Add support for defmt 0.3

[newAM]

Update defmt (and other knurling-rs tools) to 0.3, see https://ferrous-systems.com/blog/defmt-3/

[talhaHavadar]

Looks ok to me, but there is a failure in build.

[korken89]

This is how I'm solving it in heapless to support both 0.2 and 0.3: rust-embedded/heapless#251
Might be of interest.

[newAM]

This is how I'm solving it in heapless to support both 0.2 and 0.3: japaric/heapless#251 Might be of interest.

That's a good idea, I updated it to use a range.

Looks ok to me, but there is a failure in build.

I cannot reproduce the same failure on Linux, and unfortunately I don't have a Windows install easily accessible right now.

Are you able to help me out with this?

[jonas-schievink]

please ping me once CI is fixed

[newAM]

Somebody on matrix pointed out the Windows build is not building for an embedded target, which is not supported by defmt: knurling-rs/defmt#463

I fixed the failure by removing that build for Windows 😅.

@jonas-schievink CI is fixed.

[jonas-schievink]

hmm, why did it work with 0.2?

[newAM]

hmm, why did it work with 0.2?

I did a quick scan through the code.

defmt 0.3 introduced some new global symbols for flushing:

https://github.com/knurling-rs/defmt/blob/124a6f6f3abe4e77e885d6fab001872a2da08ee8/defmt/src/lib.rs#L377-L382

These symbols get defined by the global logger:

https://github.com/knurling-rs/defmt/blob/8a6e8eebe40f943d9b0ba8725cd6da033b9c399e/macros/src/lib.rs#L24-L28

https://github.com/knurling-rs/defmt/blob/e240ba99bc0c2258bc8ba2d7e4694e568f19c758/macros/src/attributes/global_logger.rs#L41-L45

I am guessing there is something about Windows that doesn't like GNU linker script or the export_name attributes that were introduced for these new symbols.

[jonas-schievink]

bors r+

[bors]

Build succeeded:

• ci

[newAM]

Thanks for the review & merge!

Would it be possible to get a 0.6.1 release with this change?

[jonas-schievink]

Published 0.6.1

Regarding the linker error, I don't think that's a problem with defmt 0.3.0 specifically, since #49 also fails to link again defmt 0.2.3 (https://github.com/stm32-rs/bxcan/runs/4213689874?check_suite_focus=true)