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From: "kallisti5 at unixzen dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug go/113143] Remove usage of ucontext.h
Date: Tue, 26 Dec 2023 13:13:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113143

--- Comment #3 from Alexander von Gluck <kallisti5 at unixzen dot com> ---
Good call out.  It looks like in 2004 these functions were flagged as
obsolescent though:
https://pubs.opengroup.org/onlinepubs/009695399/functions/makecontext.html

Here's the note on it in the linux man page for getcontext:
"
  glibc 2.1.  SUSv2, POSIX.1-2001.  Removed in POSIX.1-2008, citing
  portability issues, and recommending that applications be
  rewritten to use POSIX threads instead.
"


upstream go usage:

* makecontext: no code matches as of go 1.22 (main)
* getcontext:  netbsd,solaris,freebsd code usage as of go 1.22 (main)
* setcontext:  netbsd,freebsd code usages as of go 1.22 (main)
* swapcontext: freebsd code usages as of go 1.22 (main)


Per the 2004 spec:

"The obsolescent functions getcontext(), makecontext(), and swapcontext() c=
an
be replaced using POSIX threads functions."

Essentially, for quite some time, (get|make|set)context are only used on the
BSD's and Solaris... thus invocation of include<ucontext.h> should be guard=
ed /
masked off on all other platforms.=