[CrossTU] Fix handling of Cross Translation Unit directory path

[xazax.hun]

Summary

The function map generator tool always creates absolute path. The correct logic to determine whether a path should be handled as absolute depends on the value of the CrossTU directory. Added a unit test to avoid regressions.

[r.stahl]

I'm gonna go ahead and approve this now, because I reported the issue. Note that I'm not a regular contributor, yet!

lib/CrossTU/CrossTranslationUnit.cpp

99

Here you could drop the if/else completely and just append.

[szepet]

LGTM as well, but same note applies.

lib/CrossTU/CrossTranslationUnit.cpp

while (std::getline(ExternalFnMapFile, Line)) {
     if (Pos > 0 && Pos != std::string::npos) {
       StringRef LineRef{Line};
       StringRef FunctionLookupName = LineRef.substr(0, Pos);
       if (Result.count(FunctionLookupName))
         return llvm::make_error<IndexError>(
             index_error_code::multiple_definitions, IndexPath.str(), LineNo);
       StringRef FileName = LineRef.substr(Pos + 1);
       SmallString<256> FilePath = CrossTUDir;
-      if (llvm::sys::path::is_absolute(FileName))
+      if (CrossTUDir.empty())
         FilePath = FileName;
       else
         llvm::sys::path::append(FilePath, FileName);
       Result[FunctionLookupName] = FilePath.str().str();
     } else
       return llvm::make_error<IndexError>(
           index_error_code::invalid_index_format, IndexPath.str(), LineNo);
     LineNo++;
   }
   return Result;
 }

unittests/CrossTU/CrossTranslationUnitTest.cpp

 TEST(CrossTranslationUnit, CanLoadFunctionDefinition) {
   bool Success = false;
   EXPECT_TRUE(tooling::runToolOnCode(new CTUAction(&Success), "int f(int);"));
   EXPECT_TRUE(Success);
 }
 
 TEST(CrossTranslationUnit, IndexFormatCanBeParsed) {
   llvm::StringMap<std::string> Index;
-  Index["a"] = "b";
-  Index["c"] = "d";
-  Index["e"] = "f";
+  Index["a"] = "/b/f1";
+  Index["c"] = "/d/f2";
+  Index["e"] = "/f/f3";
   std::string IndexText = createCrossTUIndexString(Index);
 
   int IndexFD;
   llvm::SmallString<256> IndexFileName;
   ASSERT_FALSE(llvm::sys::fs::createTemporaryFile("index", "txt", IndexFD,
                                                   IndexFileName));
   llvm::ToolOutputFile IndexFile(IndexFileName, IndexFD);
   IndexFile.os() << IndexText;
   IndexFile.os().flush();
   EXPECT_TRUE(llvm::sys::fs::exists(IndexFileName));
   llvm::Expected<llvm::StringMap<std::string>> IndexOrErr =
       parseCrossTUIndex(IndexFileName, "");
   EXPECT_TRUE((bool)IndexOrErr);
   llvm::StringMap<std::string> ParsedIndex = IndexOrErr.get();
   for (const auto &E : Index) {
     EXPECT_TRUE(ParsedIndex.count(E.getKey()));
     EXPECT_EQ(ParsedIndex[E.getKey()], E.getValue());
   }
   for (const auto &E : ParsedIndex)
     EXPECT_TRUE(Index.count(E.getKey()));
 }
 
+TEST(CrossTranslationUnit, CTUDirIsHandledCorrectly) {
+  llvm::StringMap<std::string> Index;
+  Index["a"] = "/b/c/d";
+  std::string IndexText = createCrossTUIndexString(Index);
+
+  int IndexFD;
+  llvm::SmallString<256> IndexFileName;
+  ASSERT_FALSE(llvm::sys::fs::createTemporaryFile("index", "txt", IndexFD,
+                                                  IndexFileName));
+  llvm::ToolOutputFile IndexFile(IndexFileName, IndexFD);
+  IndexFile.os() << IndexText;
+  IndexFile.os().flush();
+  EXPECT_TRUE(llvm::sys::fs::exists(IndexFileName));
+  llvm::Expected<llvm::StringMap<std::string>> IndexOrErr =
+      parseCrossTUIndex(IndexFileName, "/ctudir");
+  EXPECT_TRUE((bool)IndexOrErr);
+  llvm::StringMap<std::string> ParsedIndex = IndexOrErr.get();
+  EXPECT_EQ(ParsedIndex["a"], "/ctudir/b/c/d");
+}
+
 } // end namespace cross_tu
 } // end namespace clang