# 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:** 18
**Page:** 1
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 11:26am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/1 "2025-06-16T11:26:10Z")
### import std does also not work with `gcc-15` on `ubuntu 25.04`!
```bash
builder@5b11ff1f2350:~/workdir$ cmake -S . -B build -G Ninja --fresh
-- The CXX compiler identification is GNU 15.0.1
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/g++-15 - skipped
-- Detecting CXX compile features
CMake Warning (dev) at /usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/Compiler/CMakeCommonCompilerMacros.cmake:248 (cmake_language):
CMake's support for `import std;` in C++23 and newer is experimental. It
is meant only for experimentation and feedback to CMake developers.
Call Stack (most recent call first):
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake:113 (cmake_create_cxx_import_std)
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CMakeTestCXXCompiler.cmake:83 (CMAKE_DETERMINE_COMPILER_SUPPORT)
CMakeLists.txt:36 (project)
This warning is for project developers. Use -Wno-dev to suppress it.
-- Detecting CXX compile features - done
-- Performing Test COMPILER_HAS_HIDDEN_VISIBILITY
-- Performing Test COMPILER_HAS_HIDDEN_VISIBILITY - Success
-- Performing Test COMPILER_HAS_HIDDEN_INLINE_VISIBILITY
-- Performing Test COMPILER_HAS_HIDDEN_INLINE_VISIBILITY - Success
-- Performing Test COMPILER_HAS_DEPRECATED_ATTR
-- Performing Test COMPILER_HAS_DEPRECATED_ATTR - Success
-- Configuring done (0.9s)
CMake Error at build/CMakeFiles/4.0.3/CMakeCXXCompiler.cmake:119 (target_sources):
Cannot find source file:
/usr/lib/gcc/x86_64-linux-gnu/include/c++/15/bits/std.cc
Call Stack (most recent call first):
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CMakeTestCXXCompiler.cmake:91 (include)
CMakeLists.txt:36 (project)
CMake Error in CMakeLists.txt:
No SOURCES given to target: __CMAKE__ CXX26@synth_228b59946540
CMake Generate step failed. Build files cannot be regenerated correctly.
builder@5b11ff1f2350:~/workdir$ find /usr -iname 'std.cc'
/usr/include/c++/15/bits/std.cc
builder@5b11ff1f2350:~/workdir$ uname -a
Linux 5b11ff1f2350 6.10.14-linuxkit #1 SMP PREEMPT_DYNAMIC Thu Mar 20 16:36:58 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
builder@5b11ff1f2350:~/workdir$ cat /etc/issue
Ubuntu 25.04 \n \l
builder@5b11ff1f2350:~/workdir$ cat /usr/lib/gcc/x86_64-linux-gnu/15/libstdc++.modules.json
{
"version": 1,
"revision": 1,
"modules": [
{
"logical-name": "std",
"source-path": "../include/c++/15/bits/std.cc",
"is-std-library": true
},
{
"logical-name": "std.compat",
"source-path": "../include/c++/15/bits/std.compat.cc",
"is-std-library": true
}
]
}
builder@5b11ff1f2350:~/workdir$
```
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 11:59am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/2 "2025-06-16T11:59:03Z")
### import std does also not work with `clang-20` on `ubuntu 25.04`!
```bash
builder@98757d772b6f:~/workdir$ CXX=clang++ cmake -S . -B build -G Ninja --fresh
-- The CXX compiler identification is Clang 20.1.2
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/clang++ - skipped
-- Detecting CXX compile features
CMake Warning (dev) at /usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/Compiler/CMakeCommonCompilerMacros.cmake:248 (cmake_language):
CMake's support for `import std;` in C++23 and newer is experimental. It
is meant only for experimentation and feedback to CMake developers.
Call Stack (most recent call first):
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CMakeDetermineCompilerSupport.cmake:113 (cmake_create_cxx_import_std)
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CMakeTestCXXCompiler.cmake:83 (CMAKE_DETERMINE_COMPILER_SUPPORT)
CMakeLists.txt:36 (project)
This warning is for project developers. Use -Wno-dev to suppress it.
