[SyntaxModel] Don't mark custom attribute as attribute-builtin

rdar://problem/50074156

Author: rintaro

lib/AST/Decl.cpp

@@ -441,7 +441,7 @@ SourceRange Decl::getSourceRangeIncludingAttrs() const {
   }
 
   // Attributes on VarDecl syntactically belong to PatternBindingDecl.
-  if (isa<VarDecl>(this))
+  if (isa<VarDecl>(this) && !isa<ParamDecl>(this))
     return Range;
 
   // Attributes on PatternBindingDecls are attached to VarDecls in AST.

lib/IDE/SyntaxModel.cpp

@@ -1026,7 +1026,7 @@ bool ModelASTWalker::handleSpecialDeclAttribute(const DeclAttribute *D,
                                                 ArrayRef<Token> Toks) {
   if (!D)
     return false;
-  if (isa<AvailableAttr>(D)) {
+  if (isa<AvailableAttr>(D) || isa<CustomAttr>(D)) {
     unsigned I = 0;
     for (; I < TokenNodes.size(); ++ I) {
       auto Node = TokenNodes[I];