MDEV-27972: Unexpected behavior with negative zero (-0) in

JSON Path

Analysis: When we have '-' followed by 0, then the state is
changed to JE_SYN, meaning syntax error.
Fix: Change the state to PS_INT instead, because we are
reading '0' next (integer) and it is not a syntax error.

mysql-test/main/func_json.result

@@ -2013,5 +2013,21 @@ SELECT JSON_VALUE(@json, '$.A[last-1][last-1].key1');
 JSON_VALUE(@json, '$.A[last-1][last-1].key1')
 123
 #
+# MDEV-27972: Unexpected behavior with negative zero (-0) in JSON Path
+#
+SET @json='{ "x": [0,1]}';
+SELECT JSON_VALUE(@json,'$.x[last]');
+JSON_VALUE(@json,'$.x[last]')
+1
+SELECT JSON_VALUE(@json,'$.x[last-0]');
+JSON_VALUE(@json,'$.x[last-0]')
+1
+SELECT JSON_VALUE(@json,'$.x[-0]');
+JSON_VALUE(@json,'$.x[-0]')
+0
+SELECT JSON_VALUE(@json,'$.x[0]');
+JSON_VALUE(@json,'$.x[0]')
+0
+#
 # End of 10.9 Test
 #

mysql-test/main/func_json.test

@@ -1306,6 +1306,16 @@ SET @json='{
 SELECT JSON_VALUE(@json, '$.A[-2][-2].key1');
 SELECT JSON_VALUE(@json, '$.A[last-1][last-1].key1');
 
+--echo #
+--echo # MDEV-27972: Unexpected behavior with negative zero (-0) in JSON Path
+--echo #
+
+SET @json='{ "x": [0,1]}';
+SELECT JSON_VALUE(@json,'$.x[last]');
+SELECT JSON_VALUE(@json,'$.x[last-0]');
+SELECT JSON_VALUE(@json,'$.x[-0]');
+SELECT JSON_VALUE(@json,'$.x[0]');
+
 --echo #
 --echo # End of 10.9 Test
 --echo #

strings/json_lib.c

@@ -1079,7 +1079,7 @@ static int json_path_transitions[N_PATH_STATES][N_PATH_CLASSES]=
 /* AWD */ { JE_EOS, JE_SYN, JE_SYN, JE_SYN, PS_PT,  JE_SYN,JE_SYN, JE_SYN,
             JE_SYN, JE_SYN, JE_SYN, PS_AS,  JE_SYN, JE_SYN, JE_SYN,
             JE_NOT_JSON_CHR, JE_BAD_CHR},
-/* NEG */ { JE_EOS, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN,JE_SYN,
+/* NEG */ { JE_EOS, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN, PS_INT,
             PS_INT, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN, JE_SYN,
             JE_NOT_JSON_CHR, JE_BAD_CHR},
 /* Z */   { JE_EOS, JE_SYN, JE_SYN, JE_SYN, PS_PT,  JE_SYN,JE_SYN, JE_SYN,