The Requirement Machine explicitly rejects the generic signature in protocol-conformance-rdar39805133.swift

Author: slavapestov

test/multifile/protocol-conformance-rdar39805133.swift

@@ -1,5 +1,5 @@
-// RUN: %target-swift-frontend -emit-ir -o - -primary-file %s %S/Inputs/protocol-conformance-rdar39805133-other.swift -module-name foo
-// RUN: %target-swift-frontend -emit-ir -o - %s -primary-file %S/Inputs/protocol-conformance-rdar39805133-other.swift -module-name foo
+// RUN: %target-swift-frontend -verify -emit-ir -o - -primary-file %s %S/Inputs/protocol-conformance-rdar39805133-other.swift -module-name foo -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
+// RUN: %target-swift-frontend -emit-ir -o - %s -primary-file %S/Inputs/protocol-conformance-rdar39805133-other.swift -module-name foo -requirement-machine-protocol-signatures=on -requirement-machine-inferred-signatures=on
 
 protocol _Int : DefaultInit {
     associatedtype Minus1 : _Int
@@ -27,3 +27,5 @@ protocol AtLeast0 : _Int {}
 extension _0_ : AtLeast0 {}
 protocol AtLeast1 : AtLeast0 {}
 extension Inc : AtLeast1, AtLeast0 where T == _0_ {}
+// expected-error@-1 {{cannot build rewrite system for generic signature; rule length limit exceeded}}
+// expected-note@-2 {{failed rewrite rule is τ_0_0.[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[concrete: Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<_0_>>>>>>>>>>>] => τ_0_0.[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1].[_Int:Plus1]}}