[clangd] Check for include overlapping looks for only the line now.

[kadircet]

Summary

Currently we match an include only if we are inside filename, with this patch we
will match whenever we are on the starting line of the include.

[ilya-biryukov]

LGTM.

clangd/XRefs.cpp

 
 std::vector<Location> findDefinitions(ParsedAST &AST, Position Pos,
                                       const SymbolIndex *Index) {
   const SourceManager &SourceMgr = AST.getASTContext().getSourceManager();
 
   std::vector<Location> Result;
   // Handle goto definition for #include.
   for (auto &Inc : AST.getIncludeStructure().MainFileIncludes) {
-    if (!Inc.Resolved.empty() && Inc.R.contains(Pos))
+    if (!Inc.Resolved.empty() && Inc.R.start.line == Pos.line)
       Result.push_back(Location{URIForFile{Inc.Resolved}, {}});
   }
   if (!Result.empty())
     return Result;
 
   // Identified symbols at a specific position.
   SourceLocation SourceLocationBeg =
       getBeginningOfIdentifier(AST, Pos, SourceMgr.getMainFileID());

unittests/clangd/XRefsTests.cpp

TEST(GoToInclude, All) {
 
   // Test a few positions that do not result in Locations.
   Locations = runFindDefinitions(Server, FooCpp, SourceAnnotations.point("4"));
   ASSERT_TRUE(bool(Locations)) << "findDefinitions returned an error";
   EXPECT_THAT(*Locations, IsEmpty());
 
   Locations = runFindDefinitions(Server, FooCpp, SourceAnnotations.point("5"));
   ASSERT_TRUE(bool(Locations)) << "findDefinitions returned an error";
-  EXPECT_THAT(*Locations, IsEmpty());
+  EXPECT_THAT(*Locations,
+              ElementsAre(Location{FooHUri, HeaderAnnotations.range()}));
 
   Locations = runFindDefinitions(Server, FooCpp, SourceAnnotations.point("7"));
   ASSERT_TRUE(bool(Locations)) << "findDefinitions returned an error";
-  EXPECT_THAT(*Locations, IsEmpty());
+  EXPECT_THAT(*Locations,
+              ElementsAre(Location{FooHUri, HeaderAnnotations.range()}));
 }
 
 TEST(GoToDefinition, WithPreamble) {
   // Test stragety: AST should always use the latest preamble instead of last
   // good preamble.
   MockFSProvider FS;
   IgnoreDiagnostics DiagConsumer;
   MockCompilationDatabase CDB;