Defined macro CT in blitz/tau.h causes trouble when compiling project that uses Qt5/QColor.h

[Iceman9]

blitz/blitz/tau.h

Line 52 in 39f8859

#define CT(obj)

This defined macro causes an issue of compiling projects that include blitz and Qt5, specifically QColor.h as shown in the following link:

https://github.com/qt/qtbase/blob/40143c189b7c1bf3c2058b77d00ea5c4e3be8b28/src/gui/painting/qcolor.h#L266

The error output doesn't help much. as the compiler only complains that the there is a mismatch in the number of arguments provided to the macro. It took as a while to hunt through the army of headers.

The solution was simple. I #undef the macro before including the Qt headers. We just wanted to know where was the origin.

I don't think something should be done, but I just want to mark it if someone else gets into this situation in the future.

Best regards

[denisri]

I run into the exact same problem compiling existing code on a prerelease of Ubuntu 22.04.
Defining a two-letter maco is prone to ambiguity and, thus, is dangerous, isn't it ? Isnt't there a way to change this CT maco name (for, say, BLITZ_CT for instance), or is it a public API ?

[slayoo]

Thanks @Iceman9 for reporting and @denisri following up.
The origin of the problem seems to be outside of Blitz, it is the tau profiler that defines the CT macro: https://www.cs.uoregon.edu/research/tau/docs/newguide/bk03rn01re146.html

In Blitz code, this definition is within an "#else" block of an "#ifdef BZ_TAU_PROFILING".

I guess, the best solution is to include this #ifdef BZ_TAU_PROFILING wherever the CT macro is used, i.e.:

• https://github.com/blitzpp/blitz/blob/master/blitz/memblock.cc#L91
• https://github.com/blitzpp/blitz/blob/master/blitz/array/methods.cc#L290
• https://github.com/blitzpp/blitz/blob/master/blitz/array-impl.h#L200