Update to C11 coding standard

PHP 8.5 uses C11 coding standard.

Author: petk

README.md

@@ -2,7 +2,7 @@
 
 [![PHP version](https://img.shields.io/badge/PHP-8.5-777BB4?logo=php&labelColor=17181B)](https://www.php.net/)
 [![CMake version](https://img.shields.io/badge/CMake-3.25-064F8C?logo=cmake&labelColor=17181B)](https://cmake.org)
-[![C99](https://img.shields.io/badge/standard-C99-A8B9CC?logo=C&labelColor=17181B)](https://port70.net/~nsz/c/c99/n1256.html)
+[![C11](https://img.shields.io/badge/standard-C11-A8B9CC?logo=C&labelColor=17181B)](https://port70.net/~nsz/c/c11/n1570.html)
 [![GNU](https://img.shields.io/badge/-GNU-A42E2B?logo=gnu&labelColor=17181B)](https://www.gnu.org/)
 [![Ninja](https://img.shields.io/badge/%F0%9F%A5%B7-Ninja%20build-DD6620?labelColor=17181B)](https://ninja-build.org/)
 

cmake/CMakeLists.txt

@@ -22,7 +22,7 @@ project(
   LANGUAGES C CXX ASM
 )
 
-set(CMAKE_C_STANDARD 99)
+set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED TRUE)
 
 # Configure project.

cmake/cmake/Flags.cmake

@@ -471,30 +471,6 @@ if(PHP_MEMORY_SANITIZER OR PHP_ADDRESS_SANITIZER OR PHP_UNDEFINED_SANITIZER)
   endif()
 endif()
 
-# Check if compiler supports the -Wno-typedef-redefinition compile option. PHP
-# is written with C99 standard in mind, yet there is a possibility that typedef
-# redefinitions could happened in the source code. Since PHP CMake-based build
-# system also uses the CMAKE_C_STANDARD_REQUIRED (which adds the -std=...
-# compilation option), GCC recent versions usually ignore this and don't emit
-# the warnings, however Clang emits warnings that redeclaring typedef is a C11
-# feature. Clang has this option to turn off these warnings. As of C11, the
-# typedef redefinitions are valid programming, and this can be removed once a
-# required CMAKE_C_STANDARD 11 will be used.
-if(CMAKE_C_STANDARD EQUAL 99)
-  php_check_compiler_flag(
-    C
-    -Wno-typedef-redefinition
-    _HAVE_WNO_TYPEDEF_REDEFINITION
-  )
-  if(_HAVE_WNO_TYPEDEF_REDEFINITION)
-    target_compile_options(
-      php_configuration
-      INTERFACE
-        $<$<COMPILE_LANGUAGE:C>:-Wno-typedef-redefinition>
-    )
-  endif()
-endif()
-
 ################################################################################
 # Check linker flags.
 ################################################################################

cmake/ext/opcache/CMakeLists.txt

@@ -260,23 +260,6 @@ if(EXT_OPCACHE_JIT)
       RUNTIME_OUTPUT_DIRECTORY jit/ir
   )
 
-  # Suppress typedef redefinition warnings on Clang. At time of writing, PHP is
-  # using C99.
-  if(CMAKE_C_STANDARD EQUAL 99)
-    php_check_compiler_flag(
-      C
-      -Wno-typedef-redefinition
-      _HAVE_WNO_TYPEDEF_REDEFINITION
-    )
-    if(_HAVE_WNO_TYPEDEF_REDEFINITION)
-      target_compile_options(
-        php_opcache_jit_generator
-        PRIVATE
-          $<$<COMPILE_LANGUAGE:C>:-Wno-typedef-redefinition>
-      )
-    endif()
-  endif()
-
   # Generate IR folding engine rules header.
   add_custom_command(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/jit/ir/ir_fold_hash.h

docs/evolution.md

@@ -128,7 +128,7 @@ including the removal of `aclocal.m4` in favor of the php related M4 macros in
 
 ## PHP 8.0 (2020)
 
-PHP coding standard now use the C99 standard.
+PHP coding standards now use the C99 standard.
 
 ## 2021
 
@@ -146,3 +146,7 @@ current Autoconf syntax for the current systems at the time. Cross-compiling was
 improved one step forward with cache variables synced enabling the manual
 overrides on many places. C preprocessor macros inconsistencies between Windows
 and Autotools configuration headers were synced to a nearly identical behavior.
+
+## PHP 8.5 (2025)
+
+PHP coding standards now use the C11 standard.