assignment operation inside an 'if' condition should be marked with a warning

[AGiorgetti]

If we want to spot some more bugs at compile time, I believe that something like:

if (data.id = id) { ...

while being perfectly legal, it can be a coding bug most of the times.
it would be nice if TsLint could spot this type of code and give us a warning instead of using a custom regex that scan all our files.

[adidahiya]

sounds good. it could be called... no-assignment-in-conditional? cc @ashwinr for thoughts on rule name

[ashwinr]

eslint has the same rule. even just no-conditional-assignment seems good.

[jkillian]

ESLint has an option for the rule where they allow assignments that are wrapped in parenthesis. Do we want the same option or should we ust flag all assignments in a conditional no matter what?

[adidahiya]

let's just do the simple thing for now and disallow all assignments in a conditional. we can add the other option later if it's requested.