-- Detecting CXX compile features - done
-- Performing Test COMPILER_HAS_HIDDEN_VISIBILITY
CMake Error at /home/builder/workdir/build/CMakeFiles/4.0.3/CMakeCXXCompiler.cmake:111 (target_sources):
Cannot find source file:
/usr/lib/gcc/x86_64-linux-gnu/include/c++/15/bits/std.cc
Call Stack (most recent call first):
/home/builder/workdir/build/CMakeFiles/CMakeScratch/TryCompile-u2A8qJ/CMakeLists.txt:2 (project)
CMake Error at /home/builder/workdir/build/CMakeFiles/4.0.3/CMakeCXXCompiler.cmake:103 (add_library):
No SOURCES given to target: __cmake_cxx23
Call Stack (most recent call first):
/home/builder/workdir/build/CMakeFiles/CMakeScratch/TryCompile-u2A8qJ/CMakeLists.txt:2 (project)
CMake Error at /home/builder/workdir/build/CMakeFiles/4.0.3/CMakeCXXCompiler.cmake:127 (add_library):
No SOURCES given to target: __cmake_cxx26
Call Stack (most recent call first):
/home/builder/workdir/build/CMakeFiles/CMakeScratch/TryCompile-u2A8qJ/CMakeLists.txt:2 (project)
CMake Error at /usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/Internal/CheckSourceCompiles.cmake:104 (try_compile):
Failed to generate test project build system.
Call Stack (most recent call first):
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/Internal/CheckCompilerFlag.cmake:18 (cmake_check_source_compiles)
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/CheckCompilerFlag.cmake:56 (cmake_check_compiler_flag)
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/GenerateExportHeader.cmake:244 (check_compiler_flag)
/usr/local/lib/python3.13/dist-packages/cmake/data/share/cmake-4.0/Modules/GenerateExportHeader.cmake:425 (_test_compiler_hidden_visibility)
CMakeLists.txt:50 (generate_export_header)
-- Configuring incomplete, errors occurred!
builder@98757d772b6f:~/workdir$ find /usr -name std.cppm
/usr/lib/llvm-20/share/libc++/v1/std.cppm
builder@98757d772b6f:~/workdir$ find /usr -name '*modules.json'
/usr/lib/gcc/x86_64-linux-gnu/15/libstdc++.modules.json
/usr/lib/llvm-20/lib/libc++.modules.json
builder@98757d772b6f:~/workdir$ cat /usr/lib/llvm-20/lib/libc++.modules.json
{
"version": 1,
"revision": 1,
"modules": [
{
"logical-name": "std",
"source-path": "../share/libc++/v1/std.cppm",
"is-std-library": true,
"local-arguments": {
"system-include-directories": [
"../share/libc++/v1"
]
}
},
{
"logical-name": "std.compat",
"source-path": "../share/libc++/v1/std.compat.cppm",
"is-std-library": true,
"local-arguments": {
"system-include-directories": [
"../share/libc++/v1"
]
}
}
]
}
builder@98757d772b6f:~/workdir$
```
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [June 16, 2025, 2:53pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/3 "2025-06-16T14:53:11Z")
Looks like a packaging problem to me; the mentioned source files should be included in the `-dev` package that provides the stdlib modules’ `.json` file.
Or, perhaps, the paths are not correct? In any case, this is an Ubuntu issue based on the information provided.
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 3:22pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/4 "2025-06-16T15:22:51Z")
For the `gcc-15` case, I agree.
But in the `clang-20` case, it seems a `CMake` problem, the `/usr/lib/llvm-20/lib/libc++.modules.json` is correct!
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [June 16, 2025, 5:28pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/5 "2025-06-16T17:28:57Z")
Can you please trace the paths made in `Clang-CXX-CXXImportStd.cmake` to see where CMake goes astray?
