Activity

1. skirpichev

   added

   type-featureA feature request or enhancementA feature request or enhancement

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Jun 11, 2026
2. Aniketsy commented on Jun 11, 2026

   

   Aniketsy

   on Jun 11, 2026

   ContributorAuthor

   More actions

   diff --git a/Grammar/python.gram b/Grammar/python.gram
   index 9bf3a67939..8d2cf58616 100644
   --- a/Grammar/python.gram
   +++ b/Grammar/python.gram
   @@ -801,8 +801,14 @@ compare_op_bitwise_or_pair[CmpopExprPair*]:
        | in_bitwise_or
        | isnot_bitwise_or
        | is_bitwise_or
   +    | invalid_diamond_op
   +    | invalid_eqeqeq
   
   +invalid_diamond_op:
   +    | a='<' b='>' { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax.  Maybe you meant '!=' instead of '<>'") }
    eq_bitwise_or[CmpopExprPair*]: '==' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, Eq, a) }
   +invalid_eqeqeq:
   +    | a='==' b='=' { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax.  Maybe you meant '==' instead of '==='") }
    noteq_bitwise_or[CmpopExprPair*]:
        | (tok='!=' { _PyPegen_check_barry_as_flufl(p, tok) ? NULL : tok}) a=bitwise_or {_PyPegen_cmpop_expr_pair(p, NotEq, a) }
    lte_bitwise_or[CmpopExprPair*]: '<=' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, LtE, a) }
   @@ -1313,6 +1319,9 @@ invalid_assignment:
                "'%s' is an illegal expression for augmented assignment",
                _PyPegen_get_expr_name(a)
            )}
   +    | star_expressions a='=' b='<' { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax.  Maybe you meant '<=' instead of '=<'") }
   +    | star_expressions a='=' b='>' { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax.  Maybe you meant '>=' instead of '=>'") }
   +    | star_expressions a='=' b='!' { RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "invalid syntax.  Maybe you meant '!=' instead of '=!'") }
    invalid_ann_assign_target[expr_ty]:
        | list
        | tuple
   

   with these changes got these outputs, kind of stuck with our first case @skirpichev could you please share your thoughts on this. Thanks!

   aniket@DESKTOP-074O80J:/mnt/d/cpython/cpython$ ./python.exe -c "a, b = 1, 2; a <> b"
     File "<string>", line 1
       a, b = 1, 2; a <> b
                      ^^
   SyntaxError: invalid syntax
   aniket@DESKTOP-074O80J:/mnt/d/cpython/cpython$ ./python.exe -c "a, b = 1, 2; a === b"
     File "<string>", line 1
       a, b = 1, 2; a === b
                      ^^^
   SyntaxError: invalid syntax.  Maybe you meant '==' instead of '==='
   aniket@DESKTOP-074O80J:/mnt/d/cpython/cpython$ ./python.exe -c "a, b = 1, 2; a =< b"
     File "<string>", line 1
       a, b = 1, 2; a =< b
                      ^^
   SyntaxError: invalid syntax.  Maybe you meant '<=' instead of '=<'
   aniket@DESKTOP-074O80J:/mnt/d/cpython/cpython$ ./python.exe -c "a, b = 1, 2; a => b"
     File "<string>", line 1
       a, b = 1, 2; a => b
                      ^^
   SyntaxError: invalid syntax.  Maybe you meant '>=' instead of '=>'
   aniket@DESKTOP-074O80J:/mnt/d/cpython/cpython$ ./python.exe -c "a, b = 1, 2; a =! b"
     File "<string>", line 1
       a, b = 1, 2; a =! b
                      ^^
   SyntaxError: invalid syntax.  Maybe you meant '!=' instead of '=!'
   
3. skirpichev

   self-assigned this

   on Jun 12, 2026
4. skirpichev commented on Jun 12, 2026

   

   skirpichev

   on Jun 12, 2026

   Member

   More actions

   Hmm, I'm not sure about the reason. Though:

   >>> 1 <> 2
     File "<python-input-0>", line 1
       1 <> 2
         ^^
   SyntaxError: invalid syntax
   >>> 1 < > 2
     File "<python-input-1>", line 1
       1 < > 2
         ^^^
   SyntaxError: invalid syntax.  Maybe you meant '!=' instead of '<>'?

   PS: Please don't post images where you can just show repl output as a plain text.

   Reacted by Aniket
5. skirpichev

   assigned

   skirpichev

   and unassigned

   skirpichev

   on Jun 12, 2026
6. skirpichev commented on Jun 14, 2026

   

   skirpichev

   on Jun 14, 2026

   Member

   More actions

   Currently, you can customize error message for '<>' token by:

   diff --git a/Parser/action_helpers.c b/Parser/action_helpers.c
   index c74eb34deb7..ae6ab8839eb 100644
   --- a/Parser/action_helpers.c
   +++ b/Parser/action_helpers.c
   @@ -931,6 +931,10 @@ _PyPegen_check_barry_as_flufl(Parser *p, Token* t) {
            return -1;
        }
        if (!(p->flags & PyPARSE_BARRY_AS_BDFL)) {
   +        if (strcmp(tok_str, "<>") == 0) {
   +            RAISE_SYNTAX_ERROR("Are you trying to overthrow the SC?  Use operator "!="!");
   +            return -1;
   +        }
            return strcmp(tok_str, "!=");
        }
        return 0;

   Though, see #151464.

   Reacted by Aniket

   Reacted by Aniket
7. skirpichev

   removed their assignment

   on Jun 14, 2026
8. serhiy-storchaka

   added

   topic-parser

   on Jul 3, 2026