Merge remote-tracking branch 'origin/master' into windows

Conflicts:
	proc/proc.go

proc/proc.go

@@ -4,6 +4,7 @@ import (
 	"debug/dwarf"
 	"debug/gosym"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"go/constant"
 	"os"
@@ -408,22 +409,18 @@ func (dbp *Process) pickCurrentThread(trapthread *Thread) error {
 	return dbp.SwitchThread(trapthread.ID)
 }
 
-// Step will continue the debugged process for exactly
-// one instruction.
+// Step will continue the current thread for exactly
+// one instruction. This method affects only the thread
+// asssociated with the selected goroutine. All other
+// threads will remain stopped.
 func (dbp *Process) Step() (err error) {
-	fn := func() error {
-		for _, th := range dbp.Threads {
-			if th.blocked() || !th.canStep() {
-				continue
-			}
-			if err := th.Step(); err != nil {
-				return err
-			}
-		}
-		return nil
+	if dbp.SelectedGoroutine == nil {
+		return errors.New("cannot single step: no selected goroutine")
 	}
-
-	return dbp.run(fn)
+	if dbp.SelectedGoroutine.thread == nil {
+		return fmt.Errorf("cannot single step: no thread associated with goroutine %d", dbp.SelectedGoroutine.ID)
+	}
+	return dbp.run(dbp.SelectedGoroutine.thread.Step)
 }
 
 // SwitchThread changes from current thread to the thread specified by `tid`.

proc/threads_darwin.go

@@ -89,10 +89,6 @@ func (t *Thread) stopped() bool {
 	return C.thread_blocked(t.os.threadAct) > C.int(0)
 }
 
-func (t *Thread) canStep() bool {
-	return true
-}
-
 func (t *Thread) writeMemory(addr uintptr, data []byte) (int, error) {
 	if len(data) == 0 {
 		return 0, nil

proc/threads_linux.go

@@ -39,10 +39,6 @@ func (t *Thread) resume() (err error) {
 	return
 }
 
-func (thread *Thread) canStep() bool {
-	return true
-}
-
 func (t *Thread) singleStep() (err error) {
 	for {
 		t.dbp.execPtraceFunc(func() { err = sys.PtraceSingleStep(t.ID) })

proc/threads_windows.go

@@ -134,10 +134,6 @@ func (t *Thread) stopped() bool {
 	return true
 }
 
-func (t *Thread) canStep() bool {
-	return t.dbp.os.breakThread == t.ID
-}
-
 func (t *Thread) writeMemory(addr uintptr, data []byte) (int, error) {
 	var (
 		vmData = C.LPCVOID(unsafe.Pointer(&data[0]))

terminal/command.go

@@ -235,6 +235,8 @@ func goroutines(t *Term, argstr string) error {
 			fgl = fglRuntimeCurrent
 		case "-g":
 			fgl = fglGo
+		case "":
+			// nothing to do
 		default:
 			return fmt.Errorf("wrong argument: '%s'", args[0])
 		}