Implement SA1139: Use literal suffix notation instead of casting

New rule proposal: Use literal suffix notation instead of casting

Category: Readability Rule: When a numeric literal is immediately cast to another numeric type, it should be replaced with a literal suffix. Rationale: Improves readability of code, and (presumably) run time casts.

Bad:

long foo = (long)50;

Good:

long foo = 50L;

See https://msdn.microsoft.com/en-us/library/aa691085(v=vs.71).aspx and https://msdn.microsoft.com/en-us/library/aa664674(v=vs.71).aspx for the specification for integer/real literals.

Things that might need considering:

The literal suffix can be upper and lower case. I would prefer uppercase, (and if you read the integer literal specification above, it recommends this).

This should work on nullable types as well:

long? foo = (long?)50;

Should be fixed to

long? foo = 50L;

[tmaczynski]

I’ve decided to make some contributions to DotNetAnalyzers during next 2 or 3 months. I want to implement this analyzer and code fix first (it seems to be relatively easy). You can track my progress on a branch at forked repo; I’ll do a pull request when I’m finished.

[sharwell]

📝 Make sure to not report a warning on the following code:

var foo = (long?)50;