[binutils-gdb] Report GetLastError value when DebugActiveProcess fails

[gdb-buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT c9739b6a06730b65df135766dec4c4d14d78bd38 ***

commit c9739b6a06730b65df135766dec4c4d14d78bd38
Author:     Tom Tromey <tromey@adacore.com>
AuthorDate: Wed Nov 6 09:43:52 2019 -0700
Commit:     Tom Tromey <tromey@adacore.com>
CommitDate: Tue Nov 19 08:33:53 2019 -0700

    Report GetLastError value when DebugActiveProcess fails
    
    When DebugActiveProcess fails, the error message is fairly generic:
    
        error (_("Can't attach to process."));
    
    It would be more useful for diagnosing problems if the Windows error
    code was included in the message.  This patch implements this.
    
    gdb/ChangeLog
    2019-11-19  Tom Tromey  <tromey@adacore.com>
    
            * windows-nat.c (windows_nat_target::attach): Include GetLastError
            result in error when DebugActiveProcess fails.
    
    Change-Id: Ie1bf502a0d96bb7c09bd5b1c5e0c924ba58cd68c

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 80ec8f3522..0305d67bd6 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-19  Tom Tromey  <tromey@adacore.com>
+
+	* windows-nat.c (windows_nat_target::attach): Include GetLastError
+	result in error when DebugActiveProcess fails.
+
 2019-11-18  Sergio Durigan Junior  <sergiodj@redhat.com>
 	    Pedro Alves  <palves@redhat.com>
 
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index 5901f63b28..fdc21f38bf 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -1983,7 +1983,8 @@ windows_nat_target::attach (const char *args, int from_tty)
 #endif
 
   if (!ok)
-    error (_("Can't attach to process."));
+    error (_("Can't attach to process %u (error %u)"),
+	   (unsigned) pid, (unsigned) GetLastError ());
 
   DebugSetProcessKillOnExit (FALSE);