[Ada] Make string_char_type a true TYPE_CODE_CHAR type in Ada

Before this change, trying to call an overloaded function with at least
one character literal in argument would fail.  For instance, given these
two functions:

   function F (C : Character) return Integer is
   begin
      return Character'Pos (C);
   end F;

   function F (I : Integer) return Integer is
   begin
      return -I;
   end F;

We would get the following GDB session:

    (gdb) p f('A')
    $1 = -65
    (gdb) p f(1)
    $1 = -1

This is wrong because the first call should select the first F function
and thus return 65.

The root problem is that ada-lang.c:ada_language_arch_info stores in
string_char_type a type whose code is TYPE_CODE_INT instead of
TYPE_CODE_CHAR.  As a result, all parsed character literals are turned
into integer values and during overload matching, the TYPE_CODE_CHAR
formal rejects the TYPE_CODE_INT actual.

This change turns string_char_type into a true TYPE_CODE_CHAR type in
ada-lang.c so that we have instead the expected:

    (gdb) p f('A')
    $1 = 65

gdb/ChangeLog:

	* ada-lang.c (ada_language_arch_info): Create a TYPE_CODE_CHAR
	type instead of a TYPE_CODE_INT one for the string_char_type
	and the ada_primitive_type_char types.

gdb/testsuite/ChangeLog:

	* gdb.ada/funcall_char.exp: New testcase.
	* gdb.ada/funcall_char/foo.adb: New file.

Tested on x86_64-linux, no regression.

2 files changed, 65 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.ada/funcall_char.exp b/gdb/testsuite/gdb.ada/funcall_char.exp
new file mode 100644
index 0000000000..ee53966ef7
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/funcall_char.exp
@@ -0,0 +1,32 @@
+# Copyright 2015 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 foo
+
+if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug]] != "" } {
+  return -1
+}
+
+clean_restart ${testfile}
+
+set bp_location [gdb_get_line_number "BREAK" ${testdir}/foo.adb]
+runto "foo.adb:$bp_location"
+
+# Make sure we can call a function that takes a character with a character
+# literal.  If we cannot, then GDB will instead invoke the function that takes
+# an integer and will return a negative number.
+gdb_test "print f('A')" " = 65"
diff --git a/gdb/testsuite/gdb.ada/funcall_char/foo.adb b/gdb/testsuite/gdb.ada/funcall_char/foo.adb
new file mode 100644
index 0000000000..b5c0506203
--- /dev/null
+++ b/gdb/testsuite/gdb.ada/funcall_char/foo.adb
@@ -0,0 +1,33 @@
+--  Copyright 2015 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/>.
+
+procedure Foo is
+
+   function F (C : Character) return Integer is
+   begin
+      return Character'Pos (C);
+   end F;
+
+   function F (I : Integer) return Integer is
+   begin
+      return -I;
+   end F;
+
+   I1 : constant Integer := F ('A'); --  BREAK
+   I2 : constant Integer := F (1);
+
+begin
+   null;
+end Foo;