gdb: don't use the global thread-id in the saved breakpoints file

I noticed that breakpoint::print_recreate_thread was printing the
global thread-id.  This function is used to implement the 'save
breakpoints' command, and should be writing out suitable CLI commands
for recreating the current breakpoints.  The CLI does not use global
thread-ids, but instead uses the inferior specific thread-ids,
e.g. "2.1".

After some discussion on the mailing list it was suggested that the
most consistent solution would be for the saved breakpoints file to
always contain the inferior-qualified thread-id, so the file would
include "thread 1.1" instead of just "thread 1", even when there is
only a single inferior.

So, this commit adds print_full_thread_id, which is just like the
existing print_thread_id, only it always prints the inferior-qualified
thread-id.

I then update the existing print_thread_id to make use of this new
function, and finally, I update  breakpoint::print_recreate_thread to
also use this new function.

There's a multi-inferior test that confirms the saved breakpoints file
correctly includes the fully-qualified thread-id, and I've also
updated the single inferior test gdb.base/save-bp.exp to have it
validate that the saved breakpoints file includes the
inferior-qualified thread-id, even for this single inferior case.

1 files changed, 16 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/save-bp.exp b/gdb/testsuite/gdb.base/save-bp.exp
index 41d71837fb6..68933d36427 100644
--- a/gdb/testsuite/gdb.base/save-bp.exp
+++ b/gdb/testsuite/gdb.base/save-bp.exp
@@ -89,3 +89,19 @@ gdb_test_sequence "info break" "info break" [list				\
   "\[\r\n\]+\[ \t\]+printf"							\
   "\[\r\n\]+$disabled_row_start main at \[^\r\n\]*$srcfile:$loc_bp8"		\
 ]
+
+# Copy the saved breakpoints file to the local machine (if necessary),
+# and then check its contents.
+if {[is_remote host]} {
+    set bps [remote_upload host bps [standard_output_file bps]]
+}
+set fh [open $bps]
+set lines [split [read $fh] "\n"]
+close $fh
+
+with_test_prefix "in bps file" {
+    gdb_assert {[lsearch -regexp $lines "break ${srcfile}:${loc_bp2}$"] != -1} \
+	"check for general breakpoint"
+    gdb_assert {[lsearch -regexp $lines "break ${srcfile}:${loc_bp3} thread 1\\.1"] != -1} \
+	"check for thread-specific breakpoint"
+}