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bpo-40334: produce specialised errors for del by hauntsaninja · Pull Request #19911 · python/cpython · GitHub
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bpo-40334: produce specialised errors for del #19911

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Merged
gvanrossum merged 12 commits into from
May 11, 2020
Conversation 26 Commits 12 Checks 0 Files changed
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bpo-40334: produce specialised errors for del #19911

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c2219f7
pegen: produce specialised messages for del
May 4, 2020
343ccb5
pegen: further improve del error messages
May 4, 2020
4029ee5
del: add more tests
May 4, 2020
f6b219f
pegen: fix del error messages for binary ops and others
May 5, 2020
9b11bed
pegen: add doctest back in
May 5, 2020
8b4ead5
grammar: reorder and add comment
May 5, 2020
fa21224
del: add even more tests
May 5, 2020
d101ac1
pegen: fix more del test cases
May 5, 2020
850ba88
grammar: reuse del_target_end in invalid_del_target
May 5, 2020
461fe85
grammar: add ENDMARKER to del_target_end
May 5, 2020
d462df9
Revert "grammar: add ENDMARKER to del_target_end"
May 11, 2020
566745e
make regen-pegen
May 11, 2020
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13 changes: 10 additions & 3 deletions Grammar/python.gram
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Original file line number Diff line number Diff line change
Expand Up @@ -583,15 +583,19 @@ ann_assign_subscript_attribute_target[expr_ty]:
| a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Store, EXTRA) }

del_targets[asdl_seq*]: a=','.del_target+ [','] { a }
# The lookaheads to del_target_end ensure that we don't match expressions where a prefix of the
# expression matches our rule, thereby letting these cases fall through to invalid_del_target.
del_target[expr_ty] (memo):
| a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Del, EXTRA) }
| a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Del, EXTRA) }
| a=t_primary '.' b=NAME &del_target_end { _Py_Attribute(a, b->v.Name.id, Del, EXTRA) }
| a=t_primary '[' b=slices ']' &del_target_end { _Py_Subscript(a, b, Del, EXTRA) }
| del_t_atom
del_t_atom[expr_ty]:
| a=NAME { _PyPegen_set_expr_context(p, a, Del) }
| a=NAME &del_target_end { _PyPegen_set_expr_context(p, a, Del) }
| '(' a=del_target ')' { _PyPegen_set_expr_context(p, a, Del) }
| '(' a=[del_targets] ')' { _Py_Tuple(a, Del, EXTRA) }
| '[' a=[del_targets] ']' { _Py_List(a, Del, EXTRA) }
| invalid_del_target
del_target_end: ')' | ']' | ',' | ';' | NEWLINE
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targets[asdl_seq*]: a=','.target+ [','] { a }
target[expr_ty] (memo):
Expand Down Expand Up @@ -649,3 +653,6 @@ invalid_lambda_star_etc:
invalid_double_type_comments:
| TYPE_COMMENT NEWLINE TYPE_COMMENT NEWLINE INDENT {
RAISE_SYNTAX_ERROR("Cannot have two type comments on def") }
invalid_del_target:
| a=star_expression &del_target_end {
RAISE_SYNTAX_ERROR("cannot delete %s", _PyPegen_get_expr_name(a)) }
17 changes: 17 additions & 0 deletions Lib/test/test_grammar.py
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Expand Up @@ -801,6 +801,23 @@ def test_del_stmt(self):
del abc
del x, y, (z, xyz)

x, y, z = "xyz"
del x
del y,
del (z)
del ()

a, b, c, d, e, f, g = "abcdefg"
del a, (b, c), (d, (e, f))

a, b, c, d, e, f, g = "abcdefg"
del a, [b, c], (d, [e, f])

abcd = list("abcd")
del abcd[1:2]

compile("del a, (b[0].c, (d.e, f.g[1:2])), [h.i.j], ()", "<testcase>", "exec")

def test_pass_stmt(self):
# 'pass'
pass
Expand Down
41 changes: 33 additions & 8 deletions Lib/test/test_syntax.py
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Original file line number Diff line number Diff line change
Expand Up @@ -63,10 +63,9 @@
Traceback (most recent call last):
SyntaxError: cannot assign to function call

# Pegen does not support this yet
# >>> del f()
# Traceback (most recent call last):
# SyntaxError: cannot delete function call
>>> del f()
Traceback (most recent call last):
SyntaxError: cannot delete function call

>>> a + 1 = 2
Traceback (most recent call last):
Expand Down Expand Up @@ -665,7 +664,7 @@ def _check_error(self, code, errtext,
self.fail("SyntaxError is not a %s" % subclass.__name__)
mo = re.search(errtext, str(err))
if mo is None:
self.fail("SyntaxError did not contain '%r'" % (errtext,))
self.fail("SyntaxError did not contain %r" % (errtext,))
self.assertEqual(err.filename, filename)
if lineno is not None:
self.assertEqual(err.lineno, lineno)
Expand All @@ -677,10 +676,36 @@ def _check_error(self, code, errtext,
def test_assign_call(self):
self._check_error("f() = 1", "assign")

@support.skip_if_new_parser("Pegen does not produce a specialized error "
"message yet")
def test_assign_del(self):
self._check_error("del f()", "delete")
self._check_error("del (,)", "invalid syntax")
self._check_error("del 1", "delete literal")
self._check_error("del (1, 2)", "delete literal")
self._check_error("del None", "delete None")
self._check_error("del *x", "delete starred")
self._check_error("del (*x)", "delete starred")
self._check_error("del (*x,)", "delete starred")
self._check_error("del [*x,]", "delete starred")
self._check_error("del f()", "delete function call")
self._check_error("del f(a, b)", "delete function call")
self._check_error("del o.f()", "delete function call")
self._check_error("del a[0]()", "delete function call")
self._check_error("del x, f()", "delete function call")
self._check_error("del f(), x", "delete function call")
self._check_error("del [a, b, ((c), (d,), e.f())]", "delete function call")
self._check_error("del (a if True else b)", "delete conditional")
self._check_error("del +a", "delete operator")
self._check_error("del a, +b", "delete operator")
self._check_error("del a + b", "delete operator")
self._check_error("del (a + b, c)", "delete operator")
self._check_error("del (c[0], a + b)", "delete operator")
self._check_error("del a.b.c + 2", "delete operator")
self._check_error("del a.b.c[0] + 2", "delete operator")
self._check_error("del (a, b, (c, d.e.f + 2))", "delete operator")
self._check_error("del [a, b, (c, d.e.f[0] + 2)]", "delete operator")
self._check_error("del (a := 5)", "delete named expression")
# We don't have a special message for this, but make sure we don't
# report "cannot delete name"
self._check_error("del a += b", "invalid syntax")

def test_global_param_err_first(self):
source = """if 1:
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