MaskRay added inline comments.
================
Comment at: clang/tools/driver/CMakeLists.txt:123
+
+check_linker_flag("-Wl,-z,relax=transtls" LINKER_SUPPORTS_Z_RELAX_TRANSTLS)
----------------
ro wrote:
> 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.
> warning: -z.* ignored
Doesn't this stop working if binutils starts to use `error: -z.* ignored`?
Isn't there a way to call `check_linker_flag` only when the target is Solaris?
Does `LLVM_LINKER_IS_SOLARISLD` work?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91605/new/
https://reviews.llvm.org/D91605
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