fix(fmt): dropped statements for single-line **nested** if statements

[quangloc99]

Motivation

Originally I attempted to fix #13555 (now fix #13675 ). After it is closes with #13566, to be frank I was still a bit skeptical with the solution. After some testing, the following case fails:

// before forge fmt
if (condition) if (condition) { execute(); execute(); }


// after forge fmt
if (condition) if (condition) execute();
execute();

A more realistic case for this is while (cond) if (cond) { ... }.

More tests can be seen in the commit daf10d2

Solution

The solution presented in this PR is to change is_multiline_block_stmt to check the deeper structure of the statement. But besides the missing checks, I think the root cause is the caching of single_line_stmt: this variable is updated only at the top level of when looking at the if statement, and only the top if statement is examined carefully, while the nested if is only consider a normal statement. So imo my fix might not be enough.

I understand that caching here is necessary to make sure the work is done once. But to fix this root cause, a more reliable way should be calculating this variable for all nodes of the tree from bottom-up instead of top-down like this.

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[zerosnacks]

cc @DaniPopes / @0xrusowsky when time permits