javascript: update C++ standard to C++17 for compatibility with newer Node.js versions

When compiling mraa on Debian 13, the following error occurs:

```
/usr/include/node/node.h:696:8: error: ‘optional’ in namespace ‘std’ does not name a template type
  696 |   std::optional<std::string> builder_script_path;
      |        ^~~~~~~~
/usr/include/node/node.h:696:3: note: ‘std::optional’ is only available from C++17 onwards
  696 |   std::optional<std::string> builder_script_path;
      |   ^~~
```

Root cause: Node.js version on Debian 13 is 20+, which requires C++17 feature support.

Signed-off-by: Chun Jiao Zhao <[email protected]>

Author: ChunJiaoZhao

CMakeLists.txt

@@ -90,6 +90,17 @@ if (BUILDCPP)
       message(FATAL_ERROR "Target '${targetname}' requires c++11 which is not supported by this compiler")
     endif()
   endfunction()
+
+  # This function adds the c++17 flag to a c++ target (if supported)
+  function(use_cxx_17 targetname)
+    include(CheckCXXCompilerFlag)
+    CHECK_CXX_COMPILER_FLAG("-std=c++17" COMPILER_SUPPORTS_CXX17)
+    if (COMPILER_SUPPORTS_CXX17)
+      set_target_properties(${targetname} PROPERTIES COMPILE_FLAGS "-std=c++17")
+    else()
+      message(FATAL_ERROR "Target '${targetname}' requires c++17 which is not supported by this compiler")
+    endif()
+  endfunction()
 endif()
 
 # Set CMAKE_INSTALL_LIBDIR if not defined

src/javascript/CMakeLists.txt

@@ -44,23 +44,35 @@ if (BUILDCPP)
     # Node 0.12.x V8 engine major version is '3'.
     # Node 2.1.0  V8 engine major version is '4'.
     # Node 16.0.0  V8 engine major version is '9'.
+    # Node 18.0.0+ requires C++17 for std::string_view, std::optional, etc.
     if (${V8_VERSION_MAJOR} GREATER 8)
-      set_property (TARGET mraajs PROPERTY CXX_STANDARD 14)
+      set_property (TARGET mraajs PROPERTY CXX_STANDARD 17)
     else ()
       set_property (TARGET mraajs PROPERTY CXX_STANDARD 11)
     endif ()
     set_property (TARGET mraajs PROPERTY CXX_STANDARD_REQUIRED ON)
     if (CMAKE_VERSION VERSION_LESS "3.1")
       message (WARNING "Need to use CMAKE version 3.1+, but it is ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION}, using a workaround.")
       if (CMAKE_COMPILER_IS_GNUCXX)
-        if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS "4.7")
-          message (FATAL_ERROR "GNU gcc compiler is also too old (need 4.7+, but ${CMAKE_CXX_COMPILER_VERSION}) and does not support C++11 standard.")
+        if (${V8_VERSION_MAJOR} GREATER 8)
+          if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7.0")
+            message (FATAL_ERROR "GNU gcc compiler is too old (need 7.0+, but ${CMAKE_CXX_COMPILER_VERSION}) and does not support C++17 standard.")
+          endif ()
+          set (MRAA_CXX_WORKAROUND_OPTION "-std=gnu++17")
+        else ()
+          if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS "4.7")
+            message (FATAL_ERROR "GNU gcc compiler is too old (need 4.7+, but ${CMAKE_CXX_COMPILER_VERSION}) and does not support C++11 standard.")
+          endif ()
+          set (MRAA_CXX_WORKAROUND_OPTION "-std=gnu++11")
         endif ()
-        set (MRAA_CXX11_WORKAROUND_OPTION "-std=gnu++11")
       else ()
-        set (MRAA_CXX11_WORKAROUND_OPTION "-std=c++11")
+        if (${V8_VERSION_MAJOR} GREATER 8)
+          set (MRAA_CXX_WORKAROUND_OPTION "-std=c++17")
+        else ()
+          set (MRAA_CXX_WORKAROUND_OPTION "-std=c++11")
+        endif ()
       endif ()
-      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${MRAA_CXX11_WORKAROUND_OPTION} ")
+      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${MRAA_CXX_WORKAROUND_OPTION} ")
     endif ()
   endif ()
 endif ()