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bpo-42997: Improve error message for missing : before suites (GH-24292)

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* Add to the peg generator a new directive ('&&') that allows to expect
  a token and hard fail the parsing if the token is not found. This
  allows to quickly emmit syntax errors for missing tokens.

* Use the new grammar element to hard-fail if the ':' is missing before
  suites.
This commit is contained in:
Pablo Galindo 2021-02-02 19:54:22 +00:00 • committed by GitHub
parent 802b645e81
commit 58fb156edd
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11 changed files with 1219 additions and 428 deletions
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Grammar/python.gram
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@ -162,22 +162,22 @@ dotted_name[expr_ty]:
| NAME
if_stmt[stmt_ty]:
| 'if' a=named_expression ':' b=block c=elif_stmt {
| 'if' a=named_expression &&':' b=block c=elif_stmt {
_Py_If(a, b, CHECK(asdl_stmt_seq*, _PyPegen_singleton_seq(p, c)), EXTRA) }
| 'if' a=named_expression ':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
| 'if' a=named_expression &&':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
elif_stmt[stmt_ty]:
| 'elif' a=named_expression ':' b=block c=elif_stmt {
| 'elif' a=named_expression &&':' b=block c=elif_stmt {
_Py_If(a, b, CHECK(asdl_stmt_seq*, _PyPegen_singleton_seq(p, c)), EXTRA) }
| 'elif' a=named_expression ':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
else_block[asdl_stmt_seq*]: 'else' ':' b=block { b }
| 'elif' a=named_expression &&':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
else_block[asdl_stmt_seq*]: 'else' &&':' b=block { b }
while_stmt[stmt_ty]:
| 'while' a=named_expression ':' b=block c=[else_block] { _Py_While(a, b, c, EXTRA) }
| 'while' a=named_expression &&':' b=block c=[else_block] { _Py_While(a, b, c, EXTRA) }
for_stmt[stmt_ty]:
| 'for' t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
| 'for' t=star_targets 'in' ~ ex=star_expressions &&':' tc=[TYPE_COMMENT] b=block el=[else_block] {
_Py_For(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA) }
| ASYNC 'for' t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
| ASYNC 'for' t=star_targets 'in' ~ ex=star_expressions &&':' tc=[TYPE_COMMENT] b=block el=[else_block] {
CHECK_VERSION(stmt_ty, 5, "Async for loops are", _Py_AsyncFor(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
| invalid_for_target
@ -190,18 +190,20 @@ with_stmt[stmt_ty]:
CHECK_VERSION(stmt_ty, 5, "Async with statements are", _Py_AsyncWith(a, b, NULL, EXTRA)) }
| ASYNC 'with' a[asdl_withitem_seq*]=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
CHECK_VERSION(stmt_ty, 5, "Async with statements are", _Py_AsyncWith(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
| invalid_with_stmt
with_item[withitem_ty]:
| e=expression 'as' t=star_target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
| invalid_with_item
| e=expression { _Py_withitem(e, NULL, p->arena) }
try_stmt[stmt_ty]:
| 'try' ':' b=block f=finally_block { _Py_Try(b, NULL, NULL, f, EXTRA) }
| 'try' ':' b=block ex[asdl_excepthandler_seq*]=except_block+ el=[else_block] f=[finally_block] { _Py_Try(b, ex, el, f, EXTRA) }
| 'try' &&':' b=block f=finally_block { _Py_Try(b, NULL, NULL, f, EXTRA) }
| 'try' &&':' b=block ex[asdl_excepthandler_seq*]=except_block+ el=[else_block] f=[finally_block] { _Py_Try(b, ex, el, f, EXTRA) }
except_block[excepthandler_ty]:
| 'except' e=expression t=['as' z=NAME { z }] ':' b=block {
| 'except' e=expression t=['as' z=NAME { z }] &&':' b=block {
_Py_ExceptHandler(e, (t) ? ((expr_ty) t)->v.Name.id : NULL, b, EXTRA) }
| 'except' ':' b=block { _Py_ExceptHandler(NULL, NULL, b, EXTRA) }
| 'except' &&':' b=block { _Py_ExceptHandler(NULL, NULL, b, EXTRA) }
finally_block[asdl_stmt_seq*]: 'finally' ':' a=block { a }
return_stmt[stmt_ty]:
@ -216,11 +218,11 @@ function_def[stmt_ty]:
| function_def_raw
function_def_raw[stmt_ty]:
| 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] ':' tc=[func_type_comment] b=block {
| 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] &&':' tc=[func_type_comment] b=block {
_Py_FunctionDef(n->v.Name.id,
(params) ? params : CHECK(arguments_ty, _PyPegen_empty_arguments(p)),
b, NULL, a, NEW_TYPE_COMMENT(p, tc), EXTRA) }
| ASYNC 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] ':' tc=[func_type_comment] b=block {
| ASYNC 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] &&':' tc=[func_type_comment] b=block {
CHECK_VERSION(
stmt_ty,
5,
@ -300,7 +302,7 @@ class_def[stmt_ty]:
| a=decorators b=class_def_raw { _PyPegen_class_def_decorators(p, a, b) }
| class_def_raw
class_def_raw[stmt_ty]:
| 'class' a=NAME b=['(' z=[arguments] ')' { z }] ':' c=block {
| 'class' a=NAME b=['(' z=[arguments] ')' { z }] &&':' c=block {
_Py_ClassDef(a->v.Name.id,
(b) ? ((expr_ty) b)->v.Call.args : NULL,
(b) ? ((expr_ty) b)->v.Call.keywords : NULL,
@ -718,7 +720,7 @@ invalid_double_type_comments:
| TYPE_COMMENT NEWLINE TYPE_COMMENT NEWLINE INDENT {
RAISE_SYNTAX_ERROR("Cannot have two type comments on def") }
invalid_with_item:
| expression 'as' a=expression {
| expression 'as' a=expression &(',' | ')' | ':') {
RAISE_SYNTAX_ERROR_INVALID_TARGET(STAR_TARGETS, a) }
invalid_for_target:
@ -731,3 +733,7 @@ invalid_group:
invalid_import_from_targets:
| import_from_as_names ',' {
RAISE_SYNTAX_ERROR("trailing comma not allowed without surrounding parentheses") }
invalid_with_stmt:
| [ASYNC] 'with' ','.(expression ['as' star_target])+ &&':'
| [ASYNC] 'with' '(' ','.(expressions ['as' star_target])+ ','? ')' &&':'