build(cmake): simplify instructions (cmake -B build && cmake --build build ...)

[ochafik]

• Updated instructions & CI to skip the mkdir -p build && cd build steps using config-time flag -B and build-time flag --build

  mkdir -b build
  cd build
  cmake ..
  make # or `cmake --build . --config Release`

  Becomes:

  cmake -B build
  cmake --build build --config Release
  # --config flag is ignored for Makefile generation (default) but crucial for Release builds w/ Xcode / MSVC, as pointed out by reviewers

• Documented how to do Debug builds

• Removed --config Release from most cmake build commands (except for Visual Studio) as Release is the default and the --config flag is often useless anyway)

  Note: To build in Debug w/ CMake one generally needs to set -DCMAKE_BUILD_TYPE=Debug in the "config" command (--config Debug on the build command works only for Ninja Multi-Config, XCode or Visual Studio generators)

[cebtenzzre]

The source directory defaults to the current directory when using -B. So cmake . -B build should just be cmake -B build.

[ochafik]

The source directory defaults to the current directory when using -B. So cmake . -B build should just be cmake -B build.

@cebtenzzre Neat! Updated.

[slaren]

• Removed --config Release from most cmake build commands (except for Visual Studio) as Release is the default and the --config flag is often useless anyway)

I am not sure that this is entirely correct. CMAKE_BUILD_TYPE configures the build type for single-config generators, while --config selects the build type for multi-config generators (ie. MSVC). I have been trying to find what is the default value of --config, but I have not been able to find any references. Are you sure that removing --config will still build in release with MSVC in all cases?

[slaren]

I just ran a quick test, and without --config Release, it will result in a debug build. Therefore I think it is important to keep the --config Release, at least in the documentation that is meant to be applicable for all the platforms.

[ochafik]

Removed --config Release from most cmake build commands (except for Visual Studio) as Release is the default and the --config flag is often useless anyway)

I am not sure that this is entirely correct

@slaren Oops I misspoke, it's the default for single-generator configs (as set here), and the default is generator dependent for the others.

I just ran a quick test, and without --config Release, it will result in a debug build. Therefore I think it is important to keep the --config Release, at least in the documentation that is meant to be applicable for all the platforms.

Thanks a lot for catching this! I just checked if setting -DCMAKE_CONFIGURATION_TYPES=Release;Debug;MinSizeRel;RelWithDebInfo would give control over the default (hoping it'd pick the first) but it's not the case at least for Xcode.

I've reverted the --config Release bit and added instructions for Debug builds on the main README, PTAL 😁

Already addressed.