shader: Check the existence of 'return'

internal/shader/shader.go

@@ -645,6 +645,28 @@ func (cs *compileState) parseFunc(block *block, d *ast.FuncDecl) (function, bool
 		return function{}, false
 	}
 
+	if len(outParams) > 0 {
+		var hasReturn func(stmts []shaderir.Stmt) bool
+		hasReturn = func(stmts []shaderir.Stmt) bool {
+			for _, stmt := range stmts {
+				if stmt.Type == shaderir.Return {
+					return true
+				}
+				for _, b := range stmt.Blocks {
+					if hasReturn(b.Stmts) {
+						return true
+					}
+				}
+			}
+			return false
+		}
+
+		if !hasReturn(b.ir.Stmts) {
+			cs.addError(d.Pos(), fmt.Sprintf("function %s must have a return statement but not", d.Name))
+			return function{}, false
+		}
+	}
+
 	var inT, outT []shaderir.Type
 	for _, v := range inParams {
 		inT = append(inT, v.typ)

internal/shader/testdata/func.expected.vs

@@ -1,4 +1,6 @@
 void F0(in vec2 l0, out vec4 l1);
 
 void F0(in vec2 l0, out vec4 l1) {
+	l1 = vec4(0.0);
+	return;
 }

internal/shader/testdata/func.go

@@ -1,4 +1,5 @@
 package main
 
 func Foo(foo vec2) vec4 {
+	return vec4(0)
 }

shader_test.go

@@ -259,6 +259,26 @@ func Foo() (float, float) {
 func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 	return vec4(0);
 }
+`)); err == nil {
+		t.Errorf("error must be non-nil but was nil")
+	}
+
+	if _, err := NewShader([]byte(`package main
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+}
+`)); err == nil {
+		t.Errorf("error must be non-nil but was nil")
+	}
+
+	if _, err := NewShader([]byte(`package main
+
+func Foo() float {
+}
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	return vec4(0)
+}
 `)); err == nil {
 		t.Errorf("error must be non-nil but was nil")
 	}