[PATCH 0/2] Improve constraints on gdb::array_view::array_view

[Lancelot SIX <lsix@lancelotsix.com>]

Hi,

Wile reading around, I realized that the gdb::array_view interface has a
potential of being miss-used.  No worry, it is not miss-used in practice
in the current codebase, but fixing this might save debugging time in
the future.

It is possible to create a gdb::array_view<T> to refer to data inside a
std::vector<U> (or any contiguous container of U) if a U* is convertible
to a T*.  If U is a class that inherits from T this condition holds but
U and T most likely do not have the same memory layout. In such
situation the array_view will get it wrong (the second patch gives an
example of a miss-use of a gdb::array_view).

In this series I propose to change slightly the requirements on the
gdb::array_view::array_view constructor so this scenario cannot
compile.  No change is expected from this series.

The first patch just adds a const version of gdb_argv::as_array_view that
will be used in the second patch.  The second patch implements the
change on the gdb::array_view and makes minor adjustments so everything
still compiles.

All feedback are welcome.

Best,
Lancelot.

P.S.  Since I started this series, Simon Marchi have sent another series
dealing with array_view[1].  I have applied this series on top of mine
and check that everything still compiles.

[1] https://sourceware.org/pipermail/gdb-patches/2021-October/182657.html

Lancelot SIX (2):
  Add a const version of gdb_argv:as_array_view
  Improve gdb::array_view ctor from contiguous containers

 gdb/dwarf2/read.c       |  2 +-
 gdb/maint.c             |  2 +-
 gdb/utils.h             | 10 ++++++++++
 gdbsupport/array-view.h |  7 ++++---
 4 files changed, 16 insertions(+), 5 deletions(-)

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2.33.0