swiftlang/swift

[SR-11397] FixedWidthInteger.init?(_: radix:) fails for Self with short bitWidth

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#53,798 opened on Aug 30, 2019

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Description
Previous ID SR-11397
Radar None
Original Reporter CTMacUser (JIRA User)
Type Bug
Votes 0
Component/s Standard Library
Labels Bug, StarterBug
Assignee @theblixguy
Priority Medium

md5: 71036ce9352bad83dc05a0cfcdea3df7

Issue Description:

The current implementation of FixedWidthInteger.init?(_: radix: ) converts the radix to the receiver type. If that type has less than 6 bits of width, not all radix values are supported and a run error happens at the conversion.

Theoretically, any width above zero should work if we go to a bignum implementation. I'm not suggesting we do that, but that workaround indicates we shouldn't return a nil from the initializer in such cases, because that would imply a user error and not a implementation error. I guess a fatal error is more appropriate.

(BTW, my code was testing with a zero-width type, so there may be other problems.)

Contributor guide

Research direction
Examine the implementation of FixedWidthInteger.init?( :radix:). The issue is that when the type's bit width is less than 6, the radix conversion to Self fails. Consider returning a fatal error or using a wider intermediate type for the conversion.
Tech stack
swift
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Swift
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85