[Python-checkins] bpo-34013: Don't consider a grouped expression when reporting legacy print syntax errors (GH-27521)

[miss-islington]

https://github.com/python/cpython/commit/35035bc35a9cb8617ab9fe9aac38aaf67c926aef
commit: 35035bc35a9cb8617ab9fe9aac38aaf67c926aef
branch: 3.10
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-07-31T18:31:44-07:00
summary:

bpo-34013: Don't consider a grouped expression when reporting legacy print syntax errors (GH-27521)

(cherry picked from commit 208a7e957b812ad3b3733791845447677a704f3e)

Co-authored-by: Pablo Galindo Salgado <Pablogsal at gmail.com>

files:
M Grammar/python.gram
M Lib/test/test_exceptions.py
M Parser/parser.c

diff --git a/Grammar/python.gram b/Grammar/python.gram
index 70f2de8b9dece5..057bcb641a6666 100644
--- a/Grammar/python.gram
+++ b/Grammar/python.gram
@@ -849,7 +849,7 @@ expression_without_invalid[expr_ty]:
     | disjunction
     | lambdef
 invalid_legacy_expression:
-    | a=NAME b=star_expressions {
+    | a=NAME !'(' b=star_expressions {
         _PyPegen_check_legacy_stmt(p, a) ? RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b,
             "Missing parentheses in call to '%U'. Did you mean %U(...)?", a->v.Name.id, a->v.Name.id) : NULL}
 
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index 8ffebebaeb83d1..339801ebaeaef2 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -182,6 +182,15 @@ def ckmsg(src, msg, exception=SyntaxError):
         s = 'exec f(a+b,c)'
         ckmsg(s, "Missing parentheses in call to 'exec'. Did you mean exec(...)?")
 
+        # Check that we don't incorrectly identify '(...)' as an expression to the right
+        # of 'print'
+
+        s = 'print (a+b,c) $ 42'
+        ckmsg(s, "invalid syntax")
+
+        s = 'exec (a+b,c) $ 42'
+        ckmsg(s, "invalid syntax")
+
         # should not apply to subclasses, see issue #31161
         s = '''if True:\nprint "No indent"'''
         ckmsg(s, "expected an indented block after 'if' statement on line 1", IndentationError)
diff --git a/Parser/parser.c b/Parser/parser.c
index cda5c635276dde..c4a4eb651b3e78 100644
--- a/Parser/parser.c
+++ b/Parser/parser.c
@@ -18180,7 +18180,7 @@ expression_without_invalid_rule(Parser *p)
     return _res;
 }
 
-// invalid_legacy_expression: NAME star_expressions
+// invalid_legacy_expression: NAME !'(' star_expressions
 static void *
 invalid_legacy_expression_rule(Parser *p)
 {
@@ -18191,21 +18191,23 @@ invalid_legacy_expression_rule(Parser *p)
     }
     void * _res = NULL;
     int _mark = p->mark;
-    { // NAME star_expressions
+    { // NAME !'(' star_expressions
         if (p->error_indicator) {
             D(p->level--);
             return NULL;
         }
-        D(fprintf(stderr, "%*c> invalid_legacy_expression[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "NAME star_expressions"));
+        D(fprintf(stderr, "%*c> invalid_legacy_expression[%d-%d]: %s\n", p->level, ' ', _mark, p->mark, "NAME !'(' star_expressions"));
         expr_ty a;
         expr_ty b;
         if (
             (a = _PyPegen_name_token(p))  // NAME
             &&
+            _PyPegen_lookahead_with_int(0, _PyPegen_expect_token, p, 7)  // token='('
+            &&
             (b = star_expressions_rule(p))  // star_expressions
         )
         {
-            D(fprintf(stderr, "%*c+ invalid_legacy_expression[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "NAME star_expressions"));
+            D(fprintf(stderr, "%*c+ invalid_legacy_expression[%d-%d]: %s succeeded!\n", p->level, ' ', _mark, p->mark, "NAME !'(' star_expressions"));
             _res = _PyPegen_check_legacy_stmt ( p , a ) ? RAISE_SYNTAX_ERROR_KNOWN_RANGE ( a , b , "Missing parentheses in call to '%U'. Did you mean %U(...)?" , a -> v . Name . id , a -> v . Name . id ) : NULL;
             if (_res == NULL && PyErr_Occurred()) {
                 p->error_indicator = 1;
@@ -18216,7 +18218,7 @@ invalid_legacy_expression_rule(Parser *p)
         }
         p->mark = _mark;
         D(fprintf(stderr, "%*c%s invalid_legacy_expression[%d-%d]: %s failed!\n", p->level, ' ',
-                  p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "NAME star_expressions"));
+                  p->error_indicator ? "ERROR!" : "-", _mark, p->mark, "NAME !'(' star_expressions"));
     }
     _res = NULL;
   done: