Clang detects the GCC version from the libdir. However, modern
GCC versions only include the major version in the libdir
(something like lib/gcc/powerpc64le-linux-gnu/12/), not all
version components. For this reason, even though the system has
a supported libstdcxx, it will still fail the check against the
12.1.0 version requirement.
Fix this by doing the same thing we do for patch versions: Assume
that a missing minor version is larger than any specific version.
To allow this to be tested, we need to fix two additional issues:
First, the GCC toolchain directories used for testing need to
contain a crtbegin.o file to be properly detected. The existing
tests actually ended up using a 0.0.0 version, rather the intended
one. Second, we also need to satisfy the glibc version check based
on the dynamic linker. To do so, respect the --dyld-prefix argument
and add the necessary file to the test toolchain directory.
Differential Revision: https://reviews.llvm.org/D136258
--overlay-platform-toolchain inserts a whole new toolchain path with
higher priority than system default, which could be achieved by
composing smaller options. We need to figure out alternative solution
and what is missing among these basic options.
In some cases, we need to set alternative toolchain path other than the
default with system (headers, libraries, dynamic linker prefix, ld path,
etc.), e.g., to pick up newer components, but keep sysroot at the same
time (to pick up extra packages).
This change introduces a new option --overlay-platform-toolchain to set
up such alternative toolchain path.
Reviewed By: hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D121992
GCC 12 should have proper support for IEEE-754 compliant 128-bit
floating point in libstdc++. So warning is needed when linking against
older libstdc++ versions or LLVM libc++.
Glibc starts supporting float128 in both header and libraries since
2.32.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D112906
