macros: Make bindings work as expected.

procedural-masquerade/lib.rs

@@ -137,7 +137,7 @@
 //! ## For users
 //!
 //! Users of `libfoo` don’t need to worry about any of these implementation details.
-//! They can use the `foo_stringify` macro as if it were a simle `macro_rules` macro:
+//! They can use the `foo_stringify` macro as if it were a simple `macro_rules` macro:
 //!
 //! ```rust
 //! #[macro_use] extern crate libfoo;

src/macros.rs

@@ -40,11 +40,17 @@ macro_rules! match_ignore_ascii_case {
             }
 
             {
+                let __input = $input;
+
                 // MAX_LENGTH is generated by cssparser_internal__assert_ascii_lowercase__max_len
-                cssparser_internal__to_lowercase!($input, MAX_LENGTH => lowercase);
-                // "A" is a short string that we know is different for every string pattern,
-                // since we’ve verified that none of them include ASCII upper case letters.
-                match lowercase.unwrap_or("A") {
+                cssparser_internal__to_lowercase!(__input, MAX_LENGTH => lowercase);
+
+                // We know __input will never match if it reaches the
+                // `unwrap_or`, but this is needed to make pattern bindings work
+                // as expected, see:
+                //
+                // https://github.com/servo/rust-cssparser/issues/126
+                match lowercase.unwrap_or(__input) {
                     $( $match_body )*
                 }
             }

src/tests.rs

@@ -843,3 +843,21 @@ fn procedural_masquerade_whitespace() {
         _ => panic!("4"),
     }
 }
+
+#[test]
+fn known_not_matching() {
+    match_ignore_ascii_case! { "fo",
+        "bar" => {},
+        value => assert_eq!(value, "fo"),
+    }
+
+    match_ignore_ascii_case! { "foo",
+        "bar" => {},
+        value => assert_eq!(value, "foo"),
+    }
+
+    match_ignore_ascii_case! { "fooo",
+        "bar" => {},
+        value => assert_eq!(value, "fooo"),
+    }
+}