C++ module sources should not be included by any other TUs, so their
presence cannot matter for order-only dependencies of the entire target.
Exclude them.
Update CMP0154 to take this into consideration and add tests to the
`CXXModules` suite (which already deals with module support detection).
Under CMP0155's NEW behavior, projects that explicitly enable C++20
support with `set(CMAKE_CXX_STANDARD 20)` may also explicitly
disable scanning with `set(CMAKE_CXX_SCAN_FOR_MODULES OFF)`.
We already propagate `CMAKE_CXX_STANDARD` into `try_compile` test
projects, so propagate `CMAKE_CXX_SCAN_FOR_MODULES` too.
Fixes: #25313
Now that scanning support is no longer experimental, the logic for
whether or not to scan C++ 20 sources is now important because all
projects are now exposted to the logic. Make the scanning rules explicit
in the documentation and rework the queries to localize all of the
associated logic.
A policy to handle the ultimate fallback logic will be implemented in a
following commit.
42654cc818 Tests/CXXModules: add tests for modules with include requirements
7217cb78cf Tests/CXXModules: relax line number matching in stderr
b3d1bbbbcc cmExportFileGenerator: relocate include directories for C++ modules
349ff8b080 cmGeneratorTarget: remove not-INTERFACE assertion
681a763425 cmGeneratorTarget: use a character literal
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !8838
Previously an internal error was raised which ended up causing an
internal exception to be thrown. This is a typo situation that should
fall into an explicit error.
Fixes: #25207
571b5e1f2c cxxmodules: improve error messages for C++ module setup
8b4d32c18b cmStandardLevelResolver: add query for the effective standard level
17ddc4ac76 cmStandardLevelResolver: compare with static string literals
6f1dae2b01 cmStandardLevelResolver: use `cmStrCat` where possible
0d45d40e13 cmStandardLevelResolver: use character literals where possible
Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !8755
When consuming exported targets which contain C++ modules, the consuming
project must be able to recompile BMI files using the original target's
flags. This is because a module source may use some private target usage
requirement but not want to propagate it to consumers. To facilitate
this, export the private information as necessary for consumers to be
able to perform the BMI compilations.
Clang 17 is in a transition where it warns about transitive usages. Turn
it into an error if the flag is available to make sure we're testing the
feature properly.
When multiple source files in a single target have the same name, we
already set `ObjectFileName` explicitly to avoid a `.obj` collision. For
C++ module sources, set `Module{Output,Dependencies}File` to avoid
`.ifc` and `.module.json` collisions.
Fixes: #25038
When generating the `IMPORTED_CXX_MODULES_[CONFIG]` target property,
there was a missing path separator after a non-empty relative directory
part of the path to a module source file.
Co-authored-by: Brad King <brad.king@kitware.com>
Calling `install(EXPORT)` with the `CXX_MODULES_DIRECTORY` parameter
leads to installation rules being generated which `include()` CMake
scripts that set the `IMPORTED_CXX_MODULES_[CONFIG]` target property for
relevant targets. However, these scripts don't get generated for
targets in an export set which don't have any C++20 modules. When the
installation rules attempt to `include()` the missing scripts, the
install fails.
Co-authored-by: Brad King <brad.king@kitware.com>
Ben Boeckel