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Symbol versioning in C++ (two ld bugs)
- From: Phil Edwards <phil at jaj dot com>
- To: binutils at sources dot redhat dot com
- Cc: bkoz at redhat dot com, rth at redhat dot com
- Date: Mon, 11 Feb 2002 16:48:29 -0500
- Subject: Symbol versioning in C++ (two ld bugs)
[cc'd to the other people who have been involved so far]
None of what follows is mentioned in the current ld manual. Consider that
as bug #0, if you will. (I volunteer to update ld/ld.texinfo if y'all
will help me work these out.)
For libstdc++-v3 we need to start versioning the symbols of the shared
library. I am exploring the option of requiring GNU ld and making use
of the "extern 'lang'" extension in the version scripts. Right now I'm
playing with a --version-script consisting of
which binds everything in namespace std to version FOO. The problem is
that there are all kinds of things in std which we must make local; the
script above exposes (and versions!) std::__random_implementation_detail,
which is bad.
So I tried to list something like
and that's where the fun begins.
The parser routine which stores the symbol patterns for later comparison
is named "lang_new_vers_regex", implying that the symbol pattern is a
The routines which compare the pattern with a given symbol,
"lang_vers_match_lang_X" where X is c, cplsuplus, or java, all call
fnmatch() matches shell filename patterns, i.e., globbing, not regexps.
So: which kind of patterns are supposed to be accepted?
The ldlex.l lexer only specifies
for a version symbol pattern (see V_IDENTIFIER). No brackets, no ranges,
no braces -- that is, we can't even use the globbing patterns that fnmatch()
The only "wildcard" used in the examples in the manual is a trailing
'*', and there's no documentation of what exactly it's supposed to mean,
although I think I can guess in the presence of fnmatch().
Should I be trying things like
instead? That would seem exceptionally and needlessly pathetic. We ought
to be able to do better than that. :-)
For the record, std::* is not the only problem; there are other namespaces
and other patterns which also need to be exposed (the __cxa_* stuff for
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