Merge pull request #204 from dtolnay/assoc

Parse associated type constraints in dyn trait object types
dtolnay · Nov 27, 2021 · 11d3eb7 · 11d3eb7
2 parents 210d741 + 6f18821
commit 11d3eb7
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Showing 2 changed files with 16 additions and 4 deletions.
diff --git a/src/ensure.rs b/src/ensure.rs
@@ -503,6 +503,10 @@ macro_rules! __parse_ensure {
         $crate::__parse_ensure!(arglist $stack $bail ($($fuel)*) {($($buf)* $life) $($parse)*} ($($rest)*) $($rest)*)
     };
 
+    (generic $stack:tt $bail:tt (~$($fuel:tt)*) {($($buf:tt)*) $($parse:tt)*} ($assoc:ident $eq:tt $($dup:tt)*) $ident:ident = $($rest:tt)*) => {
+        $crate::__parse_ensure!(type (arglist $stack) $bail ($($fuel)*) {($($buf)* $assoc $eq) $($parse)*} ($($rest)*) $($rest)*)
+    };
+
     (generic $stack:tt $bail:tt (~$($fuel:tt)*) $parse:tt $dup:tt $($rest:tt)*) => {
         $crate::__parse_ensure!(type (arglist $stack) $bail ($($fuel)*) $parse $dup $($rest)*)
     };

diff --git a/tests/test_ensure.rs b/tests/test_ensure.rs
@@ -536,13 +536,21 @@ fn test_as() {
         "Condition failed: `f as fn() -> ! as usize * 0 != 0` (0 vs 0)",
     );
 
-    trait EqDebug<T>: PartialEq<T> + Debug {}
-    impl<S, T> EqDebug<T> for S where S: PartialEq<T> + Debug {}
+    trait EqDebug<T>: PartialEq<T> + Debug {
+        type Assoc;
+    }
+
+    impl<S, T> EqDebug<T> for S
+    where
+        S: PartialEq<T> + Debug,
+    {
+        type Assoc = bool;
+    }
 
-    let test = || Ok(ensure!(&0 as &dyn EqDebug<i32> != &0));
+    let test = || Ok(ensure!(&0 as &dyn EqDebug<i32, Assoc = bool> != &0));
     assert_err(
         test,
-        "Condition failed: `&0 as &dyn EqDebug<i32> != &0` (0 vs 0)",
+        "Condition failed: `&0 as &dyn EqDebug<i32, Assoc = bool> != &0` (0 vs 0)",
     );
 
     let test = || {