[libcxx-commits] [PATCH] D92131: [libc++] Attempt to fix spurious modules-related failures in the CI

Louis Dionne via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Wed Nov 25 13:18:44 PST 2020


ldionne created this revision.
Herald added subscribers: libcxx-commits, jkorous, arichardson.
Herald added a project: libc++.
Herald added a reviewer: libc++.
ldionne requested review of this revision.

I'm not 100% sure what the issue actually is since I can't reproduce it
locally, however what I explain in the comment is my best attempt to
explain what's going on.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92131

Files:
  libcxx/utils/libcxx/test/features.py


Index: libcxx/utils/libcxx/test/features.py
===================================================================
--- libcxx/utils/libcxx/test/features.py
+++ libcxx/utils/libcxx/test/features.py
@@ -40,7 +40,15 @@
   Feature(name='has-fobjc-arc',                 when=lambda cfg: hasCompileFlag(cfg, '-xobjective-c++ -fobjc-arc') and
                                                                  sys.platform.lower().strip() == 'darwin'), # TODO: this doesn't handle cross-compiling to Apple platforms.
   Feature(name='objective-c++',                 when=lambda cfg: hasCompileFlag(cfg, '-xobjective-c++ -fobjc-arc')),
-  Feature(name='modules-support',               when=lambda cfg: hasCompileFlag(cfg, '-fmodules')),
+
+  # Note: We use a custom modules cache path to make sure that we don't reuse
+  #       the default one, which can be shared across builds. This is important
+  #       because we define macros in headers files, and a change in these macros
+  #       doesn't seem to invalidate modules cache entries, which means we could
+  #       build against now-invalid cached headers from a previous build.
+  Feature(name='modules-support',
+          when=lambda cfg: hasCompileFlag(cfg, '-fmodules'),
+          actions=lambda cfg: [AddCompileFlag('-fmodules-cache-path=%t/ModuleCache')]),
 
   Feature(name='non-lockfree-atomics',
           when=lambda cfg: sourceBuilds(cfg, """


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