ro added inline comments.
================
Comment at: clang/tools/driver/CMakeLists.txt:123
+
+check_linker_flag("-Wl,-z,relax=transtls" LINKER_SUPPORTS_Z_RELAX_TRANSTLS)
----------------
MaskRay wrote:
> ro wrote:
> > MaskRay wrote:
> > > ro wrote:
> > > > MaskRay wrote:
> > > > > GNU ld reports a warning instead of an error when an unknown `-z` is
> > > > > seen. The warning remains a warning even with `--fatal-warnings`.
> > > > > GNU ld reports a warning instead of an error when an unknown `-z` is
> > > > > seen. The warning remains a warning even with `--fatal-warnings`.
> > > >
> > > > Thanks for reminding me about that misfeature of GNU `ld`. I guess
> > > > `check_linker_flags` needs to be updated to handle that.
> > > > In the case at hand, it won't matter either way: the flag is only
> > > > passed to `ld`, which on Solaris is guaranteed to be the native linker.
> > > > Once (if at all) I get around to completing D85309, I can deal with
> > > > that. For now, other targets won't see linker warnings about this
> > > > flag, other than when the flag is used at build time.
> > > OK. Then I guess you can condition this when the OS is Solaris?
> > > OK. Then I guess you can condition this when the OS is Solaris?
> >
> > I fear not: `LINKER_SUPPORTS_Z_RELAX_TRANSTLS` is tested inside an `if` in
> > `Solaris.cpp`: this code is also compiled on non-Solaris hosts. Why are
> > you worried about the definition being always present?
> It is not suitable if LINKER_SUPPORTS_Z_RELAX_TRANSTLS returns a wrong result
> for GNU ld, even if it is not used for non-Solaris. We should make the value
> correct in other configurations.
> It is not suitable if LINKER_SUPPORTS_Z_RELAX_TRANSTLS returns a wrong result
> for GNU ld, even if it is not used for non-Solaris. We should make the value
> correct in other configurations.
Tell the binutils maintainers that ;-) While I'm still unconcerned about this
particular case (it's only used on a Solaris host where `clang` hardcodes the
use of `/usr/bin/ld`), I continue to be annoyed by GNU `ld`'s nonsensical (or
even outright dangerous) behaviour of accepting every `-z` option.
It took me some wrestling with `cmake` , but now `check_linker_flag` correctly
rejects `-z ` flags where GNU `ld` produces the warning.
Some caveats about the implementation:
- `check_cxx_compiler_flag` doesn't support the `FAIL_REGEX` arg, so I had to
switch to `check_cxx_source_compiles` instead.
- While it would be more appropriate to add the linker flag under test to
`CMAKE_REQUIRED_LINK_OPTIONS`, that is only present since `cmake` 3.14 while
LLVM still only requires 3.13.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91605/new/
https://reviews.llvm.org/D91605
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