[lldb/IRExecutionUnit] Stop searching based on demangled names

[labath]

Summary

This was causing problems on linux, where we'd end up calling the
deleting destructor instead of a regular one (because they have the same
demangled name), making a lot of mischief in the process.

The only place where this was necessary (according to the test suite, at
least) was to call a base structor instead of a complete one, but this
is now handled in a more targeted fashion.

TestCallOverriddenMethod is now re-enabled as it now passes reliably.

[JDevlieghere]

Seems reasonable. @teemperor wdyt?

[teemperor]

LGTM, thanks for fixing this!

lldb/packages/Python/lldbsuite/test/commands/expression/call-overridden-method/TestCallOverriddenMethod.py

def test_call_on_derived(self):
 
         self.runCmd("run", RUN_SUCCEEDED)
 
         # Test call to overridden method in derived class (this will fail if the
         # overrides table is not correctly set up, as Derived::foo will be assigned
         # a vtable entry that does not exist in the compiled program).
         self.expect("expr d.foo()", substrs=["2"])
 
-    @skipIfLinux # Calling constructor causes SIGABRT
     @expectedFailureAll(oslist=["windows"], bugnumber="llvm.org/pr43707")
     def test_call_on_temporary(self):
         """Test calls to overridden methods in derived classes."""
         self.build()
 
         # Set breakpoint in main and run exe
         self.runCmd("file " + self.getBuildArtifact("a.out"),
                     CURRENT_EXECUTABLE_SET)
         lldbutil.run_break_set_by_file_and_line(
             self, "main.cpp", self.line, num_expected_locations=-1, loc_exact=True)
 
         self.runCmd("run", RUN_SUCCEEDED)
 
         # Test with locally constructed instances.
         self.expect("expr Base().foo()", substrs=["1"])
         self.expect("expr Derived().foo()", substrs=["2"])

lldb/source/Expression/IRExecutionUnit.cpp

if (CPlusPlusLanguage::IsCPPMangledName(name.GetCString())) {
 
       if (demangled) {
         ConstString best_alternate_mangled_name = FindBestAlternateMangledName(
             demangled, lldb::eLanguageTypeC_plus_plus, sc);
 
         if (best_alternate_mangled_name) {
           CPP_specs.push_back(best_alternate_mangled_name);
         }
-
-        CPP_specs.push_back(SearchSpec(demangled, lldb::eFunctionNameTypeFull));
       }
     }
 
     std::set<ConstString> alternates;
     CPlusPlusLanguage::FindAlternateFunctionManglings(name, alternates);
     CPP_specs.insert(CPP_specs.end(), alternates.begin(), alternates.end());
   }
 }