From e3de11f3b3363c656a58fc79fb31836a9cb1c081 Mon Sep 17 00:00:00 2001
From: kasiafi <30203062+kasiafi@users.noreply.github.com>
Date: Thu, 20 Jan 2022 11:35:51 +0100
Subject: [PATCH] Add comments showing deviation from the standard

---
 .../trino-main/src/main/java/io/trino/util/DateTimeUtils.java | 4 ++++
 .../src/test/java/io/trino/sql/TestExpressionInterpreter.java | 1 +
 .../src/test/java/io/trino/type/TestDateTimeOperators.java    | 1 +
 3 files changed, 6 insertions(+)

diff --git a/core/trino-main/src/main/java/io/trino/util/DateTimeUtils.java b/core/trino-main/src/main/java/io/trino/util/DateTimeUtils.java
index a8643633230f..bb7e57c75303 100644
--- a/core/trino-main/src/main/java/io/trino/util/DateTimeUtils.java
+++ b/core/trino-main/src/main/java/io/trino/util/DateTimeUtils.java
@@ -61,6 +61,10 @@ private DateTimeUtils() {}
 
     public static int parseDate(String value)
     {
+        // in order to follow the standard, we should validate the value:
+        // - the required format is 'YYYY-MM-DD'
+        // - all components should be unsigned numbers
+        // https://github.com/trinodb/trino/issues/10677
         return toIntExact(TimeUnit.MILLISECONDS.toDays(DATE_FORMATTER.parseMillis(value)));
     }
 
diff --git a/core/trino-main/src/test/java/io/trino/sql/TestExpressionInterpreter.java b/core/trino-main/src/test/java/io/trino/sql/TestExpressionInterpreter.java
index 990cc7df39c6..f2ec1e416956 100644
--- a/core/trino-main/src/test/java/io/trino/sql/TestExpressionInterpreter.java
+++ b/core/trino-main/src/test/java/io/trino/sql/TestExpressionInterpreter.java
@@ -837,6 +837,7 @@ public void testCastRealToBoundedVarchar()
     public void testCastDateToBoundedVarchar()
     {
         assertEvaluatedEquals("CAST(DATE '2013-02-02' AS varchar(10))", "'2013-02-02'");
+        // according to the SQL standard, this literal is incorrect. Year should be unsigned. https://github.com/trinodb/trino/issues/10677
         assertEvaluatedEquals("CAST(DATE '-2013-02-02' AS varchar(50))", "'-2013-02-02'");
 
         // the result value does not fit in the type
diff --git a/core/trino-main/src/test/java/io/trino/type/TestDateTimeOperators.java b/core/trino-main/src/test/java/io/trino/type/TestDateTimeOperators.java
index aa54cba89ada..2d8c3a8d7cdb 100644
--- a/core/trino-main/src/test/java/io/trino/type/TestDateTimeOperators.java
+++ b/core/trino-main/src/test/java/io/trino/type/TestDateTimeOperators.java
@@ -269,6 +269,7 @@ public void testDateCastFromVarchar()
     public void testDateCastToVarchar()
     {
         assertFunction("cast(DATE '2013-02-02' AS varchar)", VARCHAR, "2013-02-02");
+        // according to the SQL standard, this literal is incorrect. The required format is 'YYYY-MM-DD'. https://github.com/trinodb/trino/issues/10677
         assertFunction("cast(DATE '13-2-2' AS varchar)", VARCHAR, "0013-02-02");
         assertFunction("cast(DATE '2013-02-02' AS varchar(50))", createVarcharType(50), "2013-02-02");
         assertFunction("cast(DATE '2013-02-02' AS varchar(10))", createVarcharType(10), "2013-02-02");