[take 2] [libc++] Include <__config_site> from <__config>
Prior to this patch, we would generate a fancy <__config> header by
concatenating <__config_site> and <__config>. This complexifies the
build system and also increases the difference between what's tested
and what's actually installed.
This patch removes that complexity and instead simply installs <__config_site>
alongside the libc++ headers. <__config_site> is then included by <__config>,
which is much simpler. Doing this also opens the door to having different
<__config_site> headers depending on the target, which was impossible before.
It does change the workflow for testing header-only changes to libc++.
Previously, we would run `lit` against the headers in libcxx/include.
After this patch, we run it against a fake installation root of the
headers (containing a proper <__config_site> header). This makes use
closer to testing what we actually install, which is good, however it
does mean that we have to update that root before testing header changes.
Thus, we now need to run `ninja check-cxx-deps` before running `lit` by
hand.
This commit was originally applied in 1e46d1aa3 and reverted in eb60c487
because it broke the libc++abi and libunwind test suites. This has now
been fixed.
Differential Revision: https://reviews.llvm.org/D89041
GitOrigin-RevId: 5d796645d6c8cadeb003715c33e231a8ba05b6de
diff --git a/docs/TestingLibcxx.rst b/docs/TestingLibcxx.rst
index d42becf..ec017e2 100644
--- a/docs/TestingLibcxx.rst
+++ b/docs/TestingLibcxx.rst
@@ -26,8 +26,8 @@
After building libc++, you can run parts of the libc++ test suite by simply
running ``llvm-lit`` on a specified test or directory. If you're unsure
-whether the required libraries have been built, you can use the
-`check-cxx-deps` target. For example:
+whether the required targets have been built, you can use the `check-cxx-deps`
+target to build them. For example:
.. code-block:: bash
@@ -37,6 +37,12 @@
$ <build>/bin/llvm-lit -sv libcxx/test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test
$ <build>/bin/llvm-lit -sv libcxx/test/std/atomics libcxx/test/std/threads # Test std::thread and std::atomic
+In the default configuration, the tests are built against headers that form a
+fake installation root of libc++. This installation root has to be updated when
+changes are made to the headers, so you should re-run the `check-cxx-deps` target
+before running the tests manually with `lit` when you make any sort of change,
+including to the headers.
+
Sometimes you'll want to change the way LIT is running the tests. Custom options
can be specified using the `--param=<name>=<val>` flag. The most common option
you'll want to change is the standard dialect (ie -std=c++XX). By default the