gdb/testsuite: use 'return' in gdb_test_no_output

A TCL proc will return the return value of the last command executed
within the proc's body if there is no explicit return call, so
gdb_test_no_output is already returning the return value of
gdb_test_multiple.

However, I'm not a fan of (relying on) this implicit return value
behaviour -- I prefer to be explicit about what we are doing.  So in
this commit I have extended the comment on gdb_test_no_output to
document the possible return values (just as gdb_test does), and
explicitly call return.

This should make no different to our testing, but I think it's clearer
now what the gdb_test_no_output proc is expected to do.

The two tests gdb.base/auxv.exp and gdb.base/list.exp both rely on the
return value of gdb_test_no_output, and continue to pass after this
change.

I also spotted that gdb.base/watchpoint.exp could be updated to make
use of gdb_test_no_output, so I did that.

Reviewed-By: Tom Tromey <tom@tromey.com>

2 files changed, 17 insertions, 9 deletions

diff --git a/gdb/testsuite/gdb.base/watchpoint.exp b/gdb/testsuite/gdb.base/watchpoint.exp
index 2827668..917439e 100644
--- a/gdb/testsuite/gdb.base/watchpoint.exp
+++ b/gdb/testsuite/gdb.base/watchpoint.exp
@@ -80,7 +80,7 @@ proc initialize {} {
     # to use it.  This allows the test program to run at full speed until
     # we get to the first marker function.
 
-    if [gdb_test "disable 3" "disable 3\[\r\n\]+" "disable watchpoint" ] { 
+    if [gdb_test_no_output "disable 3" "disable watchpoint" ] {
       return 0
     }
 
@@ -99,7 +99,8 @@ proc test_simple_watchpoint {} {
 
     # Ensure that the watchpoint is disabled when we startup.
 
-    if [gdb_test "disable 3" "^disable 3\[\r\n\]+" "disable watchpoint in test_simple_watchpoint" ] { 
+    if [gdb_test_no_output "disable 3" \
+	    "disable watchpoint in test_simple_watchpoint" ] {
       return 0
     }
 
@@ -120,7 +121,7 @@ proc test_simple_watchpoint {} {
 
     # After reaching the marker function, enable the watchpoint.
 
-    if [gdb_test "enable 3" "^enable 3\[\r\n\]+" "enable watchpoint" ] { 
+    if [gdb_test_no_output "enable 3" "enable watchpoint" ] {
       return
     }
 
@@ -187,7 +188,7 @@ Continuing.*\[Ww\]atchpoint.*ival3.*Old value = -1.*New value = 0.*ival3 = count
 
     # Disable the watchpoint so we run at full speed until we exit.
 
-    if [gdb_test "disable 3" "^disable 3\[\r\n\]+" "watchpoint disabled" ] { 
+    if [gdb_test_no_output "disable 3" "watchpoint disabled" ] {
       return
     }
 
@@ -212,7 +213,8 @@ proc test_disabling_watchpoints {} {
 
     # Ensure that the watchpoint is disabled when we startup.
 
-    if [gdb_test "disable 3" "^disable 3\[\r\n\]+" "disable watchpoint in test_disabling_watchpoints" ] { 
+    if [gdb_test_no_output "disable 3" \
+	    "disable watchpoint in test_disabling_watchpoints" ] {
       return 0
     }
 
@@ -234,7 +236,7 @@ proc test_disabling_watchpoints {} {
 
     # After reaching the marker function, enable the watchpoint.
 
-    if [gdb_test "enable 3" "^enable 3\[\r\n\]+" "watchpoint enabled" ] { 
+    if [gdb_test_no_output "enable 3" "watchpoint enabled" ] {
       return
     }
 
@@ -249,7 +251,8 @@ proc test_disabling_watchpoints {} {
     
     # Disable the watchpoint but leave breakpoints
 
-    if [gdb_test "disable 3" "^disable 3\[\r\n\]+" "disable watchpoint #2 in test_disabling_watchpoints" ] { 
+    if [gdb_test_no_output "disable 3" \
+	    "disable watchpoint #2 in test_disabling_watchpoints" ] {
       return 0
     }
 
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index d30e2a5..5dc7945 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1536,6 +1536,11 @@ if { [tcl_version_at_least 8 6] == 0 } {
 #
 # See gdb_test for a description of the -prompt, -no-prompt-anchor, -nopass,
 # COMMAND, and MESSAGE parameters.
+#
+# Returns:
+#    1 if the test failed,
+#    0 if the test passes,
+#   -1 if there was an internal error.
 
 proc gdb_test_no_output { args } {
     global gdb_prompt
@@ -1551,13 +1556,13 @@ proc gdb_test_no_output { args } {
     set prompt [fill_in_default_prompt $prompt [expr !${no-prompt-anchor}]]
 
     set command_regex [string_to_regexp $command]
-    gdb_test_multiple $command $message -prompt $prompt {
+    return [gdb_test_multiple $command $message -prompt $prompt {
 	-re "^$command_regex\r\n$prompt" {
 	    if {!$nopass} {
 		pass $gdb_test_name
 	    }
 	}
-    }
+    }]
 }
 
 # Send a command and then wait for a sequence of outputs.