cmd/dist: simplify work list functions

There are no uses of addCmd, so delete it. The only use of bgDirCmd is
dirCmd, so inline it. Now the only function that interacts with the
work queue is registerTest and dist's "background commands" are used
exclusively in goTest.bgCommand and registerTest (which calls
goTest.bgCommand).

For #37486.

Change-Id: Iebbb24cf9dbee45f3975fe9504d858493e1cd947
Reviewed-on: https://go-review.googlesource.com/c/go/+/494956
Reviewed-by: Dmitri Shuralyov <[email protected]>
Run-TryBot: Austin Clements <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: aclements

src/cmd/dist/test.go

@@ -957,25 +957,17 @@ func (t *tester) registerTest(name, heading string, test *goTest, opts ...regist
 	})
 }
 
-// bgDirCmd constructs a Cmd intended to be run in the background as
-// part of the worklist. The worklist runner will buffer its output
-// and replay it sequentially. The command will be run in dir.
-func (t *tester) bgDirCmd(dir, bin string, args ...string) *exec.Cmd {
+// dirCmd constructs a Cmd intended to be run in the foreground.
+// The command will be run in dir, and Stdout and Stderr will go to os.Stdout
+// and os.Stderr.
+func (t *tester) dirCmd(dir string, cmdline ...interface{}) *exec.Cmd {
+	bin, args := flattenCmdline(cmdline)
 	cmd := exec.Command(bin, args...)
 	if filepath.IsAbs(dir) {
 		setDir(cmd, dir)
 	} else {
 		setDir(cmd, filepath.Join(goroot, dir))
 	}
-	return cmd
-}
-
-// dirCmd constructs a Cmd intended to be run in the foreground.
-// The command will be run in dir, and Stdout and Stderr will go to os.Stdout
-// and os.Stderr.
-func (t *tester) dirCmd(dir string, cmdline ...interface{}) *exec.Cmd {
-	bin, args := flattenCmdline(cmdline)
-	cmd := t.bgDirCmd(dir, bin, args...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	if vflag > 1 {
@@ -995,7 +987,7 @@ func flattenCmdline(cmdline []interface{}) (bin string, args []string) {
 		case []string:
 			list = append(list, x...)
 		default:
-			panic("invalid addCmd argument type: " + reflect.TypeOf(x).String())
+			panic("invalid dirCmd argument type: " + reflect.TypeOf(x).String())
 		}
 	}
 
@@ -1006,19 +998,6 @@ func flattenCmdline(cmdline []interface{}) (bin string, args []string) {
 	return bin, list[1:]
 }
 
-// addCmd adds a command to the worklist. Commands can be run in
-// parallel, but their output will be buffered and replayed in the
-// order they were added to worklist.
-func (t *tester) addCmd(dt *distTest, dir string, cmdline ...interface{}) *exec.Cmd {
-	bin, args := flattenCmdline(cmdline)
-	w := &work{
-		dt:  dt,
-		cmd: t.bgDirCmd(dir, bin, args...),
-	}
-	t.worklist = append(t.worklist, w)
-	return w.cmd
-}
-
 func (t *tester) iOS() bool {
 	return goos == "ios"
 }