Eliminate codespan dependency

[BinderDavid]

During parsing we annotate every syntax node with a Span which consists of two byte-indizes which measure the distance to the beginning of the document in bytes. We later need to convert these Spans to a new format which takes line-endings into account and uses positions with line and column numbers; this format is used by the miette error reporting library and by the LSP protocol.

So far we used the codespan library to perform these transformations, but due to the fact that we needed to change internal representations we used our own fork at www.github.com/polarity-lang/codespan. This is problematic because we cannot publish polarity on www.crates.io if we have dependencies which are not themselves on crates.io. This PR therefore inlines the few parts of the codespan library that we actually need in the codebase: the conversions of different position/span/range representations.

This repository is currently dual-licensed using both the Apache-2.0 and the MIT license, whereas the codespan library is mono-licensed as Apache-2.0. We will therefore ask the contributors of the codespan library if they agree to also grant us a MIT license for their respective contributions.

[codecov]

Codecov Report

Attention: Patch coverage is 21.23894% with 89 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
lang/driver/src/codespan.rs	17.02%	39 Missing ⚠️
lang/miette_util/src/codespan.rs	30.00%	21 Missing ⚠️
lang/driver/src/spans.rs	0.00%	12 Missing ⚠️
lang/driver/src/info/collect.rs	0.00%	5 Missing ⚠️
lang/lsp/src/codeactions.rs	0.00%	5 Missing ⚠️
lang/lsp/src/diagnostics.rs	0.00%	2 Missing ⚠️
lang/lsp/src/gotodefinition.rs	0.00%	2 Missing ⚠️
lang/lsp/src/hover.rs	0.00%	2 Missing ⚠️
lang/miette_util/src/lib.rs	66.66%	1 Missing ⚠️

Files with missing lines	Coverage Δ
lang/ast/src/decls.rs	94.46% <ø> (ø)
lang/ast/src/exp/anno.rs	92.30% <ø> (ø)
lang/ast/src/exp/args.rs	90.85% <ø> (ø)
lang/ast/src/exp/call.rs	100.00% <ø> (ø)
lang/ast/src/exp/case.rs	100.00% <ø> (ø)
lang/ast/src/exp/dot_call.rs	100.00% <ø> (ø)
lang/ast/src/exp/hole.rs	77.08% <ø> (ø)
lang/ast/src/exp/local_comatch.rs	92.40% <ø> (ø)
lang/ast/src/exp/local_match.rs	75.32% <ø> (ø)
lang/ast/src/exp/mod.rs	85.53% <ø> (ø)
... and 36 more

[BinderDavid]

We probably can remove this:

polarity/contrib/nix/package.nix

Line 10 in e679bff

"codespan-0.11.1" = "sha256-Wq99v77bqSGIOK/iyv+x/EG1563XSeaTDW5K2X3kSXU=";

[BinderDavid]

Hello @Johann150 @Marwes @brendanzab @jyn514 @etaoins

In the description #425 (comment) above we describe why we would like to inline some code from the codespan library into this repository. Since we would like the entire codebase to be licensed under the same conditions we would need your agreement to grant us the rights to use your code additionally under the MIT license. If all of you agree, then I will add a comment on top of the file lang/driver/src/codespan.rs and lang/miette_util/src/codespan.rs which identifies you as the authors of those files and merge this PR.

If you agree to this, then please respond with a short comment "I do agree to license my contributions contained in this PR under the MIT license to the polarity project".

Many thanks in advance :D

(We used the git history to identify you as contributers which changed the code contained within this PR)

[Marwes]

I do agree to license my contributions contained in this PR under the MIT license to the polarity project

[jyn514]

I do agree to license my contributions contained in this PR under the MIT license to the polarity project

[etaoins]

I do agree to license my contributions contained in this PR under the MIT license to the polarity project

[brendanzab]

I do agree to license my contributions contained in this PR under the MIT license to the polarity project

[Johann150]

I agree to relicense my contributions too. There's not much difference between the licenses in practice anyway and I'm surprised it isn't dual-licensed in the first place.

[brendanzab]

More my fault than anything 😔