OpenSystemsDevelopment / qpdf

GCC 15 starts to no longer include this by default, requiring it to be
explicitly included.

Error message:
libtests/cxx11.cc:75:16: error: ‘uint8_t’ was not declared in this scope
   75 |     check_size<uint8_t>(1, false);
      |                ^~~~~~~
libtests/cxx11.cc:10:1: note: ‘uint8_t’ is defined in header ‘<cstdint>’; this is probably fixable by adding ‘#include <cstdint>’
    9 | #include <regex>
  +++ |+#include <cstdint>
   10 | #include <type_traits>

Signed-off-by: Christopher Fore <csfore@posteo.net>

Prevent my future self or other contributors from using assert in
tests and then having that assert not do anything because of the
NDEBUG macro.

Change .clang-format and commit automated changes from a fresh run of
format-code

Run this:

for i in  **/*.cc **/*.c **/*.h **/*.hh; do
  clang-format < $i >| $i.new && mv $i.new $i
done

This comment expands all tabs using an 8-character tab-width. You
should ignore this commit when using git blame or use git blame -w.

In the early days, I used to use tabs where possible for indentation,
since emacs did this automatically. In recent years, I have switched
to only using spaces, which means qpdf source code has been a mixture
of spaces and tabs. I have avoided cleaning this up because of not
wanting gratuitous whitespaces change to cloud the output of git
blame, but I changed my mind after discussing with users who view qpdf
source code in editors/IDEs that have other tab widths by default and
in light of the fact that I am planning to start applying automatic
code formatting soon.

When possible, use `for (auto&` or `for (auto const&` when iterating
using C++-11 style iterators.

Build fails on gcc 4.8 since version 9.1.1 and commit
752416554086d5d34323bc14164d5084db83cfbd:

libtests/cxx11.cc: In function 'void do_regex()':
libtests/cxx11.cc:347:42: error: 'strlen' is not a member of 'std'
     std::cregex_iterator m3(str7, str7 + std::strlen(str7), expr4);
                                          ^

To fix the build failure, add missing include on cstring

Fixes:
 - http://autobuild.buildroot.org/results/ad7fb68ae87850a85509eed80fd0cae8721b10c5

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>