If you put a trivial "hello, world" in program in hello.go, what is the output of

go build hello.go
gdb hello
start
info goroutines

On Mon, Apr 18, 2016 at 03:23:00PM -0700, Ian Lance Taylor wrote:

If you put a trivial "hello, world" in program in hello.go, what is the output of

go build hello.go
gdb hello
start
info goroutines

william@linux1 hello $ cat hello.go
package main

import "fmt"
func main() {
fmt.Println("Hello world")
}
william@linux1 hello $ go build hello
william@linux1 hello $ gdb hello
GNU gdb (Gentoo 7.11 vanilla) 7.11
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
https://bugs.gentoo.org/.
Find the GDB manual and other documentation resources online at:
http://www.gnu.org/software/gdb/documentation/.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from hello...done.
warning: File "/usr/lib64/go/src/runtime/runtime-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
To enable execution of this file add
add-auto-load-safe-path /usr/lib64/go/src/runtime/runtime-gdb.py
line to your configuration file "/home/william/.gdbinit".
To completely disable this security protection add
set auto-load safe-path /
line to your configuration file "/home/william/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual. E.g., run from the shell:
info "(gdb)Auto-loading safe path"
(gdb) start
Temporary breakpoint 1 at 0x401000: file /home/william/go/src/hello/hello.go, line 4.
Starting program: /home/william/go/src/hello/hello
[New LWP 5764]
[New LWP 5765]
[New LWP 5766]
[New LWP 5767]

Thread 1 "hello" hit Temporary breakpoint 1, main.main ()
at /home/william/go/src/hello/hello.go:4
4 func main() {
(gdb) info goroutines
Undefined info command: "goroutines". Try "help info".
(gdb) quit
A debugging session is active.

Inferior 1 [process 5760] will be killed.

Quit anyway? (y or n) y
william@linux1 hello $ exit
exit

Well, that didn't work, because of this:

warning: File "/usr/lib64/go/src/runtime/runtime-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".

Try the same thing, but this time run

gdb -iex 'add-auto-load-safe-path /usr/lib64/go/src/runtime' hello

william@linux1 hello $ gdb -iex 'add-auto-load-safe-path /usr/lib64/go/src/runti me' hello
GNU gdb (Gentoo 7.11 vanilla) 7.11
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
https://bugs.gentoo.org/.
Find the GDB manual and other documentation resources online at:
http://www.gnu.org/software/gdb/documentation/.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from hello...done.
Loading Go Runtime support.
(gdb) start
Temporary breakpoint 1 at 0x401000: file /home/william/go/src/hello/hello.go, line 4.
Starting program: /home/william/go/src/hello/hello
[New LWP 10142]
[New LWP 10143]
[New LWP 10144]
[New LWP 10145]

Thread 1 "hello" hit Temporary breakpoint 1, main.main ()
at /home/william/go/src/hello/hello.go:4
4 func main() {
(gdb) info goroutines

• 1 running runtime.systemstack_switch
  2 waiting runtime.gopark
  3 waiting runtime.gopark
  4 waiting runtime.gopark
  (gdb) quit
  A debugging session is active.

  Inferior 1 [process 10138] will be killed.

Quit anyway? (y or n) y
william@linux1 hello $ exit

Thanks. Unfortunately I have no idea why the test is failing. Someone with access to the failing system is going to have to debug this.

Hi,

Now there is more information about what is going on in the Gentoo bug, see
https://bugs.gentoo.org/show_bug.cgi?id=581072#C1

I experienced the same issue on my amd64 Ubuntu 14.04 machine. I was able to get around it using the following patch:

--- a/src/runtime/runtime-gdb_test.go
+++ b/src/runtime/runtime-gdb_test.go
@@ -98,6 +98,7 @@ func TestGdbPython(t *testing.T) {

        args := []string{"-nx", "-q", "--batch", "-iex",
               fmt.Sprintf("add-auto-load-safe-path %s/src/runtime", runtime.GO
+              "-ex", "set startup-with-shell off",
               "-ex", "info auto-load python-scripts",
               "-ex", "br main.go:10",
               "-ex", "run",

I must admit I don't understand why "startup-with-shell" is set to "on" by default on my machine.

Actually, I had to add the same line twice to pass all the tests:

--- a/src/runtime/runtime-gdb_test.go
+++ b/src/runtime/runtime-gdb_test.go
@@ -98,6 +98,7 @@ func TestGdbPython(t *testing.T) {

        args := []string{"-nx", "-q", "--batch", "-iex",
                fmt.Sprintf("add-auto-load-safe-path %s/src/runtime", runtime.GO
+               "-ex", "set startup-with-shell off",
                "-ex", "info auto-load python-scripts",
                "-ex", "br main.go:10",
                "-ex", "run",
@@ -226,6 +227,7 @@ func TestGdbBacktrace(t *testing.T) {

        // Execute gdb commands.
        args := []string{"-nx", "-batch",
+               "-ex", "set startup-with-shell off",
                "-ex", "break main.eee",
                "-ex", "run",
                "-ex", "backtrace",

Submitted the patch for review: https://go-review.googlesource.com/#/c/23142/

CL https://golang.org/cl/23142 mentions this issue.