Wrong deparse of particular BooleanTest

[lelit]

Yesterday I fixed this issue in pglast, and trying now I see that the same problem afflicts also the deparse() machinery.

Basically,

SELECT (false AND true) IS FALSE

and

SELECT a = (true IS FALSE)

come out without the needed parens.

I was able to mimick the fix for the first case, but I'm not sure how to address the second case: in pglast I consulted the BooleanTest's parent node, and when its a A_Expr I encoded it within parens.

Here is a diff, with test cases and the mentioned fix:

diff --git a/src/postgres_deparse.c b/src/postgres_deparse.c
index e4cac50..a9c5bd0 100644
--- a/src/postgres_deparse.c
+++ b/src/postgres_deparse.c
@@ -3950,7 +3950,16 @@ static void deparseMinMaxExpr(StringInfo str, MinMaxExpr *min_max_expr)
 
 static void deparseBooleanTest(StringInfo str, BooleanTest *boolean_test)
 {
+	bool need_parens = IsA(boolean_test->arg, BoolExpr);
+
+	if (need_parens)
+		appendStringInfoChar(str, '(');
+
 	deparseExpr(str, (Node *) boolean_test->arg);
+
+	if (need_parens)
+		appendStringInfoChar(str, ')');
+
 	switch (boolean_test->booltesttype)
 	{
 		case IS_TRUE:
diff --git a/test/deparse_tests.c b/test/deparse_tests.c
index 2860797..8ac26bf 100644
--- a/test/deparse_tests.c
+++ b/test/deparse_tests.c
@@ -398,6 +398,8 @@ const char* tests[] = {
   "CREATE PROCEDURE returns_one() LANGUAGE sql BEGIN ATOMIC RETURN 1; END",
   "CREATE PROCEDURE updates_and_returns_one() LANGUAGE sql BEGIN ATOMIC UPDATE tbl SET a = 1; RETURN 1; END",
   "SELECT 1 FROM tbl LIMIT COALESCE($1, $2)",
+  "SELECT (false AND true) IS FALSE",
+  "SELECT a = (true IS FALSE)",
 };
 
 size_t testsLength = __LINE__ - 4;

Maybe if you can gimme some hint I may find some time to implement a complete PR fixing the issue.

Thanks&bye!

[lelit]

Well, dunno what confused me at the first attempt, but I found my way... going the other way around! 😋