internal/shaderir/metal: rename to msl

Closes #2010

internal/graphicsdriver/metal/shader_darwin.go

@@ -20,7 +20,7 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver"
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/metal/mtl"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
-	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/metal"
+	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/msl"
 )
 
 type shaderRpsKey struct {

internal/shader/shader_test.go

@@ -26,7 +26,7 @@ import (
 
 	"github.com/hajimehoshi/ebiten/v2/internal/shader"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/glsl"
-	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/metal"
+	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/msl"
 )
 
 func glslVertexNormalize(str string) string {

internal/shaderir/ir_test.go

@@ -20,7 +20,7 @@ import (
 
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/glsl"
-	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/metal"
+	"github.com/hajimehoshi/ebiten/v2/internal/shaderir/msl"
 )
 
 func block(localVars []shaderir.Type, offset int, stmts ...shaderir.Stmt) *shaderir.Block {

internal/shaderir/msl/msl.go

@@ -36,7 +36,7 @@ type compileContext struct {
 
 func (c *compileContext) structName(p *shaderir.Program, t *shaderir.Type) string {
 	if t.Main != shaderir.Struct {
-		panic("metal: the given type at structName must be a struct")
+		panic("msl: the given type at structName must be a struct")
 	}
 	s := t.String()
 	if n, ok := c.structNames[s]; ok {

internal/shaderir/msl/type.go

@@ -30,7 +30,7 @@ func typeString(t *shaderir.Type, packed bool, ref bool) string {
 		}
 		return t
 	case shaderir.Struct:
-		panic("metal: a struct is not implemented")
+		panic("msl: a struct is not implemented")
 	default:
 		t := basicTypeString(t.Main, packed)
 		if ref {