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 6:38pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/6 "2025-06-16T18:38:13Z")
[cmake.log](https://discourse.cmake.org/uploads/short-url/vAOqsBgE2KO7JhtEBKHn3OlidYc.log) (40.7 KB)
My `CMakeLists.txt`:
```cmake
cmake_minimum_required(VERSION 4.0)
if(APPLE)
set(CMAKE_CXX_COMPILER /usr/local/bin/g++-15)
# set(LLVM_ROOT /usr/local/Cellar/llvm/20.1.6)
# set(CMAKE_CXX_COMPILER ${LLVM_ROOT}/bin/clang++)
# add_link_options(-L${LLVM_ROOT}/lib/c++)
endif()
if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
add_compile_options(-stdlib=libc++)
add_link_options(-stdlib=libc++)
endif()
set(CMAKE_CXX_STANDARD 26)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS ON)
set(CMAKE_SKIP_TEST_ALL_DEPENDENCY FALSE)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
if(CMAKE_VERSION VERSION_LESS 4.0.3)
# cmake v4.0.2:
set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD a9e1cf81-9932-4810-974b-6eccaf14e457)
else()
# cmake release branch
set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD d0edc3af-4c50-42ea-a356-e2862fe7a444)
endif()
set(CMAKE_CXX_MODULE_STD ON)
# Ensure non-empty default build type for single-config
get_property(isMultiConfig GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
if(NOT isMultiConfig)
set(CMAKE_BUILD_TYPE Debug CACHE STRING "Build type")
endif()
set(CMAKE_DEBUG_POSTFIX _debug)
project(example-modules VERSION 0.1.0 LANGUAGES CXX)
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
set(CMAKE_VISIBILITY_INLINES_HIDDEN TRUE)
add_library(Algo SHARED)
target_sources(
Algo
PRIVATE algo-impl.cpp
PUBLIC FILE_SET CXX_MODULES FILES algo-interface.cppm
)
target_compile_features(Algo PUBLIC cxx_std_23)
include(GenerateExportHeader)
generate_export_header(Algo)
target_sources(
Algo
PUBLIC
FILE_SET HEADERS
BASE_DIRS ${CMAKE_CURRENT_BINARY_DIR}
FILES ${CMAKE_CURRENT_BINARY_DIR}/algo_export.h
)
add_executable(algo-example algo-example.cpp)
target_link_libraries(algo-example PRIVATE Algo)
enable_testing()
add_test(NAME algo-example COMMAND algo-example)
include(GNUInstallDirs)
install(
TARGETS Algo
EXPORT Algo
FILE_SET HEADERS
FILE_SET CXX_MODULES
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package/src
CXX_MODULES_BMI
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package/bmi-$
# Other things to install
)
install(
EXPORT Algo
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package
FILE algo-targets.cmake
NAMESPACE Algo
CXX_MODULES_DIRECTORY
algo
)
```
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [June 16, 2025, 7:37pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/7 "2025-06-16T19:37:03Z")
> [@ClausKlein](#):
>
> ```auto
> add_compile_options(-stdlib=libc++)
> add_link_options(-stdlib=libc++)
>
> ```
I don’t think these get used at all during compiler detection; I see no `libc++` usage in the logs you’ve provided, so they’re both using the broken `libstdc++.modules.json` file.
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 7:39pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/8 "2025-06-16T19:39:31Z")
How may I control to use libc++ with clang++?
This is magic on `linux`:
```bash
builder@3be174728abe:~/workdir$ /usr/bin/clang++-20 -print-file-name=libstdc++.modules.json
/usr/lib/gcc/x86_64-linux-gnu/15/libstdc++.modules.json
builder@3be174728abe:~/workdir$ /usr/bin/clang++-20 -print-file-name=libc++.modules.json
/usr/lib/llvm-20/bin/../lib/libc++.modules.json
builder@3be174728abe:~/workdir$
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
builder@3be174728abe:~/workdir$ g++-15 -print-file-name=libstdc++.modules.json
/usr/lib/gcc/x86_64-linux-gnu/15/libstdc++.modules.json
builder@3be174728abe:~/workdir$ g++-15 -print-file-name=libc++.modules.json
libc++.modules.json
builder@3be174728abe:~/workdir$
```
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 16, 2025, 7:53pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/9 "2025-06-16T19:53:01Z")
an other miracle on `OSX`:
```bash
bash-5.2$ g++-15 -print-file-name=libc++.modules.json
libc++.modules.json
bash-5.2$ g++-15 -print-file-name=libstdc++.modules.json
/usr/local/Cellar/gcc/15.1.0/bin/../lib/gcc/current/gcc/x86_64-apple-darwin23/15/../../../libstdc++.modules.json
bash-5.2$ clang++ -print-file-name=libstdc++.modules.json
libstdc++.modules.json
bash-5.2$ clang++ -print-file-name=libc++.modules.json
libc++.modules.json
bash-5.2$ clang++ -print-file-name=c++/libc++.modules.json
/usr/local/Cellar/llvm/20.1.6/lib/clang/20/../../c++/libc++.modules.json
bash-5.2$
```
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [June 17, 2025, 5:01am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/10 "2025-06-17T05:01:31Z")
> [@ClausKlein](#):
>
> How may I control to use libc++ with clang++?
