The original addition of CMD_INSTALL_ABSOLUTE_DIR by commit
39a56136a3 (Diagnostic: Add warn or error on absolute install paths,
2026-03-25) didn't cover all install signatures. Add checks to cover
those install types that weren't covered by the original commit.
Usage effects describe the relationship between a provider and a
consumer of C++ module interface units. They encompass the flags and
features used to construct BMIs for those units. If the usage effects of
a provider and consumer match, then the provider's BMI may be reused
as-is. If they do not match, then a synthetic target describing the
interface units with the consumer's usage effects applied must be
created.
This commit makes three major changes to how usage effects are reified
in CMake. The first is simple, usage effect hashes now use compile
options and features as the input to their hash instead of the consumer
name. A simply warning flag filter is also applied, mostly to
demonstrate the mechanism. This is the "correct calculation" for usage
effects.
The second is more impactful, usage effects now entirely replace the
compile options of providers with those of consumers if unmatched.
Compile definitions, includes, and links remain unchanged. This is
necessary to ensure successful builds, but is a tricky semantic change.
The third is mostly source-facing, the discovery model for CxxModule
synthetic targets is no longer the global target namespace. Instead,
non-synthetic targets manage their synthetic derivatives. Every target
maintains a usage effect-keyed cache of synthetic targets. When
determining if a synthetic target is necessary, a given provider checks
for compatibility with itself, then for presence in the cache, and if
the cache misses a new synthetic target is created.
Fixes: #27597
Add new diagnostic categories CMD_POLICY and CMD_EXPERIMENTAL, both as
children of CMD_AUTHOR. Use the former when issuing policy warnings. Use
the latter when issuing experimental feature warnings.
Tweak `cmMessenger` to also show the "warning is for project developers"
notice for all diagnostics that are descendants of the `CMD_AUTHOR`
category. When doing so, also show both command-line options which can
suppress the message.
Update expected test output to account for the new format of diagnostic
messages. These changes were applied entirely by `sed` using the
following commands:
- `/Use -Wno-dev to suppress/s/-Wno-dev/-Wno-author/g`
- `s/Warning [\\][(]dev[\\][)]/Warning \\(author\\)/g`
- `s/CMake Deprecation Warning/CMake Warning \\(deprecated\\)/g`
This is not a complete fix, but covers a significant fraction of the
needed changes, and this commit is strictly automated changes.
Several problems with this feature came up while testing 4.3.0-rc1.
These include both broken stdlib distributions and regressions in our
implementation of the feature since CMake 4.2.
Revert commit 70c1f0f43d (Experimental: Remove import std experimental
gate, 2026-02-04, v4.3.0-rc1~61^2) except for its incidental fixes.
Remove the 4.3 release notes related to `import std`.
Rotate the experimental gate's UUID.
Issue: #27426
Issue: #27597
Issue: #27626
Issue: #27635
The OLD behaviors of all policies are deprecated, but only by
documentation. Add an explicit deprecation diagnostic for policies
introduced in CMake 3.28 and below to encourage projects to port
away from setting policies to OLD.
Support the module manifest format added in !11422 as an output format
of dyndep collation for exports. This is necessary for CPS support of
modules, as CPS uses module manifests to describe C++20 modules.
Additionally, adds some CMake-vendor fields to the module manifest to
support compile-options and compile-features on module sources.
Adds a parser and serializer for the EcoStd Module Metadata format
RFC: https://github.com/ecostd/rfcs/pull/3
This adapts the existing experimental support for import std; to use
the new parser. The CMAKE_CXX_STDLIB_MODULES_JSON is now the canonical
variable for controlling how CMake discovers the stdlib module metadata,
and is used directly by compiler detection.
Toolchains can still override the __CMAKE::CXX## targets if they wish,
either in conjunction with CMAKE_CXX_STDLIB_MODULE_JSON or not. It is
possible to disable automatic detection of
CMAKE_CXX_STDLIB_MODULE_JSON by setting it to the empty string.
When available, the CMAKE_CXX_STDLIB_MODULE_JSON will be used to create
all requested C++ stdlibs which do not already have targets.
Clang 21 now enforces placement of the module declaration:
.../scan_properties/module.cxx:7:8: error: module
declaration must occur at the start of the translation unit
When targeting the MSVC ABI, define `_MBCS` by default if the project
does not define `_SBCS` or `_UNICODE`. Visual Studio has long defined
one of the three character set macros automatically. For consistency,
define it when compiling for the MSVC ABI with other generators.
Add policy CMP0204 for compatibility.
Fixes: #27275
Since it can be set in the environment when running the test suite,
guard tests which are sensitive to intermediate directory strategy
changes with explicit settings.
In tests that compare multiple files, knowing which file(s) errors come
from is difficult. Log the actual filepaths when this occurs to help
debugging.
Account for changes to upstream ninja:
* commit `5d93f2da28` (Add exit code to the failed target, 2024-12-03)
* commit `311bf93416` (Propagate jobs' exit codes to the ninja's exit code,
2024-12-03)
In commit 9c0491a3e4 (cmDyndepCollation: write out scanned source
information too, 2024-03-25) via !9708, the `sf_map` gained a new job of
also being used to track non-file set sources which could import
modules. This was implemented by removing processed `FILE_SET TYPE
CXX_MODULES` sources from the map and working with the sources
remaining. When a `FILE_SET TYPE CXX_MODULES` source appeared multiple
times, this would then erroneously complain that it "was not scheduled
for compilation". Use a set of source paths to track sources that have
already been processed. If duplicates are found, trigger an author
warning and skip the duplicate file.
Fixes: #26549
854eba0c53 target_sources: Improve error message for CXX_MODULES on INTERFACE libraries
cd179e7560 Tests/RunCMake/CXXModules: Rename FileSetModules cases to be more specific
Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !10090
854eba0c53 target_sources: Improve error message for CXX_MODULES on INTERFACE libraries
cd179e7560 Tests/RunCMake/CXXModules: Rename FileSetModules cases to be more specific
Acked-by: Kitware Robot <kwrobot@kitware.com>
Tested-by: buildbot <buildbot@kitware.com>
Merge-request: !10090
We support non-compiled `SOURCES` on `INTERFACE` libraries, and also
support `CXX_MODULES` on *imported* `INTERFACE` libraries (via synthetic
targets that compile module interface units). However, we do not
support `CXX_MODULES` on non-imported `INTERFACE` libraries because
there is no place to hold module interface unit's object files for their
module initializers. Previously this was not explicitly rejected, and
so was diagnosed only by "CMake Internal Error" messages due to
assumption violations in the implementation.
Fixes: #26524
Co-authored-by: Ben Boeckel <ben.boeckel@kitware.com>
Marc Chevrier
Vito Gamberini
Vito Gamberini
Robert Maynard
Ben Boeckel
Matthew Woehlke
Brad King
AJIOB
Hanna Rusakovich