[lldb/Test] Run dotest.py with the Python LLDB was built with

[JDevlieghere]

Summary

The Python used to run lit can be different from the Python LLDB was build with. One scenario where this happens is when LLVM can find the Python 3 interpreter, but not the Python 3 libraries, in which case LLDB build and links against Python 3. Without this change, you end up with an ModuleNotFoundError because of the mismatch.

Instead of looking at the Python interpreter that's used to run lit, we should use the interpreter that matches the Python version LLDB was build against.

[mib]

LGTM!

[aprantl]

That makes sense to me. Thanks!

lldb/test/API/lldbtest.py

def execute(self, test, litConfig):
 
         if not test.config.lldb_enable_python:
             return (lit.Test.UNSUPPORTED, 'Python module disabled')
 
         if test.config.unsupported:
             return (lit.Test.UNSUPPORTED, 'Test is unsupported')
 
         testPath, testFile = os.path.split(test.getSourcePath())
+
+        # The Python used to run lit can be different from the Python LLDB was
+        # build with.
+        executable = test.config.python_executable
+
         # On Windows, the system does not always correctly interpret
         # shebang lines.  To make sure we can execute the tests, add
         # python exe as the first parameter of the command.
-        cmd = [sys.executable] + self.dotest_cmd + [testPath, '-p', testFile]
+        cmd = [executable] + self.dotest_cmd + [testPath, '-p', testFile]
 
         builddir = getBuildDir(cmd)
         mkdir_p(builddir)
 
         # The macOS system integrity protection (SIP) doesn't allow injecting
         # libraries into system binaries, but this can be worked around by
         # copying the binary into a different location.
         if 'DYLD_INSERT_LIBRARIES' in test.config.environment and \
-                (sys.executable.startswith('/System/') or \
-                sys.executable.startswith('/usr/bin/')):
+                (executable.startswith('/System/') or \
+                executable.startswith('/usr/bin/')):
             copied_python = os.path.join(builddir, 'copied-system-python')
             if not os.path.isfile(copied_python):
                 import shutil, subprocess
                 python = subprocess.check_output([
-                    sys.executable,
+                    executable,
                     '-c',
                     'import sys; print(sys.executable)'
                 ]).decode('utf-8').strip()
                 shutil.copy(python, copied_python)
             cmd[0] = copied_python
 
         if 'lldb-repro-capture' in test.config.available_features or \
            'lldb-repro-replay' in test.config.available_features: