Don't treat VARCHAR columns as GUIDs. Fixes #1565 (#1566)

* Only treat CHAR(n) columns as Guids.
* Add test to reproduce bug.

This reverts a change in #1546 that was introduced to fix #1528. However, none of the integration tests fail locally when reverting this change, so it's not clear why it was necessary.

Author: bgrainger

src/MySqlConnector/ColumnReaders/ColumnReader.cs

@@ -45,13 +45,13 @@ public static ColumnReader Create(bool isBinary, ColumnDefinitionPayload columnD
 				return BitColumnReader.Instance;
 
 			case ColumnType.String:
-			case ColumnType.VarString:
 				if (connection.GuidFormat == MySqlGuidFormat.Char36 && columnDefinition.ColumnLength / ProtocolUtility.GetBytesPerCharacter(columnDefinition.CharacterSet) == 36)
 					return GuidChar36ColumnReader.Instance;
 				if (connection.GuidFormat == MySqlGuidFormat.Char32 && columnDefinition.ColumnLength / ProtocolUtility.GetBytesPerCharacter(columnDefinition.CharacterSet) == 32)
 					return GuidChar32ColumnReader.Instance;
-				goto case ColumnType.VarChar;
+				goto case ColumnType.VarString;
 
+			case ColumnType.VarString:
 			case ColumnType.VarChar:
 			case ColumnType.TinyBlob:
 			case ColumnType.Blob:

tests/IntegrationTests/DataTypes.cs

@@ -329,6 +329,8 @@ public void QueryDecimal(string column, object[] expected)
 	[InlineData("latin1", new[] { null, "", "ASCII", "Lãtïñ", c_251ByteString })]
 	[InlineData("latin1bin", new[] { null, "", "ASCII", "Lãtïñ", c_251ByteString })]
 	[InlineData("cp1251", new[] { null, "", "ASCII", "АБВГабвг", c_251ByteString })]
+	[InlineData("nonguid_utf8", new[] { null, "", "ASCII", "Ũńıċōđĕ", "This string has 36 characters in it." })]
+	[InlineData("nonguid_latin1", new[] { null, "", "ASCII", "Lãtïñ", "This string has 36 characters in it." })]
 	public void QueryString(string column, string[] expected)
 	{
 		DoQuery("strings", column, "VARCHAR", expected, reader => reader.GetString(0));
@@ -1328,6 +1330,8 @@ public void GetSchemaTableAfterNextResult()
 	[InlineData("cp1251", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR", 300, typeof(string), "N", -1, 0)]
 	[InlineData("guid", "datatypes_strings", MySqlDbType.Guid, "CHAR(36)", 36, typeof(Guid), "N", -1, 0)]
 	[InlineData("guidbin", "datatypes_strings", MySqlDbType.Guid, "CHAR(36)", 36, typeof(Guid), "N", -1, 0)]
+	[InlineData("nonguid_utf8", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR", 36, typeof(string), "N", -1, 0)]
+	[InlineData("nonguid_latin1", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR", 36, typeof(string), "N", -1, 0)]
 	[InlineData("Date", "datatypes_times", MySqlDbType.Date, "DATE", 10, typeof(DateTime), "N", -1, 0)]
 	[InlineData("DateTime", "datatypes_times", MySqlDbType.DateTime, "DATETIME", 26, typeof(DateTime), "N", -1, 6)]
 	[InlineData("Timestamp", "datatypes_times", MySqlDbType.Timestamp, "TIMESTAMP", 26, typeof(DateTime), "N", -1, 6)]
@@ -1420,6 +1424,8 @@ public void GetColumnSchema(string column, string table, MySqlDbType mySqlDbType
 	[InlineData("BigDecimal", "datatypes_reals", MySqlDbType.NewDecimal, "DECIMAL(50,30)", typeof(decimal), 3, null)]
 	[InlineData("utf8", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR(300)", typeof(string), 3, "ASCII")]
 	[InlineData("latin1", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR(300)", typeof(string), 3, "ASCII")]
+	[InlineData("nonguid_utf8", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR(36)", typeof(string), 3, "ASCII")]
+	[InlineData("nonguid_latin1", "datatypes_strings", MySqlDbType.VarChar, "VARCHAR(36)", typeof(string), 3, "ASCII")]
 	[InlineData("Date", "datatypes_times", MySqlDbType.Date, "DATE", typeof(DateTime), 2, null)]
 	[InlineData("DateTime", "datatypes_times", MySqlDbType.DateTime, "DATETIME", typeof(DateTime), 2, null)]
 	[InlineData("Timestamp", "datatypes_times", MySqlDbType.Timestamp, "TIMESTAMP", typeof(DateTime), 2, null)]

