Use Ninja on AppVeyor

[janisozaur]

This brings up improved compilation speed and saner error messages.

[coveralls]

Coverage remained the same at 100.0% when pulling ba3cf64 on janisozaur:ninja into be35975 on skypjack:master.

[skypjack]

How does this represent an improvement over the actual configuration? I don't get it to be honest.

[OvermindDL1]

Ninja's primary use is significantly faster dependency tracking and job handling, it's often quite a bit faster on compiling larger projects than make/nmake/etc... So I think it's just to reduce the build times. In addition it's logs don't get mangled with errors from different threads if there is a failure to build like make/nmake do.

[skypjack]

Does it use VC under the hood? Because the compatibility with MSVC is the whole point of using appveyor. I develop on linux usually, so the CI is what I use for this purpose.

[OvermindDL1]

Yes, ninja is just the build orchestrator, it still uses gcc/clang/visual-studio-tools/icc/whatever.

[janisozaur]

As was already stated, ninja is just a tool to invoke compiler. That and (almost) just that, which makes it fast, much faster than msbuild. You can verify what ninja does under the hood by passing -v option.
It also ensures each compiler invocation reports its output in single chunk, even from multiple instances.
From another ninja-ified project:

Before:

  LHVMViewer.cpp
C:\projects\openblack\src\LHScriptX\FeatureScriptCommands.cpp(240,24): warning C4244:  '=': conversion from 'double' to 'float', possible loss of data [C:\projects\openblack\_build_vs-16-2019-win64-cxx17_Debug\openblack.vcxproj]
C:\projects\openblack\src\LHVMViewer.cpp(171,54): warning C4267:  'argument': conversion from 'size_t' to 'int', possible loss of data [C:\projects\openblack\_build_vs-16-2019-win64-cxx17_Debug\openblack.vcxproj]
  MeshViewer.cpp
  Renderer.cpp
C:\projects\openblack\src\LHVMViewer.cpp(213,109): warning C4267:  'argument': conversion from 'size_t' to 'int', possible loss of data [C:\projects\openblack\_build_vs-16-2019-win64-cxx17_Debug\openblack.vcxproj]

After:

[32/50] Building CXX object CMakeFiles\openblack.dir\src\LHVMViewer.cpp.obj
..\src\LHVMViewer.cpp(171): warning C4267: 'argument': conversion from 'size_t' to 'int', possible loss of data
..\src\LHVMViewer.cpp(213): warning C4267: 'argument': conversion from 'size_t' to 'int', possible loss of data

[Milerius]

Ninja is the best thing's that can happen in your life ;)