VTM-6.0 tracing crashes with recent gcc

[crosewarne]

When running the VTM-6.0 encoder with tracing compiled using gcc-9.1.0 and activated, the following error occurred:

terminate called after throwing an instance of 'std::logic_error'

what(): basic_string::_M_construct null not valid

Aborted (core dumped)

However, using gcc-4.8.5 tracing is working OK.

[ksuehring]

I was unsuccessful reproducing the issue with current master. But I only have gcc-9.2 available on MacOS.

Could you please:

• try with current master
• if the problem persists, post the exact command line and where/when the problem appears?

[crosewarne]

On further investigation I had invoked tracing with a slightly different command line:

OK: --TraceRule=D_HEADER,D_SYNTAX:final==1
NG: --TraceRule=D_HEADER,D_SYNTAX

So it is not related to gcc after all - although I thought omitting specifying 'final' would be equivalent to 'final==0', but it seems not. Furthermore, I found that if 'poc' is specified, e.g. 'poc>=0' then final==[0|1] could be omitted.

[ksuehring]

According to the documentation a trace condition is required. But I agree that the software should rather give an error instead of crashing (or use a reasonable default).

Patches are appreciated.