Fix parsing of negative integer constants

Currently the value of negative constants are omitted. Only omit *0*
constants.

An earlier attempt (pganalyze#244) caused a mismatch with the protobuf json
output, since that wants to omit values that are equal to the default
value.

I don't *really* think that is particularly sensible behavior for an
integer constant in an AST, but oh well.

Fixes pganalyze#243.

src/pg_query_outfuncs_json.c

@@ -203,7 +203,9 @@ _outOidList(StringInfo out, const List *node)
 static void
 _outInteger(StringInfo out, const Integer *node)
 {
-	if (node->ival > 0)
+	/* Don't output anything if the value is the default (0), to match
+	* protobuf's behavior. */
+	if (node->ival != 0)
 		appendStringInfo(out, "\"ival\":%d", node->ival);
 }
 

test/parse_tests.c

@@ -3,8 +3,12 @@ const char* tests[] = {
   "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"boolval\":{},\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}}}]}",
   "SELECT NULL",
   "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"isnull\":true,\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}}}]}",
+  "SELECT 0",
+  "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"ival\":{},\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}}}]}",
   "SELECT 1",
   "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"ival\":{\"ival\":1},\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}}}]}",
+  "SELECT -1",
+  "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"ival\":{\"ival\":-1},\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}}}]}",
   "SELECT 1; SELECT 2",
   "{\"version\":160001,\"stmts\":[{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"ival\":{\"ival\":1},\"location\":7}},\"location\":7}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}},\"stmt_len\":8},{\"stmt\":{\"SelectStmt\":{\"targetList\":[{\"ResTarget\":{\"val\":{\"A_Const\":{\"ival\":{\"ival\":2},\"location\":17}},\"location\":17}}],\"limitOption\":\"LIMIT_OPTION_DEFAULT\",\"op\":\"SETOP_NONE\"}},\"stmt_location\":9}]}",
   "select sum(unique1) FILTER (WHERE unique1 IN (SELECT unique1 FROM onek where unique1 < 100)) FROM tenk1",