Merge pull request python#54 from sunmy2019/handle-invalid-expressions

Author: pablogsal

Grammar/python.gram

@@ -884,11 +884,11 @@ fstring_middle[expr_ty]:
 # or otherwise it will try to parse the first token with the regular tokenizer mode (due to the EXTRA).
 # TODO: (Ideally we need a way similar to 'memo' so the parser can set the tokenize mode on fstring/normal)
 fstring_replacement_field[expr_ty]:
-    | expr_start='{' a=(yield_expr | star_expressions) debug_expr="="? conversion=[
+    | '{' a=(yield_expr | star_expressions) debug_expr="="? conversion=[
         conv_token="!" conv=NAME { _PyPegen_check_fstring_conversion(p, conv_token, conv) ? NULL : conv }
     ] format=[
         ':' spec=fstring_format_spec* { spec ? _PyAST_JoinedStr((asdl_expr_seq*)spec, EXTRA) : NULL }
-    ] &&'}' {
+    ] '}' {
         _PyPegen_formatted_value(p, a, debug_expr, conversion, format, EXTRA)
     }
     | invalid_replacement_field

Lib/test/test_exceptions.py

@@ -155,6 +155,7 @@ def ckmsg(src, msg):
 
         ckmsg(s, "'continue' not properly in loop")
         ckmsg("continue\n", "'continue' not properly in loop")
+        ckmsg("f'{6 0}'", "invalid syntax. Perhaps you forgot a comma?")
 
     def testSyntaxErrorMissingParens(self):
         def ckmsg(src, msg, exception=SyntaxError):
@@ -227,7 +228,7 @@ def testSyntaxErrorOffset(self):
         check('Python = "\u1e54\xfd\u0163\u0125\xf2\xf1" +', 1, 20)
         check(b'# -*- coding: cp1251 -*-\nPython = "\xcf\xb3\xf2\xee\xed" +',
               2, 19, encoding='cp1251')
-        check(b'Python = "\xcf\xb3\xf2\xee\xed" +', 1, 18)
+        check(b'Python = "\xcf\xb3\xf2\xee\xed" +', 1, 10)
         check('x = "a', 1, 5)
         check('lambda x: x = 2', 1, 1)
         check('f{a + b + c}', 1, 2)
@@ -293,7 +294,7 @@ def baz():
 
             {
             6
-            0="""''', 5, 13)
+            0="""''', 6, 15)
 
         # Errors thrown by symtable.c
         check('x = [(yield i) for i in range(3)]', 1, 7)