cmd/link: deprecate -X name value in favor of -X name=value

People invoking the linker directly already have to change their scripts
to use the new "go tool link", so this is a good time to make the -X flag
behave like all other Go flags and take just a single argument.

The old syntax will continue to be accepted (it is rewritten into the new
syntax before flag parsing). Maybe some day we will be able to retire it.

Even if we never retire the old syntax, having the new syntax at least
makes the rewriting much less of a kludge.

Change-Id: I91e8df94f4c22b2186e81d7f1016b8767d777eac
Reviewed-on: https://go-review.googlesource.com/10310
Reviewed-by: Rob Pike <r@golang.org>

diff --git a/src/cmd/link/internal/ld/data.go b/src/cmd/link/internal/ld/data.go
index 2ffba875c5234539d1aad3e2628874365142486d..52c6f4cd14b85b5f5ff8dc791cae2e4f4767c2bf 100644 (file)
--- a/src/cmd/link/internal/ld/data.go
+++ b/src/cmd/link/internal/ld/data.go
@@ -917,14 +917,12 @@ func strnput(s string, n int) {
        }
 }
 
-var addstrdata_name string
-
 func addstrdata1(arg string) {
-       if strings.HasPrefix(arg, "VALUE:") {
-               addstrdata(addstrdata_name, arg[6:])
-       } else {
-               addstrdata_name = arg
+       i := strings.Index(arg, "=")
+       if i < 0 {
+               Exitf("-X flag requires argument of the form importpath.name=value")
        }
+       addstrdata(arg[:i], arg[i+1:])
 }
 
 func addstrdata(name string, value string) {

diff --git a/src/cmd/link/internal/ld/pobj.go b/src/cmd/link/internal/ld/pobj.go
index 60d584fc73e7787fbee9b72044bc6a6a9be9fb9e..20f060cb05c10864af55f019f6220b70d2466929 100644 (file)
--- a/src/cmd/link/internal/ld/pobj.go
+++ b/src/cmd/link/internal/ld/pobj.go
@@ -102,7 +102,7 @@ func Ldmain() {
        obj.Flagint64("T", "set text segment `address`", &INITTEXT)
        obj.Flagfn0("V", "print version and exit", doversion)
        obj.Flagcount("W", "disassemble input", &Debug['W'])
-       obj.Flagfn1("X", "set the value of a string variable; the next two arguments are its name and value", addstrdata1)
+       obj.Flagfn1("X", "add string value `definition` of the form importpath.name=value", addstrdata1)
        obj.Flagcount("Z", "clear stack frame on entry", &Debug['Z'])
        obj.Flagcount("a", "disassemble output", &Debug['a'])
        obj.Flagstr("buildid", "record `id` as Go toolchain build id", &buildid)
@@ -132,21 +132,39 @@ func Ldmain() {
        obj.Flagcount("v", "print link trace", &Debug['v'])
        obj.Flagcount("w", "disable DWARF generation", &Debug['w'])
 
