fix: support inlined or aliased structs as type enum variants (#1535)

small changes + fixes preempting the refactor

fixes #1531, #1527, #1496

buildengine/testdata/projects/another/another.go

@@ -27,7 +27,6 @@ type One int
 
 func (One) typeEnum() {}
 
-//ftl:typealias export
 type Two string
 
 func (Two) typeEnum() {}

buildengine/testdata/projects/other/other.go

@@ -35,21 +35,21 @@ type MyTime time.Time
 
 func (MyTime) tag() {}
 
-type List []string
+type MyList []string
 
-func (List) tag() {}
+func (MyList) tag() {}
 
-type Map map[string]string
+type MyMap map[string]string
 
-func (Map) tag() {}
+func (MyMap) tag() {}
 
 type MyString string
 
 func (MyString) tag() {}
 
-type Struct struct{}
+type MyStruct struct{}
 
-func (Struct) tag() {}
+func (MyStruct) tag() {}
 
 type MyOption ftl.Option[string]
 

go-runtime/compile/build.go

@@ -350,6 +350,19 @@ var scaffoldFuncs = scaffolder.FuncMap{
 		return out
 	},
 	"schemaType": schemaType,
+	// A standalone enum variant is one that is purely an alias to a type and does not appear
+	// elsewhere in the schema.
+	"isStandaloneEnumVariant": func(v schema.EnumVariant) bool {
+		tv, ok := v.Value.(*schema.TypeValue)
+		if !ok {
+			return false
+		}
+		if ref, ok := tv.Value.(*schema.Ref); ok {
+			return ref.Name != v.Name
+		}
+
+		return false
+	},
 }
 
 func schemaType(t schema.Type) string {

go-runtime/compile/schema.go

@@ -239,7 +239,7 @@ func extractTypeDeclsForNode(pctx *parseContext, node *ast.GenDecl) {
 		switch dir := dir.(type) {
 		case *directiveEnum:
 			typ := pctx.pkg.TypesInfo.TypeOf(t.Type)
-			switch typ.Underlying().(type) {
+			switch underlying := typ.Underlying().(type) {
 			case *types.Basic:
 				enum := &schema.Enum{
 					Pos:      goPosToSchemaPos(node.Pos()),
@@ -251,6 +251,23 @@ func extractTypeDeclsForNode(pctx *parseContext, node *ast.GenDecl) {
 				pctx.module.Decls = append(pctx.module.Decls, enum)
 				pctx.nativeNames[enum] = nativeName
 			case *types.Interface:
+				if underlying.NumMethods() == 0 {
+					pctx.errors.add(errorf(node, "enum discriminator %q must define at least one method", t.Name.Name))
+					break
+				}
+
+				hasExportedMethod := false
+				for i, n := 0, underlying.NumMethods(); i < n; i++ {
+					if underlying.Method(i).Exported() {
+						pctx.errors.add(noEndColumnErrorf(underlying.Method(i).Pos(), "enum discriminator %q cannot "+
+							"contain exported methods", t.Name.Name))
+						hasExportedMethod = true
+					}
+				}
+				if hasExportedMethod {
+					break
+				}
+
 				enum := &schema.Enum{
 					Pos:      goPosToSchemaPos(node.Pos()),
 					Comments: visitComments(node.Doc),
@@ -670,7 +687,7 @@ func visitGenDecl(pctx *parseContext, node *ast.GenDecl) {
 							}
 						}
 					} else if _, ok := dir.(*directiveTypeAlias); ok {
-						decl, ok := pctx.getDeclForTypeName(t.Name.Name)
+						decl, ok := pctx.getDeclForTypeName(t.Name.Name).Get()
 						if !ok {
 							pctx.errors.add(errorf(node, "could not find type alias declaration for %q", t.Name.Name))
 							return
@@ -781,10 +798,7 @@ func maybeVisitTypeEnumVariant(pctx *parseContext, node *ast.GenDecl, directives
 		isExported := enum.IsExported()
 		for _, dir := range directives {
 			if exportableDir, ok := dir.(exportable); ok {
-				if enum.Export && !exportableDir.IsExported() {
-					pctx.errors.add(errorf(node, "parent enum %q is exported, but directive %q on %q is not: all variants of exported enums that have a directive must be explicitly exported as well", enumName, exportableDir, t.Name.Name))
-				}
-				isExported = exportableDir.IsExported()
+				isExported = exportableDir.IsExported() || isExported
 			}
 		}
 		vType, ok := visitTypeValue(pctx, named, t.Type, nil, isExported).Get()
@@ -864,7 +878,11 @@ func visitTypeValue(pctx *parseContext, named *types.Named, tnode ast.Expr, inde
 		}
 
