bpo-28936: Detect lexically first syntax error first (#4097)

Lexically first global and nonlocal syntax errors at given scope should be detected first.

Lib/test/test_syntax.py

@@ -399,6 +399,13 @@ build.  The number of blocks must be greater than CO_MAXBLOCKS.  SF #1565514
 
 Misuse of the nonlocal and global statement can lead to a few unique syntax errors.
 
+   >>> def f():
+   ...     print(x)
+   ...     global x
+   Traceback (most recent call last):
+     ...
+   SyntaxError: name 'x' is used prior to global declaration
+
    >>> def f():
    ...     x = 1
    ...     global x
@@ -406,6 +413,12 @@ Misuse of the nonlocal and global statement can lead to a few unique syntax erro
      ...
    SyntaxError: name 'x' is assigned to before global declaration
 
+   >>> def f(x):
+   ...     global x
+   Traceback (most recent call last):
+     ...
+   SyntaxError: name 'x' is parameter and global
+
    >>> def f():
    ...     x = 1
    ...     def g():
@@ -560,7 +573,6 @@ Corner-cases that used to crash:
 
 import re
 import unittest
-import warnings
 
 from test import support
 
@@ -596,19 +608,25 @@ class SyntaxTestCase(unittest.TestCase):
     def test_assign_del(self):
         self._check_error("del f()", "delete")
 
-    def test_global_err_then_warn(self):
-        # Bug #763201:  The SyntaxError raised for one global statement
-        # shouldn't be clobbered by a SyntaxWarning issued for a later one.
+    def test_global_param_err_first(self):
         source = """if 1:
             def error(a):
                 global a  # SyntaxError
-            def warning():
+            def error2():
                 b = 1
-                global b  # SyntaxWarning
+                global b  # SyntaxError
             """
-        warnings.filterwarnings(action='ignore', category=SyntaxWarning)
-        self._check_error(source, "global")
-        warnings.filters.pop(0)
+        self._check_error(source, "parameter and global", lineno=3)
+
+    def test_nonlocal_param_err_first(self):
+        source = """if 1:
+            def error(a):
+                nonlocal a  # SyntaxError
+            def error2():
+                b = 1
+                global b  # SyntaxError
+            """
+        self._check_error(source, "parameter and nonlocal", lineno=3)
 
     def test_break_outside_loop(self):
         self._check_error("break", "outside loop")