[Ada] Allow assignment to wide string.

Given the following variable declaration...

   Www : Wide_String := "12345";

... this patch allows the following assignment to work:

   (gdb) set variable www := "qwert"

Without this patch, the debugger rejects the assignment because
the size of the array elements are different:

   (gdb) set www := "asdfg"
   Incompatible types in assignment

(on the lhs, we have an array of 2-bytes elements, and on the rhs,
we have a standard 1-byte string).

gdb/ChangeLog:

        * ada-lang.c (ada_same_array_size_p): New function.
        (ada_promote_array_of_integrals): New function.
        (coerce_for_assign): Add handling of arrays where the elements
        are integrals of a smaller size than the size of the target
        array element type.

gdb/testsuite/ChangeLog:

        * gdb.ada/set_wstr: New testcase.

7 files changed, 233 insertions, 3 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 20ab7a9..55ad4d9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,13 @@
 2012-10-24  Joel Brobecker  <brobecker@adacore.com>
 
+	* ada-lang.c (ada_same_array_size_p): New function.
+	(ada_promote_array_of_integrals): New function.
+	(coerce_for_assign): Add handling of arrays where the elements
+	are integrals of a smaller size than the size of the target
+	array element type.
+
+2012-10-24  Joel Brobecker  <brobecker@adacore.com>
+
 	* doublest.c (convert_doublest_to_floatformat): Fix comparison
 	against maximum exponent value.
 
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index 9f329df..edef6bd 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -8629,6 +8629,72 @@ cast_from_fixed (struct type *type, struct value *arg)
   return value_from_double (type, val);
 }
 
+/* Given two array types T1 and T2, return nonzero iff both arrays
+   contain the same number of elements.  */
+
+static int
+ada_same_array_size_p (struct type *t1, struct type *t2)
+{
+  LONGEST lo1, hi1, lo2, hi2;
+
+  /* Get the array bounds in order to verify that the size of
+     the two arrays match.  */
+  if (!get_array_bounds (t1, &lo1, &hi1)
+      || !get_array_bounds (t2, &lo2, &hi2))
+    error (_("unable to determine array bounds"));
+
+  /* To make things easier for size comparison, normalize a bit
+     the case of empty arrays by making sure that the difference
+     between upper bound and lower bound is always -1.  */
+  if (lo1 > hi1)
+    hi1 = lo1 - 1;
+  if (lo2 > hi2)
+    hi2 = lo2 - 1;
+
+  return (hi1 - lo1 == hi2 - lo2);
+}
+
+/* Assuming that VAL is an array of integrals, and TYPE represents
+   an array with the same number of elements, but with wider integral
+   elements, return an array "casted" to TYPE.  In practice, this
+   means that the returned array is built by casting each element
+   of the original array into TYPE's (wider) element type.  */
+
+static struct value *
+ada_promote_array_of_integrals (struct type *type, struct value *val)
+{
+  struct type *elt_type = TYPE_TARGET_TYPE (type);
+  LONGEST lo, hi;
+  struct value *res;
+  LONGEST i;
+
+  /* Verify that both val and type are arrays of scalars, and
+     that the size of val's elements is smaller than the size
+     of type's element.  */
+  gdb_assert (TYPE_CODE (type) == TYPE_CODE_ARRAY);
+  gdb_assert (is_integral_type (TYPE_TARGET_TYPE (type)));
+  gdb_assert (TYPE_CODE (value_type (val)) == TYPE_CODE_ARRAY);
+  gdb_assert (is_integral_type (TYPE_TARGET_TYPE (value_type (val))));
+  gdb_assert (TYPE_LENGTH (TYPE_TARGET_TYPE (type))
+	      > TYPE_LENGTH (TYPE_TARGET_TYPE (value_type (val))));
+
+  if (!get_array_bounds (type, &lo, &hi))
+    error (_("unable to determine array bounds"));
+
+  res = allocate_value (type);
+
+  /* Promote each array element.  */
+  for (i = 0; i < hi - lo + 1; i++)
+    {
+      struct value *elt = value_cast (elt_type, value_subscript (val, lo + i));
+
+      memcpy (value_contents_writeable (res) + (i * TYPE_LENGTH (elt_type)),
+	      value_contents_all (elt), TYPE_LENGTH (elt_type));
+    }
+
+  return res;
+}
+
 /* Coerce VAL as necessary for assignment to an lval of type TYPE, and
    return the converted value.  */
 
