Merge pull request #40315 from nate-chandler/rdar84962693

[Sema] Made $main non-dynamic.

Author: nate-chandler

lib/Sema/TypeCheckAttr.cpp

@@ -2094,6 +2094,9 @@ SynthesizeMainFunctionRequest::evaluate(Evaluator &evaluator,
       /*GenericParams=*/nullptr, ParameterList::createEmpty(context),
       /*FnRetType=*/TupleType::getEmpty(context), declContext);
   func->setSynthesized(true);
+  // It's never useful to provide a dynamic replacement of this function--it is
+  // just a pass-through to MainType.main.
+  func->setIsDynamic(false);
 
   auto *params = context.Allocate<MainTypeAttrParams>();
   params->mainFunction = mainFunction;

test/attr/ApplicationMain/attr_main_implicitDynamicReplacement.swift

@@ -0,0 +1,6 @@
+// RUN: %target-swift-frontend -c -parse-as-library %s -enable-implicit-dynamic
+
+@main
+struct BasicAppApp {
+  static func main() {}
+}