This is helpful on systems with multiple LLVM installations.
For example, OpenBSD ships with LLVM in the base system, but without
support for extra targets.
A full LLVM version can be installed using the ports system, but even
when it is, `cmake` is not going to pick it up unless `/usr/local` is
explicitly added to the `cmake` search paths.
Having the full `llvm-config` path printed on error is helpful to
understand that the detected LLVM version was not the expected one.
Without this, building from source caused:
CommandLine Error: Option 'mc-relax-all' registered more than once!
LLVM ERROR: inconsistency in registered CommandLine options
This is due to LLVM static libs compiled in multiple times. But without
the LLVM static libs on the linker line, it caused undefined symbol
linker errors.
So our hands are tied. Homebrew users will have to specify
`-DZIG_PREFER_CLANG_CPP_DYLIB`.
* don't unconditionally pass -lz3 for mingw builds. If mingw builds
require this then the llvm-config executable should put it as part of
--system-libs. If there is a bug and it does not do that, and we need
a workaround, then the workaround should be an explicit cmake option.
* don't link libstage2.a against -lntdll. This causes zig to set
`builtin.link_mode == .Dynamic` and include the TLS definitions,
which then collide with the mingw-w64 symbols. This should probably
be addressed separately, but for now this solves the problem and
there is no reason to link a static library against a DLL.
* Findllvm.cmake no longer treats the libraries as "optional" and will
emit a cmake error if one is not found. Additionally, the
not-required LLVM library LLVMTableGen is omitted.
Match package-name case from CMakeLists.txt .
New warning sample:
The package name passed to `find_package_handle_standard_args` (LLVM) does
not match the name of the calling package (llvm). This can lead to
problems in calling code that expects `find_package` result variables
(e.g., `_FOUND`) to follow a certain pattern.
Rather than `zig0 build ...` the build now does
`zig0 build-lib ...`, avoiding the requirement of linking the build
script, and thus avoiding the requirement of finding native libc,
for systems where libc is the system ABI.
Distro's llvm usually have a 6.0 suffix.Any custom llvm build
names the binary as llvm-config.Keeping 6.0 variant first causes
the distro's llvm to be compiled in place of a custom one even if
given using CMAKE_PREFIX_PATH.
