Enable CXX and ASM optionally

CXX in PHP is at the time of writing only used in extensions (intl,
pdo_firebird as of PHP 8.4 etc.), and ASM in the Zend Engine for using
Boost assembly files.

This now resembles also native Autotools build system where CXX is
enabled optionally based on the extension that uses it.

So in case of a default build where CXX sources aren't being compiled,
CXX compiler is required only as needed.

Author: petk

cmake/CMakeLists.txt

@@ -18,7 +18,7 @@ project(
   VERSION ${PHP_VERSION}
   DESCRIPTION "Widely-used general-purpose scripting language"
   HOMEPAGE_URL "https://www.php.net"
-  LANGUAGES C CXX ASM
+  LANGUAGES C
 )
 
 set(CMAKE_C_STANDARD 99)

cmake/Zend/CMakeLists.txt

@@ -44,9 +44,15 @@ project(
   Zend
   VERSION ${Zend_VERSION}
   DESCRIPTION "Zend Engine library"
-  LANGUAGES C CXX ASM
+  LANGUAGES C
 )
 
+include(CheckLanguage)
+check_language(ASM)
+if(CMAKE_ASM_COMPILER)
+  enable_language(ASM)
+endif()
+
 string(APPEND Zend_VERSION "${Zend_VERSION_LABEL}")
 message(STATUS "Zend Engine version: ${Zend_VERSION}")
 

cmake/cmake/Bootstrap.cmake

@@ -4,6 +4,16 @@ Configure project after the project() call.
 
 include_guard(GLOBAL)
 
+# Optionally enable CXX for extensions and ASM for Zend Engine. ASM is enabled
+# last so CMake checks whether enabled compilers can also work for assembly.
+include(CheckLanguage)
+foreach(language CXX ASM)
+  check_language(${language})
+  if(CMAKE_${language}_COMPILER)
+    enable_language(${language})
+  endif()
+endforeach()
+
 # Output linker information.
 if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.29)
   if(CMAKE_C_COMPILER_LINKER)

cmake/cmake/Flags.cmake

@@ -8,6 +8,8 @@ include(CheckSourceRuns)
 include(CMakePushCheckState)
 include(PHP/CheckCompilerFlag)
 
+get_cmake_property(enabledLanguages ENABLED_LANGUAGES)
+
 # Check for broken GCC optimize-strlen.
 include(PHP/CheckBrokenGccStrlenOpt)
 if(PHP_HAVE_BROKEN_OPTIMIZE_STRLEN)
@@ -78,14 +80,16 @@ if(HAVE_WNO_CLOBBERED_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-Wno-clobbered>
   )
 endif()
-php_check_compiler_flag(CXX -Wno-clobbered HAVE_WNO_CLOBBERED_CXX)
-if(HAVE_WNO_CLOBBERED_CXX)
-  target_compile_options(
-    php_configuration
-    BEFORE
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-Wno-clobbered>
-  )
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(CXX -Wno-clobbered HAVE_WNO_CLOBBERED_CXX)
+  if(HAVE_WNO_CLOBBERED_CXX)
+    target_compile_options(
+      php_configuration
+      BEFORE
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-Wno-clobbered>
+    )
+  endif()
 endif()
 
 # Check for support for implicit fallthrough level 1, also add after previous
@@ -102,17 +106,19 @@ if(HAVE_WIMPLICIT_FALLTHROUGH_1_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-Wimplicit-fallthrough=1>
   )
 endif()
-php_check_compiler_flag(
-  CXX
-  -Wimplicit-fallthrough=1
-  HAVE_WIMPLICIT_FALLTHROUGH_1_CXX
-)
-if(HAVE_WIMPLICIT_FALLTHROUGH_1_CXX)
-  target_compile_options(
-    php_configuration
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-Wimplicit-fallthrough=1>
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(
+    CXX
+    -Wimplicit-fallthrough=1
+    HAVE_WIMPLICIT_FALLTHROUGH_1_CXX
   )
+  if(HAVE_WIMPLICIT_FALLTHROUGH_1_CXX)
+    target_compile_options(
+      php_configuration
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-Wimplicit-fallthrough=1>
+    )
+  endif()
 endif()
 
