libbacktrace integration for _GLIBCXX_DEBUG mode

[François Dumont]

Here is a new proposal which I think take into account all your remarks.

I discovered the great "%.*s" printf format so I was able to do some 
cleanup on the function name without any allocation.

I also agree that counting the '>' or '<' is not reliable so I remove 
this and limit the cleanup to the __cxx1998 namespace and the __ 
uglification, it is still better than nothing.

I complete the doc as advised. I also added a note about making sure 
that _GLIBCXX_DEBUG_BACKTRACE is defined consistently throughout the 
application otherwise it would break the famous ODR rule.

I introduced a _GLIBCXX_DEBUG_USE_LIBBACKTRACE to know when the system 
is able to handle libbacktrace even if the user didn't activate it. I 
could undef if when I am not building the library but I don't remember 
if there is a macro to signal that library is being built ?

Here is an output sample now:

/home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:177:
In function:
 Â Â Â  gnu_debug::basic_string<_CharT, _Traits, 
_Allocator>::basic_string(const
 Â Â Â  _CharT*, gnu_debug::basic_string<_CharT, _Traits,
 Â Â Â  _Allocator>::size_type, const _Allocator&) [with _CharT = char; 
_Traits
 Â Â Â  = std::char_traits<char>; _Allocator = std::allocator<char>;
 Â Â Â  gnu_debug::basic_string<_CharT, _Traits, _Allocator>::size_type = long
 Â Â Â  unsigned int]

Backtrace:
 Â Â Â  0x400afd char const* gnu_debug::check_string<char, unsigned 
long>(char const*, unsigned long, char const*, unsigned int, char const*)
/home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:56
 Â Â Â  0x400afd char const* gnu_debug::check_string<char, unsigned 
long>(char const*, unsigned long, char const*, unsigned int, char const*)
/home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:49
 Â Â Â  0x400afd gnu_debug::basic_string<char, std::char_traits<char>, 
std::allocator<char> >::basic_string(char const*, unsigned long, 
std::allocator<char> const&)
/home/fdt/dev/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/debug/string:177
 Â Â Â  0x400afd test01()
/home/fdt/dev/gcc/git/libstdc++-v3/testsuite/21_strings/basic_string/debug/1_neg.cc:27
 Â Â Â  0x4009c8 main
/home/fdt/dev/gcc/git/libstdc++-v3/testsuite/21_strings/basic_string/debug/1_neg.cc:32

Error: __s != 0 || __n == 0.
XFAIL: 21_strings/basic_string/debug/1_neg.cc execution test

 Â Â Â  * include/debug/formatter.h [_GLIBCXX_DEBUG_BACKTRACE]:
 Â Â Â  Include <backtrace-supported.h>.
 Â Â Â  [_GLIBCXX_DEBUG_BACKTRACE && BACKTRACE_SUPPORTED]:
 Â Â Â  Include <backtrace.h>.
 Â Â Â  [(!_GLIBCXX_DEBUG_BACKTRACE || !BACKTRACE_SUPPORTED) &&
 Â Â Â  _GLIBCXX_USE_C99_STDINT_TR1]: Include <stdint.h>.
 Â Â Â  [BACKTRACE_SUPPORTED || _GLIBCXX_USE_C99_STDINT_TR1]
 Â Â Â  (_GLIBCXX_DEBUG_USE_LIBBACKTRACE): New.
 Â Â Â  [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_error_cb): New.
 Â Â Â  [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_full_cb): New.
 Â Â Â  [_GLIBCXX_DEBUG_USE_LIBBACKTRACE](__backtrace_state): New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_Bt_full_t):
 Â Â Â  New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_print_backtrace):
 Â Â Â  New.
[_GLIBCXX_DEBUG_USE_LIBBACKTRACE](_Error_formatter::_M_backtrace_state):
 Â Â Â  New.
 Â Â Â  [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
 Â Â Â  (_Error_formatter::_M_backtrace_full_func): New.
 Â Â Â  * src/c++11/debug.cc: Include <cstring>.
 Â Â Â  (_Print_func_t): New.
 Â Â Â  (print_word): Use '%.*s' format in fprintf to render only expected
 Â Â Â  chars.
 Â Â Â  (print_raw(PrintContext&, const char*, ptrdiff_t)): New.
 Â Â Â  (print_function(PrintContext&, const char*, _Print_func_t)): New.
 Â Â Â  (print_type): Use latter.
 Â Â Â  (print_string(PrintContext&, const char*, const _Parameter*, size_t)):
 Â Â Â  Change signature to...
 Â Â Â  (print_string(PrintContext&, const char*, ptrdiff_t, const _Parameter*,
 Â Â Â  size_t)): ...this and adapt. Remove intermediate buffer to render input
 Â Â Â  string.
 Â Â Â  (print_string(PrintContext&, const char*, ptrdiff_t)): New.
 Â Â Â  [_GLIBCXX_DEBUG_USE_LIBBACKTRACE]
 Â Â Â  (print_backtrace(void*, uintptr_t, const char*, int, const char*)): 
New.
 Â Â Â  (_Error_formatter::_M_error()): Adapt.
 Â Â Â  * doc/xml/manual/debug_mode.xml: Document _GLIBCXX_DEBUG_BACKTRACE.
 Â Â Â  * doc/xml/manual/using.xml: Likewise.

Tested under Linux x86_64 normal and debug modes.

Ok to commit ?

François


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