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Do not require explicit casting for small comptime literals that can fit in a typed integer #747
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Why not simply consider the integer to have a type equal to the smallest type capable of representing this integer when passed through a function call?
5would assume the typeu3(oru8if it's more useful internally for the compiler) when passed into the variadic component offmt.format.The advantage of this is that this issue is fixed across the breadth of the language, rather than just the narrow case of
fmt.formatinstd.I think this can be fixed without casting number literals (soon to be renamed to
comptime_intor maybe even justint#556)I think there's a place in the compiler where we disallow an comptime int as a var args parameter, but we can remove this restriction.
Reacted by Joshua Barretto4 remaining items
This works today.
Currently we emit an error if we attempt to pass a comptime literal to be formatted.
This example requires that the 5 be explicitly cast to an integer of specified size before we can actually print.
Often, we just want any readable value we can so we could instead check whether the literal fits into the range of a specific large integer type (i.e.
u64) and cast within theprintfroutine.This proposal suggest doing automatic casting within
printfin order to simplify and make code clearer. Also note we have a similar issue for floats, however casting/narrowing there is likely a bit more nuanced in respect to preserving precision.The following would compile and work if accepted.