sql: ariphmetic of unsigned values

After this patch, the result type of arithmetic between two unsigned
values will be INTEGER.

Closes tarantool#7295

NO_DOC=bugfix

changelogs/unreleased/gh-7295-unit-arith-res-type.md

@@ -0,0 +1,4 @@
+## bugfix/sql
+
+* The result type of arithmetic between two unsigned values is now
+  INTEGER (gh-7295).

src/box/sql/expr.c

@@ -413,11 +413,10 @@ sql_type_result(enum field_type lhs, enum field_type rhs)
 			return FIELD_TYPE_DOUBLE;
 		if (lhs == FIELD_TYPE_DECIMAL || rhs == FIELD_TYPE_DECIMAL)
 			return FIELD_TYPE_DECIMAL;
-		if (lhs == FIELD_TYPE_INTEGER || rhs == FIELD_TYPE_INTEGER)
-			return FIELD_TYPE_INTEGER;
 		assert(lhs == FIELD_TYPE_UNSIGNED ||
-		       rhs == FIELD_TYPE_UNSIGNED);
-		return FIELD_TYPE_UNSIGNED;
+		       lhs == FIELD_TYPE_INTEGER ||
+		       rhs == FIELD_TYPE_UNSIGNED || rhs == FIELD_TYPE_INTEGER);
+		return FIELD_TYPE_INTEGER;
 	}
 	if ((lhs == FIELD_TYPE_DATETIME && rhs == FIELD_TYPE_DATETIME) ||
 	    (lhs == FIELD_TYPE_INTERVAL && rhs == FIELD_TYPE_INTERVAL))

test/sql-luatest/gh_7295_uint_and_int_def_err_test.lua

@@ -0,0 +1,43 @@
+local server = require('test.luatest_helpers.server')
+local t = require('luatest')
+local g = t.group()
+
+g.before_all(function()
+    g.server = server:new({alias = 'test_uint_int'})
+    g.server:start()
+    g.server:exec(function()
+        box.execute([[CREATE TABLE t(i UNSIGNED PRIMARY KEY, a UNSIGNED);]])
+        box.execute([[INSERT INTO t VALUES (1, 2);]])
+    end)
+end)
+
+g.after_all(function()
+    g.server:exec(function()
+        box.execute([[DROP TABLE t;]])
+    end)
+    g.server:stop()
+end)
+
+g.test_uint_int_1 = function()
+    g.server:exec(function()
+        local t = require('luatest')
+        local res = {{name = "COLUMN_1", type = "integer"}}
+        t.assert_equals(box.execute([[SELECT i + a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i - a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i * a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i / a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i % a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i & a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i | a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i >> a FROM t;]]).metadata, res)
+        t.assert_equals(box.execute([[SELECT i << a FROM t;]]).metadata, res)
+    end)
+end
+
+g.test_uint_int_2 = function()
+    g.server:exec(function()
+        local t = require('luatest')
+        local sql = [[SELECT i - a FROM t ORDER BY 1 LIMIT 1;]]
+        t.assert_equals(box.execute(sql).rows, {{-1}})
+    end)
+end