[llvm-dwp] Give more information when incompatible version found (#168511)

Provide more information when detecting a DWARF version mismatch in .dwo
files to help locate the issue and align with other similar errors.

Author: Jinjie-Huang

llvm/lib/DWP/DWP.cpp

@@ -706,6 +706,7 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
   uint32_t ContributionOffsets[8] = {};
   uint16_t Version = 0;
   uint32_t IndexVersion = 0;
+  StringRef FirstInput;
   bool AnySectionOverflow = false;
 
   DWPStringPool Strings(Out, StrSection);
@@ -764,8 +765,12 @@ Error write(MCStreamer &Out, ArrayRef<std::string> Inputs,
     if (Version == 0) {
       Version = Header.Version;
       IndexVersion = Version < 5 ? 2 : 5;
+      FirstInput = Input;
     } else if (Version != Header.Version) {
-      return make_error<DWPError>("incompatible DWARF compile unit versions.");
+      return make_error<DWPError>(
+          "incompatible DWARF compile unit version: " + Input + " (version " +
+          utostr(Header.Version) + ") and " + FirstInput.str() + " (version " +
+          utostr(Version) + ")");
     }
 
     writeStringsAndOffsets(Out, Strings, StrOffsetSection, CurStrSection,

llvm/test/tools/llvm-dwp/X86/incompatible_dwarf_version.test

@@ -0,0 +1,6 @@
+RUN: rm -rf %t && mkdir -p %t && cd %t
+RUN: llvm-mc --triple=x86_64-unknown-linux --filetype=obj --split-dwarf-file=%t/main_v5.dwo -dwarf-version=5 %p/../Inputs/overflow/main_v5.s -o %t/main_v5.o
+RUN: llvm-mc --triple=x86_64-unknown-linux --filetype=obj --split-dwarf-file=%t/debug_info_v4.dwo -dwarf-version=4 %p/../Inputs/overflow/debug_info_v4.s -o %t/debug_info_v4.o
+RUN: not llvm-dwp %t/main_v5.dwo %t/debug_info_v4.dwo -o main.dwp 2>&1 | FileCheck %s
+
+CHECK: error: incompatible DWARF compile unit version: {{.*}}debug_info_v4.dwo (version 4) and {{.*}}main_v5.dwo (version 5)