gh-94192: Fix error for dictionary literals with invalid expression as value. (#94304)

* Fix error for dictionary literals with invalid expression as value.

* Remove trailing whitespace

Grammar/python.gram

@@ -1314,4 +1314,4 @@ invalid_kvpair:
     | a=expression !(':') {
         RAISE_ERROR_KNOWN_LOCATION(p, PyExc_SyntaxError, a->lineno, a->end_col_offset - 1, a->end_lineno, -1, "':' expected after dictionary key") }
     | expression ':' a='*' bitwise_or { RAISE_SYNTAX_ERROR_STARTING_FROM(a, "cannot use a starred expression in a dictionary value") }
-    | expression a=':' {RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "expression expected after dictionary key and ':'") }
+    | expression a=':' &('}'|',') {RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "expression expected after dictionary key and ':'") }

Lib/test/test_syntax.py

@@ -1265,12 +1265,22 @@ Incomplete dictionary literals
    Traceback (most recent call last):
    SyntaxError: expression expected after dictionary key and ':'
 
-   # Ensure that the error is not raise for syntax errors that happen after sets
+   # Ensure that the error is not raised for syntax errors that happen after sets
 
    >>> {1} $
    Traceback (most recent call last):
    SyntaxError: invalid syntax
 
+   # Ensure that the error is not raised for invalid expressions
+
+   >>> {1: 2, 3: foo(,), 4: 5}
+   Traceback (most recent call last):
+   SyntaxError: invalid syntax
+
+   >>> {1: $, 2: 3}
+   Traceback (most recent call last):
+   SyntaxError: invalid syntax
+
 Specialized indentation errors:
 
    >>> while condition:

Misc/NEWS.d/next/Core and Builtins/2022-06-26-14-37-03.gh-issue-94192.ab7tn7.rst

@@ -0,0 +1 @@
+Fix error for dictionary literals with invalid expression as value.