Move __alignof__ check into a separate file

Author: petk

cmake/cmake/ConfigureChecks.cmake

@@ -12,7 +12,6 @@ include_guard(GLOBAL)
 
 include(CheckFunctionExists)
 include(CheckIncludeFiles)
-include(CheckSourceCompiles)
 include(CheckStructHasMember)
 include(CheckSymbolExists)
 include(CheckTypeSize)
@@ -438,24 +437,6 @@ else()
   message(CHECK_PASS "using system default")
 endif()
 
-message(CHECK_START "Checking whether the compiler supports __alignof__")
-cmake_push_check_state(RESET)
-  set(CMAKE_REQUIRED_QUIET TRUE)
-  check_source_compiles(C [[
-    int main(void)
-    {
-      int align = __alignof__(int);
-      (void)align;
-      return 0;
-    }
-  ]] HAVE_ALIGNOF)
-cmake_pop_check_state()
-if(HAVE_ALIGNOF)
-  message(CHECK_PASS "yes")
-else()
-  message(CHECK_FAIL "no")
-endif()
-
 # Check for GCC function attributes on all systems except ones without glibc.
 # Fix for these systems is already included in GCC 7, but not on GCC 6. At least
 # some versions of FreeBSD seem to have buggy ifunc support, see

cmake/cmake/checks/CheckAlignof.cmake

@@ -0,0 +1,38 @@
+#[=============================================================================[
+This check determines whether the compiler supports __alignof__.
+
+Result variables:
+
+* HAVE_ALIGNOF
+#]=============================================================================]
+
+include(CheckSourceCompiles)
+include(CMakePushCheckState)
+
+if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
+  set(HAVE_ALIGNOF FALSE)
+  return()
+endif()
+
+# Skip in consecutive configuration phases.
+if(NOT DEFINED PHP_HAS_ALIGNOF)
+  message(CHECK_START "Checking whether the compiler supports __alignof__")
+  cmake_push_check_state(RESET)
+    set(CMAKE_REQUIRED_QUIET TRUE)
+    check_source_compiles(C [[
+      int main(void)
+      {
+        int align = __alignof__(int);
+        (void)align;
+        return 0;
+      }
+    ]] PHP_HAS_ALIGNOF)
+  cmake_pop_check_state()
+  if(PHP_HAS_ALIGNOF)
+    message(CHECK_PASS "yes")
+  else()
+    message(CHECK_FAIL "no")
+  endif()
+endif()
+
+set(HAVE_ALIGNOF ${PHP_HAS_ALIGNOF})

cmake/cmake/platforms/Windows.cmake

@@ -54,7 +54,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
   # known on Windows targets.
   ##############################################################################
 
-  set(HAVE_ALIGNOF FALSE)
   set(HAVE_ALPHASORT FALSE)
   set(HAVE_ARPA_INET_H FALSE)
   set(HAVE_ARPA_NAMESER_H FALSE)