Add ability to dump all makefile variables for the specified target.

[tzarc]

Description

Adds a new subtarget to builds, dump_vars, which allows for printing out all the variables that make knows about, after all substitutions occur.

Example: make handwired/onekey/proton_c:default:dump_vars

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[drashna]

I'm assuming that this for more than the makefile stuff, but for system stuff too?

[tzarc]

Well it enables printing all the variables after all substitutions have been made.
In the case of qmk_compiler, it was complaining that things like the F4xx on the Noah and any parts with the flash size suffix were unknown, beacuse the supported MCUs were explicitly whitelisted in the compiler work.

This, at least, allows for invoking the command in the description to get the post-resolved value.

% make wete:default:dump_vars | grep MCU=
MCU=cortex-m0
% make matrix/noah:default:dump_vars | grep MCU=
MCU=cortex-m4

Those values are already whitelisted.
If you look at their respective rules.mk file, they've got the original MCU=.... lines as they've not yet been transformed by mcu_selection.mk.

[zvecr]

Getting some issues on some avr targets,

$ make handwired/onekey/promicro:default:dump_vars | grep ^BOOTLOADER=
BOOTLOADER=caterina
tmk_core/rules.mk:394: *** Makefile  option cannot be blank. Stop.
make: *** [Makefile:579: handwired/onekey/promicro:default:dump_vars] Error 1

[stale]

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[Erovia]

Works with AVR boards if the following options are passed:

make handwired/onekey/promicro:default:dump_vars ERROR_IF_EMPTY="" ERROR_IF_NONBOOL="" ERROR_IF_UNSET=""

[tzarc]

Fixed up for the failing AVR's. Now working when doing make all:default:dump_vars for all boards.

[noroadsleft]

__attribute__ ((weak)) ✔️

[noroadsleft]

Thanks!