Last call for bikeshedding on attribute sym/exalias/reverse_alias

[Alexandre Oliva <oliva@adacore.com>]

Since 2020 I've been trying to introduce an attribute that operates a
bit like alias, but instead of defining a declaration as an alias to
another defined declaration, it merely exposes the present declaration
with an alternate mnemonic symbol name, so that it can be further
aliased, imported or referenced elsewhere with an invariant name, rather
than with a mangled name.  E.g.:

// C++
namespace foo {
  int __attribute__ ((__???__ ("FOOVAR")))
  var = 42; // FOOVAR is an asm alias to the mangled name for foo::var
}

--  Ada
package Foo is
  Var : Integer;
  pragma Import (CPP, FooVar, "FOOVAR");
  --  use the mnemonic alias rather than the mangled name.


The implementation also handles C++ cdtors, modifying the mnemonic alias
of each clone so that they don't clash, and typeinfo objects generated
for classes when the attribute is associated with a class.


There don't seem to be objections to the feature per se, but discussions
about it have invariably got stuck in debating the attribute name.

https://gcc.gnu.org/pipermail/gcc-patches/2020-August/551614.html
https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624560.html
https://gcc.gnu.org/pipermail/gcc-patches/2023-July/624977.html


The customer report that motivated this development didn't require its
full generality, and asm("symbol") satisfies it.  But I've implemented
the feature, I find it useful, others seem to have liked it, and so I'd
like it to find its way into GCC.  However, I'm advised to not spend
much more time on it.

So, instead of updating the patch for every suggested attribute name, my
last-attempt plan is to try to reach consensus on the attribute name,
and then adjust the patch and submit it one more time.  If that doesn't
succeed, I'll leave it for anyone else to take it from there.

Attribute sym, named after symver, is the one in the latest version of
the patch.  mnemonic_alias, convenience_alias and asm_alias are other
possibilities that comes to mind.  The 2020-August thread has many more.

-- 
Alexandre Oliva, happy hacker            https://FSFLA.org/blogs/lxo/
   Free Software Activist                   GNU Toolchain Engineer
More tolerance and less prejudice are key for inclusion and diversity
Excluding neuro-others for not behaving ""normal"" is *not* inclusive