I know that if if we set -DCMAKE_BUILD_TYPE=Release (or Debug etc.), then the values of CMAKE_C_FLAGS_RELEASE and CMAKE_CXX_FLAGS_RELEASE will be appended to CMAKE_C_FLAGS and CMAKE_C_FLAGS respectively.
But is this the only effect of setting the build type? If not, what are the other effects?
Actually, build type affects on many things. Among them:
Expression $<$<CONFIG:DEBUG>:XXX> will be expanded to XXX with CMAKE_BUILD_TYPE set to Debug and to nothing otherwise.
Because generator expressions can be used in a number of commands, setting build type affects all commands which uses expressions dependent on build type.
libraries added by target_link_libraries with debug keyword take an effect only in Debug build type.
Similar to optimized keyword.
(Implicitely, this uses generator expressions described above).
Some properies of IMPORTED libraries.
Properties like IMPORTED_LOCATION have config-specific variants, which are choosen dependent on configuration type.
Often IMPORTED libraries are created as a result of find_package() call, so your project may be linked with 3d-party project in configuration-dependent manner.
CONFIGURATION-specific part of install command.
Only those CONFIGURATION <conf> part are applies, which corresponds to active configuration.
Multi-configuration tools doesn't use CMAKE_BUILD_TYPE variable, but they still have a notion of the "build type". That build type is NOT known at configuration stage, when CMake parses CMakeLists.txt, it is set only when performing a build of the project. Nevertheless, this build type "retroactively" affects on all properties described above.
Also, with multi-configuration build tools selected build type is appended to the location of output artifacts, like executables and libraries (see e.g. description of RUNTIME_OUTPUT_DIRECTORY target's property).