[clangd] Do not rebuild AST if inputs have not changed

Summary:
If the contents are the same, the update most likely comes from the
fact that compile commands were invalidated. In that case we want to
avoid rebuilds in case the compile commands are actually the same.

Reviewers: ioeric

Reviewed By: ioeric

Subscribers: simark, javed.absar, MaskRay, jkorous, arphaman, jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D49783

llvm-svn: 338012

1 files changed, 6 insertions, 4 deletions

diff --git a/clang-tools-extra/unittests/clangd/TestFS.cpp b/clang-tools-extra/unittests/clangd/TestFS.cpp
index 741eb8cee7c..b3081d6430b 100644
--- a/clang-tools-extra/unittests/clangd/TestFS.cpp
+++ b/clang-tools-extra/unittests/clangd/TestFS.cpp
@@ -19,13 +19,15 @@ namespace clangd {
 using namespace llvm;
 
 IntrusiveRefCntPtr<vfs::FileSystem>
-buildTestFS(StringMap<std::string> const &Files) {
+buildTestFS(llvm::StringMap<std::string> const &Files,
+            llvm::StringMap<time_t> const &Timestamps) {
   IntrusiveRefCntPtr<vfs::InMemoryFileSystem> MemFS(
       new vfs::InMemoryFileSystem);
   for (auto &FileAndContents : Files) {
-    MemFS->addFile(FileAndContents.first(), time_t(),
-                   MemoryBuffer::getMemBufferCopy(FileAndContents.second,
-                                                  FileAndContents.first()));
+    StringRef File = FileAndContents.first();
+    MemFS->addFile(
+        File, Timestamps.lookup(File),
+        MemoryBuffer::getMemBufferCopy(FileAndContents.second, File));
   }
   return MemFS;
 }