[SR-10431] Failure to compile `let n = 1️⃣0️⃣` - "invalid Swift parseable output message (malformed JSON)"

[belkadan]

Previous ID	SR-10431
Radar	rdar://problem/49345107
Original Reporter	@belkadan
Type	Bug

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, Driver
Assignee	None
Priority	Medium

md5: 18face5829cef04080b9bb5d906bc661

Issue Description:

Compiling the following code with swiftc -parseable-output leads to ANSI escape sequences getting into the parseable output. This shouldn't be the case, and someone needs to track down why!

let n = 1️⃣0️⃣
Swift.print(n)

[belkadan]

Not quite a StarterBug because we don't know what the problem is, but even just having someone trace through why this is different from, say let n = blah would be very useful!