shader: Refactoring

internal/shader/stmt.go

@@ -393,24 +393,23 @@ func (cs *compileState) parseStmt(block *block, fname string, stmt ast.Stmt, inP
 				return nil, false
 			}
 			stmts = append(stmts, ss...)
-			if len(exprs) == 0 {
+
-				if len(exprs) != len(outParams) {
-					cs.addError(stmt.Pos(), fmt.Sprintf("the number of returning variables must be %d but %d", len(outParams), len(stmt.Results)))
-				}
-				continue
-			}
 			if len(exprs) > 1 {
 				if len(stmt.Results) > 1 || len(outParams) == 1 {
 					cs.addError(r.Pos(), "single-value context and multiple-value context cannot be mixed")
 					return nil, false
 				}
 			}
-			// TODO: Is this logic really true?
+
-			if len(exprs) > 1 || len(outParams) > 1 {
+			if len(outParams) > 1 && len(stmt.Results) == 1 {
-				if len(exprs) != len(outParams) && len(stmt.Results) != len(outParams) {
+				if len(exprs) == 1 {
 					cs.addError(stmt.Pos(), fmt.Sprintf("the number of returning variables must be %d but %d", len(outParams), len(stmt.Results)))
 					return nil, false
 				}
+				if len(exprs) > 1 && len(exprs) != len(outParams) {
+					cs.addError(stmt.Pos(), fmt.Sprintf("the number of returning variables must be %d but %d", len(outParams), len(exprs)))
+					return nil, false
+				}
 			}
 
 			for j, t := range ts {

shader_test.go

@@ -283,3 +283,78 @@ func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 		t.Errorf("error must be non-nil but was nil")
 	}
 }
+
+func TestShaderMultipleValueReturn(t *testing.T) {
+	if _, err := NewShader([]byte(`package main
+
+func Foo() (float, float) {
+	return 0.0
+}
+
+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 Foo() float {
+	return 0.0, 0.0
+}
+
+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 Foo() (float, float, float) {
+	return 0.0, 0.0
+}
+
+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 Foo() (float, float) {
+	return 0.0, 0.0
+}
+
+func Foo2() (float, float, float) {
+	return Foo()
+}
+
+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 Foo() (float, float, float) {
+	return 0.0, 0.0, 0.0
+}
+
+func Foo2() (float, float, float) {
+	return Foo()
+}
+
+func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
+	return vec4(0.0)
+}
+`)); err != nil {
+		t.Error(err)
+	}
+}