Display parameter name in string conversion warning (#57145)

Add prefix to error message for nested options. This is helpful if a subelement key has the same name as a top level key.

changelogs/fragments/string-conversion-warning-add-parameter-name.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - add parameter name to warning message when values are converted to strings (https://github.com/ansible/ansible/pull/57145)

lib/ansible/module_utils/basic.py

@@ -1613,7 +1613,7 @@ class AnsibleModule(object):
     def safe_eval(self, value, locals=None, include_exceptions=False):
         return safe_eval(value, locals, include_exceptions)
 
-    def _check_type_str(self, value):
+    def _check_type_str(self, value, param=None, prefix=''):
         opts = {
             'error': False,
             'warn': False,
@@ -1626,12 +1626,22 @@ class AnsibleModule(object):
             return check_type_str(value, allow_conversion)
         except TypeError:
             common_msg = 'quote the entire value to ensure it does not change.'
+            from_msg = '{0!r}'.format(value)
+            to_msg = '{0!r}'.format(to_text(value))
+
+            if param is not None:
+                if prefix:
+                    param = '{0}{1}'.format(prefix, param)
+
+                from_msg = '{0}: {1!r}'.format(param, value)
+                to_msg = '{0}: {1!r}'.format(param, to_text(value))
+
             if self._string_conversion_action == 'error':
                 msg = common_msg.capitalize()
                 raise TypeError(to_native(msg))
             elif self._string_conversion_action == 'warn':
-                msg = ('The value {0!r} (type {0.__class__.__name__}) in a string field was converted to {1!r} (type string). '
-                       'If this does not look like what you expect, {2}').format(value, to_text(value), common_msg)
+                msg = ('The value "{0}" (type {1.__class__.__name__}) was converted to "{2}" (type string). '
+                       'If this does not look like what you expect, {3}').format(from_msg, value, to_msg, common_msg)
                 self.warn(to_native(msg))
                 return to_native(value, errors='surrogate_or_strict')
 
@@ -1716,7 +1726,7 @@ class AnsibleModule(object):
 
                     if not self.bypass_checks:
                         self._check_required_arguments(spec, param)
-                        self._check_argument_types(spec, param)
+                        self._check_argument_types(spec, param, new_prefix)
                         self._check_argument_values(spec, param)
 
                         self._check_required_together(v.get('required_together', None), param)
@@ -1751,9 +1761,16 @@ class AnsibleModule(object):
     def _handle_elements(self, wanted, param, values):
         type_checker, wanted_name = self._get_wanted_type(wanted, param)
         validated_params = []
+        # Get param name for strings so we can later display this value in a useful error message if needed
+        kwargs = {}
+        if wanted_name == 'str':
+            if isinstance(param, string_types):
+                kwargs['param'] = param
+            elif isinstance(param, dict):
+                kwargs['param'] = list(param.keys())[0]
         for value in values:
             try:
-                validated_params.append(type_checker(value))
+                validated_params.append(type_checker(value, **kwargs))
             except (TypeError, ValueError) as e:
                 msg = "Elements value for option %s" % param
                 if self._options_context:
@@ -1762,7 +1779,7 @@ class AnsibleModule(object):
                 self.fail_json(msg=msg)
         return validated_params
 
-    def _check_argument_types(self, spec=None, param=None):
+    def _check_argument_types(self, spec=None, param=None, prefix=''):
         ''' ensure all arguments have the requested type '''
 
         if spec is None:
@@ -1780,8 +1797,17 @@ class AnsibleModule(object):
                 continue
 
             type_checker, wanted_name = self._get_wanted_type(wanted, k)
+            # Get param name for strings so we can later display this value in a useful error message if needed
+            kwargs = {}
+            if wanted_name == 'str':
+                kwargs['param'] = list(param.keys())[0]
+
+                # Get the name of the parent key if this is a nested option
+                if prefix:
+                    kwargs['prefix'] = prefix
+
             try:
-                param[k] = type_checker(value)
+                param[k] = type_checker(value, **kwargs)
                 wanted_elements = v.get('elements', None)
                 if wanted_elements:
                     if wanted != 'list' or not isinstance(param[k], list):