[SR-15847] Circular required convenience init pattern not caught by compiler

[swift-ci]

Previous ID	SR-15847
Radar	rdar://problem/89076581
Original Reporter	Kaspra (JIRA User)
Type	Bug

Environment

All OS, platforms and hardware on Swift 5.5.2

Additional Detail from JIRA

Votes	1
Component/s	Compiler
Labels	Bug, 5.1Regression, SILDiagnostics
Assignee	None
Priority	Medium

md5: 9f39cfcea60e60ce15f9f5b749a489f0

Issue Description:

class Foo {

required convenience init(x: Int) {

self.init(x: x)

}

}

This circular init pattern is not caught by the compiler, but dropping the required or convenience individually gives a warning or error as expected.

[itaiferber]

I don't know how related these issues are, but some additional info:

• I do see the expected warning when compiling with swift from the command line:

  $ swift Test.swift
  Test.swift:3:14: warning: function call causes an infinite recursion
          self.init(x: x)
               ^
  $

  This happens with or without optimization enabled

• I don't see a warning when compiling with swiftc directly, regardless of optimizations:

  $ swiftc Test.swift
  $

• I don't see a warning for the above code in Xcode when building a Debug build, but do when building a Release build

Also for reference, Swift forums thread: https://forums.swift.org/t/circular-init-pattern-not-caught-by-compiler/55249

[theblixguy]

This is a regression from Swift 5.1 onwards, on Swift 5.0 we correctly diagnose the infinite recursion. cc @eeckstein

[eeckstein]

@swift-ci create