-       // Clumsy hack to preserve old behavior of -X taking two arguments.
+       obj.Flagstr("cpuprofile", "write cpu profile to `file`", &cpuprofile)
+       obj.Flagstr("memprofile", "write memory profile to `file`", &memprofile)
+       obj.Flagint64("memprofilerate", "set runtime.MemProfileRate to `rate`", &memprofilerate)
+
+       // Clumsy hack to preserve old two-argument -X name val syntax for old scripts.
+       // Rewrite that syntax into new syntax -X name=val.
+       // TODO(rsc): Delete this hack in Go 1.6 or later.
+       var args []string
        for i := 0; i < len(os.Args); i++ {
                arg := os.Args[i]
-               if (arg == "--X" || arg == "-X") && i+2 < len(os.Args) {
-                       os.Args[i+2] = "-X=VALUE:" + os.Args[i+2]
+               if (arg == "-X" || arg == "--X") && i+2 < len(os.Args) && !strings.Contains(os.Args[i+1], "=") {
+                       fmt.Fprintf(os.Stderr, "link: warning: option %s %s %s may not work in future releases; use %s %s=%s\n",
+                               arg, os.Args[i+1], os.Args[i+2],
+                               arg, os.Args[i+1], os.Args[i+2])
+                       args = append(args, arg)
+                       args = append(args, os.Args[i+1]+"="+os.Args[i+2])
                        i += 2
-               } else if (strings.HasPrefix(arg, "--X=") || strings.HasPrefix(arg, "-X=")) && i+1 < len(os.Args) {
-                       os.Args[i+1] = "-X=VALUE:" + os.Args[i+1]
+                       continue
+               }
+               if (strings.HasPrefix(arg, "-X=") || strings.HasPrefix(arg, "--X=")) && i+1 < len(os.Args) && strings.Count(arg, "=") == 1 {
+                       fmt.Fprintf(os.Stderr, "link: warning: option %s %s may not work in future releases; use %s=%s\n",
+                               arg, os.Args[i+1],
+                               arg, os.Args[i+1])
+                       args = append(args, arg+"="+os.Args[i+1])
                        i++
+                       continue
                }
+               args = append(args, arg)
        }
-       obj.Flagstr("cpuprofile", "write cpu profile to `file`", &cpuprofile)
-       obj.Flagstr("memprofile", "write memory profile to `file`", &memprofile)
-       obj.Flagint64("memprofilerate", "set runtime.MemProfileRate to `rate`", &memprofilerate)
+       os.Args = args
+
        obj.Flagparse(usage)
+
        startProfile()
        Ctxt.Bso = &Bso
        Ctxt.Debugvlog = int32(Debug['v'])

diff --git a/test/linkx.go b/test/linkx.go
index 151b6db1eca8aaa793258d1aa6eeb89ece04f64d..40ec1b99f69219112d777e0c6ca09ee7dc150988 100644 (file)
--- a/test/linkx.go
+++ b/test/linkx.go
@@ -9,10 +9,12 @@
 
 package main
 
+import "fmt"
+
 var tbd string
 var overwrite string = "dibs"
 
 func main() {
-       println(tbd)
-       println(overwrite)
+       fmt.Println(tbd)
+       fmt.Println(overwrite)
 }

diff --git a/test/linkx_run.go b/test/linkx_run.go
index f3029f50a97a8269ff3a1878b6b7d9edef9ebd7d..cc0f55cf9281f309e362472c2332b5ce3c5aaf8b 100644 (file)
--- a/test/linkx_run.go
+++ b/test/linkx_run.go
@@ -10,23 +10,33 @@
 package main
 
 import (
+       "bytes"
        "fmt"
        "os"
        "os/exec"
 )
 
 func main() {
+       test(" ") // old deprecated syntax
+       test("=") // new syntax
+}
+
+func test(sep string) {
        // Successful run
-       cmd := exec.Command("go", "run", "-ldflags=-X main.tbd hello -X main.overwrite trumped -X main.nosuchsymbol neverseen", "linkx.go")
-       out, err := cmd.CombinedOutput()
+       cmd := exec.Command("go", "run", "-ldflags=-X main.tbd"+sep+"hello -X main.overwrite"+sep+"trumped -X main.nosuchsymbol"+sep+"neverseen", "linkx.go")
+       var out, errbuf bytes.Buffer
+       cmd.Stdout = &out
+       cmd.Stderr = &errbuf
+       err := cmd.Run()
        if err != nil {
-               fmt.Println(string(out))
+               fmt.Println(errbuf.String())
+               fmt.Println(out.String())
                fmt.Println(err)
                os.Exit(1)
        }
 
        want := "hello\ntrumped\n"
-       got := string(out)
+       got := out.String()
        if got != want {
                fmt.Printf("got %q want %q\n", got, want)
                os.Exit(1)