HPCC-22968 Fix build break with gcc versions < 7.0

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>

common/deftype/CMakeLists.txt

@@ -44,7 +44,11 @@ include_directories (
     )
 
 if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
-  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor -Wimplicit-fallthrough=3")
+  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor")
+
+  if (CMAKE_COMPILER_IS_GNUCC AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0.0")
+    SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wimplicit-fallthrough=3")
+  endif()
 endif()
 
 ADD_DEFINITIONS( -D_USRDLL -DDEFTYPE_EXPORTS )

ecl/hql/CMakeLists.txt

@@ -148,7 +148,11 @@ add_custom_command ( OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/hqllex.cpp
 )
 
 if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
-  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor -Wimplicit-fallthrough=3")
+  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor")
+
+  if (CMAKE_COMPILER_IS_GNUCC AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0.0")
+    SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wimplicit-fallthrough=3")
+  endif()
 
   #Compiler complains about a memcpy of a structure that contains a union
   if (CMAKE_COMPILER_IS_GNUCC AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "8.0.0")

ecl/hqlcpp/CMakeLists.txt

@@ -128,8 +128,12 @@ IF (NOT WIN32)
 ENDIF()
 
 if (CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_CLANG)
+  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor")
+
   #implicit-fallthrough is currently disabled because it does not seem to process noreturn attributes on a virtual function correctly (throwStringExceptionV)
-  SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-switch -Wno-unused-parameter -Werror -Wno-error=delete-non-virtual-dtor -Wimplicit-fallthrough=0")
+  if (CMAKE_COMPILER_IS_GNUCC AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0.0")
+    SET (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wimplicit-fallthrough=0")
+  endif()
 endif()
 
 ADD_DEFINITIONS( -DHQLCPP_EXPORTS -D_USRDLL )