Module groups: if group name collector is enabled, we continuously serialize doc-comment table for comment-free decls to preserve the group information.

Author: nkcsgexi

lib/Serialization/Serialization.cpp

@@ -3607,6 +3607,9 @@ class DeclGroupNameContext {
     GroupNameCollectorFromJson(StringRef RecordPath) :
       GroupNameCollector(!RecordPath.empty()), RecordPath(RecordPath) {}
     StringRef getGroupNameInternal(const ValueDecl *VD) override {
+      // We need the file path, so there has to be a location.
+      if (VD->getLoc().isInvalid())
+        return NullGroupName;
       auto PathOp = VD->getDeclContext()->getParentSourceFile()->getBufferID();
       if (!PathOp.hasValue())
         return NullGroupName;
@@ -3647,6 +3650,10 @@ class DeclGroupNameContext {
     }
     return llvm::makeArrayRef(ViewBuffer);
   }
+
+  bool isEnable() {
+    return pNameCollector->Enable;
+  }
 };
 
 static void writeGroupNames(const comment_block::GroupNamesLayout &GroupNames,
@@ -3691,7 +3698,7 @@ static void writeDeclCommentTable(
 
       // Skip the decl if it does not have a comment.
       RawComment Raw = VD->getRawComment();
-      if (Raw.Comments.empty())
+      if (Raw.Comments.empty() && !GroupContext.isEnable())
         return true;
 
       // Compute USR.

test/SourceKit/SourceDocInfo/cursor_info.swift

@@ -100,6 +100,7 @@ func nonDefaultArgNames(external1 local1: Int, _ local2: Int, external3 local3:
 // CHECK2-NEXT: s:ZFsoi1pFTSiSi_Si
 // CHECK2-NEXT: (Int, Int) -> Int{{$}}
 // CHECK2-NEXT: Swift{{$}}
+// CHECK2-NEXT: <Group>Math</Group>
 // CHECK2-NEXT: SYSTEM
 // CHECK2-NEXT: <Declaration>func +(lhs: <Type usr="s:Si">Int</Type>, rhs: <Type usr="s:Si">Int</Type>) -&gt; <Type usr="s:Si">Int</Type></Declaration>
 // CHECK2-NEXT: <decl.function.operator.infix>func <decl.name>+</decl.name>(<decl.var.parameter><decl.var.parameter.name.local>lhs</decl.var.parameter.name.local>: <ref.struct usr="s:Si">Int</ref.struct></decl.var.parameter>, <decl.var.parameter><decl.var.parameter.name.local>rhs</decl.var.parameter.name.local>: <ref.struct usr="s:Si">Int</ref.struct></decl.var.parameter>) -&gt; <ref.struct usr="s:Si">Int</ref.struct></decl.function.operator.infix>