fix: Parse an if followed by a tuple as a block

[jfecher]

Description

Problem*

Resolves #1310

Summary*

Previously an if followed by a tuple expression was parsed as a function call, with the return result of the if being the function. This is ambiguous with the grammar of an if expression sequenced with a tuple. Since the later parse is more desirable (and matches what rust does in this scenario) I've resolved the parse by arbitrarily always taking the later over the former.

Since I've added a check when constructing an Expression::call this means unfortunately that any if expression surrounded by parenthesis is also affected. So (if c { f } else { g })(1, 2) is also parsed as a sequence rather than a function call.

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[kevaundray]

Does it make sense to include a regression test for this due to it being ambiguous?

[jfecher]

@kevaundray I added a regression test for it in the parser already. I think it does make sense to add one as it also helps document the behavior since it can be easy for it to go unnoticed otherwise.

Edit: Ah, I should actually assert in that test that it parsed a block and not a function call though. I'll update it.

[kevaundray]

LGTM