Displaying CMake variables

Suppose I have a package called Foo. If I run CMake on a CMakeLists.txt file that contains find_package(Foo), then I can print out the values of variables such as ${Foo_LIBRARIES} and ${Foo_INCLUDES}.

Is there an easy way to display these variables without having to run CMake on a CMakeLists.txt file, and without having to manually inspect the config.cmake file?

You asked: (1) Is there an easy way to display these variables without having to run cmake on a CMakeLists.txt file, and (2) without having to manually inspect the config.cmake file?

I can give you a yes answer to (2) but it does require that you (re)run cmake. But since you can re-run your cmake configure step by simply executing cmake . in the build directory, re-running cmake should not keep you from trying this approach. My answer is given in this SO answer and uses the get_cmake_property command. Here is that code encapsulated into a cmake macro, print_all_variables, so I can use it when debugging my cmake scripts.

macro(print_all_variables)
    message(STATUS "print_all_variables------------------------------------------{")
    get_cmake_property(_variableNames VARIABLES)
    foreach (_variableName ${_variableNames})
        message(STATUS "${_variableName}=${${_variableName}}")
    endforeach()
    message(STATUS "print_all_variables------------------------------------------}")
endmacro()

The macros are invoked with same syntax as cmake functions:

print_all_variables()

To simply print a value, you could do something like this:

message(STATUS "foo include dir: ${foo_INCLUDE}")

where ${foo_INCLUDE} is the value you desire to print.

Note: I'm using cmake > 3.14

Run cmake in find-package mode. Example to display a package`s include directories:

cmake -DNAME=ZLIB -DCOMPILER_ID=GNU -DLANGUAGE=C -DMODE=COMPILE --find-package

Example to display the libraries:

cmake -DNAME=ZLIB -DCOMPILER_ID=GNU -DLANGUAGE=C -DMODE=LINK --find-package

The NAME must be set to the package name. You can obtain your COMPILER_ID on this page. LANGUAGE can be C, CXX or Fortran.