`mbed compile -t GCC_ARM -m K64F --tests` should set the default toolchain and target

[LiyouZhou]

Description

• Type: Enhancement

---

Enhancement

Reason to enhance/problem with existing solution
If user compiled the code with explicit target and toolchain on command line:
mbed compile -t GCC_ARM -m K64F --tests
and run mbed test afterwards, the default target and toolchain would be used rather than the latest one. This behaviour would not be expected by the user.
Suggested enhancement
mbed compile -t GCC_ARM -m K64F --tests should set the default toolchain and target

[screamerbg]

This conflicts with a workflow where:

• I've already set a default toolchain/target through mbed config target/toolchain <name> which I'm using most of the time.
• I'd like to use -t <name> -m <name> temporarily, and I don't expect that this would change my defaults.

Perhaps this could be changed to set the default toolchain/target if they are not set by the user (would happen only once)

[LiyouZhou]

Validation is needed before setting the default otherwise a typo could be come the default.

[theotherjimmy]

My recommendation is to only update the setting after a successful compile when the setting is not present. This would implicitly do validation with the build tools. Further it would reduce code duplication of validation between the mbedmicro/mbed tools and mbedcli. Alternatively, you could run tools/get_config.py with -t and -m to verify that the toolchain and mcu are supported/valid/not-a-typo.

[screamerbg]

Successful execution is fine.

[screamerbg]

Patch was pushed as PR #221

[screamerbg]

Implemented in mbed CLI 0.7.17