[PATCH 0/3] Introduce gdb::array_view, symtabs_and_lines -> std::vector

[Pedro Alves <palves at redhat dot com>]

Looking at the "list and multiple locations" patch [1], I thought that
it's a bit annoying/frustrating to have do remember to free the sals
array that a symtabs_and_lines object wraps, with 'xfree (sals.sals)'
or the equivalent make_cleanup(xfree, ...), not to mention how
error-prone manual memory management is.  We can do better in C++.

So I wrote a patch to replace 'struct symtabs_and_lines' with 'typedef
std::vector<symtab_and_line> symtabs_and_lines'.  That works nicelly,
except that I wasn't entirely happy that that would introduce heap
allocations in a few cases where there is none nowadays.

I then addressed that by adding an array_view abstraction, which is
something that I've wanted at other times before.

After that, we'd end up with some places using a std::vector disguised
behind the symtabs_and_lines typedef, while in other places we'd be
spelling out gdb::array_view.  With that, I no longer see any value in
keeping the symtabs_and_lines typedef, kind of giving preference to
std::vector, so I removed the typedef, choosing to spell out
std::vector explicitly.

(I'm aware that there are several proposals for adding something like
array_view to the standard C++ library.  In this implementation, which
was written from scratch and developed in parallel with the unit
tests, I chose to keep it as simple and safe as possible.  For
example, there is no support for ranks != 1, simply because the main
use case this aims at addressing is abstracting out std::vector vs
stack arrays in APIs.)

[1] https://sourceware.org/ml/gdb-patches/2017-07/msg00280.html

Note that the net increase shown below is mostly caused by the new
unit tests.  If we only count patches 2 and 3, then we get instead:

  33 files changed, 537 insertions(+), 820 deletions(-)

Pedro Alves (3):
  Introduce gdb::array_view
  struct symtabs_and_lines -> std::vector<symtab_and_line>
  Kill init_sal

 gdb/Makefile.in                      |   2 +
 gdb/ada-lang.c                       |   3 +-
 gdb/ax-gdb.c                         |  12 +-
 gdb/break-catch-throw.c              |  12 +-
 gdb/breakpoint.c                     | 359 +++++++++++--------------
 gdb/breakpoint.h                     |  20 +-
 gdb/cli/cli-cmds.c                   | 158 +++++------
 gdb/common/array-view.h              | 179 +++++++++++++
 gdb/elfread.c                        |  14 +-
 gdb/frame.c                          |  25 +-
 gdb/frame.h                          |   3 +-
 gdb/guile/scm-frame.c                |   2 +-
 gdb/guile/scm-symtab.c               |   6 +-
 gdb/infcall.c                        |  11 +-
 gdb/infcmd.c                         |  35 +--
 gdb/infrun.c                         |  52 ++--
 gdb/linespec.c                       | 264 ++++++++-----------
 gdb/linespec.h                       |  32 +--
 gdb/macrocmd.c                       |   8 +-
 gdb/mi/mi-main.c                     |  17 +-
 gdb/probe.c                          |  33 +--
 gdb/probe.h                          |  14 +-
 gdb/python/py-frame.c                |   3 +-
 gdb/python/python.c                  |  47 ++--
 gdb/reverse.c                        |   8 +-
 gdb/source.c                         |  54 ++--
 gdb/source.h                         |   3 +-
 gdb/stack.c                          |  56 ++--
 gdb/stack.h                          |   2 +-
 gdb/symtab.c                         |  26 +-
 gdb/symtab.h                         |  27 +-
 gdb/tracepoint.c                     |  39 +--
 gdb/tui/tui-disasm.c                 |   2 +-
 gdb/tui/tui-stack.c                  |   3 +-
 gdb/tui/tui-winsource.c              |   7 +-
 gdb/unittests/array-view-selftests.c | 489 +++++++++++++++++++++++++++++++++++
 36 files changed, 1207 insertions(+), 820 deletions(-)
 create mode 100644 gdb/common/array-view.h
 create mode 100644 gdb/unittests/array-view-selftests.c

-- 
2.5.5