137 Mixing Xc++ and C++

As of Nov 2022 we either have Xc++ or C++ projects, we don't support a mixture within a single project. Given the downsides of using Xc++ related to dealing with compilation errors, it would be preferable to support both kinds of files in a single project. To allow this we shall use the extension xcpp and xh for source files written in Xc++. This is a good time to review the build system.

Currently a project file (.xcpj) uses xcpp to declare that the project is pure Xc++. We shall add a new mode using mixed to declare the project to be using the mixed mode. Eventually we can make this the default?

When an Xc++ file is translated the extension is changed (from .xcpp to .cpp and from .xh to .h).

We allow for a mixture of #include of C++ headers and @import of Xc++ headers.

Ensuring the relevant files are recompiled when the project changes

The cmake documentation says it is a bad idea to use file GLOB to automatically define the files to be compiled.

cmake_minimum_required(VERSION 3.3)
project(myproj)
add_definitions("-Wall" "-g")
include_directories(${PROJECT_SOURCE_DIR})
file(GLOB SRC_FILES ${PROJECT_SOURCE_DIR}/*.cpp)
add_executable(myproj ${SRC_FILES})

It is proposed that we take the following approach:

• Xc++ and C++ files uses different extensions so we can tell them apart
• We avoid the need for the file project/src/project.xcpj
• A file named project/src/sourcefiles.txt defines the set of source files in the project. This uses logical paths. This file is checked into the repository and is used to perform a build.
• There is a script which can be run manually to update project/src/sourcefiles.txt by looking at the files on the file system. The files are ordered lexicographically. This script can be run at the root level.
• Xcpp uses project/src/sourcefiles.txt to work out what files exist

Alternatively: We try to keep the xcpj format, but instead allow a script to be used to update it automatically.