ASTMangler: Check isValidTypeParameter() to work around broken generalized existential mangling

Author: slavapestov

lib/AST/ASTMangler.cpp

@@ -3164,9 +3164,13 @@ void ASTMangler::appendGenericSignatureParts(
 
 /// Determine whether an associated type reference into the given set of
 /// protocols is unambiguous.
-static bool associatedTypeRefIsUnambiguous(ArrayRef<ProtocolDecl *> protocols) {
+static bool associatedTypeRefIsUnambiguous(GenericSignature sig, Type t) {
+  // FIXME: This should be an assertion.
+  if (!sig->isValidTypeParameter(t))
+    return false;
+
   unsigned numProtocols = 0;
-  for (auto proto : protocols) {
+  for (auto proto : sig->getRequiredProtocols(t)) {
     // Skip marker protocols, which cannot have associated types.
     if (proto->isMarkerProtocol())
       continue;
@@ -3186,7 +3190,7 @@ ASTMangler::dropProtocolFromAssociatedType(DependentMemberType *dmt,
   auto baseTy = dmt->getBase();
   bool unambiguous =
       (!dmt->getAssocType() ||
-       associatedTypeRefIsUnambiguous(sig->getRequiredProtocols(baseTy)));
+       associatedTypeRefIsUnambiguous(sig, baseTy));
 
   if (auto *baseDMT = baseTy->getAs<DependentMemberType>())
     baseTy = dropProtocolFromAssociatedType(baseDMT, sig);
@@ -3223,7 +3227,7 @@ void ASTMangler::appendAssociatedTypeName(DependentMemberType *dmt,
     // associated type name by protocol.
     if (!OptimizeProtocolNames || !sig ||
         !associatedTypeRefIsUnambiguous(
-            sig->getRequiredProtocols(dmt->getBase()))) {
+            sig, dmt->getBase())) {
       appendAnyGenericType(assocTy->getProtocol());
     }
     return;

test/SILGen/parameterized_existentials_variadic.swift

@@ -0,0 +1,24 @@
+// RUN: %target-swift-emit-silgen -module-name parameterized -disable-availability-checking %s -enable-experimental-feature VariadicGenerics | %FileCheck %s
+
+protocol P<A> {
+  associatedtype A
+}
+
+// The mangling for generalized existentials is buggy; we decide whether to
+// qualify the primary associated type requirement with a protocol or not
+// by looking at the first generic parameter of the outer generic context.
+
+struct S1 {
+  // CHECK-LABEL: sil hidden [ossa] @$s13parameterized2S1V1fAA1P_pSi1AAaEPRts_XPyF : $@convention(method) (S1) -> @out any P<Int> {
+  func f() -> any P<Int> {}
+}
+
+struct S2<T> {
+  // CHECK-LABEL: sil hidden [ossa] @$s13parameterized2S2V1fAA1P_pSi1ARts_XPyF : $@convention(method) <T> (S2<T>) -> @out any P<Int> {
+  func f() -> any P<Int> {}
+}
+
+struct S3<each T> {
+  // CHECK-LABEL: sil hidden [ossa] @$s13parameterized2S3V1fAA1P_pSi1AAaEPRts_XPyF : $@convention(method) <each T> (S3<repeat each T>) -> @out any P<Int> {
+  func f() -> any P<Int> {}
+}