feat: Add CONAN_RUNTIME_LIB_DIRS to the conan_toolchain.cmake

[ErniGH]

Changelog: Feature: Add CONAN_RUNTIME_LIB_DIRS variable to the conan_toolchain.cmake.
Docs: conan-io/docs#3698

Close: #15810

[memsharded]

Is it possible to make the libdirs multi-config with a generator expression, as done with MSVC_RUNTIME and flags? It would be important for VS, otherwise it might be failing and collecting Debug runtime libs even if in a Release build, just because Debug configuration was the last installed one.

[memsharded]

I still think that it would be important to make CONAN_RUNTIME_LIB_DIRS a generator expression for multi-config systems, or at least a _RELEASE, _DEBUG one. There is risk of bringing the wrong runtime just because -s build_type=Debug was executed last.

[jcar87]

I still think that it would be important to make CONAN_RUNTIME_LIB_DIRS a generator expression for multi-config systems, or at least a _RELEASE, _DEBUG one. There is risk of bringing the wrong runtime just because -s build_type=Debug was executed last.

indeed! This was a further step - we first need to check whether the file(GET_RUNTIME_DEPENDENCIES ...) functionality accepts a generator expression - probably works during install, but unsure about configure time

[memsharded]

This is much better, getting close, just a couple of minor comments.

[jcar87]

The changes in this PR cause a warning to be issued:

CMake Warning (dev) at build/generators/conan_toolchain.cmake:106:
  Syntax Warning in cmake code at column 213

  Argument not separated from preceding token by whitespace.
Call Stack (most recent call first):
  build/CMakeFiles/3.27.4/CMakeSystem.cmake:6 (include)
  CMakeLists.txt:3 (project)

I can get it to not show that warning by doing semi-colon ; separated lists inside the generator expression, rather than space separated. However, then it doesn't work

The cmake_install.cmake file then generates something like this:

  elseif(CMAKE_INSTALL_CONFIG_NAME MATCHES "^([Rr][Ee][Ll][Ee][Aa][Ss][Ee])$")
    file(GET_RUNTIME_DEPENDENCIES
      RESOLVED_DEPENDENCIES_VAR _CMAKE_DEPS
      EXECUTABLES
        "C:/Users/xxx/conan-cmake-install-runtime-dependencies/build/Release/my_app.exe"
      DIRECTORIES
        "\$<1:\"C:/Users/xxx/.conan2/p/b/libpn0bfb1d18b1c7b/p/bin"
        "C:/Users/xxx/.conan2/p/zlib47a1fa7d4bdbe/p/bin"
        "C:/Users/xxx/.conan2/p/gtestd45050d57d0d9/p/bin\">\$<0:\"C:/Users/xxx/.conan2/p/b/libpn185873a63e4d5/p/bin"
        "C:/Users/xxx/.conan2/p/b/zlib00e783ae4582e/p/bin"
        "C:/Users/xxx/.conan2/p/b/gtest2d6a2ca931073/p/bin\">"

the 0 and the 1 in the generator expression here seems correct in the sense that it matches the configuration in the generated file - but something is off and it doesn't seem that cmake is picking up the correct directories because the install command then fails.
Using this https://github.com/jcar87/conan-cmake-install-runtime-dependencies as a test project on windows