Adjust GCC broken strlen optimization check

GCC 8.3 has this fixed. Also cross-compiling for the dlsym underscore
prefix check improved and simplified.

Author: petk

cmake/cmake/Flags.cmake

@@ -11,7 +11,7 @@ include(PHP/CheckCompilerFlag)
 
 # Check for broken GCC optimize-strlen.
 include(PHP/CheckBrokenGccStrlenOpt)
-if(HAVE_BROKEN_OPTIMIZE_STRLEN)
+if(PHP_HAVE_BROKEN_OPTIMIZE_STRLEN)
   php_check_compiler_flag(C -fno-optimize-strlen HAVE_FNO_OPTIMIZE_STRLEN_C)
   if(HAVE_FNO_OPTIMIZE_STRLEN_C)
     target_compile_options(

cmake/cmake/modules/PHP/CheckBrokenGccStrlenOpt.cmake

@@ -1,24 +1,31 @@
 #[=============================================================================[
-Early releases of GCC 8 shipped with a strlen() optimization bug, so they didn't
-properly handle the 'char val[1]' struct hack. See https://bugs.php.net/76510.
-If check is successful the -fno-optimize-strlen compiler flag should be used.
+GCC 8.2 shipped with a strlen() optimization bug, so it didn't properly handle
+the 'char val[1]' struct hack. Fixed in GCC 8.3. See https://bugs.php.net/76510
+and https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86914. If below check is
+successful the -fno-optimize-strlen compiler flag should be used.
 
 Cache variables:
 
-  HAVE_BROKEN_OPTIMIZE_STRLEN
-    Whether GCC's optimize-strlen is broken.
+  PHP_HAVE_BROKEN_OPTIMIZE_STRLEN
+    Whether GCC has broken strlen() optimization.
 ]=============================================================================]#
 
 include_guard(GLOBAL)
 
 include(CheckSourceRuns)
 include(CMakePushCheckState)
 
-if(NOT CMAKE_C_COMPILER_ID STREQUAL "GNU")
+if(
+  NOT CMAKE_C_COMPILER_ID STREQUAL "GNU"
+  OR (
+    CMAKE_C_COMPILER_ID STREQUAL "GNU"
+    AND CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 8.3
+  )
+)
   return()
 endif()
 
-message(CHECK_START "Checking for broken GCC optimize-strlen")
+message(CHECK_START "Checking if GCC has broken strlen() optimization")
 
 cmake_push_check_state(RESET)
   set(CMAKE_REQUIRED_QUIET TRUE)
@@ -41,10 +48,10 @@ cmake_push_check_state(RESET)
 
       return strlen(s->c+1) == 2;
     }
-  ]] HAVE_BROKEN_OPTIMIZE_STRLEN)
+  ]] PHP_HAVE_BROKEN_OPTIMIZE_STRLEN)
 cmake_pop_check_state()
 
-if(HAVE_BROKEN_OPTIMIZE_STRLEN)
+if(PHP_HAVE_BROKEN_OPTIMIZE_STRLEN)
   message(CHECK_PASS "yes")
 else()
   message(CHECK_FAIL "no")

cmake/cmake/modules/Zend/CheckDlsym.cmake

@@ -20,7 +20,7 @@ message(
   "Checking whether dlsym() requires a leading underscore in symbol names"
 )
 
-if(NOT CMAKE_CROSSCOMPILING)
+if(CMAKE_CROSSCOMPILING_EMULATOR OR NOT CMAKE_CROSSCOMPILING)
   check_include_file(dlfcn.h HAVE_DLFCN_H)
 
   block()
@@ -78,7 +78,8 @@ if(NOT CMAKE_CROSSCOMPILING)
 
         int fnord(void) { return 42; }
 
-        int main(void) {
+        int main(void)
+        {
           void *self = dlopen(0, LT_DLGLOBAL|LT_DLLAZY_OR_NOW);
           int status = 0;
 

cmake/cmake/toolchains/template.cmake

@@ -2,8 +2,9 @@
 # cross-compiling to help identify the target system when cross-compiling
 # emulator is not available.
 
-# Set the exit code for the GNU C compiler with broken strlen check.
-set(HAVE_BROKEN_OPTIMIZE_STRLEN_EXITCODE 1)
+# Set the exit code for check of GNU C compiler with broken strlen optimization
+# (relevant only for GCC version 8.2).
+set(PHP_HAVE_BROKEN_OPTIMIZE_STRLEN_EXITCODE 1)
 
 # Set the exit code for the clock_get_time() check.
 set(HAVE_CLOCK_GET_TIME_EXITCODE 0)