[lldb] Avoid resource leak

[kwk]

Summary

Before the pointer variable args_dict was assigned the result of an
allocation with new and then args_dict is passed to
GetValueForKeyAsDictionary which immediatly and unconditionally
assigns args_dict to nullptr:

bool GetValueForKeyAsDictionary(llvm::StringRef key,
                                Dictionary *&result) const {
  result = nullptr;

This caused a memory leak which was found in my coverity scan instance
under CID 224753: https://scan.coverity.com/projects/kwk-llvm-project.

[teemperor]

LGTM. Also, this whole function seems to have no tests. So if you find an easy way to test this, then please add a test to functionalities/breakpoint/scripted_bkpt/TestScriptedResolver.py. You can also check this in as-is if the test turns out to be too complicated (I'm not a big fan of the whole "you touched my spaghetti so you also have to come up with a way to test the whole thing".)

lldb/source/Breakpoint/BreakpointResolverScripted.cpp

BreakpointResolverScripted::CreateFromStructuredData(
   }
   if (depth_as_int >= (int) OptionNames::LastOptionName) {
     error.SetErrorString("BRFL::CFSD: Invalid value for search depth.");
     return nullptr;
   }
   depth = (lldb::SearchDepth) depth_as_int;
   
   StructuredDataImpl *args_data_impl = new StructuredDataImpl();
-  StructuredData::Dictionary *args_dict = new StructuredData::Dictionary();
+  StructuredData::Dictionary *args_dict = nullptr;
   success = options_dict.GetValueForKeyAsDictionary(
     GetKey(OptionNames::ScriptArgs), args_dict);
   if (success) {
     // FIXME: The resolver needs a copy of the ARGS dict that it can own,
     // so I need to make a copy constructor for the Dictionary so I can pass
     // that to it here.  For now the args are empty.
     //StructuredData::Dictionary *dict_copy = new StructuredData::Dictionary(args_dict);