gdb/testsuite: fix FAIL in gdb.base/clear_non_user_bp.exp

Tom and Simon feedback that there is a test failing in this commit:

  commit a5c69b1e49bae4d0dcb20f324cebb310c63495c6
  Date:   Sun Apr 17 15:09:46 2022 +0800

    gdb: fix using clear command to delete non-user breakpoints(PR cli/7161)

Then, I reproduced the same fail with Ubuntu 20.04 as Simon said, and I
fixed the nit in this patch.  The root of the problem is not correctly
matching the presentation of internal breakpoints.

In addition, as Pedro pointed out, the original testcase is not portable
in some methods, so this patch fixes this issue and some other
improvements.

Tested on x86_64 ubuntu 20.04.4 and openSUSE Tumbleweed(VERSION_ID="20220425").

1 files changed, 48 insertions, 18 deletions

diff --git a/gdb/testsuite/gdb.base/clear_non_user_bp.exp b/gdb/testsuite/gdb.base/clear_non_user_bp.exp
index d7bb8ab..26d7a31 100644
--- a/gdb/testsuite/gdb.base/clear_non_user_bp.exp
+++ b/gdb/testsuite/gdb.base/clear_non_user_bp.exp
@@ -16,17 +16,45 @@
 # Regression test for PR gdb/7161.  Test that GDB cannot delete non-user
 # breakpoints with clear command.
 
-proc get_maint_info_bp { var } {
-    global expect_out
-    global gdb_prompt
-
-    gdb_test_multiple "maint info break $var" "find address of internal bp $var" {
-	-re ".*(0x\[0-9a-f\]+).*$gdb_prompt $" {
+# get_maint_bp_addr num
+#
+# Purpose:
+#    Get address of the specified internal breakpoint when using command
+#    "maint info breakpoints $num".
+#
+# Parameter:
+#    The parameter "num" indicates the number of the internal breakpoint
+#    to get.  Note that this parameter must be a negative number.
+#    E.g., -1 means that we're gonna get the first internal breakpoint.
+#
+# Return:
+#    Internal breakpoint address.
+#
+proc get_maint_bp_addr { num } {
+    gdb_test_multiple "maint info break $num" "find address of internal bp $num" {
+	-re -wrap ".*(0x\[0-9a-f\]+).*" {
 	    return $expect_out(1,string)
 	}
-	timeout {
-	    perror "couldn't find address of $var"
-	    return ""
+    }
+    return ""
+}
+
+# get_first_maint_bp_num
+#
+# Purpose:
+#    Get the first number of all internal breakpoints when using command
+#    "maint info breakpoints".
+#
+# Parameter:
+#    None.
+#
+# Return:
+#    Internal breakpoint number, which is negative.
+#
+proc get_first_maint_bp_num { } {
+    gdb_test_multiple "maint info break" "find first internal bp num" {
+	-re -wrap "(-\[0-9\]).*" {
+	    return $expect_out(1,string)
 	}
     }
     return ""
@@ -48,17 +76,19 @@ if ![runto_main] then {
     return 0
 }
 
-gdb_test "break main.c:21" \
-    ".*Breakpoint.* at .*" \
-    "set breakpoint"
+set bp_num [get_first_maint_bp_num]
+set bp_addr [get_maint_bp_addr $bp_num]
 
-set bp_addr [get_maint_info_bp "-1"]
-
-gdb_test "maint info break -1" \
-    "-1.*shlib events.*keep y.*$bp_addr.*" \
-    "maint info breakpoint -1 error"
+gdb_test "maint info break $bp_num" \
+    "$bp_num.*$bp_addr.*" \
+    "maint info breakpoint \$bp_num"
 
 gdb_test "clear *$bp_addr" \
     "No breakpoint at \\*$bp_addr." \
-    "clear internal breakpoint error"
+    "clear internal breakpoint"
+
+# Check again, make sure that GDB really didn't delete the internal breakpoint.
+gdb_test "maint info break $bp_num" \
+    "$bp_num.*$bp_addr.*" \
+    "maint info breakpoint \$bp_num after clear"