cmd/compile: print usage to stderr for consistency

All the other tools and commands print the usage text to standard error.
"go tool compile" was the odd one out, so fix it.

While at it, make objabi.Flagprint a bit more Go-like with an io.Writer
instead of a file descriptor, which is likely a leftover from the C
days.

Fixes #23234.

Change-Id: I9abf2e79461e61c8c8bfaee2c6bf8faf26e0e6c3
Reviewed-on: https://go-review.googlesource.com/85418
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index f1591c16d2deb7547c52790508587c0ac28480eb..802e02896de59f59f8b69746ceef3fa8b14633bf 100644 (file)
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -94,8 +94,8 @@ Key "pctab" supports values:
 `
 
 func usage() {
-       fmt.Printf("usage: compile [options] file.go...\n")
-       objabi.Flagprint(1)
+       fmt.Fprintf(os.Stderr, "usage: compile [options] file.go...\n")
+       objabi.Flagprint(os.Stderr)
        Exit(2)
 }
 

diff --git a/src/cmd/internal/objabi/flag.go b/src/cmd/internal/objabi/flag.go
index 1bd4bc9063ae15f4312a8b13b6e0433ae665a9fd..d0522c8f4314ac3ab8f4bf4841e72fa9ca88bb68 100644 (file)
--- a/src/cmd/internal/objabi/flag.go
+++ b/src/cmd/internal/objabi/flag.go
@@ -7,6 +7,7 @@ package objabi
 import (
        "flag"
        "fmt"
+       "io"
        "os"
        "strconv"
        "strings"
@@ -20,10 +21,8 @@ func Flagfn1(name, usage string, f func(string)) {
        flag.Var(fn1(f), name, usage)
 }
 
-func Flagprint(fd int) {
-       if fd == 1 {
-               flag.CommandLine.SetOutput(os.Stdout)
-       }
+func Flagprint(w io.Writer) {
+       flag.CommandLine.SetOutput(w)
        flag.PrintDefaults()
 }
 

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 6dcaf64122f918c85d9e3bcb46d59e60dae38672..bfff5209a6b779638af33816982cebe0311596b2 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -1953,7 +1953,7 @@ func stkprint(ctxt *Link, ch *chain, limit int) {
 
 func usage() {
        fmt.Fprintf(os.Stderr, "usage: link [options] main.o\n")
-       objabi.Flagprint(2)
+       objabi.Flagprint(os.Stderr)
        Exit(2)
 }