Cleanup to simplify the formatter for std::map of libstdc++.

[sivachandra]

Summary

GCC does not emit some DWARF required for the simplified formatter
to work. A workaround for it has been incorporated in the formatter.
The corresponding test TestDataFormatterStdMap has also been enabled
for GCC.

[granata.enrico]

Looks good to me, assuming you're not going to need any of those lines you removed. The comment seems to imply they're clang-specific so you might be fine.

examples/synthetic/gnu_libstdcpp.py

try:
       self.Mt = self.valobj.GetChildMemberWithName('_M_t')
       self.Mimpl = self.Mt.GetChildMemberWithName('_M_impl')
       self.Mheader = self.Mimpl.GetChildMemberWithName('_M_header')
       
       map_type = self.valobj.GetType()
       if map_type.IsReferenceType():
         logger >> "Dereferencing type"
         map_type = map_type.GetDereferencedType()
-      
-      map_arg_0 = str(map_type.GetTemplateArgumentType(0).GetName())
-      map_arg_1 = str(map_type.GetTemplateArgumentType(1).GetName())
-      
-      logger >> "map has args " + str(map_arg_0) + " and " + str(map_arg_1)
-      
-      map_arg_0,fixed_0 = self.fixup_class_name(map_arg_0)
-      map_arg_1,fixed_1 = self.fixup_class_name(map_arg_1)
-      
-      logger >> "arg_0 has become: " + str(map_arg_0) + " (fixed: " + str(fixed_0) + ")"
-      logger >> "arg_1 has become: " + str(map_arg_1) + " (fixed: " + str(fixed_1) + ")"
-      
-      # HACK: this is related to the above issue with the typename for std::string
-      # being shortened by clang - the changes to typename display and searching to honor
-      # namespaces make it so that we go looking for std::pair<const std::basic_string<char>, ...>
-      # but when we find a type for this, we then compare it against the fully-qualified
-      # std::pair<const std::basic_string<char, std::char_traits... and of course fail
-      # the way to bypass this problem is to avoid using the std:: prefix in this specific case
-      if fixed_0 or fixed_1:
-        map_arg_type = "pair<const " + map_arg_0 + ", " + map_arg_1
-      else:
-        map_arg_type = "std::pair<const " + map_arg_0 + ", " + map_arg_1
-      
-      if map_arg_1[-1] == '>':
-        map_arg_type = map_arg_type + " >"
-      else:
-        map_arg_type = map_arg_type + ">"
-      
-      logger >> "final contents datatype is: " + str(map_arg_type)
-      
-      self.data_type = self.valobj.GetTarget().FindFirstType(map_arg_type)
-      
-      logger >> "and the SBType is: " + str(self.data_type)
+      # Get the type of std::pair<key, value>. It is the first template
+      # argument type of the 4th template argument to std::map.
+      allocator_type = map_type.GetTemplateArgumentType(3)
+      self.data_type = allocator_type.GetTemplateArgumentType(0)
+      if not self.data_type:
+        # GCC does not emit DW_TAG_template_type_parameter for
+        # std::allocator<...>. For such a case, get the type of
+        # std::pair from a member of std::map.
+        rep_type = self.valobj.GetChildMemberWithName('_M_t').GetType()
+        self.data_type = rep_type.GetTypedefedType().GetTemplateArgumentType(1)
       
       # from libstdc++ implementation of _M_root for rbtree
       self.Mroot = self.Mheader.GetChildMemberWithName('_M_parent')
       self.data_size = self.data_type.GetByteSize()
       self.skip_size = self.Mheader.GetType().GetByteSize()
     except:
       pass
 

test/functionalities/data-formatter/data-formatter-stl/libstdcpp/map/TestDataFormatterStdMap.py

class StdMapDataFormatterTestCase(TestBase):
 
     @unittest2.skipUnless(sys.platform.startswith("darwin"), "requires Darwin")
     @dsym_test
     def test_with_dsym_and_run_command(self):
         """Test data formatter commands."""
         self.buildDsym()
         self.data_formatter_commands()
 
-    @skipIfGcc # llvm.org/pr15036: When built with GCC, this test causes lldb to crash with
-               # assert DeclCXX.h:554 queried property of class with no definition
     @expectedFailureIcc   # llvm.org/pr15301: LLDB prints incorrect size of
                           # libstdc++ containers
     @skipIfFreeBSD
     @dwarf_test
     def test_with_dwarf_and_run_command(self):
         """Test data formatter commands."""
         self.buildDwarf()
         self.data_formatter_commands()