显示 CMake 变量而不在 CMakeLists.txt 文件上运行 CMake 或手动检查 config.CMake？

假设我有一个名为 Foo 的包。如果我在包含 find_package(Foo)的 CMakeLists.txt 文件上运行 CMake，那么我可以打印出变量(如 ${Foo_LIBRARIES}和 ${Foo_INCLUDES})的值。

有没有一种简单的方法可以显示这些变量，而不必在 CMakeLists.txt 文件上运行 CMake，也不必手动检查 config.CMake 文件？

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小开

These variables are generally hardcoded into FindFoo.cmake so that it is not possible to extract them without running the function first. Note that sometimes the value of Foo_LIBRARIES depends on the system configuration, which is unknown until find_package(Foo) is run.

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Run CMake and have a look at the cache with the ccmake GUI tool. Then you'll get all the variables.

Or run CMake with -LH then you will get all variables printed after configuration.

So I think it is not possible to get the variables without running CMake.

小开

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.

小开

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()
小开

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

小开

I am always suspicious of variables changing values throughout a script somewhere so I like to see the value of a variable at a particular point in the running script. Combining the ideas from both Phil and Aaron B. this is what I'm using:

function(PRINT_VAR VARNAME)
message(STATUS "${VARNAME}: ${${VARNAME}}")
endfunction()
PRINT_VAR("CMAKE_CXX_COMPILER")

Then I can just litter PRINT_VAR statements around like I'm debugging code back in 1980


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