[clangd] Don't insert absolute paths, give up instead.

Summary: Also implement resolution of paths relative to mainfile without HeaderSearchInfo.

Reviewers: kadircet

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64293

llvm-svn: 365364

1 files changed, 5 insertions, 1 deletions

diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index 71d7035c12d..dc82b5d6c46 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -327,8 +327,12 @@ struct CodeCompletionBuilder {
       auto ResolvedInserted = toHeaderFile(Header, FileName);
       if (!ResolvedInserted)
         return ResolvedInserted.takeError();
+      auto Spelled = Includes.calculateIncludePath(*ResolvedInserted, FileName);
+      if (!Spelled)
+        return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                       "Header not on include path");
       return std::make_pair(
-          Includes.calculateIncludePath(*ResolvedInserted, FileName),
+          std::move(*Spelled),
           Includes.shouldInsertInclude(*ResolvedDeclaring, *ResolvedInserted));
     };
     bool ShouldInsert = C.headerToInsertIfAllowed(Opts).hasValue();