Merge pull request #38656 from hamishknight/up-for-interpolation

[test] Add test for inout arg in strange interpolation

Author: hamishknight

test/Sema/diag_invalid_interpolation_4_2.swift

@@ -0,0 +1,15 @@
+// RUN: %target-typecheck-verify-swift -swift-version 4.2
+
+var x = 0
+_ = "\(&x)"
+// expected-error@-1 {{'&' used with non-inout argument of type 'Int'}}
+
+_ = "\(y: &x)"
+// expected-error@-1 {{'&' used with non-inout argument of type 'Int'}}
+// expected-warning@-2 {{labeled interpolations will not be ignored in Swift 5}}
+// expected-note@-3 {{remove 'y' label to keep current behavior}}
+
+_ = "\(x, y: &x)"
+// expected-error@-1 {{use of extraneous '&'}}
+// expected-warning@-2 {{interpolating multiple values will not form a tuple in Swift 5}}
+// expected-note@-3 {{insert parentheses to keep current behavior}}