Bug#169161: libstdc++5: Questionable type usage in mangled names

Daniel Jacobowitz dan@debian.org
Thu Nov 14 18:37:00 GMT 2002


forwarded 169161 libstdc++@gcc.gnu.org
thanks

This should presumably be reported to GCC rather than to us... 
Libstdc++ folks, please maintain the CC's.  Any thoughts?

On Thu, Nov 14, 2002 at 09:13:37PM -0500, Stuart Anderson wrote:
> Package: libstdc++5
> Version: 1:3.2.1-0pre6
> Severity: normal
> Tags: upstream
> 
> 
> Underlying types are used when creating the mangled name of symbols in C++. In
> libstdc++, many symbols contains the type mbstate_t. As encoded in the mangled
> name, the underlying type, __mbstate_t is used. When unmangled, this results
> in a different source name than what was used in the source.
> 
> Here is an example:
> 
> libstdc++ contains the symbol _ZNKSt7codecvtIcc11__mbstate_tE11do_encodingEv.
> c++filt de-mangles this as
> 
> 	std::codecvt<char, char, __mbstate_t>::do_encoding() const,
> 
> which is not the same thing as in the ISO C++ specification, which would be
> 
> 	std::codecvt<char, char, mbstate_t>::do_encoding() const
> 
> (ref ISO C++ 22.2.1.5). The difference is __mbstate_t vs mbstate_t.
> 
> It seem that an unmangling operation should produce the original source symbol.
> 
> This seems like it may be an ABI issue as the C++ headers produce different
> mangled symbol if headers other than GNU libc headers are used. We ran into
> this when testing the LSB development environment in conjunction with C++. The
> LSB description of mbstate_t is a typedef of an anonymous structure, and
> doesn't have the intermediate __mbstate_t as the glibc headers do. Since
> __mbstate_t doesn't seem to be present in the source standards, we didn't want
> to include it in the LSB descriptions.
> 
> 
> -- System Information:
> Debian Release: testing/unstable
> Architecture: i386
> Kernel: Linux bego 2.4.18 #25 Tue Aug 6 14:04:58 EDT 2002 i686
> Locale: LANG=C, LC_CTYPE=C
> 
> Versions of packages libstdc++5 depends on:
> ii  gcc-3.2-base               1:3.2.1-0pre6 The GNU Compiler Collection (base 
> ii  libc6                      2.3.1-3       GNU C Library: Shared libraries an
> ii  libgcc1                    1:3.2.1-0pre6 GCC support library.
> 
> -- no debconf information
> 
> 
> 
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> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer



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