From ecbe2b99264ed344967628f67acef4d2c82155f7 Mon Sep 17 00:00:00 2001
From: Dave Halter <davidhalter88@gmail.com>
Date: Sun, 9 Jun 2019 21:14:55 +0200
Subject: [PATCH] Add positional only arguments to grammar

---
 parso/python/grammar38.txt | 16 ++++++++++++++--
 test/test_parser.py        | 15 +++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/parso/python/grammar38.txt b/parso/python/grammar38.txt
index b5798e1..1cea0fa 100644
--- a/parso/python/grammar38.txt
+++ b/parso/python/grammar38.txt
@@ -20,13 +20,25 @@ async_funcdef: 'async' funcdef
 funcdef: 'def' NAME parameters ['->' test] ':' suite
 
 parameters: '(' [typedargslist] ')'
-typedargslist: (tfpdef ['=' test] (',' tfpdef ['=' test])* [',' [
+typedargslist: (
+  (tfpdef ['=' test] (',' tfpdef ['=' test])* ',' '/' [',' [ tfpdef ['=' test] (
+        ',' tfpdef ['=' test])* ([',' [
+        '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
+      | '**' tfpdef [',']]])
+  | '*' [tfpdef] (',' tfpdef ['=' test])* ([',' ['**' tfpdef [',']]])
+  | '**' tfpdef [',']]] )
+|  (tfpdef ['=' test] (',' tfpdef ['=' test])* [',' [
         '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
       | '**' tfpdef [',']]]
   | '*' [tfpdef] (',' tfpdef ['=' test])* [',' ['**' tfpdef [',']]]
   | '**' tfpdef [','])
+)
 tfpdef: NAME [':' test]
-varargslist: (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
+varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
+        '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
+      | '**' vfpdef [',']]]
+  | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
+  | '**' vfpdef [',']) ]] | (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
         '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
       | '**' vfpdef [',']]]
   | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
diff --git a/test/test_parser.py b/test/test_parser.py
index a2091b4..e36ad50 100644
--- a/test/test_parser.py
+++ b/test/test_parser.py
@@ -193,3 +193,18 @@ def test_no_error_nodes(each_version):
 
 def test_named_expression(works_ge_py38):
     works_ge_py38.parse("(a := 1, a + 1)")
+
+
+@pytest.mark.parametrize(
+    'param_code', [
+        'a=1, /',
+        'a, /',
+        'a=1, /, b=3',
+        'a, /, b',
+        'a, /, b',
+        'a, /, *, b',
+        'a, /, **kwargs',
+    ]
+)
+def test_positional_only_arguments(works_ge_py38, param_code):
+    works_ge_py38.parse("def x(%s): pass" % param_code)