[PATCH 1/2] gdb/testsuite: make gdb_test_multiple return immediately if send_gdb fails

[Simon Marchi <simon.marchi@efficios.com>]

From: Simon Marchi <simon.marchi@polymtl.ca>

In the failure seen by Philippe here:

  https://inbox.sourceware.org/gdb-patches/20221120173024.3647464-1-philippe.waroquiers@skynet.be/

... the testsuite only outputs PASSes, and an ERROR, resulting from an
uncaught exception.  This is a bit sneaky, because ERRORs are not
reported in the test summary.  In certain circumstances, it can be easy
to miss.

Normally, gdb_test_multiple outputs an UNRESOLVED when GDB crashes.  But
this is only if it manages to send the command, and it's that command
that crashes GDB.  Here, the ERROR is due to the fact that GDB had
already crashed by the time we entered gdb_test_multiple and tried to
send a command.  GDB was crashed by the previous "file" command, sent by
gdb_unload.  Because gdb_unload uses bare expect, it didn't record a
test failure when crashing GDB (this will be addressed separately).

In this patch, I propose to make gdb_test_multiple call unresolved
directly and return -1 send_gdb fails.  This way, if GDB is already
crashed by the time we enter gdb_test_multiple, it will leave a trace in
the test results in the form of an UNRESOLVED.  It will also spare us of
the not-so-useful-in-my-opinion TCL backtrace.

Before, it looks like:

    ERROR: Couldn't send python print(objfile.filename) to GDB.
    ERROR: : spawn id exp9 not open
        while executing
    "expect {
    -i exp9 -timeout 10
            -re ".*A problem internal to GDB has been detected" {
                fail "$message (GDB internal error)"
                gdb_internal_error..."
        ("uplevel" body line 1)
        invoked from within
    "uplevel $body" NONE : spawn id exp9 not open

And after:

    Couldn't send python print(objfile.filename) to GDB.
    UNRESOLVED: gdb.python/py-objfile.exp: objfile.filename after objfile is unloaded

Change-Id: I72af8dc0d687826fc3f76911c27a9e5f91b677ba
---
 gdb/testsuite/lib/gdb.exp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 7d05fbe557bb..fcd54c88f251 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1161,7 +1161,9 @@ proc gdb_test_multiple { command message args } {
 	    if { $foo < [expr $len - 1] } {
 		set str [string range "$string" 0 $foo]
 		if { [send_gdb "$str"] != "" } {
-		    perror "Couldn't send $command to GDB."
+		    verbose -log "Couldn't send $command to GDB."
+		    unresolved $message
+		    return -1
 		}
 		# since we're checking if each line of the multi-line
 		# command are 'accepted' by GDB here,
@@ -1180,7 +1182,9 @@ proc gdb_test_multiple { command message args } {
 	}
 	if { "$string" != "" } {
 	    if { [send_gdb "$string"] != "" } {
-		perror "Couldn't send $command to GDB."
+		verbose -log "Couldn't send $command to GDB."
+		unresolved $message
+		return -1
 	    }
 	}
     }
-- 
2.38.1