From 665ce4ccf96b78f3a52e9b6ef1c1eeff580756ea Mon Sep 17 00:00:00 2001
From: Unrud <unrud@outlook.com>
Date: Thu, 8 Dec 2022 00:51:30 +0100
Subject: [PATCH] Fix lua modulo

---
 _glua-tests/issues.lua | 17 +++++++++++++++++
 _vm.go                 |  2 +-
 vm.go                  |  2 +-
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/_glua-tests/issues.lua b/_glua-tests/issues.lua
index fadabf3a..a4b830b6 100644
--- a/_glua-tests/issues.lua
+++ b/_glua-tests/issues.lua
@@ -387,3 +387,20 @@ function test()
     assert(a == 1 and b == nil and c == nil)
 end
 test()
+
+-- issue #412
+-- issue #418
+-- Conversion from symmetric modulo is incorrect.
+function test()
+    assert(-2 % -2 == 0)
+    assert(-1 % -2 == -1)
+    assert(0 % -2 == 0)
+    assert(1 % -2 == -1)
+    assert(2 % -2 == 0)
+    assert(-2 % 2 == 0)
+    assert(-1 % 2 == 1)
+    assert(0 % 2 == 0)
+    assert(1 % 2 == 1)
+    assert(2 % 2 == 0)
+end
+test()
diff --git a/_vm.go b/_vm.go
index 049107e1..687fe797 100644
--- a/_vm.go
+++ b/_vm.go
@@ -840,7 +840,7 @@ func luaModulo(lhs, rhs LNumber) LNumber {
 	flhs := float64(lhs)
 	frhs := float64(rhs)
 	v := math.Mod(flhs, frhs)
-	if flhs < 0 || frhs < 0 && !(flhs < 0 && frhs < 0) {
+	if frhs > 0 && v < 0 || frhs < 0 && v > 0 {
 		v += frhs
 	}
 	return LNumber(v)
diff --git a/vm.go b/vm.go
index aaa04dc9..470855f2 100644
--- a/vm.go
+++ b/vm.go
@@ -1533,7 +1533,7 @@ func luaModulo(lhs, rhs LNumber) LNumber {
 	flhs := float64(lhs)
 	frhs := float64(rhs)
 	v := math.Mod(flhs, frhs)
-	if flhs < 0 || frhs < 0 && !(flhs < 0 && frhs < 0) {
+	if frhs > 0 && v < 0 || frhs < 0 && v > 0 {
 		v += frhs
 	}
 	return LNumber(v)