Rust: Fix default source and sink in inline flow test

[paldepind]

Before toString was called on a PathExpr and we want to call it on the Path. This fixes a test failure in the very simple sink(source("taint")) case.

[aibaars]

I think we should define the toString of PathExpr to be result = this.getPath().toString() .

[paldepind]

That sounds good to me. I'll update the PR to do that instead :)

[hvitved]

In general, we ought to implement a lot of more sensible toStrings, but that is of course not for this PR...

[paldepind]

I've added the suggested toString on PathExpr. Note that this added two inconsistencies here because the Path nodes on the last two lines in gen_path_expr.rs doesn't have a string representation. I don't know if this is a bug in the extractor? When I explore the AST for that file I also see that the last two let statements doesn't have an initializer which seems odd?

[aibaars]

That's not an extractor error. The qualifier of a path like <TypeRef as Trait>::foo does not have a nameRef so the toString() fails. See also:

codeql/rust/ql/lib/codeql/rust/elements/internal/PathSegmentImpl.qll

Lines 23 to 26 in e081b9a

	// TODO: this does not cover everything
	if this.hasGenericArgList()
	then result = this.getNameRef().toString() + "::<...>"
	else result = this.getNameRef().toString()

[aibaars]

If it's too much hassle to address this in the current PR, then we can also accept the inconsistencies and fix them in a follow-up.

[paldepind]

Thanks, that makes sense. I've accepted the inconsistencies for now.