[Tarantool-patches] [PATCH v1 3/3] sql: do not truncate DECIMAL in LIMIT and OFFSET

[Mergen Imeev via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

This patch removes the DECIMAL truncation in LIMIT and OFFSET, because
according to the implicit casting rules, DECIMAL with digits after the
decimal point cannot be implicitly cast to INTEGER.

Closes #6485
---
 .../unreleased/gh-6485-bug-of-decimal.md      |  8 +++++++
 src/box/sql/mem.c                             |  2 +-
 test/sql-tap/gh-6485-bugs-in-decimal.test.lua | 21 ++++++++++++++++++-
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 changelogs/unreleased/gh-6485-bug-of-decimal.md

diff --git a/changelogs/unreleased/gh-6485-bug-of-decimal.md b/changelogs/unreleased/gh-6485-bug-of-decimal.md
new file mode 100644
index 000000000..bcf023b31
--- /dev/null
+++ b/changelogs/unreleased/gh-6485-bug-of-decimal.md
@@ -0,0 +1,8 @@
+## bugfix/sql
+
+* Fixed truncation of DECIMAL during implicit cast to INTEGER in LIMIT and
+  OFFSET.
+* Fixed truncation of DECIMAL during implicit cast to INTEGER when value is used
+  in an index.
+* Fixed assert on cast of DECIMAL value that greater than -1.0 and less than 0.0
+  to INTEGER (gh-6485).
diff --git a/src/box/sql/mem.c b/src/box/sql/mem.c
index bc6f9b35a..7e94dc8bb 100644
--- a/src/box/sql/mem.c
+++ b/src/box/sql/mem.c
@@ -1338,7 +1338,7 @@ mem_to_int_precise(struct Mem *mem)
 	if (mem->type == MEM_TYPE_DOUBLE)
 		return double_to_int_precise(mem);
 	if (mem->type == MEM_TYPE_DEC)
-		return dec_to_int(mem);
+		return dec_to_int_precise(mem);
 	return -1;
 }
 
diff --git a/test/sql-tap/gh-6485-bugs-in-decimal.test.lua b/test/sql-tap/gh-6485-bugs-in-decimal.test.lua
index 0b9b2ea0a..fc2ac963d 100755
--- a/test/sql-tap/gh-6485-bugs-in-decimal.test.lua
+++ b/test/sql-tap/gh-6485-bugs-in-decimal.test.lua
@@ -1,6 +1,6 @@
 #!/usr/bin/env tarantool
 local test = require("sqltester")
-test:plan(3)
+test:plan(5)
 
 -- Make sure DECIMAL is not truncated when used in an index.
 test:do_execsql_test(
@@ -35,4 +35,23 @@ test:do_execsql_test(
     ]], {
     })
 
+-- Make sure DECIMAL is not truncated when used in LIMIT and OFFSET.
+test:do_catchsql_test(
+    "gh-6485-4",
+    [[
+        SELECT 1 LIMIT CAST(1.5 AS DECIMAL);
+    ]], {
+        1, [[Failed to execute SQL statement: ]]..
+        [[Only positive integers are allowed in the LIMIT clause]]
+    })
+
+test:do_catchsql_test(
+    "gh-6485-5",
+    [[
+        SELECT 1 LIMIT 1 OFFSET CAST(1.5 AS DECIMAL);
+    ]], {
+        1, [[Failed to execute SQL statement: ]]..
+        [[Only positive integers are allowed in the OFFSET clause]]
+    })
+
 test:finish_test()
-- 
2.25.1