kenmirrors/asterisk
1
0
Fork 0
mirror of https://github.com/asterisk/asterisk.git synced 2025-09-02 19:16:15 +00:00
Code Issues Packages Projects Releases Wiki Activity

Add C++ Standard detection to configure and fix a new C++20 compile issue

Browse Source 
* The autoconf-archive package contains macros useful for detecting C++
  standard and testing other C++ capabilities but that package was never
  included in the install_prereq script so many existing build environments
  won't have it.  Even if it is installed, older versions won't newer C++
  standards and will actually cause an error if you try to test for that
  version. To make it available for those environments, the
  ax_cxx_compile_stdcxx.m4 macro has copied from the latest release of
  autoconf-archive into the autoconf directory.

* A convenience wrapper(ast_cxx_check_std) around ax_cxx_compile_stdcxx was
  also added so checking the standard version and setting the
  asterisk-specific PBX_ variables becomes a one-liner:
  `AST_CXX_CHECK_STD([std], [force_latest_std])`.
  Calling that with a version of `17` for instance, will set PBX_CXX17
  to 0 or 1 depending on whether the current c++ compiler supports stdc++17.
  HAVE_CXX17 will also be 'defined" or not depending on the result.

* C++ compilers hardly ever default to the latest standard they support.  g++
  version 14 for instance supports up to C++23 but only uses C++17 by default.
  If you want to use C++23, you have to add `-std=gnu++=23` to the g++
  command line.  If you set the second argument of AST_CXX_CHECK_STD to "yes",
  the macro will automatically keep the highest `-std=gnu++` value that
  worked and pass that to the Makefiles.

* The autoconf-archive package was added to install_prereq for future use.

* Updated configure.ac to use AST_CXX_CHECK_STD() to check for C++
  versions 11, 14, 17, 20 and 23.

* Updated configure.ac to accept the `--enable-latest-cxx-std` option which
  will set the second option to AST_CXX_CHECK_STD() to "yes".  The default
  is "no".

* ast_copy_string() in strings.h declares the 'sz' variable as volatile and
  does an `sz--` on it later.  C++20 no longer allows the `++` and `--`
  increment and decrement operators to be used on variables declared as
  volatile however so that was changed to `sz -= 1`.

(cherry picked from commit 79427c1ac1)
This commit is contained in:
George Joseph
2025-01-03 15:38:52 -07:00
committed by Asterisk Development Team
parent 3fe5aafd03
commit 4eae3395a7
10 changed files with 16995 additions and 3614 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
configure.ac
View File

@@ -240,6 +240,25 @@ fi
AC_PROG_CXX
AC_PROG_CPP
AC_PROG_CXXCPP
# Do we want to force the C++ compiler to use the latest standard it supports?
AC_ARG_ENABLE([latest-cxx-std],
[AS_HELP_STRING([--enable-latest-cxx-std],
[Force C++ compiler to use the latest standard it supports])],
[case "${enableval}" in
y|ye|yes) ENABLE_LATEST_CXX_STD=yes ;;
n|no) ENABLE_LATEST_CXX_STD=no ;;
*) AC_MSG_ERROR(bad value ${enableval} for --enable-latest-cxx-std) ;;
esac], [ENABLE_LATEST_CXX_STD=no])
# Check to see if the C++ compiler supports STDC++11,14,17,20,23
# These MUST be in ascending order.
AST_CXX_CHECK_STD([11], [${ENABLE_LATEST_CXX_STD}])
AST_CXX_CHECK_STD([14], [${ENABLE_LATEST_CXX_STD}])
AST_CXX_CHECK_STD([17], [${ENABLE_LATEST_CXX_STD}])
AST_CXX_CHECK_STD([20], [${ENABLE_LATEST_CXX_STD}])
AST_CXX_CHECK_STD([23], [${ENABLE_LATEST_CXX_STD}])
# This macro is just copied into our local acinclude.m4 from libtool.m4 so that
# the developers regenerating the configure script don't have to install libtool.
AST_PROG_LD # note, does not work on FreeBSD
@@ -844,7 +863,7 @@ AC_FUNC_CLOSEDIR_VOID
AC_FUNC_ERROR_AT_LINE
AST_FUNC_FORK
AC_FUNC_FSEEKO
AC_PROG_GCC_TRADITIONAL
# AC_PROG_GCC_TRADITIONAL Obsolete
# XXX: these are commented out until we determine whether it matters if our malloc()
# acts exactly like glibc's or not
# AC_FUNC_MALLOC