Make no_std compatible

[simpsoneric]

This PR is a WIP for making the crate no_std compatible.

I would like to use nom-derive in a no_std context, and have the following attempt below.

• It compiles and builds for my embedded target.
• It passes the same cargo test results as the current master

I'm not sure of the larger context for how you'd like the crate to operate. Thought I'd pass along the "request for feature".

[simpsoneric]

@chifflier, would you like me to keep this PR up to date by rebasing or merging?

[chifflier]

Hi,
Sorry I somehow missed this and broke this PR in the recent commits.
I am interested in adding support for no_std. Can you rebase and re-send? Thanks!

[dne]

I'm not @simpsoneric, but I managed to rebase this PR to make v0.10.0 build for no_std. I also added dne/nom-derive@1331a4e.

Unfortunately, nom 7 broke no_std support but there's trivial fix, rust-bakery/nom@615e6a4, that's not in a release yet. The current nom master branch works though.

[simpsoneric]

@dne, thanks for taking the time to update this. Last week I started the update, but also ran into the nom7 no_std issue, thanks for moving it forward.

Does it make more sense to let the changes to https://github.com/dne/nom/commits/7.0-no_std get merged to upstream nom before rebasing this? (Or just create a new PR based on your branch, no preferences here).

[dne]

Well, the necessary changes are already in nom's master branch; it's only a release that's missing. I posted a comment in rust-bakery/nom#1371 asking about that.

[ball-hayden]

@simpsoneric any chance of rebasing this again please, now that nom does have support for no_std - we're also looking for support (otherwise I'm happy to take ownership of this)?

[simpsoneric]

@ball-hayden, funny timing. I haven't looked at this in almost two years and some problems with syn 2.0 just came up today for me as well.

I just did a quick look through your #51.

Looks like you've got it updated, thanks! Feel free to go forward with it.

[ball-hayden]

Sorry! I thought I'd have a look to see how hard it would be and got carried away 😆