[PATCH] D86166: sanitizer_common: Use void* for madvise first argument on Solaris.

[Rainer Orth via Phabricator via llvm-commits]

ro added a comment.

In D86166#2224690 <https://reviews.llvm.org/D86166#2224690>, @pcc wrote:

> @ro On D85870 <https://reviews.llvm.org/D85870> you mentioned that the declaration has been changed in Solaris 11.4 to use `void *` which causes a build break on 11.4 due to the incompatible declaration. I checked illumos and it looks like their declaration still has `caddr_t`, although the comment above this declaration implies that that shouldn't matter because the system's declaration isn't visible. But what about older versions of Solaris? Presumably they still have a declaration with `caddr_t` so I imagine the build would break with an incompatible declaration error there. Or do we not care about older versions?

As was discussed in D84046 <https://reviews.llvm.org/D84046>, Solaris doesn't need an explicit declaration **at all**: with `__EXTENSIONS__` defined, a declaration of `madvise` will be visible without doing anything special.

However, on Illumos with `_XOPEN_SOURCE` defined (as `g++` does on Solaris), **there is no way to make an `madvise` declaration visible**.  So on Illumos, it doesn't matter if it uses `void *` or `caddr_t` since there can be no conflict with a system declaration.  However the declaration currently needs to agree with the Solaris one to avoid the build breakage.

Part of the trouble is that we currently cannot distinguish between Solaris and Illumos at all at compile time; I have a patch to define `__illumos__` based on `uname -o` for cases where it's difficult otherwise. All a royal mess, but done **for the benefit** of Illumos, not for not caring about it.

With respect to other older versions of Solaris, the only one even remotely interesting (and the oldest one I still test in GCC) is 11.3.  I have a bunch of patches to at least allow LLVM to compile, but there are so many issues (`ld` not wrapping sections in `__start_<sec>/__stop_<sec>` symbols, lack of `__cxa_atexit`, lack of `fmemopen`, lack of constructor priority support, and that's just the tip of the iceberg) that I strongly doubt there's any value in trying to pursue this further.  In fact the 11.3 `madvise` declaration still using `caddr_t` prompted me to do the `__illumos__` patch so an Illumos-only declaration wouldn't interfere with Solaris.


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