The CMake build script breaks check_ipo_supported

[andyroiiid]

Describe the bug check_ipo_supported fails after adding zstd as a subdirectory.

To Reproduce Steps to reproduce the behavior:

1. Here's a repro for the bug: https://github.com/andyroiiid/zstd-cmake-lto-bug.git
2. Clone the repo and run CMake
3. The configuring process will fail:

"C:\Users\username\AppData\Local\Programs\CLion 2\bin\cmake\win\x64\bin\cmake.exe" -DCMAKE_BUILD_TYPE=RelWithDebInfo "-DCMAKE_MAKE_PROGRAM=C:/Users/username/AppData/Local/Programs/CLion 2/bin/ninja/win/x64/ninja.exe" -G Ninja -S E:\Projects\zstd-cmake-lto-bug -B E:\Projects\zstd-cmake-lto-bug\cmake-build-relwithdebinfo
-- CMAKE_VERSION = 3.28.1
-- LANGUAGES = CXX;RC
-- ZSTD VERSION: 1.5.6
-- CMAKE_INSTALL_PREFIX: C:/Program Files (x86)/zstd_cmake_lto_bug
-- CMAKE_INSTALL_LIBDIR: lib
-- ZSTD_LEGACY_SUPPORT not defined!
-- ZSTD_MULTITHREAD_SUPPORT is enabled
-- LANGUAGES = ASM;C;CXX;RC
CMake Error at C:/Users/username/AppData/Local/Programs/CLion 2/bin/cmake/win/x64/share/cmake-3.28/Modules/CheckIPOSupported.cmake:68 (message):
  IPO is not supported (CMake doesn't support IPO for current C compiler).
Call Stack (most recent call first):
  C:/Users/username/AppData/Local/Programs/CLion 2/bin/cmake/win/x64/share/cmake-3.28/Modules/CheckIPOSupported.cmake:250 (_ipo_not_supported)
  CMakeLists.txt:20 (check_ipo_supported)


-- Configuring incomplete, errors occurred!

[Finished]

Here's a copy of the CMakeLists.txt:

cmake_minimum_required(VERSION 3.9)
project(zstd_cmake_lto_bug CXX)

set(CMAKE_CXX_STANDARD 20)

message(STATUS "CMAKE_VERSION = ${CMAKE_VERSION}")

include(CheckIPOSupported)

get_property(LANGUAGES GLOBAL PROPERTY ENABLED_LANGUAGES)
message(STATUS "LANGUAGES = ${LANGUAGES}")

check_ipo_supported() # <----------------- This succeeds

add_subdirectory(zstd/build/cmake EXCLUDE_FROM_ALL)

get_property(LANGUAGES GLOBAL PROPERTY ENABLED_LANGUAGES)
message(STATUS "LANGUAGES = ${LANGUAGES}")

check_ipo_supported() # <----------------- This fails

Expected behavior check_ipo_supported should not fail after zstd is included.

Screenshots and charts N/A

Desktop: Repro environment 1:

• OS: Microsoft Windows 11 Home
• Version: 10.0.22631 Build 22631
• Compiler: Microsoft (R) C/C++ Optimizing Compiler Version 19.40.33811 for x64
• Flags: N/A - The bug happens before compilation.
• Other relevant hardware specs: i9-13950HX (Not exactly sure what to put here.)
• Build system: CMake

Repro environment 2:

• OS: Ubuntu 22.04 jammy
• Version: x86_64 Linux 5.15.0-107-generic
• Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
• Flags: N/A - The bug happens before compilation.
• Other relevant hardware specs: AMD Ryzen 5 PRO 2500U (Not exactly sure what to put here.)
• Build system: CMake

Additional context I noticed that zstd adds ASM and C to the project language list. CMake will configure successfully if I change the project declaration from project(zstd_cmake_lto_bug CXX) to project(zstd_cmake_lto_bug C CXX).