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

[Stuart Anderson <anderson@netsweng.com>]

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