[clangd] Fixes for #include insertion.

Summary:
o Avoid inserting a header include into the header itself.
o Avoid inserting non-header files (by not indexing symbols in main
files at all).
o Canonicalize include paths for symbols in dynamic index.

Reviewers: sammccall, ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: klimek, jkorous-apple, cfe-commits

Differential Revision: https://reviews.llvm.org/D43462

llvm-svn: 325523

1 files changed, 12 insertions, 4 deletions

diff --git a/clang-tools-extra/clangd/Headers.cpp b/clang-tools-extra/clangd/Headers.cpp
index faf73c7f99f..db8029b2ac0 100644
--- a/clang-tools-extra/clangd/Headers.cpp
+++ b/clang-tools-extra/clangd/Headers.cpp
@@ -16,6 +16,7 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Tooling/CompilationDatabase.h"
+#include "llvm/Support/Path.h"
 
 namespace clang {
 namespace clangd {
@@ -45,10 +46,17 @@ private:
 /// FIXME(ioeric): we might not want to insert an absolute include path if the
 /// path is not shortened.
 llvm::Expected<std::string>
-shortenIncludePath(llvm::StringRef File, llvm::StringRef Code,
-                   llvm::StringRef Header,
-                   const tooling::CompileCommand &CompileCommand,
-                   IntrusiveRefCntPtr<vfs::FileSystem> FS) {
+calculateIncludePath(llvm::StringRef File, llvm::StringRef Code,
+                     llvm::StringRef Header,
+                     const tooling::CompileCommand &CompileCommand,
+                     IntrusiveRefCntPtr<vfs::FileSystem> FS) {
+  assert(llvm::sys::path::is_absolute(File) &&
+         llvm::sys::path::is_absolute(Header));
+
+  if (File == Header)
+    return "";
+  FS->setCurrentWorkingDirectory(CompileCommand.Directory);
+
   // Set up a CompilerInstance and create a preprocessor to collect existing
   // #include headers in \p Code. Preprocesor also provides HeaderSearch with
   // which we can calculate the shortest include path for \p Header.