CMake - Custom hardware targets must start with "mbed-" prefix

[ladislas]

Description of defect

Custom targets must have an mbed- prefix with a name in lower case. We have multiple custom targets for different versions of our hardware.

Using the mbed- prefix is strange enough as those targets are not coming to mbed and it is not written in the documentation. It took me quite sometime to understand what was wrong.

In the end we are forced to change the name of our targets from target_LEKA_V1_2_DEV to mbed-leka-v1-2-dev.

We can live with the leka-v1-2-dev but forcing users to format the name of their targets it wrong, the prefix should not be required and if we really can't do without it, documentation should explain the what and why

Target(s) affected by this defect ?

n/a

Toolchain(s) (name and version) displaying this defect ?

arm-none-eabi-gcc (GNU Arm Embedded Toolchain 10.3-2021.10) 10.3.1 20210824 (release)

What version of Mbed-os are you using (tag or sha) ?

mbed-os-6.15.1

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

mbed-tools 7.49.1

How is this defect reproduced ?

Create a custom target and omit the mbed- prefix

[0xc0170]

Using the mbed- prefix is strange enough as those targets are not coming to mbed and it is not written in the documentation. It took me quite sometime to understand what was wrong.

Is there an error or warning coming from the tools or our CMake? custom targets should have no requirement like that.

[multiplemonomials]

I think this requirement is created by this part of the code:

mbed-os/CMakeLists.txt

Line 189 in 6170f55

string(PREPEND MBED_TARGET_CONVERTED "mbed-")

Mbed wants to derive the CMake target name from the target.json target name, so it converts it to lowercase and prepends mbed- (e.g. NUCLEO_F429ZI -> mbed-nucleo-f429zi). This means that the CMake target has to start with mbed.