bpo-43797: Improve syntax error for invalid comparisons (#25317)
* bpo-43797: Improve syntax error for invalid comparisons
* Update Lib/test/test_fstring.py
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
* Apply review comments
* can't -> cannot
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 730c297..78b11c9 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -61,7 +61,7 @@
>>> f() = 1
Traceback (most recent call last):
-SyntaxError: cannot assign to function call
+SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
>>> yield = 1
Traceback (most recent call last):
@@ -73,7 +73,7 @@
>>> a + 1 = 2
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression here. Maybe you meant '==' instead of '='?
>>> (x for x in x) = 1
Traceback (most recent call last):
@@ -81,19 +81,19 @@
>>> 1 = 1
Traceback (most recent call last):
-SyntaxError: cannot assign to literal
+SyntaxError: cannot assign to literal here. Maybe you meant '==' instead of '='?
>>> "abc" = 1
Traceback (most recent call last):
-SyntaxError: cannot assign to literal
+SyntaxError: cannot assign to literal here. Maybe you meant '==' instead of '='?
>>> b"" = 1
Traceback (most recent call last):
-SyntaxError: cannot assign to literal
+SyntaxError: cannot assign to literal here. Maybe you meant '==' instead of '='?
>>> ... = 1
Traceback (most recent call last):
-SyntaxError: cannot assign to Ellipsis
+SyntaxError: cannot assign to Ellipsis here. Maybe you meant '==' instead of '='?
>>> `1` = 1
Traceback (most recent call last):
@@ -126,15 +126,15 @@
>>> [a, b, c + 1] = [1, 2, 3]
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> [a, b[1], c + 1] = [1, 2, 3]
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> [a, b.c.d, c + 1] = [1, 2, 3]
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> a if 1 else b = 1
Traceback (most recent call last):
@@ -181,7 +181,7 @@
>>> for (*a, b, c+1) in b: pass
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> for (x, *(y, z.d())) in b: pass
Traceback (most recent call last):
@@ -193,7 +193,7 @@
>>> for a, b, (c + 1, d()): pass
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> for i < (): pass
Traceback (most recent call last):
@@ -217,7 +217,7 @@
>>> with a as (*b, c, d+1): pass
Traceback (most recent call last):
-SyntaxError: cannot assign to operator
+SyntaxError: cannot assign to expression
>>> with a as (x, *(y, z.d())): pass
Traceback (most recent call last):
@@ -465,7 +465,7 @@
# SyntaxError: expression cannot contain assignment, perhaps you meant "=="?
# >>> f(True=2)
# Traceback (most recent call last):
-# SyntaxError: cannot assign to True
+# SyntaxError: cannot assign to True here. Maybe you meant '==' instead of '='?
>>> f(__debug__=1)
Traceback (most recent call last):
SyntaxError: cannot assign to __debug__
@@ -684,7 +684,7 @@
... pass
Traceback (most recent call last):
...
- SyntaxError: cannot assign to function call
+ SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
>>> if 1:
... pass
@@ -692,7 +692,7 @@
... x() = 1
Traceback (most recent call last):
...
- SyntaxError: cannot assign to function call
+ SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
>>> if 1:
... x() = 1
@@ -702,7 +702,7 @@
... pass
Traceback (most recent call last):
...
- SyntaxError: cannot assign to function call
+ SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
>>> if 1:
... pass
@@ -712,7 +712,7 @@
... pass
Traceback (most recent call last):
...
- SyntaxError: cannot assign to function call
+ SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
>>> if 1:
... pass
@@ -722,7 +722,7 @@
... x() = 1
Traceback (most recent call last):
...
- SyntaxError: cannot assign to function call
+ SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?
Missing ':' before suites:
@@ -843,6 +843,26 @@
Traceback (most recent call last):
SyntaxError: expected ':'
+ >>> if x = 3:
+ ... pass
+ Traceback (most recent call last):
+ SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?
+
+ >>> while x = 3:
+ ... pass
+ Traceback (most recent call last):
+ SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?
+
+ >>> if x.a = 3:
+ ... pass
+ Traceback (most recent call last):
+ SyntaxError: cannot assign to attribute here. Maybe you meant '==' instead of '='?
+
+ >>> while x.a = 3:
+ ... pass
+ Traceback (most recent call last):
+ SyntaxError: cannot assign to attribute here. Maybe you meant '==' instead of '='?
+
Make sure that the old "raise X, Y[, Z]" form is gone:
>>> raise X, Y
Traceback (most recent call last):
@@ -894,19 +914,19 @@
>>> {1, 2, 3} = 42
Traceback (most recent call last):
-SyntaxError: cannot assign to set display
+SyntaxError: cannot assign to set display here. Maybe you meant '==' instead of '='?
>>> {1: 2, 3: 4} = 42
Traceback (most recent call last):
-SyntaxError: cannot assign to dict display
+SyntaxError: cannot assign to dict literal here. Maybe you meant '==' instead of '='?
>>> f'{x}' = 42
Traceback (most recent call last):
-SyntaxError: cannot assign to f-string expression
+SyntaxError: cannot assign to f-string expression here. Maybe you meant '==' instead of '='?
>>> f'{x}-{y}' = 42
Traceback (most recent call last):
-SyntaxError: cannot assign to f-string expression
+SyntaxError: cannot assign to f-string expression here. Maybe you meant '==' instead of '='?
>>> from t import x,
Traceback (most recent call last):
@@ -988,7 +1008,7 @@ def _check_error(self, code, errtext,
def test_expression_with_assignment(self):
self._check_error(
"print(end1 + end2 = ' ')",
- 'expression cannot contain assignment, perhaps you meant "=="?',
+ "cannot assign to expression here. Maybe you meant '==' instead of '='?",
offset=19
)
@@ -1000,31 +1020,31 @@ def test_assign_call(self):
def test_assign_del(self):
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)", "use starred expression")
- 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")
+ self._check_error("del 1", "cannot delete literal")
+ self._check_error("del (1, 2)", "cannot delete literal")
+ self._check_error("del None", "cannot delete None")
+ self._check_error("del *x", "cannot delete starred")
+ self._check_error("del (*x)", "cannot use starred expression")
+ self._check_error("del (*x,)", "cannot delete starred")
+ self._check_error("del [*x,]", "cannot delete starred")
+ self._check_error("del f()", "cannot delete function call")
+ self._check_error("del f(a, b)", "cannot delete function call")
+ self._check_error("del o.f()", "cannot delete function call")
+ self._check_error("del a[0]()", "cannot delete function call")
+ self._check_error("del x, f()", "cannot delete function call")
+ self._check_error("del f(), x", "cannot delete function call")
+ self._check_error("del [a, b, ((c), (d,), e.f())]", "cannot delete function call")
+ self._check_error("del (a if True else b)", "cannot delete conditional")
+ self._check_error("del +a", "cannot delete expression")
+ self._check_error("del a, +b", "cannot delete expression")
+ self._check_error("del a + b", "cannot delete expression")
+ self._check_error("del (a + b, c)", "cannot delete expression")
+ self._check_error("del (c[0], a + b)", "cannot delete expression")
+ self._check_error("del a.b.c + 2", "cannot delete expression")
+ self._check_error("del a.b.c[0] + 2", "cannot delete expression")
+ self._check_error("del (a, b, (c, d.e.f + 2))", "cannot delete expression")
+ self._check_error("del [a, b, (c, d.e.f[0] + 2)]", "cannot delete expression")
+ self._check_error("del (a := 5)", "cannot 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")