The protobuf example would raise a "Policy CMP0077" warning and
protobuf tests would still be built, e.g. setting the variable is
ignored in latest CMake. Set an INTERNAL cache variable instead so
that CMP0077 warnings won't be triggered.
The CMAKE_VERIFY_INTERFACE_HEADER_SETS variable is intended to
be under the control of the user. It doesn't discriminate between
header sets defined in the main project and those defined by
dependencies brought into the build directly via FetchContent.
Developers will usually only be interested in verifying the main project's
header sets, not those from dependencies.
Make the variable effectively only enable header set verification of the
main project by turning it off during FetchContent_MakeAvailable() calls.
The user still has variables like CMAKE_PROJECT_INCLUDE and
CMAKE_PROJECT_<projectName>_INCLUDE available to them if they
want to enable verification of all or specific dependencies respectively.
Fixes: #23808
In c2044fdf3f (FetchContent: Respect the CMP0135 policy setting,
2022-06-02), the URL keyword was wrongly assumed to only have
a single value. Multiple URL values are allowed if they are all
non-local. Rework the logic to remove that incorrect assumption
and handle both single and multi-value URL combinations.
Fixes: #23792
The guide previously only focused on the find_package() command,
with a bias towards libraries. FetchContent was not mentioned at all.
Reorganise and update the existing content. Add new sections to cover
providing dependencies with FetchContent and dependency providers.
Improve discoverability of the guide by mentioning it at the beginning
of the find_package(), FetchContent and dependency provider docs.
The config used can be part of the path to the sub-build. On some
platforms, there are restrictions on the length of paths or file names.
Use Debug rather than Release because the former is shorter.
When CMAKE_CONFIGURATION_TYPES is left at its default, this also
makes the path the same as the previous default before 10865c8e5f
(FetchContent: Hard-code a config for the sub-build, 2022-05-01) .
If the main project overrides CMAKE_CONFIGURATION_TYPES such
that there is no Debug configuration, some multi-config generators
can fail because they might assume Debug by default (Visual Studio
might do this). Always specify the configuration for multi-config
generators so that we don't rely on any such defaults.
Fixes: #23177
Allow FetchContent_MakeAvailable() to try a call to
find_package() first, or redirect a find_package() call to
FetchContent_MakeAvailable(). The user can set variables
to control which of these are allowed or tried by default.
Fixes: #21687
This brings the patch step into line with all the others which already
had their own `USES_TERMINAL_<step>` keyword. All steps (including
patch) already have their own `LOG_<step>` keyword too, so the lack of
`USES_TERMINAL_PATCH` was inconsistent.
CMAKE_TLS_VERIFY, CMAKE_TLS_CAINFO, CMAKE_NETRC and
CMAKE_NETRC_FILE are now passed through to the underlying
ExternalProject sub-build. Previously, they were silently ignored.
Fixes: #22144
FetchContent_MakeAvailable() should be strongly preferred over
the direct use of FetchContent_Populate(). The latter was the only
method available before CMake 3.14, but the former is simpler and
offers more functionality. Restructure the docs and improve the
wording to steer the reader toward `FetchContent_MakeAvailable()`
as the preferred approach.
Also take the opportunity to pull out the variables that influence
behavior into their own section. They were easily missed when
buried in the docs for the FetchContent_Populate() command.
Refactoring of the ExternalProject and FetchContent modules moved
the commands into CMake scripts. This broke custom commands that
used shell redirection or special build tool variables of the form
$(MakeVar). Undo the sequence of commits that performed this
refactoring and follow-up fixes associated with it.
The following commits are reverted by this change:
4f3d1abbb4 (ExternalProject: Refactor pre-configure steps to support
no-target uses, 2021-02-05)
17e5516e60 (FetchContent: Invoke steps directly and avoid a separate
sub-build, 2021-01-29)
bd876f3849 (FetchContent: Restore patch command support,
2021-02-18)
404cddb7bb (ExternalProject: Fix misuse of IS_NEWER_THAN in
timestamp checks, 2021-02-21)
b0da671243 (FetchContent: Don't update timestamps if files don't
change, 2021-02-18)
Fixes: #21892
The cost of setting up and executing a separate sub-build to do the
download, update and patch steps required for FetchContent population
can be significant with some platforms and CMake generators. Avoid the
sub-build altogether by invoking the step scripts directly.
Previously, if no generator was set (e.g. population was being done in
script mode), a generator needed to be available on the default PATH.
Since we no longer use a sub-build, this restriction is also now gone.
Fixes: #21703
The git version should not change while CMake is running. When
using FetchContent with many dependencies, the repeated calls
to get the git version every time ExternalProject is used can be
measurable on some platforms. This commit queries that version
only once and then caches it in a global property for the rest of that
run. The git version can still safely change between runs because it
is not cached, only the GIT_EXECUTABLE location is cached.
Relates: #21703
A main scenario where this is needed is when a git operation
needs the password to a private key and asks for it on the
console. Without this change, such operations can appear to
hang indefinitely with no prompt if QUIET is in effect (which it
is by default).
Another scenario this addresses is when progress of a
download or update should be shown. Without this change,
all such progress is buffered with some generators and will
only be shown at the end, which defeats the purpose of logging
any progress to begin with.
Relates: #18238
