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So I have a number of CMake files - and I am trying to refactor many common things across multiple projects.

One example is we turn on features due to the compiler version (GCC)

I am having problems with: CMAKE_C_COMPILER_VERSION.

If I run cmake with --trace - I see the following:

/data/project/proj/build/thing.Debug/CMakeFiles/3.22.1/CMakeCCompiler.cmake(4):  set(CMAKE_C_COMPILER_VERSION 9.2.1 )

So - CMake knows the compiler version.

But - later in my CMake scripts I try to reference that variable and do this as a diagnostic:

  message("CMAKE_C_COMPILER_VERSION: ${CMAKE_C_COMPILER_VERSION}")

And On the console output, it is blank:

CMAKE_C_COMPILER_VERSION:

And If I try to reference the variable, it turns into blank. Why is this? Why does one part of CMake - find/understand and set a variable Only so that other parts cannot use the variable.

Improve this question
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  • There are several ways for a variable to lost a value. E.g. after returning from a scope where the variable is defined: cmake.org/cmake/help/latest/manual/…. Or after calling unset for the variable. For get a specific answer you need to show your code (in form of minimal reproducible example). Commented Feb 25 at 6:25
  • Yea, that's not so simple - I am dealing with about 1100 C files, and the Cmake code is refactored into a number of 'modules' - with functions. Commented Feb 25 at 16:42
  • Please provide a minimal working example, otherwise the question is difficult to answer. You have to keep in mind that scoping is an important topic, see cmake.org/cmake/help/latest/command/set.html Commented Feb 27 at 10:22
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