ada-lang.c: Introduce type_as_string and use it

A couple wrong things here

  - We should not use target_terminal_ours when all we want is output.
    We should use target_terminal_ours_for_output instead, which
    preserves raw/cooked terminal modes, and SIGINT forwarding.

  - Most importantly, relying on stderr output immediately preceding
    the error/exception print isn't correct.  The exception could be
    caught and handled, for example; MI frontends won't display the
    stderr part in an error dialog box.  Etc.

This commit introduces a type_as_string helper that allows building a
full error string including type info.

gdb/ChangeLog:
2016-04-12  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (type_as_string, type_as_string_and_cleanup): New
	functions.
	(ada_lookup_struct_elt_type): Use type_as_string_and_cleanup.

2 files changed, 50 insertions, 30 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 8fa4b02..8fd8ea8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2016-04-12  Pedro Alves  <palves@redhat.com>
 
+	* ada-lang.c (type_as_string, type_as_string_and_cleanup): New
+	functions.
+	(ada_lookup_struct_elt_type): Use type_as_string_and_cleanup.
+
+2016-04-12  Pedro Alves  <palves@redhat.com>
+
 	* ser-base.c (fd_event): Retry read_prim on EINTR.
 	(do_ser_base_readchar): Retry read_prim on EINTR.
 	(ser_base_write): Retry write_prim on EINTR.
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index d874129..7cdb693 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -7576,6 +7576,39 @@ ada_value_struct_elt (struct value *arg, char *name, int no_err)
 	     "a value that is not a record."));
 }
 
+/* Return a string representation of type TYPE.  Caller must free
+   result.  */
+
+static char *
+type_as_string (struct type *type)
+{
+  struct ui_file *tmp_stream = mem_fileopen ();
+  struct cleanup *old_chain;
+  char *str;
+
+  tmp_stream = mem_fileopen ();
+  old_chain = make_cleanup_ui_file_delete (tmp_stream);
+
+  type_print (type, "", tmp_stream, -1);
+  str = ui_file_xstrdup (tmp_stream, NULL);
+
+  do_cleanups (old_chain);
+  return str;
+}
+
+/* Return a string representation of type TYPE, and install a cleanup
+   that releases it.  */
+
+static char *
+type_as_string_and_cleanup (struct type *type)
+{
+  char *str;
+
+  str = type_as_string (type);
+  make_cleanup (xfree, str);
+  return str;
+}
+
 /* Given a type TYPE, look up the type of the component of type named NAME.
    If DISPP is non-null, add its byte displacement from the beginning of a
    structure (pointed to by a value) of type TYPE to *DISPP (does not
@@ -7616,22 +7649,15 @@ ada_lookup_struct_elt_type (struct type *type, char *name, int refok,
       || (TYPE_CODE (type) != TYPE_CODE_STRUCT
           && TYPE_CODE (type) != TYPE_CODE_UNION))
     {
+      char *type_str;
+
       if (noerr)
         return NULL;
-      else
-        {
-          target_terminal_ours ();
-          gdb_flush (gdb_stdout);
-	  if (type == NULL)
-	    error (_("Type (null) is not a structure or union type"));
-	  else
-	    {
-	      /* XXX: type_sprint */
-	      fprintf_unfiltered (gdb_stderr, _("Type "));
-	      type_print (type, "", gdb_stderr, -1);
-	      error (_(" is not a structure or union type"));
-	    }
-        }
+
+      type_str = (type != NULL
+		  ? type_as_string_and_cleanup (type)
+		  : _("(null)"));
+      error (_("Type %s is not a structure or union type"), type_str);
     }
 
   type = to_static_fixed_type (type);
@@ -7701,22 +7727,10 @@ ada_lookup_struct_elt_type (struct type *type, char *name, int refok,
 BadName:
   if (!noerr)
     {
-      target_terminal_ours ();
-      gdb_flush (gdb_stdout);
-      if (name == NULL)
-        {
-	  /* XXX: type_sprint */
-	  fprintf_unfiltered (gdb_stderr, _("Type "));
-	  type_print (type, "", gdb_stderr, -1);
-	  error (_(" has no component named <null>"));
-	}
-      else
-	{
-	  /* XXX: type_sprint */
-	  fprintf_unfiltered (gdb_stderr, _("Type "));
-	  type_print (type, "", gdb_stderr, -1);
-	  error (_(" has no component named %s"), name);
-	}
+      char *name_str = name != NULL ? name : _("<null>");
+
+      error (_("Type %s has no component named %s"),
+	     type_as_string_and_cleanup (type), name_str);
     }
 
   return NULL;