flag: replace fail with failf

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4254061

diff --git a/src/pkg/flag/flag.go b/src/pkg/flag/flag.go
index be972057ed74c08720e1bc6dd727fcd613223d58..ea6c82f6193f145bc23ed131f5d646ce50b62d7c 100644 (file)
--- a/src/pkg/flag/flag.go
+++ b/src/pkg/flag/flag.go
@@ -260,7 +260,9 @@ var Usage = func() {
 
 var panicOnError = false
 
-func fail() {
+// failf prints to standard output a formatted error and Usage, and then exits the program.
+func failf(format string, a ...interface{}) {
+       fmt.Fprintf(os.Stderr, format, a...)
        Usage()
        if panicOnError {
                panic("flag parse error")
@@ -415,8 +417,7 @@ func (f *allFlags) parseOne() (ok bool) {
        }
        name := s[num_minuses:]
        if len(name) == 0 || name[0] == '-' || name[0] == '=' {
-               fmt.Fprintln(os.Stderr, "bad flag syntax:", s)
-               fail()
+               failf("bad flag syntax: %s\n", s)
        }
 
        // it's a flag. does it have an argument?
@@ -434,14 +435,12 @@ func (f *allFlags) parseOne() (ok bool) {
        m := flags.formal
        flag, alreadythere := m[name] // BUG
        if !alreadythere {
-               fmt.Fprintf(os.Stderr, "flag provided but not defined: -%s\n", name)
-               fail()
+               failf("flag provided but not defined: -%s\n", name)
        }
        if fv, ok := flag.Value.(*boolValue); ok { // special case: doesn't need an arg
                if has_value {
                        if !fv.Set(value) {
-                               fmt.Fprintf(os.Stderr, "invalid boolean value %q for flag: -%s\n", value, name)
-                               fail()
+                               failf("invalid boolean value %q for flag: -%s\n", value, name)
                        }
                } else {
                        fv.Set("true")
@@ -454,13 +453,11 @@ func (f *allFlags) parseOne() (ok bool) {
                        value, f.args = f.args[0], f.args[1:]
                }
                if !has_value {
-                       fmt.Fprintf(os.Stderr, "flag needs an argument: -%s\n", name)
-                       fail()
+                       failf("flag needs an argument: -%s\n", name)
                }
                ok = flag.Value.Set(value)
                if !ok {
-                       fmt.Fprintf(os.Stderr, "invalid value %q for flag: -%s\n", value, name)
-                       fail()
+                       failf("invalid value %q for flag: -%s\n", value, name)
                }
        }
        flags.actual[name] = flag