Checking for conflicts before registering synthetic child providers/filters doesn't work correctly with regex

[slackito]

CommandObjectTypeSynthAdd::AddSynth has some code to check for conflicting filters in the same category (there's a symmetric check for conflicting synth providers when adding a new filter, but let's focus on only one case). The check looks like this:

  if (category->AnyMatches(type_name, eFormatCategoryItemFilter, false)) {
    if (error)
      error->SetErrorStringWithFormat("cannot add synthetic for type %s when "
                                      "filter is defined in same category!",
                                      type_name.AsCString());
    return false;
  }

The important detail here is that type_name can actually be either a type name or a regex (if using type synthetic add -x). However, category->AnyMatches always treats type_name as a type name, and will try to match a regex string against other regex strings, which is not correct.

For example, this is lldb working correctly and rejecting a conflicting formatter.

(lldb) script
Python Interactive Interpreter. To exit, type 'quit()', 'exit()' or Ctrl-D.
>>> class my_child_provider:
...   pass
... 
>>> ^D
now exiting InteractiveConsole...
(lldb) type synthetic add -l my_child_provider whatever
(lldb) type filter add --child a whatever
error: cannot add filter for type whatever when synthetic is defined in same category!

However, if we use regex it will happily accept conflicting formatters:

(lldb) type synthetic add -l my_child_provider -x "^whatever$"
(lldb) type filter add --child a -x "^whatever$"
(lldb) 

because the string "^whatever$" is not matched by the regex "^whatever$".

We can also make it fail the other way around, and make it incorrectly reject non-conflicting formatters. For example:

(lldb) type synthetic add -l my_child_provider -x "^MyType\[[0-9]+]$"
(lldb) type filter add --child a -x "MyType[12]"
error: cannot add filter for type MyType[12] when synthetic is defined in same category!

In this case, "^MyType\[[0-9]+]$" would accept types that look like an array of MyType, and "MyType[12]" looks like an array, but it would actually match MyType1 and MyType2 so there's no conflict.

I think the right thing to do is to just skip this check when adding a regex-based filter. I'll prepare a patch.

[llvmbot]

@llvm/issue-subscribers-lldb

[slackito]

Sent https://reviews.llvm.org/D134570 to skip the check if registering a new filter/synth using a regex.

[slackito]

Fixed in 69c661a by restricting the check to "exact match" formatters only.