[SR-13226] [Sema] Handle generic requirement failure on repairFailures

lib/Sema/CSSimplify.cpp

@@ -2229,7 +2229,7 @@ ConstraintSystem::matchDeepEqualityTypes(Type type1, Type type2,
 
     SmallVector<unsigned, 4> mismatches;
     auto result = matchDeepTypeArguments(
-        *this, subflags, args1, args2, locator,
+        *this, subflags | TMF_ApplyingFix, args1, args2, locator,
         [&mismatches](unsigned position) { mismatches.push_back(position); });
 
     if (mismatches.empty())
@@ -4270,6 +4270,24 @@ bool ConstraintSystem::repairFailures(
     break;
   }
 
+  case ConstraintLocator::GenericArgument: {
+    // If any of the types is a hole, consider it fixed.
+    if (lhs->isHole() || rhs->isHole())
+      return true;
+
+    // Ignoring the generic argument because we may have a generic requirement
+    // failure e.g. `String bind T.Element`, so let's drop the generic argument
+    // path element and recurse in repairFailures to check and potentially
+    // record the requirement failure fix.
+    path.pop_back();
+
+    if (path.empty() || !path.back().is<LocatorPathElt::AnyRequirement>())
+      break;
+
+    return repairFailures(lhs, rhs, matchKind, conversionsOrFixes,
+                          getConstraintLocator(anchor, path));
+  }
+
   default:
     break;
   }

test/Generics/sr13226.swift

@@ -0,0 +1,21 @@
+// RUN: %target-typecheck-verify-swift 
+struct W<T> {}
+
+struct S<C1: Collection> {
+  init(){}
+  // expected-note@+2 {{where 'C1.Element' = 'String', 'W<C2.Element>' = 'Int'}}
+  // expected-note@+1 {{where 'C1.Element' = 'C1', 'W<C2.Element>' = 'C2.Element'}}
+  init<C2>(_ c2: W<C2>) where C2: Collection, C1.Element == W<C2.Element> {}
+  // expected-note@+1 {{where 'C1.Element' = 'String', 'W<C2.Element>' = 'Int'}}
+  static func f<C2>(_ c2: W<C2>) where C2: Collection, C1.Element == W<C2.Element> {}
+  // expected-note@+1 {{where 'C1.Element' = 'String', 'W<C2.Element>' = 'Int'}}
+  func instancef<C2>(_ c2: W<C2>) where C2: Collection, C1.Element == W<C2.Element> {}
+}
+let _ = S<[W<String>]>(W<[Int]>()) // expected-error{{initializer 'init(_:)' requires the types 'String' and 'Int' be equivalent}}
+let _ = S<[W<String>]>.f(W<[Int]>()) // expected-error{{static method 'f' requires the types 'String' and 'Int' be equivalent}}
+let _ = S<[W<String>]>().instancef(W<[Int]>()) // expected-error{{instance method 'instancef' requires the types 'String' and 'Int' be equivalent}}
+
+// Archetypes requirement failure
+func genericFunc<C1: Collection, C2: Collection>(_ c2: W<C2>, c1: C1.Type) where C1.Element == W<C2.Element> {
+  let _ = S<[W<C1>]>(W<C2>()) // expected-error{{initializer 'init(_:)' requires the types 'C1' and 'C2.Element' be equivalent}}
+}