In GCC, if `-B $prefix` is specified, `$prefix` is used to find executable files and startup files.
`$prefix/include` is added as an include search directory.
Clang overloads -B with GCC installation detection semantics which make the
behavior less predictable (due to the "largest GCC version wins" rule) and
interact poorly with --gcc-toolchain (--gcc-toolchain can be overridden by -B).
* `clang++ foo.cpp` detects GCC installation under `/usr`.
* `clang++ --gcc-toolchain=Inputs foo.cpp` detects GCC installation under `Inputs`.
* `clang++ -BA --gcc-toolchain=B foo.cpp` detects GCC installation under A and B and the larger version wins. With this patch, only B is used for detection.
* `clang++ -BA foo.cpp` detects GCC installation under `A` and `/usr`, and the larger GCC version wins. With this patch `A` is not used for detection.
This patch changes -B to drop the GCC detection semantics. Its executable
searching semantics are preserved. --gcc-toolchain is the recommended option to
specify the GCC installation detection directory.
(
Note: Clang detects GCC installation in various target dependent directories.
`$sysroot/usr` (sysroot defaults to "") is a common directory used by most targets.
Such a directory is expected to contain something like `lib{,32,64}/gcc{,-cross}/$triple`.
Clang will then construct library/include paths from the directory.
)
Differential Revision: https://reviews.llvm.org/D97993
When testing clang that has been compiled with `-DDEFAULT_SYSROOT` set to some path,
some tests would fail. Override sysroot to be empty string for the tests to succeed
when clang is configured with `DEFAULT_SYSROOT`.
Differential Revision: https://reviews.llvm.org/D66834
Patch by Sergej Jaskiewicz <jaskiewiczs@icloud.com>.
llvm-svn: 373147
-gcc-toolchain foo -> --gcc-toolchain=foo
-target foo -> --target=foo
I've added legacy aliases for the original spellings. I've updated the
canonical tests to check both spellings, and switched all of the
-gcc-toolchain usages elsewhere in the test suite to use the new one.
I've updated some of the usages of -target to the new syntax, but will
finish that in a separate entirely mechanical change once I'm sure this
won't get rolled back for some reason (It touches a *huge* number of RUN
lines in the test suite unsurprisingly).
A nice result is that the three most common flags I end up using when
doing cross compiles are all now consistent: --target=, --sysroot=, and
--gcc-toolchain=.
llvm-svn: 184408
the linker toolchainness a bit more thoroughly. It used to work this
way, but hit buildbot issues. Hopefully subsequent fixes have addressed
those problems, but I'll be watching the bots.
llvm-svn: 151090
Fangrui Song