Rust: Use extended canonical paths to resolve calls in data flow

[hvitved]

No description provided.

[paldepind]

Looks great to me. I've suggested a refactor, but you can decide whether that makes sense :)

[paldepind]

The only thing resolvesExtendedCanonicalPath needs from DataFlowCall is the corresponding Resolvable. So what about factoring out that logic in a getResolvable predicate on DataFlowCall:

  Resolvable getResolvable() {
    result = this.asMethodCallExprCfgNode().getExpr()
    or
    result = this.asCallExprCfgNode().getExpr().(PathExprCfgNode).getPath()
  }

and changing resolvesExtendedCanonicalPath so it no longer knows about DataFlowCall:

Suggested change

	private predicate resolvesExtendedCanonicalPath(
	DataFlowCall c, CrateOriginOption crate, string path
	) {
	exists(Resolvable r |
	path = r.getResolvedPath() and
	(
	r = c.asMethodCallExprCfgNode().getExpr()
	or
	r = c.asCallExprCfgNode().getExpr().(PathExprCfgNode).getPath()
	)
	|
	crate.asSome() = r.getResolvedCrateOrigin()
	or
	crate.isNone() and
	not r.hasResolvedCrateOrigin()
	private predicate resolvesExtendedCanonicalPath(Resolvable r, CrateOriginOption crate, string path) {
	path = r.getResolvedPath() and
	(
	crate.asSome() = r.getResolvedCrateOrigin()
	or
	crate.isNone() and not r.hasResolvedCrateOrigin()

And then changing the call to it:

-      resolvesExtendedCanonicalPath(call, crate, path)
+      resolvesExtendedCanonicalPath(call.getResolvable(), crate, path)

[hvitved]

This will actually be done as part of #18078.