[clang-tools-extra] r318544 - [clangd] Release the old preamble before building a new one.

[Ilya Biryukov via cfe-commits]

Author: ibiryukov
Date: Fri Nov 17 11:05:56 2017
New Revision: 318544

URL: http://llvm.org/viewvc/llvm-project?rev=318544&view=rev
Log:
[clangd] Release the old preamble before building a new one.

Modified:
    clang-tools-extra/trunk/clangd/ClangdUnit.cpp

Modified: clang-tools-extra/trunk/clangd/ClangdUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clangd/ClangdUnit.cpp?rev=318544&r1=318543&r2=318544&view=diff
==============================================================================
--- clang-tools-extra/trunk/clangd/ClangdUnit.cpp (original)
+++ clang-tools-extra/trunk/clangd/ClangdUnit.cpp Fri Nov 17 11:05:56 2017
@@ -1245,7 +1245,9 @@ CppFile::deferRebuild(StringRef NewConte
   // Don't let this CppFile die before rebuild is finished.
   std::shared_ptr<CppFile> That = shared_from_this();
   auto FinishRebuild = [OldPreamble, VFS, RequestRebuildCounter, PCHs,
-                        That](std::string NewContents)
+                        That](std::string NewContents) mutable // 'mutable' to
+                                                               // allow changing
+                                                               // OldPreamble.
       -> llvm::Optional<std::vector<DiagWithFixIts>> {
     // Only one execution of this method is possible at a time.
     // RebuildGuard will wait for any ongoing rebuilds to finish and will put us
@@ -1276,14 +1278,19 @@ CppFile::deferRebuild(StringRef NewConte
         llvm::MemoryBuffer::getMemBufferCopy(NewContents, That->FileName);
 
     // A helper function to rebuild the preamble or reuse the existing one. Does
-    // not mutate any fields, only does the actual computation.
-    auto DoRebuildPreamble = [&]() -> std::shared_ptr<const PreambleData> {
+    // not mutate any fields of CppFile, only does the actual computation.
+    // Lamdba is marked mutable to call reset() on OldPreamble.
+    auto DoRebuildPreamble =
+        [&]() mutable -> std::shared_ptr<const PreambleData> {
       auto Bounds =
           ComputePreambleBounds(*CI->getLangOpts(), ContentsBuffer.get(), 0);
       if (OldPreamble && OldPreamble->Preamble.CanReuse(
                              *CI, ContentsBuffer.get(), Bounds, VFS.get())) {
         return OldPreamble;
       }
+      // We won't need the OldPreamble anymore, release it so it can be deleted
+      // (if there are no other references to it).
+      OldPreamble.reset();
 
       trace::Span Tracer(llvm::Twine("Preamble: ") + That->FileName);
       std::vector<DiagWithFixIts> PreambleDiags;