The main change is to detect infinite recursive calls under invariant conditions. For example:
func f() {
if #available(macOS 10.4.4, *) {
f()
}
}
or invariant conditions due to forwarded arguments:
func f(_ x: Int) {
if x > 0 {
f(x)
}
}
Also, improve the warning message. Instead of giving a warning at the function location
warning: all paths through this function will call itself
give a warning at the call location:
warning: function call causes an infinite recursion
Especially in case of multiple recursive calls, it makes it easier to locate the problem.
https://bugs.swift.org/browse/SR-11842
rdar://57460599
Add a new warning that detects when a function will call itself
recursively on all code paths. Attempts to invoke functions like this
may cause unbounded stack growth at least or undefined behavior in the
worst cases.
The detection code is implemented as DFS for a reachable exit path in
a given SILFunction.