 	default:
-		if typ, ok := visitType(pctx, tnode.Pos(), named, isExported).Get(); ok {
+		variantNode := pctx.pkg.TypesInfo.TypeOf(tnode)
+		if _, ok := variantNode.(*types.Struct); ok {
+			variantNode = named
+		}
+		if typ, ok := visitType(pctx, tnode.Pos(), variantNode, isExported).Get(); ok {
 			return optional.Some(&schema.TypeValue{Value: typ})
 		} else {
 			pctx.errors.add(errorf(tnode, "unsupported type %q for type enum variant", named))
@@ -1226,20 +1244,14 @@ func visitType(pctx *parseContext, pos token.Pos, tnode types.Type, isExported b
 	if tparam, ok := tnode.(*types.TypeParam); ok {
 		return optional.Some[schema.Type](&schema.Ref{Pos: goPosToSchemaPos(pos), Name: tparam.Obj().Id()})
 	}
+
 	if named, ok := tnode.(*types.Named); ok {
 		// Handle refs to type aliases and enums, rather than the underlying type.
-		decl, ok := pctx.getDeclForTypeName(named.Obj().Name())
+		decl, ok := pctx.getDeclForTypeName(named.Obj().Name()).Get()
 		if ok {
 			switch decl.(type) {
 			case *schema.TypeAlias, *schema.Enum:
-				if isExported {
-					pctx.markAsExported(decl)
-				}
-				return optional.Some[schema.Type](&schema.Ref{
-					Pos:    goPosToSchemaPos(pos),
-					Module: pctx.module.Name,
-					Name:   strcase.ToUpperCamel(named.Obj().Name()),
-				})
+				return visitNamedRef(pctx, pos, named, isExported)
 			case *schema.Data, *schema.Verb, *schema.Config, *schema.Secret, *schema.Database, *schema.FSM:
 			}
 		}
@@ -1248,12 +1260,8 @@ func visitType(pctx *parseContext, pos token.Pos, tnode types.Type, isExported b
 	switch underlying := tnode.Underlying().(type) {
 	case *types.Basic:
 		if named, ok := tnode.(*types.Named); ok {
-			ref, doneWithVisit := visitNamedRef(pctx, pos, named)
-			if doneWithVisit {
-				return ref
-			}
+			return visitNamedRef(pctx, pos, named, isExported)
 		}
-
 		switch underlying.Kind() {
 		case types.String:
 			return optional.Some[schema.Type](&schema.String{Pos: goPosToSchemaPos(pos)})
@@ -1315,10 +1323,7 @@ func visitType(pctx *parseContext, pos token.Pos, tnode types.Type, isExported b
 			return optional.Some[schema.Type](&schema.Any{Pos: goPosToSchemaPos(pos)})
 		}
 		if named, ok := tnode.(*types.Named); ok {
-			ref, doneWithVisit := visitNamedRef(pctx, pos, named)
-			if doneWithVisit {
-				return ref
-			}
+			return visitNamedRef(pctx, pos, named, isExported)
 		}
 		return optional.None[schema.Type]()
 
@@ -1327,29 +1332,36 @@ func visitType(pctx *parseContext, pos token.Pos, tnode types.Type, isExported b
 	}
 }
 
-func visitNamedRef(pctx *parseContext, pos token.Pos, named *types.Named) (optional.Option[schema.Type], bool) {
+func visitNamedRef(pctx *parseContext, pos token.Pos, named *types.Named, isExported bool) optional.Option[schema.Type] {
 	if named.Obj().Pkg() == nil {
-		return optional.None[schema.Type](), false
+		return optional.None[schema.Type]()
+	}
+
+	// Update the visibility of the reference if the referencer is exported (ensuring refs are transitively
+	// exported as needed).
+	if isExported {
+		if decl, ok := pctx.getDeclForTypeName(named.Obj().Name()).Get(); ok {
+			pctx.markAsExported(decl)
+		}
 	}
+
 	nodePath := named.Obj().Pkg().Path()
-	var ref *schema.Ref
+	destModule := pctx.module.Name
 	if !pctx.isPathInPkg(nodePath) {
 		if !strings.HasPrefix(named.Obj().Pkg().Path(), "ftl/") {
 			pctx.errors.add(noEndColumnErrorf(pos,
 				"unsupported external type %q", named.Obj().Pkg().Path()+"."+named.Obj().Name()))
-			return optional.None[schema.Type](), true
+			return optional.None[schema.Type]()
 		}
 		base := path.Dir(pctx.pkg.PkgPath)
-		destModule := path.Base(strings.TrimPrefix(nodePath, base+"/"))
-		ref = &schema.Ref{
-			Pos:    goPosToSchemaPos(pos),
-			Module: destModule,
-			Name:   named.Obj().Name(),
-		}
-		return optional.Some[schema.Type](ref), true
+		destModule = path.Base(strings.TrimPrefix(nodePath, base+"/"))
 	}
-	return optional.None[schema.Type](), false
-
+	ref := &schema.Ref{
+		Pos:    goPosToSchemaPos(pos),
+		Module: destModule,
+		Name:   strcase.ToUpperCamel(named.Obj().Name()),
+	}
+	return optional.Some[schema.Type](ref)
 }
 
 func visitMap(pctx *parseContext, pos token.Pos, tnode *types.Map, isExported bool) optional.Option[schema.Type] {
@@ -1492,7 +1504,7 @@ func (p *parseContext) isPathInPkg(path string) bool {
 
