[Bug testsuite/29138] New: [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[Bug testsuite/29138] New: [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

            Bug ID: 29138
           Summary: [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp:
                    _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string
           Product: gdb
           Version: 12.1
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

With trunk, I see:
...
FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r
std::string
FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: lang=c: break
f(std::string) (got interactive prompt)
FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: lang=c++: break
f(std::string) (got interactive prompt)
...

First FAIL in more detail:
...
(gdb) set language c++^M
(gdb) PASS: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: set
language c++
whatis /r std::string^M
No symbol "string" in namespace "std".^M
(gdb) FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r
std::string
...

Passes with:
- gcc 11.2.1
- gcc 10.3.0
- gcc 9.3.1
Fails with:
- gcc 8.2.1
- system gcc 7.5.0.

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |palves at sourceware dot org

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
So, with gcc-8, I have:
...
$ gdb -q -batch outputs/gdb.cp/break-f-std-string/break-f-std-string-1.o -ex
"set language c++" -ex "whatis /r std::string"
No symbol "string" in namespace "std".
...
but using std::__cxx11::string instead works:
...
$ gdb -q -batch outputs/gdb.cp/break-f-std-string/break-f-std-string-1.o -ex
"set language c++" -ex "whatis /r std::__cxx11::string"
type = std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >
...

Whereas with gcc-9, I have instead a failure using std::__cxx11::string:
...
$ gdb -q -batch outputs/gdb.cp/break-f-std-string/break-f-std-string-1.o -ex
"set language c++" -ex "whatis /r std::__cxx11::string"
No symbol "string" in namespace "std::__cxx11".
...
and using std::string works:
...
$ gdb -q -batch outputs/gdb.cp/break-f-std-string/break-f-std-string-1.o -ex
"set language c++" -ex "whatis /r std::string"
type = std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >
...

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Could be related to gcc commit:
...
commit 33b43b0d8cd2de722d177ef823930500948a7487
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Oct 9 14:06:46 2018 +0100

    Define std::string and related typedefs outside __cxx11 namespace
...

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[pedro at palves dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

Pedro Alves <pedro at palves dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pedro at palves dot net

--- Comment #3 from Pedro Alves <pedro at palves dot net> ---
Sounds like it, yes.  Thanks tracking that down.

I'm not sure off hand what is the best fix.  

I mean, it's probably something around skipping the test for gcc < 8 (C++11 ABI
support was added around GCC 5 IIRC, but older ones should just test the same
thing twice so pointless to let them run the _GLIBCXX_USE_CXX11_ABI=1 tests) or
something.

Or maybe the testcase .cc file could define std::string typedef itself on such
compilers.  

We could test std::__cxx11::string too, though that wouldn't exercise the
original issue the testcase ran into, with the special mangling feature for
"std::string", so seems a bit pointless too.

Or something else.

In any case, it doesn't look like a GDB bug.

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[pedro at palves dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

--- Comment #4 from Pedro Alves <pedro at palves dot net> ---
"older ones should" -> "older ones WOULD"

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
(In reply to Pedro Alves from comment #3)
> Or maybe the testcase .cc file could define std::string typedef itself on
> such compilers.  

Gave that a try:
https://sourceware.org/pipermail/gdb-patches/2022-May/189006.html

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[Bug testsuite/29138] [gdb/testsuite] FAIL: gdb.cp/break-f-std-string.exp: _GLIBCXX_USE_CXX11_ABI=1: whatis /r std::string

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29138

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
            Version|12.1                        |HEAD
   Target Milestone|---                         |13.1

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c8a9e88bf6ff32d90d082d07d3c5d12b938f8335

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