On 03/12/18 00:37 +0000, Iain Sandoe wrote:
Hi,
GCC does not export construction vtable symbols from shared libraries**.
The symbols are marked hidden in the objects; for Darwin that makes them also
external (“private_extern” is Darwin’s hidden) which means that they show up in
the list of possible symbols for export from libstdc++, and there are
sufficiently relaxed match conditions that they reach the exports list. When
Darwin’s static linker encounters them it generates a warning that they cannot
be exported. This patch prunes them from the list of symbols to be considered,
thus eliminating the warnings.
OK for trunk?
Yes, OK.
Iain
** This seems a design decision, rather than an ABI mandate - note that, on
Darwin at least, these symbols *are* visible in libc++.
libstdc++-v3/
* scripts/make_exports.pl (check names): Don’t try to export
construction
vtable symbols.
diff --git a/libstdc++-v3/scripts/make_exports.pl
b/libstdc++-v3/scripts/make_exports.pl
index 7c9e4e31d4..93100e17dd 100644
--- a/libstdc++-v3/scripts/make_exports.pl
+++ b/libstdc++-v3/scripts/make_exports.pl
@@ -103,6 +103,14 @@ NAME: while (<NM>) {
# Ignore undefined and local symbols.
next if (/^([^ ]+) [Ua-z] /);
+ # GCC does not export construction vtables from shared libraries.
+ # However the symbols are marked hidden, for Darwin that makes them
+ # also external "private_extern", which means that they show up in
+ # this list. When ld64 encounters them it generates a warning that
+ # they cannot be exported, so trim them from the set now.
+ next if (/^construction vtable.*$/);
+ next if (/^__ZTC.*$/);
+
