Void returning functions fix

Author: Mateusz Gajewski

cli/function.go

@@ -12,6 +12,7 @@ type function struct {
 	FunctionHeader string
 	ArgumentsCount int
 	IsVariadic     bool
+	ReturnsVoid    bool
 }
 
 func (f *function) String() string {
@@ -46,6 +47,7 @@ func (p *pluginStructure) analyzeFunctions() error {
 				Signature:      p.getFunctionSignature(typ, false),
 				FunctionHeader: p.getFunctionSignature(typ, true),
 				ArgumentsCount: typ.NumIn(),
+				ReturnsVoid:    typ.NumOut() == 0,
 				IsVariadic:     typ.IsVariadic(),
 			})
 		}

cli/reflect.go

@@ -88,5 +88,11 @@ func (p *pluginStructure) getFunctionSignature(fun reflect.Type, namedParams boo
 		out = append(out, p.getVariableSignature(fun.Out(i), fun.IsVariadic() && i == fun.NumOut()-1))
 	}
 
-	return fmt.Sprintf("func(%s) (%s)", strings.Join(in, ", "), strings.Join(out, ", "))
+	var outParams string
+
+	if fun.NumOut() > 0 {
+		outParams = fmt.Sprintf(" (%s)", strings.Join(out, ", "))
+	}
+
+	return fmt.Sprintf("func(%s)%s", strings.Join(in, ", "), outParams)
 }

cli/template.go

@@ -30,7 +30,7 @@ type {{.Config.OutputName}} struct {
 //
 // See docs at https://godoc.org/{{$pluginPackage}}#{{.Name}}
 func (p *{{$receiver}}) {{.Name}}{{.TrimmedSignature}} {
-  return p._{{ .Name }}({{ .ArgumentsCall }})
+  {{ if .ReturnsVoid | not }}return {{ end }}p._{{ .Name }}({{ .ArgumentsCall }})
 }
 {{end}}
 

internal/test_fixtures/basic_plugin/plugin.go

@@ -1,5 +1,7 @@
 package main
 
+import "fmt"
+
 func ReturningInt32() int32 {
 	return 32
 }
@@ -11,3 +13,7 @@ func ReturningStringSlice() []string {
 func ReturningIntArray() [3]int32 {
 	return [...]int32{1, 0, 1}
 }
+
+func NonReturningFunction() {
+	fmt.Println("I'm not returning anything")
+}