Merge pull request #8107 from slavapestov/multi-file-protocol-assert-fail

Sema: Fix assertion when performing conformance check of protocol in another file

Author: slavapestov

lib/Sema/TypeCheckDecl.cpp

@@ -7165,7 +7165,8 @@ void TypeChecker::validateDecl(ValueDecl *D) {
 
     validateAttributes(*this, D);
 
-    proto->computeRequirementSignature();
+    if (!proto->isRequirementSignatureComputed())
+      proto->computeRequirementSignature();
 
     // If the protocol is @objc, it may only refine other @objc protocols.
     // FIXME: Revisit this restriction.

test/multifile/Inputs/requirement-signature.swift

@@ -0,0 +1,7 @@
+protocol ObservableType {
+  func subscribe<O>(_: O)
+}
+
+protocol ConnectableObservableType : ObservableType {
+  func connect()
+}

test/multifile/requirement-signature.swift

@@ -0,0 +1,5 @@
+// RUN: %target-swift-frontend -typecheck -primary-file %s %S/Inputs/requirement-signature.swift
+
+func run<CO: ConnectableObservableType, O>(co: CO, o: O) {
+  co.subscribe(o)
+}