[SyntaxParse] Fix memory leak

Author: rintaro

include/swift/Parse/HiddenLibSyntaxAction.h

@@ -61,6 +61,10 @@ class HiddenLibSyntaxAction : public SyntaxParseActions {
   /// been created by the explicit action.
   OpaqueSyntaxNode getLibSyntaxNodeFor(OpaqueSyntaxNode explicitNode);
 
+  bool isReleaseNeeded() {
+    return ExplicitAction == LibSyntaxAction || !areBothLibSyntax();
+  }
+  
   /// Returns the underlying libSyntax SyntaxTreeCreator.
   std::shared_ptr<SyntaxTreeCreator> getLibSyntaxAction() {
     return LibSyntaxAction;

include/swift/Parse/LibSyntaxGenerator.h

@@ -55,7 +55,8 @@ class LibSyntaxGenerator {
     auto Children = Node.getDeferredChildren();
 
     auto Recorded = Recorder.recordRawSyntax(Kind, Children);
-    auto Raw = static_cast<RawSyntax *>(Recorded.getOpaqueNode());
+    RC<RawSyntax> Raw {static_cast<RawSyntax *>(Recorded.getOpaqueNode()) };
+    Raw->Release(); // -1 since it's transfer of ownership.
     return make<SyntaxNode>(Raw);
   }
 
@@ -68,6 +69,13 @@ class LibSyntaxGenerator {
     auto Raw = static_cast<RawSyntax *>(Actions->getLibSyntaxNodeFor(Node));
     return make<SyntaxNode>(Raw);
   }
+
+  void releaseLibSyntaxNodeIfNeededFor(OpaqueSyntaxNode Node) {
+    if (!Actions->isReleaseNeeded())
+      return;
+    auto Raw = static_cast<RawSyntax *>(Actions->getLibSyntaxNodeFor(Node));
+    Raw->Release();
+  }
 };
 } // namespace swift
 

lib/Parse/SyntaxParsingContext.cpp

@@ -280,6 +280,7 @@ ParsedRawSyntaxNode SyntaxParsingContext::finalizeRoot() {
     return ParsedRawSyntaxNode::null(); // already finalized.
   }
   ParsedRawSyntaxNode root = finalizeSourceFile();
+  getSyntaxCreator().releaseLibSyntaxNodeIfNeededFor(root.getOpaqueNode());
 
   // Clear the parts because we will call this function again when destroying
   // the root context.
@@ -353,6 +354,10 @@ SyntaxParsingContext::~SyntaxParsingContext() {
   // Remove all parts in this context.
   case AccumulationMode::Discard: {
     auto &nodes = getStorage();
+    for (auto i = nodes.begin()+Offset, e = nodes.end(); i != e; ++i)
+      if (i->isRecorded())
+        getSyntaxCreator().releaseLibSyntaxNodeIfNeededFor(i->getOpaqueNode());
+
     nodes.erase(nodes.begin()+Offset, nodes.end());
     break;
   }