[gdb/testsuite] Allow procs with default value args in with_override

Currently proc with_override does not work with procs with default value args.

Fix this, and add a test-case excercising this scenario.

Tested on x86_64-linux.

gdb/testsuite/gdb.testsuite/with-override.exp

@@ -0,0 +1,81 @@
+# Copyright 2023 Free Software Foundation, Inc.
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Check with_override proc.
+
+proc foo {} {
+    return 0
+}
+
+proc foo1 {} {
+    return 1
+}
+
+proc foo2 {} {
+    return 2
+}
+
+with_test_prefix no-args {
+
+    with_test_prefix before {
+	gdb_assert { [foo] == 0 }
+    }
+
+    with_override foo foo1 {
+	with_test_prefix foo1 {
+	    gdb_assert { [foo] == 1 }
+	}
+
+	with_override foo foo2 {
+	    with_test_prefix foo2 {
+		gdb_assert { [foo] == 2 }
+	    }
+	}
+    }
+
+    with_test_prefix after {
+	gdb_assert { [foo] == 0 }
+    }
+}
+
+proc foo { {a 0} } {
+    return [expr $a + 1]
+}
+
+proc foo_plus_1 { {a 0} } {
+    return [expr $a + 2]
+}
+
+with_test_prefix default-arg {
+
+    with_test_prefix before {
+	gdb_assert { [foo] == 1 }
+	gdb_assert { [foo 0] == 1 }
+	gdb_assert { [foo 1] == 2 }
+    }
+
+    with_override foo foo_plus_1 {
+	with_test_prefix foo_plus_1 {
+	    gdb_assert { [foo] == 2 }
+	    gdb_assert { [foo 0] == 2 }
+	    gdb_assert { [foo 1] == 3 }
+	}
+    }
+
+    with_test_prefix after {
+	gdb_assert { [foo] == 1 }
+	gdb_assert { [foo 0] == 1 }
+	gdb_assert { [foo 1] == 2 }
+    }
+}

gdb/testsuite/lib/gdb.exp

@@ -9062,6 +9062,22 @@ proc hex_in_list { val hexlist } {
     return [expr $index != -1]
 }
 
+# As info args, but also add the default values.
+
+proc info_args_with_defaults { name } {
+    set args {}
+
+    foreach arg [info args $name] {
+	if { [info default $name $arg default_value] } {
+	    lappend args [list $arg $default_value]
+	} else {
+	    lappend args $arg
+	}
+    }
+
+    return $args
+}
+
 # Override proc NAME to proc OVERRIDE for the duration of the execution of
 # BODY.
 
@@ -9081,7 +9097,7 @@ proc with_override { name override body } {
 
     # Save the old proc, if it exists.
     if { [info procs $name] != "" } {
-	set old_args [info args $name]
+	set old_args [info_args_with_defaults $name]
 	set old_body [info body $name]
 	set existed true
     } else {
@@ -9089,7 +9105,7 @@ proc with_override { name override body } {
     }
 
     # Install the override.
-    set new_args [info args $override]
+    set new_args [info_args_with_defaults $override]
     set new_body [info body $override]
     eval proc $name {$new_args} {$new_body}