Raise consistent NameError in ForwardRef.evaluate()

Feature or enhancement

Proposal:

The new ForwardRef.evaluate() implementation had a fast path introduced in #124337 to not call eval():

Lines 177 to 187 in cb39410

    
           if arg.isidentifier() and not keyword.iskeyword(arg): 
        
               if arg in locals: 
        
                   return locals[arg] 
        
               elif arg in globals: 
        
                   return globals[arg] 
        
               elif hasattr(builtins, arg): 
        
                   return getattr(builtins, arg) 
        
               elif is_forwardref_format: 
        
                   return self 
        
               else: 
        
                   raise NameError(arg)

However, when the NameError is raised, the format is different from the one raised by eval():

The exception message is defined as:

cpython/Python/ceval_macros.h

Line 308 in cb39410

#define NAME_ERROR_MSG "name '%.200s' is not defined"

and raised this way:

cpython/Python/ceval.c

Lines 3339 to 3351 in cb39410

    
           _PyErr_Format(tstate, exc, format_str, obj_str); 
        
           if (exc == PyExc_NameError) { 
        
               // Include the name in the NameError exceptions to offer suggestions later. 
        
               PyObject *exc = PyErr_GetRaisedException(); 
        
               if (PyErr_GivenExceptionMatches(exc, PyExc_NameError)) { 
        
                   if (((PyNameErrorObject*)exc)->name == NULL) { 
        
                       // We do not care if this fails because we are going to restore the 
        
                       // NameError anyway. 
        
                       (void)PyObject_SetAttr(exc, &_Py_ID(name), obj); 
        
                   } 
        
               } 
        
               PyErr_SetRaisedException(exc);

To have consistent exceptions raised, would it be possible to change the Python fast path implementation to match the C eval code?

diff --git a/Lib/annotationlib.py b/Lib/annotationlib.py
index 731817a9973..c83a1573ccd 100644
--- a/Lib/annotationlib.py
+++ b/Lib/annotationlib.py
@@ -27,6 +27,9 @@ class Format(enum.IntEnum):
 
 
 _sentinel = object()
+# Following `NAME_ERROR_MSG` in `ceval_macros.h`:
+_NAME_ERROR_MSG = "name '{name:.200}' is not defined"
+
 
 # Slots shared by ForwardRef and _Stringifier. The __forward__ names must be
 # preserved for compatibility with the old typing.ForwardRef class. The remaining
@@ -184,7 +187,7 @@ def evaluate(
             elif is_forwardref_format:
                 return self
             else:
-                raise NameError(arg)
+                raise NameError(_NAME_ERROR_MSG.format(name=arg), name=arg)
         else:
             code = self.__forward_code__
             try:

This requires _NAME_ERROR_MSG to be in sync with the one from ceval_macros.h.

Or at least, the NameError should have its name property set (especially as type stubs shows NameError.name as str currently).

cc @JelleZijlstra.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

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Uh oh!

Raise consistent `NameError` in `ForwardRef.evaluate()` #135646

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	if arg.isidentifier() and not keyword.iskeyword(arg):
	if arg in locals:
	return locals[arg]
	elif arg in globals:
	return globals[arg]
	elif hasattr(builtins, arg):
	return getattr(builtins, arg)
	elif is_forwardref_format:
	return self
	else:
	raise NameError(arg)

	_PyErr_Format(tstate, exc, format_str, obj_str);

	if (exc == PyExc_NameError) {
	// Include the name in the NameError exceptions to offer suggestions later.
	PyObject *exc = PyErr_GetRaisedException();
	if (PyErr_GivenExceptionMatches(exc, PyExc_NameError)) {
	if (((PyNameErrorObject*)exc)->name == NULL) {
	// We do not care if this fails because we are going to restore the
	// NameError anyway.
	(void)PyObject_SetAttr(exc, &_Py_ID(name), obj);
	}
	}
	PyErr_SetRaisedException(exc);

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Uh oh!

Raise consistent NameError in ForwardRef.evaluate() #135646

Description

Feature or enhancement

Proposal:

Has this already been discussed elsewhere?

Links to previous discussion of this feature:

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Raise consistent `NameError` in `ForwardRef.evaluate()` #135646