From 84c680c6ed33f65ead5fb9587062478f2eef34f8 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 21 Jan 2022 03:37:31 +0900
Subject: [PATCH] internal/shader: ban the operator div on a matrix

The operator div on a matrix doesn't work on Metal.
---
 internal/shader/expr.go | 4 ++++
 internal/shader/stmt.go | 7 ++++++-
 shader_test.go          | 3 +++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/internal/shader/expr.go b/internal/shader/expr.go
index 459fb04ce..dcce38b86 100644
--- a/internal/shader/expr.go
+++ b/internal/shader/expr.go
@@ -182,6 +182,10 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr, markLocalVariable
 			}
 			t = lhst
 		case lhst.Equal(&rhst):
+			if op == shaderir.Div && (rhst.Main == shaderir.Mat2 || rhst.Main == shaderir.Mat3 || rhst.Main == shaderir.Mat4) {
+				cs.addError(e.Pos(), fmt.Sprintf("invalid operation: operator %s not defined on %s", e.Op, rhst.String()))
+				return nil, nil, nil, false
+			}
 			t = lhst
 		case lhst.Main == shaderir.Float:
 			switch rhst.Main {
diff --git a/internal/shader/stmt.go b/internal/shader/stmt.go
index f87a2821f..b55fb8b51 100644
--- a/internal/shader/stmt.go
+++ b/internal/shader/stmt.go
@@ -94,7 +94,12 @@ func (cs *compileState) parseStmt(block *block, fname string, stmt ast.Stmt, inP
 				}
 			}
 
-			if lts[0].Main != rts[0].Main {
+			if lts[0].Main == rts[0].Main {
+				if op == shaderir.Div && (rts[0].Main == shaderir.Mat2 || rts[0].Main == shaderir.Mat3 || rts[0].Main == shaderir.Mat4) {
+					cs.addError(stmt.Pos(), fmt.Sprintf("invalid operation: operator / not defined on %s", rts[0].String()))
+					return nil, false
+				}
+			} else {
 				switch lts[0].Main {
 				case shaderir.Int:
 					if !cs.forceToInt(stmt, &rhs[0]) {
diff --git a/shader_test.go b/shader_test.go
index c73651f79..43e18b496 100644
--- a/shader_test.go
+++ b/shader_test.go
@@ -1594,6 +1594,7 @@ func TestShaderOperatorMultiply(t *testing.T) {
 		{stmt: "a := mat2(1) * vec3(2); _ = a", err: true},
 		{stmt: "a := mat2(1) * vec4(2); _ = a", err: true},
 		{stmt: "a := mat2(1) * mat2(2); _ = a", err: false},
+		{stmt: "a := mat2(1) / mat2(2); _ = a", err: true},
 		{stmt: "a := mat2(1) * mat3(2); _ = a", err: true},
 		{stmt: "a := mat2(1) * mat4(2); _ = a", err: true},
 	}
@@ -1641,6 +1642,7 @@ func TestShaderOperatorMultiplyAssign(t *testing.T) {
 		{stmt: "a := vec2(1); a *= vec4(2)", err: true},
 		{stmt: "a := vec2(1); a *= mat2(2)", err: false},
 		{stmt: "a := vec2(1); a += mat2(2)", err: true},
+		{stmt: "a := vec2(1); a /= mat2(2)", err: true},
 		{stmt: "a := vec2(1); a *= mat3(2)", err: true},
 		{stmt: "a := vec2(1); a *= mat4(2)", err: true},
 		{stmt: "a := mat2(1); a *= 2", err: false},
@@ -1656,6 +1658,7 @@ func TestShaderOperatorMultiplyAssign(t *testing.T) {
 		{stmt: "a := mat2(1); a *= vec4(2)", err: true},
 		{stmt: "a := mat2(1); a *= mat2(2)", err: false},
 		{stmt: "a := mat2(1); a += mat2(2)", err: false},
+		{stmt: "a := mat2(1); a /= mat2(2)", err: true},
 		{stmt: "a := mat2(1); a *= mat3(2)", err: true},
 		{stmt: "a := mat2(1); a *= mat4(2)", err: true},
 	}