[SR-15014] Large Decimals do not print correctly in the Swift REPL

[saagarjha]

Previous ID	SR-15014
Radar	rdar://problem/81467525
Original Reporter	@saagarjha
Type	Bug

Environment

Xcode Version 13.0 beta 4 (13A5201i)/macOS Monterey 12.0 Beta (21A5294g)

Additional Detail from JIRA

Votes	0
Component/s	Foundation, LLDB for Swift
Labels	Bug
Assignee	None
Priority	Medium

md5: 2c5d3fbcb8a6920685afce84c7d9a1ca

Issue Description:

Large Decimal s don't seem to print correctly in the REPL:

$ swift
Welcome to Apple Swift version 5.5 (swiftlang-1300.0.27.6 clang-1300.0.27.2).
Type :help for assistance.
  1> import Foundation
  2> Decimal.greatestFiniteMagnitude
$R0: Decimal = 3402823669209386527134573422587986984989120495220592886182567909030848074563371292545093099671415093659185923505550104482059460129780644035015876086272801474166652928.000000

  3> print(Decimal.greatestFiniteMagnitude)
3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
  4>

The extra precision is not actually present in the backing for the number so it's unclear where LLDB is getting it from.

[typesanitizer]

@swift-ci create