[llvm-dev] Build failure

[Florian Hahn via llvm-dev]

> On Jan 8, 2021, at 18:18, Paul C. Anagnostopoulos <paul at windfall.com> wrote:
> 
> At 1/8/2021 01:08 PM, Florian Hahn wrote:
> 
>>> Can I trust this message?
>> 
>> Yes, you should be able to trust this message.
>> 
>> The bot builds LLVM with the undefined behavior sanitizer, which will insert runtime checks to catch cases of undefined behavior in the source. You need a version of LLVM that is build with the UBsan enabled to reproduce it.
>> 
>>> TGParser.cpp:3213:22: runtime error: reference binding to null pointer of type 'llvm::Record'
>> 
>> Looks like the code on that line is  https://github.com/llvm/llvm-project/blob/6e2b6351d2cb1feaa88e6c92ba844ab48b4758f9/llvm/lib/TableGen/TGParser.cpp#L3213
>> 
>>   RecordResolver R(*CurRec);
>> 
>> CurRec is a pointer of type llvm::Record. The message ("runtime error: reference binding to null pointer of type 'llvm::Record’) is indicating that a null pointer is de-referenced (so it can be bound to a reference, likely RecordResolver’s constructor takes an argument `Record &`).
>> 
>> So there is a code path executed where CurRec is a nullptr.
> 
> I did indeed find the bug in that line of code. But that is line 3212 in my file.  . . . Ah, that's because that build isn't using the file I patched to eliminate the spurious Loc declaration. Okay, that makes sense.
> 
> I will push a patch to fix this. Sorry for the mess but thanks for the help!
> 
> 

No worries, glad you figured out the issue!