Only add -Wno-stringop-truncation on supported compilers

The -Wno-stringop-truncation flag is only supported by some GCC versions
and not by Clang (macOS, FreeBSD) at all.

Move the includes to the top the file to have them available when running
the check_c_compiler_flag.

Change-Id: I452bc4ee935d13f8e9095d0a31805a3bbaff0cec
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Message-Id: <20230629215611.3292788-3-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26791.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3cbba5a381f9af3f68a7f21c5fb3e82103ab7a4c..acebbb73cdc21e1178bbecda515c4f5582b2250c 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,6 +12,14 @@ project(openvpn)
 # and OpenSSL having version 1.1.1+ and generally does not offer the same
 # configurability like autoconf
 
+find_package(PkgConfig REQUIRED)
+include(CheckSymbolExists)
+include(CheckIncludeFiles)
+include(CheckCCompilerFlag)
+include(CheckTypeSize)
+include(CheckStructHasMember)
+include(CTest)
+
 option(UNSUPPORTED_BUILDS "Allow unsupported builds" OFF)
 
 if (NOT WIN32 AND NOT ${UNSUPPORTED_BUILDS})
@@ -70,7 +78,12 @@ else ()
     set(CMAKE_CXX_FLAGS_RELEASE "-O2")
     set(CMAKE_C_FLAGS_DEBUG "-g -O1")
     set(CMAKE_CXX_FLAGS_DEBUG "-g -O1")
-    add_compile_options(-Wall -Wuninitialized -Wno-stringop-truncation)
+    add_compile_options(-Wall -Wuninitialized)
+    check_c_compiler_flag(-Wno-stringop-truncation NoStringOpTruncation)
+
+    if (${NoStringOpTruncation})
+        add_compile_options(-Wno-stringop-truncation)
+    endif()
     # We are not ready for this
     #add_compile_options(-Wconversion -Wno-sign-conversion -Wsign-compare)
     if (USE_WERROR)
@@ -78,13 +91,6 @@ else ()
     endif ()
 endif ()
 
-find_package(PkgConfig REQUIRED)
-include(CheckSymbolExists)
-include(CheckIncludeFiles)
-include(CheckTypeSize)
-include(CheckStructHasMember)
-include(CTest)
-
 find_program(PYTHON NAMES python3 python)
 execute_process(
     COMMAND ${PYTHON} ${CMAKE_CURRENT_SOURCE_DIR}/contrib/cmake/parse-version.m4.py ${CMAKE_CURRENT_SOURCE_DIR}/version.m4