 php_check_compiler_flag(C -Wduplicated-cond HAVE_WDUPLICATED_COND_C)
@@ -124,14 +130,16 @@ if(HAVE_WDUPLICATED_COND_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-Wduplicated-cond>
   )
 endif()
-php_check_compiler_flag(CXX -Wduplicated-cond HAVE_WDUPLICATED_COND_CXX)
-if(HAVE_WDUPLICATED_COND_CXX)
-  target_compile_options(
-    php_configuration
-    BEFORE
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-Wduplicated-cond>
-  )
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(CXX -Wduplicated-cond HAVE_WDUPLICATED_COND_CXX)
+  if(HAVE_WDUPLICATED_COND_CXX)
+    target_compile_options(
+      php_configuration
+      BEFORE
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-Wduplicated-cond>
+    )
+  endif()
 endif()
 
 php_check_compiler_flag(C -Wlogical-op HAVE_WLOGICAL_OP_C)
@@ -143,14 +151,16 @@ if(HAVE_WLOGICAL_OP_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-Wlogical-op>
   )
 endif()
-php_check_compiler_flag(CXX -Wlogical-op HAVE_WLOGICAL_OP_CXX)
-if(HAVE_WLOGICAL_OP_CXX)
-  target_compile_options(
-    php_configuration
-    BEFORE
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-Wlogical-op>
-  )
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(CXX -Wlogical-op HAVE_WLOGICAL_OP_CXX)
+  if(HAVE_WLOGICAL_OP_CXX)
+    target_compile_options(
+      php_configuration
+      BEFORE
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-Wlogical-op>
+    )
+  endif()
 endif()
 
 php_check_compiler_flag(C -Wformat-truncation HAVE_WFORMAT_TRUNCATION_C)
@@ -162,14 +172,16 @@ if(HAVE_WFORMAT_TRUNCATION_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-Wformat-truncation>
   )
 endif()
-php_check_compiler_flag(CXX -Wformat-truncation HAVE_WFORMAT_TRUNCATION_CXX)
-if(HAVE_WFORMAT_TRUNCATION_CXX)
-  target_compile_options(
-    php_configuration
-    BEFORE
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-Wformat-truncation>
-  )
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(CXX -Wformat-truncation HAVE_WFORMAT_TRUNCATION_CXX)
+  if(HAVE_WFORMAT_TRUNCATION_CXX)
+    target_compile_options(
+      php_configuration
+      BEFORE
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-Wformat-truncation>
+    )
+  endif()
 endif()
 
 php_check_compiler_flag(C -Wstrict-prototypes HAVE_WSTRICT_PROTOTYPES_C)
@@ -191,14 +203,16 @@ if(HAVE_FNO_COMMON_C)
       $<$<COMPILE_LANGUAGE:ASM,C>:-fno-common>
   )
 endif()
-php_check_compiler_flag(CXX -fno-common HAVE_FNO_COMMON_CXX)
-if(HAVE_FNO_COMMON_C_XX)
-  target_compile_options(
-    php_configuration
-    BEFORE
-    INTERFACE
-      $<$<COMPILE_LANGUAGE:CXX>:-fno-common>
-  )
+if(CXX IN_LIST enabledLanguages)
+  php_check_compiler_flag(CXX -fno-common HAVE_FNO_COMMON_CXX)
+  if(HAVE_FNO_COMMON_C_XX)
+    target_compile_options(
+      php_configuration
+      BEFORE
+      INTERFACE
+        $<$<COMPILE_LANGUAGE:CXX>:-fno-common>
+    )
+  endif()
 endif()
 
 # Explicitly disable floating-point expression contraction, even if already done
@@ -240,14 +254,16 @@ if(PHP_MEMORY_SANITIZER)
       HAVE_MEMORY_SANITIZER_C
     )
 
-    php_check_compiler_flag(
-      CXX
-      "-fsanitize=memory;-fsanitize-memory-track-origins"
-      HAVE_MEMORY_SANITIZER_CXX
-    )
+    if(CXX IN_LIST enabledLanguages)
+      php_check_compiler_flag(
+        CXX
+        "-fsanitize=memory;-fsanitize-memory-track-origins"
+        HAVE_MEMORY_SANITIZER_CXX
+      )
+    endif()
   cmake_pop_check_state()
 
