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bpo-42123: Run the parser two times and only enable invalid rules on the second run (GH-22111)

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* Implement running the parser a second time for the errors messages

The first parser run is only responsible for detecting whether
there is a `SyntaxError` or not. If there isn't the AST gets returned.
Otherwise, the parser is run a second time with all the `invalid_*`
rules enabled so that all the customized error messages get produced.
This commit is contained in:
Lysandros Nikolaou 2020-10-27 00:42:04 +02:00 • committed by GitHub
parent c8c4200b65
commit bca7014032
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6 changed files with 70 additions and 50 deletions
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@ -551,7 +551,7 @@ yield_expr[expr_ty]:
arguments[expr_ty] (memo):
| a=args [','] &')' { a }
| incorrect_arguments
| invalid_arguments
args[expr_ty]:
| a[asdl_expr_seq*]=','.(starred_expression | named_expression !'=')+ b=[',' k=kwargs {k}] { _PyPegen_collect_call_seqs(p, a, b, EXTRA) }
| a=kwargs { _Py_Call(_PyPegen_dummy_name(p),
@ -637,7 +637,7 @@ t_atom[expr_ty]:
# From here on, there are rules for invalid syntax with specialised error messages
incorrect_arguments:
invalid_arguments:
| args ',' '*' { RAISE_SYNTAX_ERROR("iterable argument unpacking follows keyword argument unpacking") }
| a=expression for_if_clauses ',' [args | expression for_if_clauses] {
RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "Generator expression must be parenthesized") }