I used `CXXFLAGS=-stdlib=libc++` in the environment.
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 17, 2025, 5:10am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/11 "2025-06-17T05:10:58Z")
But the `CMAKE_CXX_STANDARD_LIBRARY` is set in `CMakeDetermineComilerId.cmake`:
```cmake
set(CMAKE_${lang}_STANDARD_LIBRARY "")
if ("x${lang}" STREQUAL "xCXX" AND
EXISTS "${CMAKE_CURRENT_FUNCTION_LIST_DIR}/${lang}-DetectStdlib.h" AND
("x${CMAKE_${lang}_COMPILER_ID}" STREQUAL "xClang" AND
"x${CMAKE_${lang}_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU") OR
("x${CMAKE_${lang}_COMPILER_ID}" STREQUAL "xGNU"))
# See #20851 for a proper abstraction for this.
execute_process(
COMMAND "${CMAKE_${lang}_COMPILER}"
${CMAKE_${lang}_COMPILER_ID_ARG1}
${CMAKE_CXX_COMPILER_ID_FLAGS_LIST}
-E
-x c++-header
"${CMAKE_CURRENT_FUNCTION_LIST_DIR}/${lang}-DetectStdlib.h"
-o - # Write to stdout.
OUTPUT_VARIABLE _lang_stdlib_out
ERROR_VARIABLE _lang_stdlib_err
RESULT_VARIABLE _lang_stdlib_res
ERROR_STRIP_TRAILING_WHITESPACE)
if (_lang_stdlib_res EQUAL 0)
string(REGEX REPLACE ".*CMAKE-STDLIB-DETECT: (.+)\n.*" "\\1" "CMAKE_${lang}_STANDARD_LIBRARY" "${_lang_stdlib_out}")
endif ()
endif ()
```
default set to:
**Modules/CMakeDetermineCompilerId.cmake(434): set(CMAKE\_CXX\_STANDARD\_LIBRARY libstdc++ PARENT\_SCOPE )**
But this helps:
```bash
CXX=clang++-20 CXXFLAGS=-stdlib=libc++ cmake -G Ninja -S . -B build --trace-expand --trace-source=CMakeDetermineCompilerId.cmake --fresh
```
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [June 17, 2025, 6:25am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/12 "2025-06-17T06:25:37Z")
### So I have to set for `clang-20`
```cmake
if($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 .
```
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [July 6, 2025, 10:01am UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/14 "2025-07-06T10:01:48Z")
So with this works with `clang++-20` on `ubuntu-25.04` out of the box
@ben.boeckel With `g++15` it builds only with my **workaround**!
```cmake
cmake_minimum_required(VERSION 4.0...4.1)
if(APPLE)
set(CMAKE_CXX_COMPILER /usr/local/bin/g++-15)
set(LLVM_ROOT /usr/local/Cellar/llvm/20.1.6)
# FIXME: NO usable! set(CMAKE_CXX_COMPILER ${LLVM_ROOT}/bin/clang++)
endif()
if($ENV{CXX} MATCHES "clang" OR CMAKE_CXX_COMPILER MATCHES "clang")
set(ENV{CXXFLAGS} -stdlib=libc++)
endif()
if(NOT DEFINED CMAKE_CXX_STANDARD)
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS ON)
endif()
set(CMAKE_SKIP_TEST_ALL_DEPENDENCY FALSE)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
if(CMAKE_VERSION VERSION_LESS 4.0.3)
# cmake v4.0.2:
set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD a9e1cf81-9932-4810-974b-6eccaf14e457)
else()
# cmake release branch
set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD d0edc3af-4c50-42ea-a356-e2862fe7a444)
endif()
unset(CMAKE_CXX_MODULE_STD)
# Ensure non-empty default build type for single-config
get_property(isMultiConfig GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
if(NOT isMultiConfig)
set(CMAKE_BUILD_TYPE Debug CACHE STRING "Build type")
endif()
set(CMAKE_DEBUG_POSTFIX _debug)
####################################################
project(example-modules VERSION 0.1.0 LANGUAGES CXX)
####################################################
if(APPLE AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
add_link_options(-L${LLVM_ROOT}/lib/c++)
endif()
set(CMAKE_CXX_VISIBILITY_PRESET hidden)
set(CMAKE_VISIBILITY_INLINES_HIDDEN TRUE)
add_library(Algo SHARED)
target_sources(
Algo
PRIVATE algo-impl.cpp
PUBLIC FILE_SET CXX_MODULES FILES algo-interface.cppm
)
target_compile_features(Algo PUBLIC cxx_std_23)
include(GenerateExportHeader)
generate_export_header(Algo)
target_sources(
Algo
PUBLIC
FILE_SET HEADERS
BASE_DIRS ${CMAKE_CURRENT_BINARY_DIR}
FILES ${CMAKE_CURRENT_BINARY_DIR}/algo_export.h
