A Nimble package to stop functions from allowing Exceptions to bubble up.

forceCheck takes the place of the existing raises pragma. The macro copies your function, adds a blank raises pragma, replaces every raises in the copy with a discard, and then has that compiled with your actual function. If Nim has an error, your function had a potential bubble up. Your actual function does have a raises pragma added as well, and the copy is removed from the binary as dead code by Nim.

forceCheck can be used with asynchronous functions, as long as the pragmas are in the following order: {.forceCheck: [], async.}. Every async function can raise Exception, making a raises worthless. That said, when forceCheck copies your function, it removes async from the copy and replaces every await with waitFor, allowing proper bubble-up detection. Since there's no value in adding raises to your actual function, it isn't done. To correct for the lack of raises, a second function copy is made, which is synchronous but does still have all its raises, and that copy has the raises pragma.

As some exceptions shouldn't be handled, irrecoverable exceptions, it's possible to specify those:

{.forceCheck: [
    recoverable: [
        KeyError,
        ValueError
    ],
    irrecoverable: [
        OSError
    ]
].}

The irrecoverable exception must be specified in every function it bubbles up through, as well as the function that raises it.

This library also includes two other pragmas. boundsCheck detects array operators and makes sure they're in a try block which also has an except IndexError block. If bounds checks are disabled by the compiler, undefined behavior will occur. In the case boundsCheck has a false positive (triggers on an array operator which may not cause an IndexError), it can be overriden with a fcBoundsCheckOverride block statement. The other pragma is fcRaise, a custom version of raise to get around nim-lang/Nim#11118 without affecting the raises pragma. It was originally going to be an independent macro, yet was merged for compatibility with the forceCheck macro. It's a drop in replacement for raises in raise e situations, where e is an Exception captured via as.