@@ -8653,9 +8719,21 @@ coerce_for_assign (struct type *type, struct value *val)
   if (TYPE_CODE (type2) == TYPE_CODE_ARRAY
       && TYPE_CODE (type) == TYPE_CODE_ARRAY)
     {
-      if (TYPE_LENGTH (type2) != TYPE_LENGTH (type)
-          || TYPE_LENGTH (TYPE_TARGET_TYPE (type2))
-          != TYPE_LENGTH (TYPE_TARGET_TYPE (type2)))
+      if (!ada_same_array_size_p (type, type2))
+	error (_("cannot assign arrays of different length"));
+
+      if (is_integral_type (TYPE_TARGET_TYPE (type))
+	  && is_integral_type (TYPE_TARGET_TYPE (type2))
+	  && TYPE_LENGTH (TYPE_TARGET_TYPE (type2))
+	       < TYPE_LENGTH (TYPE_TARGET_TYPE (type)))
+	{
+	  /* Allow implicit promotion of the array elements to
+	     a wider type.  */
+	  return ada_promote_array_of_integrals (type, val);
+	}
+
+      if (TYPE_LENGTH (TYPE_TARGET_TYPE (type2))
+          != TYPE_LENGTH (TYPE_TARGET_TYPE (type)))
         error (_("Incompatible types in assignment"));
       deprecated_set_value_type (val, type);
     }
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 633c0ab..5e769c2 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2012-10-24  Joel Brobecker  <brobecker@adacore.com>
 
+	* gdb.ada/set_wstr: New testcase.
+
+2012-10-24  Joel Brobecker  <brobecker@adacore.com>
+
 	* gdb.base/ldbl_e308.c, gdb.base/ldbl_e308.exp: New files.
 
 2012-10-24  Joel Brobecker  <brobecker@adacore.com>
diff --git a/gdb/testsuite/gdb.ada/set_wstr.exp b/gdb/testsuite/gdb.ada/set_wstr.exp
new file mode 100644
index 0000000..0a257be
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/set_wstr.exp
@@ -0,0 +1,74 @@
+# Copyright 2012 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/>.
+
+load_lib "ada.exp"
+
+standard_ada_testfile a
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug ]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "STOP" ${testdir}/a.adb]
+if ![runto "a.adb:$bp_location" ] then {
+  perror "Couldn't run ${testfile}"
+  return
+}
+
+# Verify that assigning to Nnn (a basic string) works...
+
+gdb_test "print nnn" \
+         "= \"12345\"" \
+         "print nnn before assignment"
+
+gdb_test_no_output "set variable nnn := \"qcyom\""
+
+gdb_test "print nnn" \
+         "= \"qcyom\"" \
+         "print nnn after assignment"
+
+# Same with Www (a wide string)...
+
+gdb_test "print www" \
+         "= \"12345\"" \
+         "print www before assignment"
+
+gdb_test_no_output "set variable www := \"zenrk\""
+
+gdb_test "print www" \
+         "= \"zenrk\"" \
+         "print www after assignment"
+
+# Same with Rws (a wide wide string)...
+
+gdb_test "print rws" \
+         "= \"12345\"" \
+         "print rws before assignment"
+
+gdb_test_no_output "set variable rws := \"ndhci\""
+
+gdb_test "print rws" \
+         "= \"ndhci\"" \
+         "print rws after assignment"
+
+# Also, check that GDB doesn't get tricked if we assign to Www a
+# string twice the length of Www.  The debugger should reject the
+# assignment, because the array lengths are different (the debugger
+# used to get tricked because the array size was the same).
+
+gdb_test "set variable www := \"1#2#3#4#5#\"" \
+         "cannot assign arrays of different length"
diff --git a/gdb/testsuite/gdb.ada/set_wstr/a.adb b/gdb/testsuite/gdb.ada/set_wstr/a.adb
new file mode 100644
index 0000000..e1b9bd8
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/set_wstr/a.adb
@@ -0,0 +1,26 @@
+--  Copyright 2012 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 A is
+   Nnn : String := "12345";
+   Www : Wide_String := "12345";
+   Rws : Wide_Wide_String := "12345";
+begin
+   Do_Nothing (Nnn'Address);  -- STOP
+   Do_Nothing (Www'Address);
+   Do_Nothing (Rws'Address);
+end A;
diff --git a/gdb/testsuite/gdb.ada/set_wstr/pck.adb b/gdb/testsuite/gdb.ada/set_wstr/pck.adb
new file mode 100644
index 0000000..1f7d45c
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/set_wstr/pck.adb
@@ -0,0 +1,21 @@
+--  Copyright 2012 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/set_wstr/pck.ads b/gdb/testsuite/gdb.ada/set_wstr/pck.ads
new file mode 100644
index 0000000..c20c0d8
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/set_wstr/pck.ads
@@ -0,0 +1,19 @@
+--  Copyright 2012 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
+   procedure Do_Nothing (A : System.Address);
+end Pck;