feat: add LSP for FTL

Add an LSP that produces document highlights when FTL outputs build errors

fixes #1122

FTL.code-workspace

@@ -46,6 +46,7 @@
 			"**/go.work.sum": true,
 			".hermit": true,
 			"**/*.zip": true,
-		}
+		},
+		"java.compile.nullAnalysis.mode": "automatic"
 	}
 }

cmd/ftl/cmd_dev.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"errors"
+	"github.com/TBD54566975/ftl/lsp"
 	"time"
 
 	"golang.org/x/sync/errgroup"
@@ -43,6 +44,10 @@ func (d *devCmd) Run(ctx context.Context) error {
 		})
 	}
 
+	g.Go(func() error {
+		return lsp.NewServer(ctx).Run()
+	})
+
 	err := d.ServeCmd.pollControllerOnine(ctx, client)
 	if err != nil {
 		return err

cmd/ftl/cmd_lsp.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"context"
+	"github.com/TBD54566975/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
+)
+
+type lspCmd struct {
+	Run runLspCmd `cmd:"" help:"Start the FTL language server."`
+}
+
+type runLspCmd struct {
+	Debug bool `help:"Run the language server in debug mode." default:"false"`
+}
+
+func (r *runLspCmd) Run(ctx context.Context, client ftlv1connect.ControllerServiceClient) error {
+	//server := lsp.NewServer(lsp.ServerOpts{
+	//	Debug: r.Debug,
+	//})
+	//return server.Run()
+	return nil
+}

cmd/ftl/main.go

@@ -43,6 +43,7 @@ type CLI struct {
 	Download downloadCmd `cmd:"" help:"Download a deployment."`
 	Secret   secretCmd   `cmd:"" help:"Manage secrets."`
 	Config   configCmd   `cmd:"" help:"Manage configuration."`
+	LSP      lspCmd      `cmd:"" help:"Run the FTL language server."`
 }
 
 var cli CLI

examples/go/echo/echo.go

@@ -4,7 +4,6 @@ package echo
 import (
 	"context"
 	"fmt"
-
 	"ftl/time"
 
 	"github.com/TBD54566975/ftl/go-runtime/ftl"

examples/kotlin/echo/src/main/kotlin/ftl/echo/Echo.kt

@@ -1,18 +1,12 @@
 package ftl.echo
 
 import ftl.builtin.Empty
-import ftl.time.time
 import xyz.block.ftl.Context
 import xyz.block.ftl.Export
 
-class InvalidInput(val field: String) : Exception()
+data class Request(val data: String)
 
-data class EchoRequest(val name: String?)
-data class EchoResponse(val message: String)
-
-@Throws(InvalidInput::class)
 @Export
-fun echo(context: Context, req: EchoRequest): EchoResponse {
-  val response = context.call(::time, Empty())
-  return EchoResponse(message = "Hello, ${req.name ?: "anonymous"}! The time is ${response.time}.")
+fun verb(context: Context, req: Request): Empty {
+  return Empty()
 }

go-runtime/compile/schema.go

@@ -542,9 +542,16 @@ func visitStruct(pctx *parseContext, pos token.Pos, tnode types.Type) (*schema.R
 			Pos:  goPosToSchemaPos(pos),
 			Name: param.Obj().Name(),
 		})
-		typeArg, err := visitType(pctx, pos, named.TypeArgs().At(i))
+		if named.TypeArgs().Len() == 0 {
+
+		}
+	}
+
+	for i := 0; i < named.TypeArgs().Len(); i++ {
+		arg := named.TypeArgs().At(i)
+		typeArg, err := visitType(pctx, pos, arg)
 		if err != nil {
-			return nil, errorf(pos, "type parameter %s: %v", param.Obj().Name(), err)
+			return nil, errorf(pos, "type parameter %s: %v", arg.String(), err)
 		}
 		dataRef.TypeParameters = append(dataRef.TypeParameters, typeArg)
 	}
@@ -559,21 +566,32 @@ func visitStruct(pctx *parseContext, pos token.Pos, tnode types.Type) (*schema.R
 	namedPos := named.Obj().Pos()
 	pkg, path, _ := pctx.pathEnclosingInterval(namedPos, namedPos)
 	if pkg != nil {
+		var doc *ast.CommentGroup
 		for i := len(path) - 1; i >= 0; i-- {
 			// We have to check both the type spec and the gen decl because the
 			// type could be declared as either "type Foo struct { ... }" or
 			// "type ( Foo struct { ... } )"
 			switch path := path[i].(type) {
 			case *ast.TypeSpec:
 				if path.Doc != nil {
-					out.Comments = visitComments(path.Doc)
+					doc = path.Doc
 				}
 			case *ast.GenDecl:
 				if path.Doc != nil {
-					out.Comments = visitComments(path.Doc)
+					doc = path.Doc
 				}
 			}
 		}
+		exported, err := isExported(doc)
+		if err != nil {
+			return nil, err
+		}
+
+		if doc == nil || !exported {
+			return nil, errorf(pos, "data type is a dependency of an exported verb or "+
+				"type but is not itself exported")
+		}
+		out.Comments = visitComments(doc)
 	}
 