tests/IntegrationTests/DataTypesFixture.cs

@@ -121,21 +121,23 @@ latin1 varchar(300) character set 'latin1' null,
   latin1bin varchar(300) character set latin1 collate latin1_bin null,
   cp1251 varchar(300) character set 'cp1251' null,
   guid char(36) null,
-  guidbin char(36) binary null
+  guidbin char(36) binary null,
+  nonguid_utf8 varchar(36) character set 'utf8mb4' null,
+  nonguid_latin1 varchar(36) character set 'latin1' null
 );
 
-insert into datatypes_strings(utf8, utf8bin, latin1, latin1bin, cp1251, guid, guidbin)
+insert into datatypes_strings(utf8, utf8bin, latin1, latin1bin, cp1251, guid, guidbin, nonguid_utf8, nonguid_latin1)
 values
-  (null, null, null, null, null, null, null),
-  ('', '', '', '', '', '00000000-0000-0000-0000-000000000000', '00000000-0000-0000-0000-000000000000'),
-  ('ASCII', 'ASCII', 'ASCII', 'ASCII', 'ASCII', '00000000-0000-0000-c000-000000000046', '00000000-0000-0000-c000-000000000046'),
-  ('Ũńıċōđĕ', 'Ũńıċōđĕ', 'Lãtïñ', 'Lãtïñ', 'АБВГабвг', 'fd24a0e8-c3f2-4821-a456-35da2dc4bb8f', 'fd24a0e8-c3f2-4821-a456-35da2dc4bb8f'),
+  (null, null, null, null, null, null, null, null, null),
+  ('', '', '', '', '', '00000000-0000-0000-0000-000000000000', '00000000-0000-0000-0000-000000000000', '', ''),
+  ('ASCII', 'ASCII', 'ASCII', 'ASCII', 'ASCII', '00000000-0000-0000-c000-000000000046', '00000000-0000-0000-c000-000000000046', 'ASCII', 'ASCII'),
+  ('Ũńıċōđĕ', 'Ũńıċōđĕ', 'Lãtïñ', 'Lãtïñ', 'АБВГабвг', 'fd24a0e8-c3f2-4821-a456-35da2dc4bb8f', 'fd24a0e8-c3f2-4821-a456-35da2dc4bb8f', 'Ũńıċōđĕ', 'Lãtïñ'),
   ('This string has exactly 251 characters in it. The encoded length is stored as 0xFC 0xFB 0x00. 0xFB (i.e., 251) is the sentinel byte indicating ""this field is null"". Incorrectly interpreting the (decoded) length as the sentinel byte would corrupt data.',
    'This string has exactly 251 characters in it. The encoded length is stored as 0xFC 0xFB 0x00. 0xFB (i.e., 251) is the sentinel byte indicating ""this field is null"". Incorrectly interpreting the (decoded) length as the sentinel byte would corrupt data.',
    'This string has exactly 251 characters in it. The encoded length is stored as 0xFC 0xFB 0x00. 0xFB (i.e., 251) is the sentinel byte indicating ""this field is null"". Incorrectly interpreting the (decoded) length as the sentinel byte would corrupt data.',
    'This string has exactly 251 characters in it. The encoded length is stored as 0xFC 0xFB 0x00. 0xFB (i.e., 251) is the sentinel byte indicating ""this field is null"". Incorrectly interpreting the (decoded) length as the sentinel byte would corrupt data.',
    'This string has exactly 251 characters in it. The encoded length is stored as 0xFC 0xFB 0x00. 0xFB (i.e., 251) is the sentinel byte indicating ""this field is null"". Incorrectly interpreting the (decoded) length as the sentinel byte would corrupt data.',
-   '6a0e0a40-6228-11d3-a996-0050041896c8', '6a0e0a40-6228-11d3-a996-0050041896c8');
+   '6a0e0a40-6228-11d3-a996-0050041896c8', '6a0e0a40-6228-11d3-a996-0050041896c8', 'This string has 36 characters in it.', 'This string has 36 characters in it.');
 
 drop table if exists datatypes_blobs;
 create table datatypes_blobs(