$<LOWER_CASE:...> doesn't work with VS generator?

Hello everyone,

I am following Step 1 of the CMake tutorial, and I am trying to control the output directory of executables. As the Visual Studio build system creates subdirectories per configuration in the build directory by default, I am also trying to make these names lowercase.

I set CMAKE_RUNTIME_OUTPUT_DIRECTORY to a generator expression with $<LOWER_CASE:...>:

cmake_minimum_required(VERSION 3.10)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY C:/_stash/_files/cmaketest/$<LOWER_CASE:$<CONFIG>>)
        DESCRIPTION "A tutorial CMake project.")
add_executable(Tutorial tutorial.cxx)

However, when the config is Debug or Release, the result subdirectory name is always capitalized, even when --config is specified:

Command Output location
cmake --build ../build/Step1 C:\_stash\_files\cmaketest\Debug\Tutorial.exe
cmake --build ../build/Step1 --config debug C:\_stash\_files\cmaketest\Debug\Tutorial.exe
cmake --build ../build/Step1 --config release C:\_stash\_files\cmaketest\Release\Tutorial.exe
cmake --build ../build/Step1 --config releaSE C:\_stash\_files\cmaketest\Release\Tutorial.exe

The other two, MinSizeRel and RelWithDebInfo, which I found in the generated .vcxproj, build as expected and output respectively to C:\_stash\_files\cmaketest\minsizerel\Tutorial.exe and C:\_stash\_files\cmaketest\relwithdebinfo\Tutorial.exe.

I tried moving the set() command after project() but nothing changed. I think this is a CMake bug… any ideas?

(CMake version: 3.25.1-msvc1)

Update: Tried again after posting this and it worked… I made it work by deleting C:\_stash\_files\cmaketest\Debug and C:\_stash\_files\cmaketest\Release and trying again.

It turned out it was because I previously built with set(CMAKE_RUNTIME_OUTPUT_DIRECTORY C:/_stash/_files/cmaketest/$<CONFIG>), causing C:\_stash\_files\cmaketest\Debug to be created; when building again with set(CMAKE_RUNTIME_OUTPUT_DIRECTORY C:/_stash/_files/cmaketest/$<LOWER_CASE:$<CONFIG>>), as C:\_stash\_files\cmaketest\Debug exists and Windows is case-insensitive, C:\_stash\_files\cmaketest\debug is equivalent to C:\_stash\_files\cmaketest\Debug, causing that directory to be reused.