validation-test: Check in a variadic generics Sema crasher

Author: AnthonyLatsis

validation-test/compiler_crashers_2/issue-78156.swift

@@ -0,0 +1,6 @@
+// RUN: not --crash %target-swift-frontend -target %target-swift-5.9-abi-triple -typecheck %s
+
+// https://github.com/apple/swift/issues/78156
+
+func f<each T>(_: repeat [each T]) -> (repeat [each T], Bool) {}
+let _ = f(f(f([4])))