gh-64660: Do not hardcode the name of the returned variable (GH-155268)

Return converters had to hardcode "return_value", because declare() sets
data.return_value to the variable which receives the value returned by
the impl.  The name of the variable returned by the parsing function is
now available as data.parser_retval.

Author: serhiy-storchaka

Misc/NEWS.d/next/Tools-Demos/2026-08-06-11-40-49.gh-issue-64660.MswRQB.rst

@@ -0,0 +1,3 @@
+Argument Clinic return converters no longer need to hardcode the name of the
+variable returned by the parsing function.
+It is now available as ``data.parser_retval``.

PC/msvcrtmodule.c

@@ -65,17 +65,18 @@ class byte_char_return_converter(CReturnConverter):
         data.declarations.append('char s[1];')
         data.return_value = 's[0]'
         data.return_conversion.append(
-            'return_value = PyBytes_FromStringAndSize(s, 1);\n')
+            f'{data.parser_retval} = PyBytes_FromStringAndSize(s, 1);\n')
 
 class wchar_t_return_converter(CReturnConverter):
     type = 'wchar_t'
 
     def render(self, function, data):
         self.declare(data)
         data.return_conversion.append(
-            'return_value = PyUnicode_FromOrdinal(_return_value);\n')
+            f'{data.parser_retval} = '
+            f'PyUnicode_FromOrdinal({data.converter_retval});\n')
 [python start generated code]*/
-/*[python end generated code: output=da39a3ee5e6b4b0d input=ff031be44ab3250d]*/
+/*[python end generated code: output=da39a3ee5e6b4b0d input=ed7a4a045a6d0496]*/
 
 /*[clinic input]
 module msvcrt

Tools/clinic/libclinic/clanguage.py

@@ -525,6 +525,7 @@ def render_function(
         template_dict['cleanup'] = libclinic.format_escape("".join(data.cleanup))
 
         template_dict['return_value'] = data.return_value
+        template_dict['parser_retval'] = data.parser_retval
         template_dict['lock'] = "\n".join(data.lock)
         template_dict['unlock'] = "\n".join(data.unlock)
 

Tools/clinic/libclinic/codegen.py

@@ -47,14 +47,17 @@ def __init__(self) -> None:
         # The arguments to the impl function at the time it's called.
         self.impl_arguments: list[str] = []
 
+        # The name of the variable which is returned by the parser.
+        self.parser_retval = "return_value"
+
         # For return converters: the name of the variable that
         # should receive the value returned by the impl.
         self.return_value = "return_value"
 
         # For return converters: the code to convert the return
         # value from the parse function.  This is also where
-        # you should check the _return_value for errors, and
-        # "goto exit" if there are any.
+        # you should check the value returned by the impl for errors,
+        # and "goto exit" if there are any.
         self.return_conversion: list[str] = []
         self.converter_retval = "_return_value"
 

Tools/clinic/libclinic/parse_args.py

@@ -320,7 +320,7 @@ def select_prototypes(self) -> None:
         self.docstring_prototype = ''
         self.docstring_definition = ''
         self.methoddef_define = METHODDEF_PROTOTYPE_DEFINE
-        self.return_value_declaration = "PyObject *return_value = NULL;"
+        self.return_value_declaration = "PyObject *{parser_retval} = NULL;"
 
         if self.is_new_or_init() and not self.func.docstring:
             pass
@@ -331,7 +331,7 @@ def select_prototypes(self) -> None:
         elif self.func.kind is SETTER:
             if self.func.docstring:
                 fail("docstrings are only supported for @getter, not @setter")
-            self.return_value_declaration = "int {return_value};"
+            self.return_value_declaration = "int {parser_retval};"
             self.methoddef_define = SETTERDEF_PROTOTYPE_DEFINE
         else:
             self.docstring_prototype = DOCSTRING_PROTOTYPE_VAR
@@ -372,7 +372,7 @@ def parser_body(
 
             {exit_label}
                 {cleanup}
-                return return_value;
+                return {parser_retval};
             }}
         """)
         for field in preamble, *fields, finale:
@@ -861,7 +861,7 @@ def handle_new_or_init(self) -> None:
         if self.func.kind is METHOD_NEW:
             self.parser_prototype = PARSER_PROTOTYPE_KEYWORD
         else:
-            self.return_value_declaration = "int return_value = -1;"
+            self.return_value_declaration = "int {parser_retval} = -1;"
             self.parser_prototype = PARSER_PROTOTYPE_KEYWORD___INIT__
 
         fields: list[str] = list(self.parser_body_fields)

Tools/clinic/libclinic/return_converters.py

@@ -110,7 +110,8 @@ def render(self, function: Function, data: CRenderData) -> None:
         self.declare(data)
         self.err_occurred_if(f"{data.converter_retval} == -1", data)
         data.return_conversion.append(
-            f'return_value = PyBool_FromLong((long){data.converter_retval});\n'
+            f'{data.parser_retval} = '
+            f'PyBool_FromLong((long){data.converter_retval});\n'
         )
 
 
@@ -124,7 +125,8 @@ def render(self, function: Function, data: CRenderData) -> None:
         self.declare(data)
         self.err_occurred_if(f"{data.converter_retval} == {self.unsigned_cast}-1", data)
         data.return_conversion.append(
-            f'return_value = {self.conversion_fn}({self.cast}{data.converter_retval});\n'
+            f'{data.parser_retval} = '
+            f'{self.conversion_fn}({self.cast}{data.converter_retval});\n'
         )
 
 
@@ -164,7 +166,8 @@ def render(self, function: Function, data: CRenderData) -> None:
         self.declare(data)
         self.err_occurred_if(f"{data.converter_retval} == -1.0", data)
         data.return_conversion.append(
-            f'return_value = PyFloat_FromDouble({self.cast}{data.converter_retval});\n'
+            f'{data.parser_retval} = '
+            f'PyFloat_FromDouble({self.cast}{data.converter_retval});\n'
         )