Merge pull request #83489 from xedin/rdar-157234317

[CSOptimizer] Fix a conditional that ignores function type parameters…

Author: xedin

lib/Sema/CSOptimizer.cpp

@@ -1598,7 +1598,7 @@ static void determineBestChoicesInContext(
             // FIXME: Let's skip matching function types for now
             // because they have special rules for e.g. Concurrency
             // (around @Sendable) and @convention(c).
-            if (paramType->is<FunctionType>())
+            if (paramType->lookThroughAllOptionalTypes()->is<FunctionType>())
               continue;
 
             // The idea here is to match the parameter type against

test/SILOptimizer/infinite_recursion.swift

@@ -352,3 +352,11 @@ func recursionMatchingTypeArgs2<T: P, V: P>(_ t: T.Type, _ v: V.Type) {
   recursionMatchingTypeArgs2(T.self, V.self) // expected-warning {{function call causes an infinite recursion}}
 }
 
+func testNoInfiniteRecursionWithOverloadingOnOptional() {
+  func test(handler: @escaping (Bool) -> Void) {
+  }
+
+  func test(handler: ((Bool) -> Void)?) {
+    test(handler: handler ?? { _ in }) // Ok
+  }
+}