Bug#42733: Type-punning warnings when compiling MySQL -- strict aliasing violations.

Due to the extent of aliasing violations in the MySQL source
code, at this time it is safer to disable strict aliasing related
optimizations in release builds.

As of this patch, only GCC enables strict aliasing by default.
Hence, use the -fno-strict-aliasing option to disable the
aliasing rules.

cmake/build_configurations/mysql_release.cmake

@@ -131,16 +131,16 @@ IF(UNIX)
 
   # Default GCC flags
   IF(CMAKE_COMPILER_IS_GNUCC)
-    SET(COMMON_C_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer")
+    SET(COMMON_C_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing")
     SET(CMAKE_C_FLAGS_DEBUG          "-O ${COMMON_C_FLAGS}")
     SET(CMAKE_C_FLAGS_RELWITHDEBINFO "-O3 ${COMMON_C_FLAGS}")
   ENDIF()
   IF(CMAKE_COMPILER_IS_GNUCXX)
-    SET(COMMON_CXX_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer")
+    SET(COMMON_CXX_FLAGS               "-g -static-libgcc -fno-omit-frame-pointer -fno-strict-aliasing")
     SET(CMAKE_CXX_FLAGS_DEBUG          "-O ${COMMON_CXX_FLAGS}")
     SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O3 ${COMMON_CXX_FLAGS}")
   ENDIF()
-  
+
   # HPUX flags
   IF(CMAKE_SYSTEM_NAME MATCHES "HP-UX")
     IF(CMAKE_C_COMPILER_ID MATCHES "HP")
@@ -156,7 +156,7 @@ IF(UNIX)
     ENDIF()
     SET(WITH_SSL no)
   ENDIF()
-  
+
   # Linux flags
   IF(CMAKE_SYSTEM_NAME MATCHES "Linux")
     IF(CMAKE_C_COMPILER_ID MATCHES "Intel")
@@ -173,18 +173,18 @@ IF(UNIX)
       SET(WITH_SSL no)
     ENDIF()
   ENDIF()
-  
+
   # OSX flags
   IF(APPLE)
-    SET(COMMON_C_FLAGS                 "-g -fno-common")
+    SET(COMMON_C_FLAGS                 "-g -fno-common -fno-strict-aliasing")
     # XXX: why are we using -felide-constructors on OSX?
-    SET(COMMON_CXX_FLAGS               "-g -fno-common -felide-constructors")
+    SET(COMMON_CXX_FLAGS               "-g -fno-common -felide-constructors -fno-strict-aliasing")
     SET(CMAKE_C_FLAGS_DEBUG            "-O ${COMMON_C_FLAGS}")
     SET(CMAKE_CXX_FLAGS_DEBUG          "-O ${COMMON_CXX_FLAGS}")
     SET(CMAKE_C_FLAGS_RELWITHDEBINFO   "-Os ${COMMON_C_FLAGS}")
     SET(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-Os ${COMMON_CXX_FLAGS}")
   ENDIF()
-  
+
   # Solaris flags
   IF(CMAKE_SYSTEM_NAME MATCHES "SunOS")
     IF(CMAKE_SYSTEM_VERSION VERSION_GREATER "5.9")
@@ -219,7 +219,7 @@ IF(UNIX)
       ENDIF()
     ENDIF()
   ENDIF()
-  
+
   IF(CMAKE_C_FLAGS_DEBUG)
     SET(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG}"
       CACHE STRING "Debug C compile flags")