[AST] Augment ArgumentList::createImplicit to accept first trailing closure index

Author: xedin

include/swift/AST/ArgumentList.h

@@ -249,11 +249,13 @@ class alignas(Argument) ArgumentList final
   static ArgumentList *
   createImplicit(ASTContext &ctx, SourceLoc lParenLoc, ArrayRef<Argument> args,
                  SourceLoc rParenLoc,
+                 Optional<unsigned> firstTrailingClosureIndex = None,
                  AllocationArena arena = AllocationArena::Permanent);
 
   /// Create a new implicit ArgumentList with a set of \p args.
   static ArgumentList *
   createImplicit(ASTContext &ctx, ArrayRef<Argument> args,
+                 Optional<unsigned> firstTrailingClosureIndex = None,
                  AllocationArena arena = AllocationArena::Permanent);
 
   /// Create a new implicit ArgumentList with a single labeled argument

lib/AST/ArgumentList.cpp

@@ -108,19 +108,22 @@ ArgumentList *ArgumentList::createTypeChecked(ASTContext &ctx,
                 originalArgs->isImplicit(), originalArgs);
 }
 
-ArgumentList *ArgumentList::createImplicit(ASTContext &ctx, SourceLoc lParenLoc,
-                                           ArrayRef<Argument> args,
-                                           SourceLoc rParenLoc,
-                                           AllocationArena arena) {
-  return create(ctx, lParenLoc, args, rParenLoc,
-                /*firstTrailingClosureIdx*/ None, /*implicit*/ true,
+ArgumentList *
+ArgumentList::createImplicit(ASTContext &ctx, SourceLoc lParenLoc,
+                             ArrayRef<Argument> args, SourceLoc rParenLoc,
+                             Optional<unsigned> firstTrailingClosureIndex,
+                             AllocationArena arena) {
+  return create(ctx, lParenLoc, args, rParenLoc, firstTrailingClosureIndex,
+                /*implicit*/ true,
                 /*originalArgs*/ nullptr, arena);
 }
 
-ArgumentList *ArgumentList::createImplicit(ASTContext &ctx,
-                                           ArrayRef<Argument> args,
-                                           AllocationArena arena) {
-  return createImplicit(ctx, SourceLoc(), args, SourceLoc(), arena);
+ArgumentList *
+ArgumentList::createImplicit(ASTContext &ctx, ArrayRef<Argument> args,
+                             Optional<unsigned> firstTrailingClosureIndex,
+                             AllocationArena arena) {
+  return createImplicit(ctx, SourceLoc(), args, SourceLoc(),
+                        firstTrailingClosureIndex, arena);
 }
 
 ArgumentList *ArgumentList::forImplicitSingle(ASTContext &ctx, Identifier label,

lib/Sema/CSSimplify.cpp

@@ -10736,12 +10736,9 @@ ConstraintSystem::simplifyApplicableFnConstraint(
         if (matchCallResult != SolutionKind::Solved)
           return SolutionKind::Error;
 
-        // Note that `createImplicit` cannot be used here because it
-        // doesn't allow us to specify trailing closure index.
-        auto *implicitCallArgumentList = ArgumentList::createParsed(
-            ctx, /*LParen=*/SourceLoc(), trailingClosures,
-            /*RParen=*/SourceLoc(),
-            /*firstTrailingClosureIndex=*/0);
+        auto *implicitCallArgumentList =
+            ArgumentList::createImplicit(ctx, trailingClosures,
+                                         /*firstTrailingClosureIndex=*/0);
 
         auto *implicitRef = createImplicitRootForCallAsFunction(
             *this, callAsFunctionResultTy, implicitCallArgumentList, calleeLoc);
@@ -11720,6 +11717,7 @@ ConstraintSystem::simplifyRestrictedConstraintImpl(
     if (!ArgumentLists.count(memberLoc)) {
       auto *argList = ArgumentList::createImplicit(
           getASTContext(), {Argument(SourceLoc(), Identifier(), nullptr)},
+          /*firstTrailingClosureIndex=*/None,
           AllocationArena::ConstraintSolver);
       ArgumentLists.insert({memberLoc, argList});
     }

lib/Sema/ConstraintSystem.cpp

@@ -2714,6 +2714,7 @@ void ConstraintSystem::bindOverloadType(
     if (!argList) {
       argList = ArgumentList::createImplicit(
           ctx, {Argument(SourceLoc(), ctx.Id_dynamicMember, /*expr*/ nullptr)},
+          /*firstTrailingClosureIndex=*/None,
           AllocationArena::ConstraintSolver);
     }