`CMAKE_AUTOMOC_RELAXED_MODE` was added for backwards compatibility with KDE 4,
which had its last release in 2014. It does not offer additional features
but complicates the `AUTOMOC` code and dependency computation considerably.
Projects that use `CMAKE_AUTOMOC_RELAXED_MODE` functionality always got
extensive warnings during builds and tips on how to convert to regular mode,
which is trivial (see commit e474dcb231, CMake 2.8.7).
It's time to consider this feature deprecated and issue a warning at
configuration time as well.
This adds a configuration time deprecation `AUTHOR_WARNING` for
`CMAKE_AUTOMOC_RELAXED_MODE`.
New features
------------
CMake's `AUTOMOC` and `AUTOUIC` now cache information extracted when parsing
source files in `CMakeFiles/<ORIGIN>_autogen.dir/ParseCache.txt`.
This leads to faster `<ORIGIN>_autogen` target rebuilds, because source files
will be parsed again only if they're newer than the `ParseCache.txt` file.
The parse cache will be recomputed if it is older than the CMake executable.
`AUTOMOC` and `AUTOUIC` now check if `moc` or `uic` output files are older
than the `moc` or `uic` executable. If an output file is older than the
compiler, it will be regenerated. Therefore if a new `moc` or `uic` version
is installed, all output files will be regenerated.
`AUTOMOC` and `AUTOUIC` error and warning messages are more detailed.
Internal changes
----------------
`moc` and `uic` output file names are not computed in the `_autogen`
target anymore but in `cmQtAutoGenInitializer`. This makes the available at
the configuration stage for improved dependency computations (to be done).
In `AutogenInfo.cmake`, equally sized lists for "source file names",
"source file flags" and "compiler output file names" are passed to the
`_autogen` target. This replaces the separate file lists for
`AUTOMOC` and `AUTOUIC`.
Files times are read from the file system only once by using `cmFileTime`
instances instead of `cmQtAutoGenerator::FileSystem::FileIsOlderThan` calls.
All calls to not thread safe file system functions are moved to non concurrent
fence jobs (see `cmWorkerPool::JobT::IsFence()`). This renders the
`cmQtAutoGenerator::FileSystem` wrapper class obsolete and it is removed.
Instead of composing a single large settings string that is fed to the
`cmCryptoHash`, now all setting sub strings are fed one by one to the
`cmCryptoHash` and the finalized result is stored.
The `std::mutex` in `cmQtAutoGenerator::Logger` is tagged `mutable` and most
`cmQtAutoGenerator::Logger` methods become `const`.
Outlook
-------
This patch provides the framework required to
- extract dependencies from `.ui` files in `AUTOUIC`.
These will help to address issue
#15420 "AUTOUIC: Track uic external inputs".
- generate adaptive `make` and `ninja` files in the `_autogen` target.
These will help to address issue
#16776 "AUTOUIC: Ninja needs two passes to correctly build Qt project".
- generate (possibly empty) `moc` and `uic` files for all headers instead of a
`mocs_compilation.cpp` file.
This will help to address issue
#17277 "AUTOMOC: Provide a option to allow AUTOMOC to compile individual "
"moc_x.cxx instead of including all in mocs_compilation.cxx"
Don't pass the desired worker thread count to the `cmWorkerPool::Process()`
method but set it separately with the new `cmWorkerPool::SetThreadCount`
method. This allows calling `cmWorkerPool::Process()` repeatedly without
having to pass the thread count every time.
