From d61e654464addbcd9319c58e81326802dfadd77a Mon Sep 17 00:00:00 2001
From: LucaCappelletti94 <cappelletti.luca94@gmail.com>
Date: Wed, 25 Feb 2026 21:33:44 +0100
Subject: [PATCH] Handle unsupported typmod nodes as deparse errors

Replace Assert(false) in deparseTypeName typmod fallback with elog(ERROR), and add deparse regression cases that require parse success and deparse error for enum typmod constructs (issue #330).
---
 src/postgres_deparse.c |  2 +-
 test/deparse.c         | 50 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/src/postgres_deparse.c b/src/postgres_deparse.c
index d4d8237a6..f2a80a51d 100644
--- a/src/postgres_deparse.c
+++ b/src/postgres_deparse.c
@@ -4478,7 +4478,7 @@ static void deparseTypeName(DeparseState *state, TypeName *type_name)
 			else if (IsA(lfirst(lc), ColumnRef))
 				deparseColumnRef(state, lfirst(lc));
 			else
-				Assert(false);
+				elog(ERROR, "deparse: unsupported typmod node type: %u", nodeTag(lfirst(lc)));
 
 			if (lnext(type_name->typmods, lc))
 				deparseAppendStringInfoString(state, ", ");
diff --git a/test/deparse.c b/test/deparse.c
index 5ffb1db3d..51ca77eb5 100644
--- a/test/deparse.c
+++ b/test/deparse.c
@@ -127,6 +127,42 @@ int run_test(const char *query, bool compare_query_text, bool pretty_print) {
 	return ret_code;
 }
 
+int run_test_expect_deparse_error(const char *query, const char *expected_message_substring) {
+	PgQueryProtobufParseResult parse_result = pg_query_parse_protobuf(query);
+	if (parse_result.error) {
+		printf("\nERROR for \"%s\"\n  unexpected parse error: %s\n", query, parse_result.error->message);
+		pg_query_free_protobuf_parse_result(parse_result);
+		return EXIT_FAILURE;
+	}
+
+	PgQueryDeparseResult deparse_result = pg_query_deparse_protobuf(parse_result.parse_tree);
+	if (!deparse_result.error) {
+		printf("\nERROR for \"%s\"\n  expected deparse error, got: %s\n",
+			   query,
+			   deparse_result.query);
+		pg_query_free_deparse_result(deparse_result);
+		pg_query_free_protobuf_parse_result(parse_result);
+		return EXIT_FAILURE;
+	}
+
+	if (expected_message_substring != NULL &&
+		strstr(deparse_result.error->message, expected_message_substring) == NULL) {
+		printf("\nERROR for \"%s\"\n  expected deparse error containing \"%s\"\n  actual: %s\n",
+			   query,
+			   expected_message_substring,
+			   deparse_result.error->message);
+		pg_query_free_deparse_result(deparse_result);
+		pg_query_free_protobuf_parse_result(parse_result);
+		return EXIT_FAILURE;
+	}
+
+	printf(".");
+
+	pg_query_free_deparse_result(deparse_result);
+	pg_query_free_protobuf_parse_result(parse_result);
+	return EXIT_SUCCESS;
+}
+
 int run_tests_from_file(const char * filename, bool compare_query_text, bool pretty_print) {
 	char *sample_buffer;
 	struct stat sample_stat;
@@ -604,6 +640,13 @@ const char* plpgsqlRegressFilenames[] =
 };
 size_t plpgsqlRegressFilenameCount = sizeof(plpgsqlRegressFilenames) / sizeof(plpgsqlRegressFilenames[0]);
 
+const char* deparseErrorTests[] = {
+	"CREATE TABLE t0 (foo ENUM8('a' = 1, 2))",
+	"CREATE TABLE t0 (foo ENUM8('a' = 1, 'b' = 2), bar ENUM16('a' = 1, 'b' = 2), baz ENUM('a', 'b'))",
+	"SELECT 1::enum8('a' = 1, 2)"
+};
+size_t deparseErrorTestsLength = sizeof(deparseErrorTests) / sizeof(deparseErrorTests[0]);
+
 int main() {
 	size_t i;
 	int ret_code = EXIT_SUCCESS;
@@ -637,6 +680,13 @@ int main() {
 			ret_code = test_ret_code;
 	}
 
+	printf("\ndeparse_error.sql\n");
+	for (i = 0; i < deparseErrorTestsLength; i += 1) {
+		test_ret_code = run_test_expect_deparse_error(deparseErrorTests[i], "unsupported typmod node type");
+		if (test_ret_code != EXIT_SUCCESS)
+			ret_code = test_ret_code;
+	}
+
 	for (i = 0; i < regressFilenameCount; i += 1) {
 		printf("\n%s\n", regressFilenames[i]);
 		char *filename = malloc(sizeof(char) * strlen("test/sql/postgres_regress/") + strlen(regressFilenames[i]) + 1);