Fix AST scoping

Author: ApolloZhu

lib/AST/ASTScopeCreation.cpp

@@ -272,6 +272,14 @@ ASTSourceFileScope::ASTSourceFileScope(SourceFile *SF,
 
     // Determine the parent source location based on the macro role.
     AbstractFunctionDecl *bodyForDecl = nullptr;
+
+    if (SF->Kind == SourceFileKind::DefaultArgument) {
+      auto genInfo = *SF->getASTContext().SourceMgr.getGeneratedSourceInfo(
+          *SF->getBufferID());
+      parentLoc = ASTNode::getFromOpaqueValue(genInfo.astNode).getStartLoc();
+      goto setParent;
+    }
+
     switch (*macroRole) {
     case MacroRole::Expression:
     case MacroRole::Declaration:
@@ -301,6 +309,7 @@ ASTSourceFileScope::ASTSourceFileScope(SourceFile *SF,
     }
     }
 
+  setParent:
     if (auto parentScope = findStartingScopeForLookup(enclosingSF, parentLoc)) {
       if (bodyForDecl) {
         auto bodyScope = new (bodyForDecl->getASTContext()) FunctionBodyScope(bodyForDecl);

lib/AST/Module.cpp

@@ -1222,7 +1222,8 @@ llvm::Optional<MacroRole> SourceFile::getFulfilledMacroRole() const {
 }
 
 SourceFile *SourceFile::getEnclosingSourceFile() const {
-  if (Kind != SourceFileKind::MacroExpansion)
+  if (Kind != SourceFileKind::MacroExpansion &&
+      Kind != SourceFileKind::DefaultArgument)
     return nullptr;
 
   auto genInfo =

lib/Sema/TypeCheckExpr.cpp

@@ -774,6 +774,7 @@ static Expr *synthesizeCallerSideDefault(const ParamDecl *param,
 #include "swift/AST/MagicIdentifierKinds.def"
 
   case DefaultArgumentKind::ExpressionMacro: {
+    // FIXME: ApolloZhu serialize and deserialize expressions instead
     SmallString<128> scratch;
     const StringRef text = param->getDefaultValueStringRepresentation(scratch);
     SourceFile *defaultArgSourceFile =