feat: support injected verb clients in Go (#2828)

https://hackmd.io/OULeRFQQQvaMURysN27eEw

only the TestLifecycle integration test is updated with the new approach
in this PR, to demonstrate that both old and new verb call strategies
are still functional. will remove other usages of `ftl.Call(...)` to
follow

- generates `<Verb>Client` signatures in external stubs and (local)
signatures in `types.ftl.go`
- generates resource registrations in `main.go` and `types.ftl.go`, e.g.
"providers" for verb clients
-`go-runtime/build.go` changes accompanying the above^ bunch of stuff to
get imports working now that we're generating full verb request/response
types rather than just function references
- updates `go-runtime/server.go` to inject the registered providers when
processing an inbound call

#2641

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

backend/schema/schema.go

@@ -93,18 +93,24 @@ func (s *Schema) resolveToDataMonomorphised(n Node, parent Node) (*Data, error)
 	}
 }
 
-// Resolve a reference to a declaration.
-func (s *Schema) Resolve(ref *Ref) optional.Option[Decl] {
+// ResolveWithModule a reference to a declaration and its module.
+func (s *Schema) ResolveWithModule(ref *Ref) (optional.Option[Decl], optional.Option[*Module]) {
 	for _, module := range s.Modules {
 		if module.Name == ref.Module {
 			for _, decl := range module.Decls {
 				if decl.GetName() == ref.Name {
-					return optional.Some(decl)
+					return optional.Some(decl), optional.Some(module)
 				}
 			}
 		}
 	}
-	return optional.None[Decl]()
+	return optional.None[Decl](), optional.None[*Module]()
+}
+
+// Resolve a reference to a declaration.
+func (s *Schema) Resolve(ref *Ref) optional.Option[Decl] {
+	decl, _ := s.ResolveWithModule(ref)
+	return decl
 }
 
 // ResolveToType resolves a reference to a declaration of the given type.

backend/schema/validate.go

@@ -295,7 +295,7 @@ func ValidateModule(module *Module) error {
 		switch n := n.(type) {
 		case *Ref:
 			mdecl := scopes.Resolve(*n)
-			if mdecl == nil && n.Module == "" {
+			if mdecl == nil && (n.Module == "" || n.Module == module.Name) {
 				merr = append(merr, errorf(n, "unknown reference %q, is the type annotated and exported?", n))
 			}
 			if mdecl != nil {

go-runtime/compile/build-template/.ftl.tmpl/go/main/main.go.tmpl

@@ -10,19 +10,29 @@ import (
 	{{.}}
 {{- end}}
 )
-{{- if or .SumTypes .ExternalTypes }}
+{{- if or .SumTypes .ExternalTypes $verbs }}
 
 func init() {
 	reflection.Register(
 {{- range .SumTypes}}
 		reflection.SumType[{{.TypeName}}](
 			{{- range .Variants}}
-			*new({{.Name}}),
+			*new({{.TypeName}}),
 			{{- end}}
 		),
 {{- end}}
 {{- range .ExternalTypes}}
 		reflection.ExternalType(*new({{.TypeName}})),
+{{- end}}
+{{- range $verbs}}
+		reflection.ProvideResourcesForVerb(
+            {{.TypeName}},
+            {{- range .Resources}}
+                {{- with getVerbClient . }}
+			server.VerbClient[{{.TypeName}}, {{.Request.TypeName}}, {{.Response.TypeName}}](),
+                {{- end }}
+			{{- end}}
+		),
 {{- end}}
 	)
 }
@@ -31,15 +41,15 @@ func init() {
 func main() {
 	verbConstructor := server.NewUserVerbServer("{{.ProjectName}}", "{{$name}}",
 {{- range $verbs }}
-	{{- if and .HasRequest .HasResponse}}
-		server.HandleCall({{.TypeName}}),
-	{{- else if .HasRequest}}
-		server.HandleSink({{.TypeName}}),
-	{{- else if .HasResponse}}
-		server.HandleSource({{.TypeName}}),
-	{{- else}}
+	{{- if and (eq .Request.TypeName "ftl.Unit") (eq .Response.TypeName "ftl.Unit") }}
 		server.HandleEmpty({{.TypeName}}),
-	{{- end}}
+	{{- else if eq .Request.TypeName "ftl.Unit" }}
+		server.HandleSource[{{.Response.TypeName}}]({{.TypeName}}),
+	{{- else if eq .Response.TypeName "ftl.Unit" }}
+		server.HandleSink[{{.Request.TypeName}}]({{.TypeName}}),
+	{{- else }}
+		server.HandleCall[{{.Request.TypeName}}, {{.Response.TypeName}}]({{.TypeName}}),
+	{{- end -}}
 {{- end}}
 	)
 	plugin.Start(context.Background(), "{{$name}}", verbConstructor, ftlv1connect.VerbServiceName, ftlv1connect.NewVerbServiceHandler)