 // getEnumForTypeName returns the enum and interface for a given type name.
 func (p *parseContext) getEnumForTypeName(name string) (optional.Option[*schema.Enum], optional.Option[*types.Interface]) {
-	aDecl, ok := p.getDeclForTypeName(name)
+	aDecl, ok := p.getDeclForTypeName(name).Get()
 	if !ok {
 		return optional.None[*schema.Enum](), optional.None[*types.Interface]()
 	}
@@ -1511,7 +1523,7 @@ func (p *parseContext) getEnumForTypeName(name string) (optional.Option[*schema.
 	return optional.Some(decl), optional.None[*types.Interface]()
 }
 
-func (p *parseContext) getDeclForTypeName(name string) (enum schema.Decl, ok bool) {
+func (p *parseContext) getDeclForTypeName(name string) optional.Option[schema.Decl] {
 	for _, decl := range p.module.Decls {
 		nativeName, ok := p.nativeNames[decl]
 		if !ok {
@@ -1520,9 +1532,9 @@ func (p *parseContext) getDeclForTypeName(name string) (enum schema.Decl, ok boo
 		if nativeName != p.pkg.Name+"."+name {
 			continue
 		}
-		return decl, true
+		return optional.Some(decl)
 	}
-	return nil, false
+	return optional.None[schema.Decl]()
 }
 
 func (p *parseContext) markAsExported(node schema.Node) {

go-runtime/compile/schema_test.go

@@ -65,7 +65,7 @@ func TestExtractModuleSchema(t *testing.T) {
   }
 
   // Comments about ColorInt.
-  enum ColorInt: Int {
+  export enum ColorInt: Int {
     // RedInt is a color.
     RedInt = 0
     BlueInt = 1
@@ -92,6 +92,13 @@ func TestExtractModuleSchema(t *testing.T) {
     Two = 2
   }
 
+  export enum TypeEnum {
+    Option String?
+    InlineStruct one.InlineStruct
+    AliasedStruct one.UnderlyingStruct
+    ValueEnum one.ColorInt
+  }
+
   data Config {
     field String
   }
@@ -107,6 +114,9 @@ func TestExtractModuleSchema(t *testing.T) {
   export data ExportedStruct {
   }
 
+  export data InlineStruct {
+  }
+
   export data Nested {
   }
 
@@ -140,6 +150,9 @@ func TestExtractModuleSchema(t *testing.T) {
   data SourceResp {
   }
 
+  export data UnderlyingStruct {
+  }
+
   data WithoutDirectiveStruct {
   }
 
@@ -305,7 +318,7 @@ func TestExtractModuleSchemaNamedTypes(t *testing.T) {
 	assert.Equal(t, normaliseString(expected), normaliseString(actual.String()))
 }
 
-func TestParseDirectives(t *testing.T) {
+func TestParsedirectives(t *testing.T) {
 	tests := []struct {
 		name     string
 		input    string
@@ -434,10 +447,11 @@ func TestErrorReporting(t *testing.T) {
 		`89:2-12: struct field unexported must be exported by starting with an uppercase letter`,
 		`101:2-24: cannot attach enum value to BadValueEnum because it is a variant of type enum TypeEnum, not a value enum`,
 		`108:2-41: cannot attach enum value to BadValueEnumOrderDoesntMatter because it is a variant of type enum TypeEnum, not a value enum`,
-		`117:1-26: parent enum "ExportedTypeEnum" is exported, but directive "ftl:data" on "PrivateData" is not: all variants of exported enums that have a directive must be explicitly exported as well`,
 		`121:21-60: config and secret names must be valid identifiers`,
 		`127:1-26: only one directive expected for type alias`,
 		`143:1-35: type can not be a variant of more than 1 type enums (TypeEnum1, TypeEnum2)`,
+		`149:27-27: enum discriminator "TypeEnum3" cannot contain exported methods`,
+		`152:1-35: enum discriminator "NoMethodsTypeEnum" must define at least one method`,
 	}
 	assert.Equal(t, expected, actual)
 }

go-runtime/compile/testdata/failing/failing.go

@@ -144,3 +144,9 @@ type ConformsToTwoTypeEnums string
 
 func (ConformsToTwoTypeEnums) typeEnum1() {}
 func (ConformsToTwoTypeEnums) typeEnum2() {}
+
+//ftl:enum
+type TypeEnum3 interface{ ExportedMethod() }
+
+//ftl:enum
+type NoMethodsTypeEnum interface{}

go-runtime/compile/testdata/one/one.go

@@ -64,6 +64,29 @@ func (List) blobOrList() {}
 type Nested struct {
 }
 
+//ftl:enum
+type TypeEnum interface {
+	tag()
+}
+
+type Option ftl.Option[string]
+
+func (Option) tag() {}
+
+type InlineStruct struct{}
+
+func (InlineStruct) tag() {}
+
+type AliasedStruct UnderlyingStruct
+
+func (AliasedStruct) tag() {}
+
+type UnderlyingStruct struct{}
+
+type ValueEnum ColorInt
+
+func (ValueEnum) tag() {}
+
 //ftl:enum
 type PrivateEnum interface{ privateEnum() }