internal/cglfw: let Terminate return an error

This change also removes flushErrors, which is only for GLFW
debuggings.

internal/cglfw/error_unix.go

@@ -119,12 +119,11 @@ func (e *Error) Error() string {
 // Note: There are many cryptic caveats to proper error handling here.
 // See: https://github.com/go-gl/glfw3/pull/86
 
-// Holds the value of the last error.
+// lastError holds the value of the last error.
 var lastError = make(chan *Error, 1)
 
 //export goErrorCB
 func goErrorCB(code C.int, desc *C.char) {
-	flushErrors()
 	err := &Error{ErrorCode(code), C.GoString(desc)}
 	select {
 	case lastError <- err:
@@ -139,28 +138,6 @@ func init() {
 	C.glfwSetErrorCallbackCB()
 }
 
-// flushErrors is called by Terminate before it actually calls C.glfwTerminate,
-// this ensures that any uncaught errors buffered in lastError are printed
-// before the program exits.
-func flushErrors() {
-	err := fetchError()
-	if err != nil {
-		fmt.Fprintln(os.Stderr, "GLFW: An uncaught error has occurred:", err)
-		fmt.Fprintln(os.Stderr, "GLFW: Please report this bug in the Go package immediately.")
-	}
-}
-
-// fetchError fetches the next error from the error channel, it does not block
-// and returns nil if there is no error present.
-func fetchError() *Error {
-	select {
-	case err := <-lastError:
-		return err
-	default:
-		return nil
-	}
-}
-
 // fetchErrorIgnoringPlatformError is fetchError igoring platformError.
 func fetchErrorIgnoringPlatformError() error {
 	select {

internal/cglfw/glfw_unix.go

@@ -10,7 +10,10 @@ package cglfw
 //#define GLFW_INCLUDE_NONE
 //#include "glfw3_unix.h"
 import "C"
-import "unsafe"
+
+import (
+	"unsafe"
+)
 
 // Version constants.
 const (
@@ -56,9 +59,12 @@ func Init() error {
 // this function, as it is called by Init before it returns failure.
 //
 // This function may only be called from the main thread.
-func Terminate() {
+func Terminate() error {
-	flushErrors()
 	C.glfwTerminate()
+	if err := fetchErrorIgnoringPlatformError(); err != nil {
+		return err
+	}
+	return nil
 }
 
 // InitHint function sets hints for the next initialization of GLFW.

internal/glfw/glfw_unix.go

@@ -353,8 +353,7 @@ func SwapInterval(interval int) error {
 }
 
 func Terminate() error {
-	cglfw.Terminate()
+	return cglfw.Terminate()
-	return nil
 }
 
 func WaitEvents() error {