fix not equal conversions (#2921)

Author: jycor

Diff for: enginetest/queries/script_queries.go

@@ -7831,6 +7831,33 @@ where
 					{123},
 				},
 			},
+			{
+				Query: "select * from t where i != (false or i);",
+				Expected: []sql.Row{
+					{123},
+				},
+			},
+		},
+	},
+	{
+		Name:    "negative int limits",
+		Dialect: "mysql",
+		SetUpScript: []string{
+			"CREATE TABLE t(i8 tinyint, i16 smallint, i24 mediumint, i32 int, i64 bigint);",
+			"INSERT INTO t VALUES(-128, -32768, -8388608, -2147483648, -9223372036854775808);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				SkipResultCheckOnServerEngine: true,
+				Query:                         "SELECT -i8, -i16, -i24, -i32 from t;",
+				Expected: []sql.Row{
+					{128, 32768, 8388608, 2147483648},
+				},
+			},
+			{
+				Query:          "SELECT -i64 from t;",
+				ExpectedErrStr: "BIGINT out of range for -9223372036854775808",
+			},
 		},
 	},
 	{

Diff for: sql/analyzer/optimization_rules.go

@@ -246,11 +246,11 @@ func simplifyFilters(ctx *sql.Context, a *Analyzer, node sql.Node, scope *plan.S
 					return e.RightChild, transform.NewTree, nil
 				}
 
-				if isFalse(e.LeftChild) {
+				if isFalse(e.LeftChild) && types.IsBoolean(e.RightChild.Type()) {
 					return e.RightChild, transform.NewTree, nil
 				}
 
-				if isFalse(e.RightChild) {
+				if isFalse(e.RightChild) && types.IsBoolean(e.LeftChild.Type()) {
 					return e.LeftChild, transform.NewTree, nil
 				}