[clangd] Auto-index watches global CDB for changes.

Summary:
Instead of receiving compilation commands, auto-index is triggered by just
filenames to reindex, and gets commands from the global comp DB internally.
This has advantages:
 - more of the work can be done asynchronously (fetching compilation commands
   upfront can be slow for large CDBs)
 - we get access to the CDB which can be used to retrieve interpolated commands
   for headers (useful in some cases where the original TU goes away)
 - fits nicely with the filename-only change observation from r347297

The interface to GlobalCompilationDatabase gets extended: when retrieving a
compile command, the GCDB can optionally report the project the file belongs to.
This naturally fits together with getCompileCommand: it's hard to implement one
without the other. But because most callers don't care, I've ended up with an
awkward optional-out-param-in-virtual method pattern - maybe there's a better
one.

This is the main missing integration point between ClangdServer and
BackgroundIndex, after this we should be able to add an auto-index flag.

Reviewers: ioeric, kadircet

Subscribers: MaskRay, jkorous, arphaman, cfe-commits, ilya-biryukov

Differential Revision: https://reviews.llvm.org/D54865

llvm-svn: 347538

1 files changed, 2 insertions, 2 deletions

diff --git a/clang-tools-extra/unittests/clangd/TestFS.h b/clang-tools-extra/unittests/clangd/TestFS.h
index 56bf8a35591..0226fc3dcb5 100644
--- a/clang-tools-extra/unittests/clangd/TestFS.h
+++ b/clang-tools-extra/unittests/clangd/TestFS.h
@@ -41,7 +41,7 @@ public:
 class MockCompilationDatabase : public GlobalCompilationDatabase {
 public:
   /// If \p Directory is not empty, use that as the Directory field of the
-  /// CompileCommand.
+  /// CompileCommand, and as project SourceRoot.
   ///
   /// If \p RelPathPrefix is not empty, use that as a prefix in front of the
   /// source file name, instead of using an absolute path.
@@ -49,7 +49,7 @@ public:
                           StringRef RelPathPrefix = StringRef());
 
   llvm::Optional<tooling::CompileCommand>
-  getCompileCommand(PathRef File) const override;
+  getCompileCommand(PathRef File, ProjectInfo * = nullptr) const override;
 
   std::vector<std::string> ExtraClangFlags;