gmic-gimp/gmic-qt @3.2.3: builds failing on older macOS releases: call to 'abs' is ambiguous

[mascguy (Christopher Nielsen)]

Details (identical failure occurring for both gmic-gimp and gmic-qt):

work/gmic-3.2.3/gmic-qt/src/FilterSelector/FiltersModelReader.cpp:534:27: error: call to 'abs' is ambiguous
          previewFactor = std::abs(previewFactor);
                          ^~~~~~~~

1 error generated.
make[2]: *** [CMakeFiles/gmic_qt.dir/src/FilterSelector/FiltersModelReader.cpp.o] Error 1

Based on a quick review of src/FilterSelector/FiltersModelReader.cpp, upstream may simply be missing #include <cstdlib> (or wherever std::abs is defined). But didn't dig too deeply.

​https://ports.macports.org/port/gmic-gimp/details/

​https://ports.macports.org/port/gmic-qt/details/

[Marius Schamschula <mschamschula@…>]

In e50d09d06f13c2e03b381ab8058ef1e76fa4032c/macports-ports (master):

gmic: attempt to fix "call to 'abs' is ambiguous"

See: #67264

[jmroot (Joshua Root)]

Ambiguous doesn't mean undefined, it means there are multiple versions of the function defined that take different types, and it's not sure which one you meant. Casting to the appropriate type may help.

[Schamschula (Marius Schamschula)]

Reported upstream.

See: ​https://github.com/GreycLab/gmic/issues/450

[jmroot (Joshua Root)]

Oh yeah, I forgot what a mess this is in C++. Some of the abs() overloads are in cstdlib and others are in cmath.

[Schamschula (Marius Schamschula)]

Indeed! In this case I guessed wrong - it was cmath.

[Schamschula (Marius Schamschula)]

Closed by ​https://github.com/macports/macports-ports/commit/cc10d1b37f5915b2d1562a2c6aec89f993c9c4dd