go-runtime/compile/build-template/types.ftl.go.tmpl

@@ -1,12 +1,11 @@
-{{- $moduleName := .Name -}}
 {{- $verbs := .Verbs -}}
 {{- $name := .Name -}}
 {{- with .TypesCtx -}}
+{{- $moduleName := .MainModulePkg -}}
 
 // Code generated by FTL. DO NOT EDIT.
 package {{$name}}
 
-{{- if or .SumTypes .ExternalTypes }}
 {{ if .Imports -}}
 import (
 {{- range .Imports }}
@@ -15,17 +14,53 @@ import (
 )
 {{- end }}
 
+{{ range $verbs -}}
+	{{ $req := .Request.LocalTypeName -}}
+	{{ $resp := .Response.LocalTypeName -}}
+
+	{{ if and (eq .Request.TypeName "ftl.Unit") (eq .Response.TypeName "ftl.Unit")}}
+type {{.Name|title}}Client func(context.Context) error
+	{{- else if eq .Request.TypeName "ftl.Unit" }}
+type {{.Name|title}}Client func(context.Context) ({{$resp}}, error)
+	{{- else if eq .Response.TypeName "ftl.Unit" }}
+type {{.Name|title}}Client func(context.Context, {{$req}}) error
+	{{- else }}
+type {{.Name|title}}Client func(context.Context, {{$req}}) ({{$resp}}, error)
+	{{- end }}
+{{ end -}}
+
+{{- if or .SumTypes .ExternalTypes $verbs }}
 func init() {
 	reflection.Register(
 {{- range .SumTypes}}
 		reflection.SumType[{{ trimModuleQualifier $moduleName .TypeName }}](
 			{{- range .Variants}}
-			*new({{ trimModuleQualifier $moduleName .Name }}),
+			*new({{ trimModuleQualifier $moduleName .TypeName }}),
 			{{- end}}
 		),
 {{- end}}
 {{- range .ExternalTypes}}
 		reflection.ExternalType(*new({{.TypeName}})),
+{{- end}}
+{{- range $verbs}}
+		reflection.ProvideResourcesForVerb(
+            {{ trimModuleQualifier $moduleName .TypeName }},
+            {{- range .Resources}}
+                {{- with getVerbClient . }}
+            	{{ $verb := trimModuleQualifier $moduleName .TypeName -}}
+
+            	{{ if and (eq .Request.TypeName "ftl.Unit") (eq .Response.TypeName "ftl.Unit")}}
+            server.EmptyClient[{{$verb}}](),
+            	{{- else if eq .Request.TypeName "ftl.Unit" }}
+            server.SourceClient[{{$verb}}, {{.Response.LocalTypeName}}](),
+            	{{- else if eq .Response.TypeName "ftl.Unit" }}
+            server.SinkClient[{{$verb}}, {{.Request.LocalTypeName}}](),
+            	{{- else }}
+            server.VerbClient[{{$verb}}, {{.Request.LocalTypeName}}, {{.Response.LocalTypeName}}](),
+            	{{- end }}
+                {{- end }}
+			{{- end}}
+		),
 {{- end}}
 	)
 }