[CS] Sink closure property wrapper application into applySolution

We need to make sure property wrappers are
applied before `checkParameterList`.

Author: hamishknight

lib/Sema/CSApply.cpp

@@ -8883,7 +8883,8 @@ namespace {
         rewriteFunction(closure);
 
         if (AnyFunctionRef(closure).hasExternalPropertyWrapperParameters()) {
-          return Action::SkipNode(rewriteClosure(closure));
+          return Action::SkipNode(Rewriter.buildSingleCurryThunk(
+              closure, closure, Rewriter.cs.getConstraintLocator(closure)));
         }
 
         return Action::SkipNode(closure);
@@ -8935,49 +8936,6 @@ namespace {
     std::optional<SyntacticElementTarget>
     rewriteTarget(SyntacticElementTarget target);
 
-    AutoClosureExpr *rewriteClosure(ClosureExpr *closure) {
-      auto &solution = Rewriter.solution;
-
-      // Apply types to synthesized property wrapper vars.
-      for (auto *param : *closure->getParameters()) {
-        if (!param->hasAttachedPropertyWrapper())
-          continue;
-
-        // Set the interface type of each property wrapper synthesized var
-        auto *backingVar = param->getPropertyWrapperBackingProperty();
-        auto backingType =
-            solution.simplifyType(solution.getType(backingVar))->mapTypeOutOfContext();
-        backingVar->setInterfaceType(backingType);
-
-        if (auto *projectionVar = param->getPropertyWrapperProjectionVar()) {
-          projectionVar->setInterfaceType(
-              solution.simplifyType(solution.getType(projectionVar))->mapTypeOutOfContext());
-        }
-
-        auto *wrappedValueVar = param->getPropertyWrapperWrappedValueVar();
-        auto wrappedValueType =
-            solution.simplifyType(solution.getType(wrappedValueVar))->mapTypeOutOfContext();
-        wrappedValueVar->setInterfaceType(wrappedValueType->getWithoutSpecifierType());
-
-        if (param->hasImplicitPropertyWrapper()) {
-          if (wrappedValueType->is<LValueType>())
-            wrappedValueVar->setImplInfo(StorageImplInfo::getMutableComputed());
-
-          // Add an explicit property wrapper attribute, which is needed for
-          // synthesizing the accessors.
-          auto &context = wrappedValueVar->getASTContext();
-          auto *typeExpr = TypeExpr::createImplicit(backingType, context);
-          auto *attr = CustomAttr::create(context, SourceLoc(), typeExpr, /*implicit=*/true);
-          wrappedValueVar->getAttrs().add(attr);
-        }
-      }
-
-      TypeChecker::checkParameterList(closure->getParameters(), closure);
-
-      return Rewriter.buildSingleCurryThunk(
-          closure, closure, Rewriter.cs.getConstraintLocator(closure));
-    }
-
     /// Rewrite the function for the given solution.
     ///
     /// \returns true if an error occurred.

lib/Sema/CSSyntacticElement.cpp

@@ -2523,6 +2523,46 @@ class ResultBuilderRewriter : public SyntacticElementSolutionApplication {
 };
 } // namespace
 
+static void applySolutionToClosurePropertyWrappers(ClosureExpr *closure,
+                                                   const Solution &solution) {
+  for (auto *param : *closure->getParameters()) {
+    if (!param->hasAttachedPropertyWrapper())
+      continue;
+
+    // Set the interface type of each property wrapper synthesized var
+    auto *backingVar = param->getPropertyWrapperBackingProperty();
+    auto backingType = solution.simplifyType(solution.getType(backingVar))
+                           ->mapTypeOutOfContext();
+    backingVar->setInterfaceType(backingType);
+
+    if (auto *projectionVar = param->getPropertyWrapperProjectionVar()) {
+      projectionVar->setInterfaceType(
+          solution.simplifyType(solution.getType(projectionVar))
+              ->mapTypeOutOfContext());
+    }
+
+    auto *wrappedValueVar = param->getPropertyWrapperWrappedValueVar();
+    auto wrappedValueType =
+        solution.simplifyType(solution.getType(wrappedValueVar))
+            ->mapTypeOutOfContext();
+    wrappedValueVar->setInterfaceType(
+        wrappedValueType->getWithoutSpecifierType());
+
+    if (param->hasImplicitPropertyWrapper()) {
+      if (wrappedValueType->is<LValueType>())
+        wrappedValueVar->setImplInfo(StorageImplInfo::getMutableComputed());
+
+      // Add an explicit property wrapper attribute, which is needed for
+      // synthesizing the accessors.
+      auto &context = wrappedValueVar->getASTContext();
+      auto *typeExpr = TypeExpr::createImplicit(backingType, context);
+      auto *attr =
+          CustomAttr::create(context, SourceLoc(), typeExpr, /*implicit=*/true);
+      wrappedValueVar->getAttrs().add(attr);
+    }
+  }
+}
+
 SolutionApplicationToFunctionResult ConstraintSystem::applySolution(
     Solution &solution, AnyFunctionRef fn,
     DeclContext *&currentDC,
@@ -2553,6 +2593,8 @@ SolutionApplicationToFunctionResult ConstraintSystem::applySolution(
     if (closure->hasExplicitResultType()) {
       closure->setExplicitResultType(closureFnType->getResult());
     }
+
+    applySolutionToClosurePropertyWrappers(closure, solution);
   }
 
   // Enter the context of the function before performing any additional