[committed] libstdc++: Fix std::any pretty printer

[committed] libstdc++: Fix std::any pretty printer

[Jonathan Wakely]

Tested x86_64-linux, with GDB 12.1. Pushed to trunk.

-- >8 --

The recent changes to FilteringTypePrinter affect the result of
gdb.lookup_type('std::string') in StdExpAnyPrinter, causing it to always
return the std::__cxx11::basic_string specialization. This then causes a
gdb.error exception when trying to lookup the std::any manager type for
a specliaization using that string, but that manager was never
instantiated in the program. This causes FAILs when running the tests
with -D_GLIBCXX_USE_CXX11_ABI=0:

FAIL: libstdc++-prettyprinters/libfundts.cc print as
FAIL: libstdc++-prettyprinters/libfundts.cc print as

The ugly solution used in this patch is to repeat the lookup for every
type that std::string could be a typedef for, and hope it only works for
one of them.

libstdc++-v3/ChangeLog:

	* python/libstdcxx/v6/printers.py (StdExpAnyPrinter): Make
	expansion of std::string in manager name more robust.
---
 libstdc++-v3/python/libstdcxx/v6/printers.py | 31 ++++++++++++++++++--
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 19c70d12035..1abf0a4bce3 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -1272,9 +1272,34 @@ class StdExpAnyPrinter(SingleObjContainerPrinter):
             mgrname = m.group(1)
             # FIXME need to expand 'std::string' so that gdb.lookup_type works
             if 'std::string' in mgrname:
-                mgrname = re.sub("std::string(?!\w)", str(gdb.lookup_type('std::string').strip_typedefs()), m.group(1))
-
-            mgrtype = gdb.lookup_type(mgrname)
+                # This lookup for std::string might return the __cxx11 version,
+                # but that's not necessarily the one used by the std::any
+                # manager function we're trying to find.
+                strings = {str(gdb.lookup_type('std::string').strip_typedefs())}
+                # So also consider all the other possible std::string types!
+                s = 'basic_string<char, std::char_traits<char>, std::allocator<char> >'
+                quals = ['std::', 'std::__cxx11::', 'std::' + _versioned_namespace]
+                strings |= {q+s for q in quals} # set of unique strings
+                mgrtypes = []
+                for s in strings:
+                    try:
+                        x = re.sub("std::string(?!\w)", s, m.group(1))
+                        # The following lookup might raise gdb.error if the
+                        # manager function was never instantiated for 's' in the
+                        # program, because there will be no such type.
+                        mgrtypes.append(gdb.lookup_type(x))
+                    except gdb.error:
+                        pass
+                if len(mgrtypes) != 1:
+                    # FIXME: this is unlikely in practice, but possible for
+                    # programs that use both old and new string types with
+                    # std::any in a single program. Can we do better?
+                    # Maybe find the address of each type's _S_manage and
+                    # compare to the address stored in _M_manager?
+                    raise ValueError('Cannot uniquely determine std::string type used in std::any')
+                mgrtype = mgrtypes[0]
+            else:
+                mgrtype = gdb.lookup_type(mgrname)
             self.contained_type = mgrtype.template_argument(0)
             valptr = None
             if '::_Manager_internal' in mgrname:
-- 
2.38.1