west: Question on west flash --hex-file behavior with build.dir-fmt

[erwango]

Describe the bug
Cf related dicussion here

To Reproduce
Steps to reproduce the behavior:
0. Configure dir-fmt as follows
[build]
dir-fmt = build/{board}/

1. cd samples/tfm_integration/tfm_ipc
2. west build -b stm32l562e_dk_ns
3. west flash --hex-file build/stm32l562e_dk_ns/tfm_merged.hex
   Reported error:

FATAL ERROR: --build-dir was not given, /local/mcu/zephyrproject/zephyr/samples/tfm_integration/tfm_ipc is not a build directory and the default build directory cannot be determined. Check your build.dir-fmt configuration option

The equivalent procedure works well w/o dir-fmt configuration

Expected behavior
west flash --hex-file has same behavior whatever dir-fmt configuration.

Impact
Annoying

[mbolivar-nordic]

I don't think this is a bug. West should not guess which build directory you are using IMO.

You can try using build.guess-dir which will work in some situations if the build directory can be guessed unambiguously. But it's not clear that we can just start at the hex file location and assume it's in a build directory, I think.

[erwango]

@mbolivar-nordic My request is not to ask west to guess the location in current case (at least this is not my understanding):
Observation is that the following works:

$ west flash --hex-file build/tfm_merged.hex

But the following reports an error, while the file location is given in the same way

$ west flash --hex-file build/stm32l562e_dk_ns/tfm_merged.hex
FATAL ERROR: --build-dir was not given, /local/mcu/zephyrproject/zephyr/samples/tfm_integration/tfm_ipc is not a build directory and the default build directory cannot be determined. Check your build.dir-fmt configuration option

[mbolivar-nordic]

The first example looks like build.dir-fmt is not set, and therefore the default build directory build can be checked and used if it exists.

The second example seems to be using build.dir-fmt, so there is no single default location. It could be build/my-board or build/my-other-board. West has to guess in this case; which you can ask it to do with build.guess-dir; but that won't always work.

[erwango]

Ok, I had a try using west flash -d build/nucleo_l552ze_q_ns/ --hex-file build/nucleo_l552ze_q_ns/tfm_merged.hex .
This works indeed. Thanks for the support.

[mbolivar-nordic]

I had a try using west flash -d build/nucleo_l552ze_q_ns/ --hex-file build/nucleo_l552ze_q_ns/tfm_merged.hex .
This works indeed.

I know that's kind of pain to specify twice but I don't see a good way to avoid it.