[llvm-profdata] Make sure to consume Error on the error path of setIsIRLevelProfile

[zero9178]

Summary

Encountered a crash while running a debug build, where this code path would be taken due to a mismatch in profile coverage data versions. Without consuming the error, an assert would be triggered inside the destructor of Error.

[vsk]

Please add a test. I think I've reproduced the bug with this:

~/src/gh-llvm-project-main/llvm/test/tools/llvm-profdata (0) % cat merge-incompatible.test 
RUN: not llvm-profdata merge %p/Inputs/fe-basic.proftext %p/Inputs/ir-basic.proftext -o /dev/null

~/src/gh-llvm-project-main/llvm/test/tools/llvm-profdata (0) % cat Inputs/{fe,ir}-basic.proftext
:fe
foo
29667547796
2
100
90

:ir
foo2
29667547796
2
100
90

[zero9178]

Thanks a lot for the help.
I have now added tests that reproduce the issue and also ensure the error is emitted.

[vsk]

Thanks, lgtm!

llvm/tools/llvm-profdata/llvm-profdata.cpp

if (Error E = ReaderOrErr.takeError()) {
     if (IPE != instrprof_error::empty_raw_profile)
       WC->Errors.emplace_back(make_error<InstrProfError>(IPE), Filename);
     return;
   }
 
   auto Reader = std::move(ReaderOrErr.get());
   bool IsIRProfile = Reader->isIRLevelProfile();
   bool HasCSIRProfile = Reader->hasCSIRLevelProfile();
-  if (WC->Writer.setIsIRLevelProfile(IsIRProfile, HasCSIRProfile)) {
+  if (Error E = WC->Writer.setIsIRLevelProfile(IsIRProfile, HasCSIRProfile)) {
+    consumeError(std::move(E));
     WC->Errors.emplace_back(
         make_error<StringError>(
             "Merge IR generated profile with Clang generated profile.",
             std::error_code()),
         Filename);
     return;
   }
   WC->Writer.setInstrEntryBBEnabled(Reader->instrEntryBBEnabled());