This defines a new policy for removal of transitive includes.
The goal of the policy it to make it relatively easy to remove
headers when needed, but avoid breaking developers using and
vendors shipping libc++.
The method used is to guard transitive includes based on the
C++ language version. For the upcoming C++23 we can remove
headers when we want, but for other language versions we try
to keep it to a minimum.
In this code the transitive include of `<chrono>` is removed
since D128577 introduces a header cycle between `<format>`
and `<chrono>`. This cycle is indirectly required by the
Standard. Our cycle dependency tool basically is a grep based
tool, so it needs some hints to ignore cycles. With the input
of our transitive include tests we can create a better tool.
However that's out of the scope of this patch.
Note the flag `_LIBCPP_REMOVE_TRANSITIVE_INCLUDES` remains
unchanged. So users can still opt-out of transitives includes
entirely.
Reviewed By: #libc, ldionne, philnik
Differential Revision: https://reviews.llvm.org/D132284
It seems to have been added back in 761e42fa3d for Clang to use it,
however it seems to have never been used for that purpose, so it is
probably fine to remove it.
Differential Revision: https://reviews.llvm.org/D122330
Some headers which require the version header depend on other headers to
provide it. Include the version header in all top-level headers to make
sure a header cleanup can't remove the version header.
Note this doesn't add the version header to the c headers.
Reviewed By: #libc, Quuxplusone, ldionne
Differential Revision: https://reviews.llvm.org/D116172
The "root nodes" of the graph are displayed in bold. My intent here
was to bold just the public-API headers, e.g. <vector> and
<experimental/coroutine> and <stdlib.h>, but not helper headers
such as <__functional_base> and <__iterator/next.h>. However,
the recent mass helper-header-ification has exposed defects in
this logic: all the new helpers were ending up bolded! Fix this.
Also, add <__undef_macros> to the list of headers we don't display
by default (like <__config>); it's not interesting to see those edges.
Also, add a sample `dot` command line to the `--help` text.
Since we have a tool to detect cycles now; and since we're entering
a phase where people can easily introduce cycles by accident (D100682)
or by request (D90999), I think it's increasingly important to shift
the burden of detecting these cycles onto the buildbot instead of
the poor human reviewer.
Also, grep for non-ASCII characters (such as U+200B and U+00AD)
and hard tabs; don't let those get checked in.
Differential Review: https://reviews.llvm.org/D100703
My attempts to play around with the old graph_header_deps.py were mostly fruitless;
I needed to modify it in various ways to make it work, and then even when I got it
working, it generated pretty ugly graphs.
Old graph_header_deps.py (after my local changes to simplify the usage)
(producing https://i.imgur.com/zATrsaP.jpg )
mkdir foo
time ./graph_header_deps.py --libcxx-only -o foo --clang-command ~/llvm-project/build/bin/clang++
dot -Tpng < foo/all_headers.dot > old.png
file old.png
real 0m37.453s
old.png: PNG image data, 25882 x 3035, 8-bit/color RGBA, non-interlaced
New graph_header_deps.py
(producing https://i.imgur.com/ZU0G52U.png )
time ./graph_header_deps.py | dot -Tpng > new.png
file new.png
real 0m1.063s
new.png: PNG image data, 6162 x 1344, 8-bit/color RGBA, non-interlaced
Differential Revision: https://reviews.llvm.org/D99124
Mark de Wever
