The main problem here is that -*-version_min= was not being passed to
the compiler when building test cases. This can cause problems when
testing on devices running older OSs because Clang would previously
assume the minimum deployment target is the the latest OS in the SDK
which could be much newer than what the device is running.
Previously the generated value looked like this:
`-arch arm64 -isysroot
With this change it now looks like:
`-arch arm64 -stdlib=libc++ -miphoneos-version-min=8.0 -isysroot
This mirrors the setting of config.target_cflags on macOS.
This change is made for ASan, LibFuzzer, TSan, and UBSan.
To implement this a new get_test_cflags_for_apple_platform() function
has been added that when given an Apple platform name and architecture
returns a string containing the C compiler flags to use when building
tests. This also calls a new helper function is_valid_apple_platform()
that validates Apple platform names.
This is the third attempt at landing the patch.
The first attempt (r359305) had to be reverted (r359327) due to a buildbot
failure. The problem was that calling get_test_cflags_for_apple_platform()
can trigger a CMake error if the provided architecture is not supported by the
current CMake configuration. Previously, this could be triggered by passing
-DCOMPILER_RT_ENABLE_IOS=OFF to CMake. The root cause is that we were
generating test configurations for a list of architectures without checking if
the relevant Sanitizer actually supported that architecture. We now intersect
the list of architectures for an Apple platform with
<SANITIZER>_SUPPORTED_ARCH (where <SANITIZER> is a Sanitizer name) to
iterate through the correct list of architectures.
The second attempt (r363633) had to be reverted (r363779) due to a build
failure. The failed build was using a modified Apple toolchain where the iOS
simulator SDK was missing. This exposed a bug in the existing UBSan test
generation code where it was assumed that COMPILER_RT_ENABLE_IOS implied that
the toolchain supported both iOS and the iOS simulator. This is not true. This
has been fixed by using the list SANITIZER_COMMON_SUPPORTED_OS for the list
of supported Apple platforms for UBSan. For consistency with the other
Sanitizers we also now intersect the list of architectures with