feat(solc): flatten

[rkrasiuk]

Motivation

Implementation of flatten feature discussed in foundry #312

Solution

Use the dependency graph to recursively resolve the file imports into a single string.

PR Checklist

• Added Tests
• Added Documentation
• Updated the changelog

[mattsse]

while this approach looks like it could work, I have some suggestions how to improve this a bit.

we're already parsing the solidity file and detecting import statements:

ethers-rs/ethers-solc/src/resolver.rs

Lines 429 to 434 in 1742630

	SourceUnitPart::ImportDirective(_, import) => {
	let import = match import {
	Import::Plain(s) => s,
	Import::GlobalSymbol(s, _) => s,
	Import::Rename(s, _) => s,
	};

all these import variants include a Loc value which has the start and end of the whole statement.
So ideally we want to use this data so we can later simply replace that slice [start..end] with the content of the file that's imported here.

however since solang only targets >0.7.0, it can happen that need to use the regex fall back, so ideally the utils::find_import_paths will also return them, which should be possible since the regex::Match type has start and end https://docs.rs/regex/latest/regex/struct.Match.html

If we roll a struct Import {path, start, end} for the SolData type we should be able to flatten the entire graph.

This depth-first operation where you start with the targeted file and then recursively loop through all imports and their imports... and replace every import statement with content. That's probably a bit tricky since we need to keep track of updated locations because after we replaced [start..end] with the first import the start and end locations of the next import are no longer valid

[mattsse]

great progress!
some suggestions and comments

[mattsse]

we can definitely do to_string_lossy here?

[mattsse]

few nits,

overall this is looking good,
I'd like to see couple more tests, for the dapp/hardhat examples
and perhaps you could try manually try this with some real repos and see if that works

[mattsse]

lgtm!

[gakonst]

test failure is unrelated, merging and we can iterate as we close the feedback loop with usage in foundry.

is there any follow up that needs to be done which we know we need? probably need to get the solidity compiler version saved in the artifacts (#755)