Iterate by index in auto_load_safe_path_vec_update

As reported by Jan, we get this error when building with -D_GLIBCXX_DEBUG:

/usr/include/c++/7/debug/safe_iterator.h:297:
Error: attempt to increment a singular iterator.
Objects involved in the operation:
    iterator "this" @ 0x0x7fffffffd140 {
      type = __gnu_debug::_Safe_iterator<__gnu_cxx::__normal_iterator<std::unique_ptr<char, gdb::xfree_deleter<char> >*, std::__cxx1998::vector<std::unique_ptr<char, gdb::xfree_deleter<char> >, std::allocator<std::unique_ptr<char, gdb::xfree_deleter<char> > > > >, std::__debug::vector<std::unique_ptr<char, gdb::xfree_deleter<char> >, std::allocator<std::unique_ptr<char, gdb::xfree_deleter<char> > > > > (mutable iterator);
      state = singular;
      references sequence with type 'std::__debug::vector<std::unique_ptr<char, gdb::xfree_deleter<char> >, std::allocator<std::unique_ptr<char, gdb::xfree_deleter<char> > > >' @ 0x0x265db40
    }

The bug was introduced by commit

commit e80aaf6183c6692ecc167bf26cbdc53f8f1a55f0
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date:   Fri Mar 2 23:22:06 2018 -0500
Make delim_string_to_char_ptr_vec return an std::vector

The problem is that we iterate using a range-based for on a vector to
which we push in the loop.  Pushing to the vector invalidates the
iterator used in the loop.  Instead, change the code to iterate by index
as was done in the previous code.

gdb/ChangeLog:

	* auto-load.c (auto_load_safe_path_vec_update): Iterate by
	index.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d46ecdd12085ad527bd74fea987bb0dc4b369cd9..6ed9d6c4f6965c22de8ff793107ef6d7a6b12691 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2018-04-10  Simon Marchi  <simon.marchi@ericsson.com>
+
+       * auto-load.c (auto_load_safe_path_vec_update): Iterate by
+       index.
+
 2018-04-10  Pedro Alves  <palves@redhat.com>
 
        * gdbthread.h (finish_thread_state_cleanup): Delete declaration.

diff --git a/gdb/auto-load.c b/gdb/auto-load.c
index e426468f5dfd1949982280017659d84c66044659..33d282afe83b8d8da0a49dc6477844512e08b6b2 100644 (file)
--- a/gdb/auto-load.c
+++ b/gdb/auto-load.c
@@ -197,20 +197,19 @@ auto_load_expand_dir_vars (const char *string)
 static void
 auto_load_safe_path_vec_update (void)
 {
-  unsigned len;
-  int ix;
-
   if (debug_auto_load)
     fprintf_unfiltered (gdb_stdlog,
                        _("auto-load: Updating directories of \"%s\".\n"),
                        auto_load_safe_path);
 
   auto_load_safe_path_vec = auto_load_expand_dir_vars (auto_load_safe_path);
+  size_t len = auto_load_safe_path_vec.size ();
 
   /* Apply tilde_expand and gdb_realpath to each AUTO_LOAD_SAFE_PATH_VEC
      element.  */
-  for (gdb::unique_xmalloc_ptr<char> &in_vec : auto_load_safe_path_vec)
+  for (size_t i = 0; i < len; i++)
     {
+      gdb::unique_xmalloc_ptr<char> &in_vec = auto_load_safe_path_vec[i];
       gdb::unique_xmalloc_ptr<char> expanded (tilde_expand (in_vec.get ()));
       gdb::unique_xmalloc_ptr<char> real_path = gdb_realpath (expanded.get ());