# No SOURCES given to target: \_\_CMAKE\_\_CXX26 on ubuntu 25.04

**URL:** https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240
**Category:** Development
**Tags:** os:linux, gen:ninja
**Created:** [June 16, 2025, 11:26am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240 "2025-06-16T11:26:10Z")
**Posts on this page:** 1
**Showing post:** 12

<div class="post-metadata">

### Author: ![ClausKlein](https://discourse.cmake.org/user_avatar/discourse.cmake.org/clausklein/32/352_2.png) [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 17, 2025, 6:25am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/12 "2025-06-17T06:25:37Z")

</div>

### So I have to set for `clang-20`

```cmake
if($ENV{CXX} MATCHES "clang" OR CMAKE_CXX_COMPILER MATCHES "clang")
    set(ENV{CXXFLAGS} -stdlib=libc++)
endif()

```

before `project(...)` in my `CMakeLists.txt`!

### And for `gcc-15` this workaround helps:

```bash
sudo mkdir -p /usr/lib/gcc/x86_64-linux-gnu/include/c++/15
cd /usr/lib/gcc/x86_64-linux-gnu/include/c++/15
sudo ln -s /usr/include/c++/15/bits .

```

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_[View the full topic](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240)._