Fix for #6151. Make UnicodeCharSeq into str for comparison.

[stuartarchibald]

Fixes #6151 by making functions implemented for UnicodeType that
also accept UnicodeCharSeq convert the input into unicode string.

Closes #6151

[sklam]

I checked the case in #6136 (comment) and can confirm reduction in the number of compilation attempts, from 133 reduced to 14.

I used the following to log the number of compilation attempts.

diff --git a/numba/core/compiler.py b/numba/core/compiler.py
index d71d8c05f..f0cd04ea0 100644
--- a/numba/core/compiler.py
+++ b/numba/core/compiler.py
@@ -1,3 +1,4 @@
+import logging
 from collections import namedtuple
 import copy
 import warnings
@@ -298,6 +299,8 @@ def _make_subtarget(targetctx, flags):
     return targetctx.subtarget(**subtargetoptions)
 
 
+_counter = 0
+
 class CompilerBase(object):
     """
     Stores and manages states for the compiler
@@ -379,6 +382,10 @@ class CompilerBase(object):
         """
         Populate and run compiler pipeline
         """
+        logger = logging.getLogger(__name__)
+        global _counter
+        _counter += 1
+        logger.debug("Compiling[%d] %s %s", _counter, self.state.func_id.func_qualname, self.state.func_id.pysig)
         pms = self.define_pipelines()
         for pm in pms:
             pipeline_name = pm.pipeline_name
             pipeline_name = pm.pipeline_name

[sklam]

Is this PR ready for review?

[stuartarchibald]

Is this PR ready for review?

Think so, will need manual test as already performed.

[sklam]

Thanks for the patch