cbuild / cmake build process fails in some cases (compiler or context-set change)

[ReinhardKeil]

The Problem To Be Solved The build process requires a rebuild in cases when a compiler is changed (using --toolchain) or context-set is changed. The output is misleading and may lead to user confusion.

Suggest A Solution A potential solution might be to force a rebuild in this situation. We should define when a rebuild is required.

[jkrech]

About CMake Caching https://cmake.org/cmake/help/book/mastering-cmake/chapter/CMake%20Cache.html

Another purpose of the cache is to allow CMake itself to persistently store values between CMake runs. These entries may not be visible or adjustable by the user. Typically, these values are system-dependent variables that require CMake to compile and run a program to determine their value. Once these values have been determined, they are stored in the cache to avoid having to recompute them every time CMake is run. CMake generally tries to limit these variables to properties that should never change (such as the byte order of the machine you are on). If you significantly change your computer, either by changing the operating system or switching to a different compiler, you will need to delete the cache file (and probably all of your binary tree’s object files, libraries, and executables).

Today cbuild is responsible for running the clean. On the other hand probably cbuild2cmake is best placed to see whether the compiler was changed. Therefore we need a mechanism that allow cbuild2cmake to instruct cbuild which targets need to be cleaned.

[ReinhardKeil]

I don't want to judge if CMake Caching is an option. I believe you are right cbuild2cmake is the right place to judge if a Rebuild is required. This are the scenarios that I discovered so far:

1. Changing Toolchain, for example.

   cbuild hello.csolution.yml --toolchain GCC
   cbuild hello.csolution.yml --toolchain AC6

   Maybe this can be triggered when a toolchain.cmake file is changed

2. Add targets or change context-set. Basically when tmp\CMakeLists.txt changes as this contains the mapping to tmp sub-directories).

[jkrech]

Revised based on @brondani comment below: a) cbuild to clean all targets: if the top level CMakeCache.txt exists and CMAKE_CACHEFILE_DIR:INTERNAL=<abs_tmp_path>") does not match the file's location. (the solution was copied to a new location or the directory renamed or the tmpdir was changed. (in these cases the build would fail without a clean) b) csolution sets a node in the <name>.cbuild-idx.yml for each context that requires a "rebuild" because

• compiler node changed
• a different context got added
• cbuild to read the <name>.cbuild-idx.yml and clean each context that is marked with "rebuild" node

[brondani]

if the top level CMakeLists.txt exists and set(SOLUTION_ROOT "") does not match the filepath of the loaded .csolution.yml

This may not cover a situation where only the tmp directory is moved or redefined. For this reason I would recommend to read CMakeCache.txt instead and check whether its location matches the path reported in CMAKE_CACHEFILE_DIR:INTERNAL=<abs_tmp_path>.

Note: a) above was updated accordingly.

[ReinhardKeil]

Problem solved