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
