Avoid crash with 'length

While testing gnat-llvm, I found a gdb crash when applying 'length to
a non-array type.  This patch fixes the crash.

5 files changed, 106 insertions, 2 deletions

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index fdb89cb..1cfd843 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -1819,7 +1819,8 @@ desc_bounds_type (struct type *type)
 }
 
 /* If ARR is an array descriptor (fat or thin pointer), or pointer to
-   one, a pointer to its bounds data.   Otherwise NULL.  */
+   one, a pointer to its bounds data.  Otherwise, throw an
+   exception.  */
 
 static struct value *
 desc_bounds (struct value *arr)
@@ -1870,7 +1871,7 @@ desc_bounds (struct value *arr)
       return p_bounds;
     }
   else
-    return NULL;
+    error (_("Not an array"));
 }
 
 /* If TYPE is the type of an array-descriptor (fat pointer),  the bit
diff --git a/gdb/testsuite/gdb.ada/p-bounds.exp b/gdb/testsuite/gdb.ada/p-bounds.exp
new file mode 100644
index 0000000..d075491
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/p-bounds.exp
@@ -0,0 +1,36 @@
+# Copyright 2025 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 for a crash with a type that looks vaguely like an array
+# descriptor.
+
+load_lib "ada.exp"
+
+require allow_ada_tests
+
+standard_ada_testfile main
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable debug] != ""} {
+    return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/main.adb]
+if {![runto "main.adb:$bp_location"]} {
+    return
+}
+
+gdb_test "print not_an_array'length" "Not an array"
diff --git a/gdb/testsuite/gdb.ada/p-bounds/main.adb b/gdb/testsuite/gdb.ada/p-bounds/main.adb
new file mode 100644
index 0000000..d6654ae
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/p-bounds/main.adb
@@ -0,0 +1,22 @@
+--  Copyright 2025 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/>.
+
+with Pck; use Pck;
+
+procedure Main is
+   Not_An_Array : Counfounding := (p_array => 23, p_bounds => 27);
+begin
+   Do_Nothing (Not_An_Array'Address); -- STOP
+end Main;
diff --git a/gdb/testsuite/gdb.ada/p-bounds/pck.adb b/gdb/testsuite/gdb.ada/p-bounds/pck.adb
new file mode 100644
index 0000000..a175b7b
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/p-bounds/pck.adb
@@ -0,0 +1,21 @@
+--  Copyright 2014-2024 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/>.
+
+package body Pck is
+   procedure Do_Nothing (A : System.Address) is
+   begin
+      null;
+   end Do_Nothing;
+end Pck;
diff --git a/gdb/testsuite/gdb.ada/p-bounds/pck.ads b/gdb/testsuite/gdb.ada/p-bounds/pck.ads
new file mode 100644
index 0000000..5668577
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/p-bounds/pck.ads
@@ -0,0 +1,24 @@
+--  Copyright 2014-2024 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/>.
+
+with System;
+package Pck is
+   type Counfounding is record
+      p_array: integer;
+      p_bounds: integer;
+   end record;
+
+   procedure Do_Nothing (A : System.Address);
+end Pck;