Re: Require C11 in PHP 8.4

> On 2 Aug 2024, at 05:26, Derick Rethans <derick@php.net> wrote: > > On 1 August 2024 22:57:36 BST, Ilija Tovilo <tovilo.ilija@gmail.com > <mailto:tovilo.ilija@gmail.com>> wrote: >> Hi everyone >> >> We've gotten a bug report about compile errors in the PHP 8.4 alpha on >> old C99 compilers (and on some modern compilers when passing the >> -std=c99 flag). Specifically, C99 does not support typedef >> redeclarations, which is a C11 feature. >> >> ```c >> // some_header.h >> typedef struct _zval_struct zval; >> void some_func(zval *zv); >> >> // zend_types.h >> struct _zval_struct { ... }; >> typedef struct _zval_struct zval; >> ``` >> >> Some headers might want to forward declare zval so that zend_types.h >> doesn't have to be included. The two primary reasons you might want to >> avoid that are 1. to reduce compile times if the header is very large >> and 2. to prevent recursive header dependencies. >> >> However, in C99 this code is actually illegal if both of these headers >> end up being included, because redeclarations of typedefs are not >> allowed. To fix it, the typedef must be removed and the signatures >> must refer to the struct directly. >> >> ```c >> // some_header.h >> struct _zval_struct; >> void some_func(struct _zval_struct *zv); >> ``` >> >> I started fixing these in a PR [1] which required more changes than >> expected. After a short discourse, we were wondering whether it might >> be better to switch to a newer C standard instead. Our coding >> standards [2] currently specify that compiling php-src requires C99. >> The Unix installation page on php.net [3] claims it is ANSI C, which >> is certainly outdated. There have been suggestions to require C11 for >> a while, which should be well supported by all compilers shipped with >> maintained distributions. >> >> GCC gained support for C11 in 4.7 [4], LLVM Clang in 3.1, both >> released in 2012. For context, Debian Bullseye comes with GCC 10.2 >> [5], Ubuntu Focal Fossa comes with GCC 9.3 [6], RHEL 8 comes with GCC >> 8.x [7]. > > Even Debian wheezy (out of extended LTS support) or Ubuntu 14.04 have GCC 4.7, so that seems > OK. > > How about Clang (for OSX) though? I can't check that easily. > > cheers > Derick Hi, According to https://releases.llvm.org/3.1/docs/ClangReleaseNotes.html#cchanges, Clang 3.1 added C11. According to https://trac.macports.org/wiki/XcodeVersionInfo, Clang 3.1 shipped with Xcode 4.3.3, in May 2012. In terms of confirming this, the oldest macOS VM I have quick access to is running Sierra (from 2016, last OS update in 2019), and default install now for Clang on that VM is 9.0.0 Hope this helps Cheers Stephen