gdb: add option to reverse order of _initialize function calls

An earlier patch in this series fixed a dependency problem between two
_initialize functions.  That problem was uncovered by reversing the
order of the initialize function calls.

In short, symtab.c tried to add the alias "maintenance
flush-symbol-cache" for the command "maintenance flush symbol-cache".
Because the "maintenance flush" prefix command was not yet created (it
happens in maint.c, initialized later in this reversed order), the
add_alias_cmd function returned NULL.  That result was passed to
deprecate_cmd, which didn't expected that value, and that caused a
segfault.  This was fixed by changing alias creation functions to take
the target command as a cmd_list_element, instead of by name.

This patch adds a runtime option to reverse the order of the initialize
calls at will.  I chose to use an environment variable for this, over a
parameter (even a "maintenance" one), because:

 - The init functions are called before the early init commands are
   executed, so we could use -iex to turn this mode on early enough.
   This is obvious when you remember that commands / parameters are
   created by initialize funcitions :).

 - This is not something anybody would want to tweak after startup
   anyway.

gdb/ChangeLog:

	* make-init-c: Add option to reverse function calls.

gdb/testsuite/ChangeLog:

	* gdb.base/reverse-init-functions.exp: New.

Change-Id: I543e609cf526e7cb145a006a794d0e6851b63f45

1 files changed, 14 insertions, 1 deletions

diff --git a/gdb/make-init-c b/gdb/make-init-c
index 1588760..e3c5985 100755
--- a/gdb/make-init-c
+++ b/gdb/make-init-c
@@ -42,6 +42,7 @@ set -e
 echo "/* Do not modify this file.  */"
 echo "/* It is created automatically by the Makefile.  */"
 echo "#include \"defs.h\"      /* For initialize_file_ftype.  */"
+echo "#include <algorithm>"
 echo ""
 sed -n -e 's/^\(_initialize_[a-zA-Z0-9_]*\) ()$/\1/p' "$@" | while read -r name; do
   echo "extern initialize_file_ftype $name;"
@@ -51,7 +52,19 @@ echo "void initialize_all_files ();"
 echo "void"
 echo "initialize_all_files ()"
 echo "{"
+echo "  std::vector<initialize_file_ftype *> functions ="
+echo "    {"
 sed -n -e 's/^\(_initialize_[a-zA-Z0-9_]*\) ()$/\1/p' "$@" | while read -r name; do
-  echo "  $name ();"
+  echo "      $name,"
 done
+echo "    };"
+echo ""
+echo "  /* If GDB_REVERSE_INIT_FUNCTIONS is set (any value), reverse the"
+echo "     order in which initialization functions are called.  This is"
+echo "     used by the testsuite.  */"
+echo "  if (getenv (\"GDB_REVERSE_INIT_FUNCTIONS\") != nullptr)"
+echo "    std::reverse (functions.begin (), functions.end ());"
+echo ""
+echo "  for (initialize_file_ftype *function : functions)"
+echo "    function ();"
 echo "}"