 	s, ok := named.Underlying().(*types.Struct)
@@ -869,3 +887,22 @@ func isIotaEnum(node ast.Node) bool {
 		return false
 	}
 }
+
+func isExported(comments *ast.CommentGroup) (bool, error) {
+	if comments == nil {
+		return false, nil
+	}
+
+	directives, err := parseDirectives(fset, comments)
+	if err != nil {
+		return false, err
+	}
+
+	for _, d := range directives {
+		if _, ok := d.(*directiveExport); ok {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}

go-runtime/compile/schema_test.go

@@ -233,3 +233,10 @@ func TestErrorReporting(t *testing.T) {
 	_, _, err := ExtractModuleSchema("testdata/failing")
 	assert.EqualError(t, err, filepath.Join(pwd, `testdata/failing/failing.go`)+`:14:2: call must have exactly three arguments`)
 }
+
+func TestUnexportedError(t *testing.T) {
+	pwd, _ := os.Getwd()
+	_, _, err := ExtractModuleSchema("testdata/unexported")
+	assert.EqualError(t, err, filepath.Join(pwd,
+		`testdata/unexported/unexported.go`)+`:13:1: data type is a dependency of an exported verb or type but is not itself exported`)
+}

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

@@ -6,7 +6,10 @@ import (
 	"github.com/TBD54566975/ftl/go-runtime/ftl"
 )
 
+//ftl:export
 type Request struct{}
+
+//ftl:export
 type Response struct{}
 
 //ftl:export

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

@@ -49,9 +49,11 @@ const (
 	Third
 )
 
+//ftl:export
 type Nested struct {
 }
 
+//ftl:export
 type Req struct {
 	Int      int
 	Int64    int64
@@ -66,8 +68,11 @@ type Req struct {
 	Bytes    []byte
 	EnumRef  two.TwoEnum
 }
+
+//ftl:export
 type Resp struct{}
 
+//ftl:export
 type Config struct {
 	Field string
 }
@@ -84,13 +89,15 @@ const Yellow Color = "Yellow"
 
 const YellowInt ColorInt = 3
 
+//ftl:export
 type SinkReq struct{}
 
 //ftl:export
 func Sink(ctx context.Context, req SinkReq) error {
 	return nil
 }
 
+//ftl:export
 type SourceResp struct{}
 
 //ftl:export

go-runtime/compile/testdata/two/two.go

@@ -19,14 +19,17 @@ const (
 type Exported struct {
 }
 
+//ftl:export
 type User struct {
 	Name string
 }
 
+//ftl:export
 type Payload[T any] struct {
 	Body T
 }
 
+//ftl:export
 type UserResponse struct {
 	User User
 }

go-runtime/compile/testdata/unexported/ftl.toml

@@ -0,0 +1,2 @@
+module = "failing"
+language = "go"

go-runtime/compile/testdata/unexported/go.mod

@@ -0,0 +1,46 @@
+module ftl/failing
+
+go 1.22.1
+
+replace github.com/TBD54566975/ftl => ../../../..
+
+require github.com/TBD54566975/ftl v0.150.3
+
+require (
+	connectrpc.com/connect v1.15.0 // indirect
+	connectrpc.com/grpcreflect v1.2.0 // indirect
+	connectrpc.com/otelconnect v0.7.0 // indirect
+	github.com/BurntSushi/toml v1.3.2 // indirect
+	github.com/TBD54566975/scaffolder v0.8.0 // indirect
+	github.com/alecthomas/concurrency v0.0.2 // indirect
+	github.com/alecthomas/kong v0.9.0 // indirect
+	github.com/alecthomas/participle/v2 v2.1.1 // indirect
+	github.com/alecthomas/types v0.13.0 // indirect
+	github.com/alessio/shellescape v1.4.2 // indirect
+	github.com/danieljoos/wincred v1.2.0 // indirect
+	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
+	github.com/jackc/pgx/v5 v5.5.5 // indirect
+	github.com/jackc/puddle/v2 v2.2.1 // indirect
+	github.com/jpillora/backoff v1.0.0 // indirect
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/swaggest/jsonschema-go v0.3.69 // indirect
+	github.com/swaggest/refl v1.3.0 // indirect
+	github.com/zalando/go-keyring v0.2.3 // indirect
+	go.opentelemetry.io/otel v1.24.0 // indirect
+	go.opentelemetry.io/otel/metric v1.24.0 // indirect
+	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+	golang.design/x/reflect v0.0.0-20220504060917-02c43be63f3b // indirect
+	golang.org/x/crypto v0.21.0 // indirect
+	golang.org/x/exp v0.0.0-20240222234643-814bf88cf225 // indirect
+	golang.org/x/mod v0.16.0 // indirect
+	golang.org/x/net v0.22.0 // indirect
+	golang.org/x/sync v0.6.0 // indirect
+	golang.org/x/sys v0.18.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
+	google.golang.org/protobuf v1.33.0 // indirect
+)