattern, e.g. `1...2` or `1..2`
+    /// A range pattern, e.g. `1...2`, `1..=2` or `1..2`
     Range(P<Expr>, P<Expr>, RangeEnd),
     /// `[a, b, ..i, y, z]` is represented as:
     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`