[lldb/Python] Add lldbconfig Python module to make the lldb module configurable.

[JDevlieghere]

Summary

Using the approach described in [1] and suggested by Pavel D77588 , this patch introduces a new lldbconfig module that lives next to the lldb module. It makes it possible to make the lldb module configurable. More specifically it makes it possible to delay initializing the debugger, which is needed for testing the reproducer.

I chose to name the module lldbconfig rather than lldb.config because I thought it would be weird to import a "submodule" before the main module, but if anyone feels the other approach is more desirable I'd be happy to change it.

[1] https://stackoverflow.com/questions/3720740/pass-variable-on-import/39360070#39360070

[JDevlieghere]

lldb/packages/Python/lldbsuite/test/dotest.py

957

This is a NO-OP for now, but just shows that we can load the lldbconfig module.

[labath]

Thanks. This looks fine, just a question about the placement of the lldbconfig module.

lldb/CMakeLists.txt

130 ↗

(On Diff #255706)

If we're not going to ship this file, should we place it under packages/Python/... (I'm sure there is some place we could put it where it would already be in sys.path ? That way it would not be accessible from regular lldb runs, only for those from dotest, which would decrease the likelyhood of lldb suddenly stopping to work after being installed.

lldb/bindings/python.swig

131

Maybe _initialize (the convention for "private" variables in python)?

[JDevlieghere]

Address code review feedback

[labath]

Let's see how this goes.

lldb/bindings/python.swig

 using namespace lldb;
 %}
 
 %include "./interfaces.swig"
 %include "./python/python-extensions.swig"
 %include "./python/python-wrapper.swig"
 
 %pythoncode%{
+_initialize = True
+try:
+   import lldbconfig
+   _initialize = lldbconfig.INITIALIZE
+except ImportError:
+   pass
 debugger_unique_id = 0
+if _initialize:
    SBDebugger.Initialize()
 debugger = None
 target = None
 process = None
 thread = None
 frame = None
 %}

lldb/packages/Python/lldbconfig/__init__.py

+INITIALIZE = True

lldb/packages/Python/lldbsuite/test/dotest.py

def run_suite():
     #
     parseOptionsAndInitTestdirs()
 
     # Setup test results (test results formatter and output handling).
     setupTestResults()
 
     setupSysPath()
 
+    import lldbconfig
     import lldb
+
     # Use host platform by default.
     lldb.selected_platform = lldb.SBPlatform.GetHostPlatform()
 
     # Now we can also import lldbutil
     from lldbsuite.test import lldbutil
 
     if configuration.lldb_platform_name:
         print("Setting up remote platform '%s'" %