-  if(HAVE_MEMORY_SANITIZER_C AND HAVE_MEMORY_SANITIZER_CXX)
+  if(HAVE_MEMORY_SANITIZER_C OR HAVE_MEMORY_SANITIZER_CXX)
     target_compile_options(
       php_configuration
       INTERFACE
@@ -284,10 +300,12 @@ if(PHP_ADDRESS_SANITIZER)
     set(CMAKE_REQUIRED_LINK_OPTIONS "-fsanitize=address")
 
     php_check_compiler_flag(C -fsanitize=address HAVE_ADDRESS_SANITIZER_C)
-    php_check_compiler_flag(CXX -fsanitize=address HAVE_ADDRESS_SANITIZER_CXX)
+    if(CXX IN_LIST enabledLanguages)
+      php_check_compiler_flag(CXX -fsanitize=address HAVE_ADDRESS_SANITIZER_CXX)
+    endif()
   cmake_pop_check_state()
 
-  if(HAVE_ADDRESS_SANITIZER_C AND HAVE_ADDRESS_SANITIZER_CXX)
+  if(HAVE_ADDRESS_SANITIZER_C OR HAVE_ADDRESS_SANITIZER_CXX)
     target_compile_options(
       php_configuration
       INTERFACE
@@ -325,14 +343,16 @@ if(PHP_UNDEFINED_SANITIZER)
       -fsanitize=undefined
       HAVE_UNDEFINED_SANITIZER_C
     )
-    php_check_compiler_flag(
-      CXX
-      -fsanitize=undefined
-      HAVE_UNDEFINED_SANITIZER_CXX
-    )
+    if(CXX IN_LIST enabledLanguages)
+      php_check_compiler_flag(
+        CXX
+        -fsanitize=undefined
+        HAVE_UNDEFINED_SANITIZER_CXX
+      )
+    endif()
   cmake_pop_check_state()
 
-  if(HAVE_UNDEFINED_SANITIZER_C AND HAVE_UNDEFINED_SANITIZER_CXX)
+  if(HAVE_UNDEFINED_SANITIZER_C OR HAVE_UNDEFINED_SANITIZER_CXX)
     target_compile_options(
       php_configuration
       INTERFACE
@@ -355,14 +375,16 @@ if(PHP_UNDEFINED_SANITIZER)
         -fno-sanitize=object-size
         HAVE_OBJECT_SIZE_SANITIZER_C
       )
-      php_check_compiler_flag(
-        CXX
-        -fno-sanitize=object-size
-        HAVE_OBJECT_SIZE_SANITIZER_CXX
-      )
+      if(CXX IN_LIST enabledLanguages)
+        php_check_compiler_flag(
+          CXX
+          -fno-sanitize=object-size
+          HAVE_OBJECT_SIZE_SANITIZER_CXX
+        )
+      endif()
     cmake_pop_check_state()
 
-    if(HAVE_OBJECT_SIZE_SANITIZER_C AND HAVE_OBJECT_SIZE_SANITIZER_CXX)
+    if(HAVE_OBJECT_SIZE_SANITIZER_C OR HAVE_OBJECT_SIZE_SANITIZER_CXX)
       target_compile_options(
         php_configuration
         INTERFACE
@@ -412,11 +434,13 @@ if(PHP_UNDEFINED_SANITIZER)
         -fno-sanitize=function
         HAVE_FNO_SANITIZE_FUNCTION_C
       )
-      php_check_compiler_flag(
-        CXX
-        -fno-sanitize=function
-        HAVE_FNO_SANITIZE_FUNCTION_CXX
-      )
+      if(CXX IN_LIST enabledLanguages)
+        php_check_compiler_flag(
+          CXX
+          -fno-sanitize=function
+          HAVE_FNO_SANITIZE_FUNCTION_CXX
+        )
+      endif()
 
       if(HAVE_FNO_SANITIZE_FUNCTION_C)
         target_compile_options(
@@ -448,11 +472,13 @@ if(PHP_MEMORY_SANITIZER OR PHP_ADDRESS_SANITIZER OR PHP_UNDEFINED_SANITIZER)
     -fno-omit-frame-pointer
     HAVE_FNO_OMIT_FRAME_POINTER_C
   )
-  php_check_compiler_flag(
-    CXX
-    -fno-omit-frame-pointer
-    HAVE_FNO_OMIT_FRAME_POINTER_CXX
-  )
+  if(CXX IN_LIST enabledLanguages)
+    php_check_compiler_flag(
+      CXX
+      -fno-omit-frame-pointer
+      HAVE_FNO_OMIT_FRAME_POINTER_CXX
+    )
+  endif()
 
   if(HAVE_FNO_OMIT_FRAME_POINTER_C)
     target_compile_options(