[lld-macho] Make ObjC category checker print the source file name of category (#80221)

When printing category conflicts in the ObjC category checker, also
print the source file name of the problematic categories. Currently we
only print the object file name. This change is mostly useful only for
thinLTO builds, where the object file name will be of form
999.arm64.lto.o and thus does not reveal any information about the
original source file.

---------

Co-authored-by: Alex Borcan <alexborcan@meta.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/lld/MachO/ObjC.cpp b/lld/MachO/ObjC.cpp
index 7e8cec026d2f..67254ec53a21 100644
--- a/lld/MachO/ObjC.cpp
+++ b/lld/MachO/ObjC.cpp
@@ -237,12 +237,23 @@ void ObjcCategoryChecker::parseMethods(const ConcatInputSection *methodsIsec,
     StringRef newCatName =
         getReferentString(*containerIsec->getRelocAt(catLayout.nameOffset));
 
+    auto formatObjAndSrcFileName = [](const InputSection *section) {
+      lld::macho::InputFile *inputFile = section->getFile();
+      std::string result = toString(inputFile);
+
+      auto objFile = dyn_cast_or_null<ObjFile>(inputFile);
+      if (objFile && objFile->compileUnit)
+        result += " (" + objFile->sourceFile() + ")";
+
+      return result;
+    };
+
     StringRef containerType = mc.kind == MCK_Category ? "category" : "class";
     warn("method '" + methPrefix + methodName.val() +
          "' has conflicting definitions:\n>>> defined in category " +
-         newCatName + " from " + toString(containerIsec->getFile()) +
+         newCatName + " from " + formatObjAndSrcFileName(containerIsec) +
          "\n>>> defined in " + containerType + " " + containerName + " from " +
-         toString(mc.isec->getFile()));
+         formatObjAndSrcFileName(mc.isec));
   }
 }