)
add_executable(algo-example algo-example.cpp)
target_link_libraries(algo-example PRIVATE Algo)
enable_testing()
add_test(NAME algo-example COMMAND algo-example)
include(GNUInstallDirs)
install(
TARGETS Algo
EXPORT Algo
FILE_SET HEADERS
FILE_SET CXX_MODULES
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package/src
CXX_MODULES_BMI
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package/bmi-$
# Other things to install
)
install(
EXPORT Algo
DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/my_package
FILE algo-targets.cmake
NAMESPACE Algo
CXX_MODULES_DIRECTORY
algo
)
# Tell CMake that we explicitly want `import std`.
# This will initialize the property on all targets declared after this to 1
if(26 IN_LIST CMAKE_CXX_COMPILER_IMPORT_STD)
set(CMAKE_CXX_MODULE_STD ON)
else()
return()
endif()
if(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
return()
endif()
add_executable(import-std main.cpp)
add_test(NAME import-std COMMAND import-std)
add_library(demo)
target_compile_features(demo PUBLIC cxx_std_26)
target_sources(demo PUBLIC FILE_SET CXX_MODULES FILES demo.cppm)
add_executable(demo-example main2.cpp)
target_link_libraries(demo-example PRIVATE demo)
add_test(NAME demo-example COMMAND demo-example)
```
---
### Author:  [@vito.gamberini](https://discourse.cmake.org/u/vito.gamberini)
#### Post date: [July 6, 2025, 5:05pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/15 "2025-07-06T17:05:17Z")
I believe these are broadly upstream and packaging bugs based on logs.
There’s nothing for CMake to do if the given compiler cannot provide a correct P3286 file describing the stdlib.
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [July 6, 2025, 8:07pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/16 "2025-07-06T20:07:51Z")
- I agree, but what is with upstream meant: `ubuntu` or `gcc` project?
- Is the a ticket at upstream?
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### Author:  [@vito.gamberini](https://discourse.cmake.org/u/vito.gamberini)
#### Post date: [July 6, 2025, 8:53pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/17 "2025-07-06T20:53:50Z")
Whoever packaged the compiler.
If the packagers need support for their use case from the compiler, ex, they need to be able to tell the compiler “I’m going to put these files here” to make `-print-file-name` work, then it is on the packagers to communicate that the various compiler upstreams.
The compiler upstreams can decide on a case-by-case basis if they want to support the packagers conventions, or if it is on the packagers to align themselves with the compiler’s expectations.
CMake’s involvement begins and ends at `-print-file-name`. We 100% need better error messages if the path we get from `-print-file-name` is invalid, or the P3286 file contains bogus metadata, but we can’t “fix” that.
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### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [July 7, 2025, 6:21pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/18 "2025-07-07T18:21:31Z")
whatever you mean with packagers?
this is at leased one [Bug #2111585 “libstdc++.modules.json contains wrong paths” : Bugs : gcc-15 package : Ubuntu](https://bugs.launchpad.net/ubuntu/+source/gcc-15/+bug/2111585)
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### Author:  [@vito.gamberini](https://discourse.cmake.org/u/vito.gamberini)
#### Post date: [July 7, 2025, 6:41pm UTC](https://discourse.cmake.org/t/no-sources-given-to-target-cmake-cxx26-on-ubuntu-25-04/14240/19 "2025-07-07T18:41:16Z")
Yep, that’s an example of a packager bug report, as Ubuntu is a packager of GCC.
For any packager who has a bugged compiler package, it’s on them to figure out how to fix their package.
Obviously we’re here to help anyone who needs it, but CMake can’t be arbitrarily re-arranging files in a given distro’s package.