[region-isolation] Fix verifier check.

After following up with @slavapestov and @xedin, I was right to be suspicious of
my changes here.

Instead of attempting to hard code this, I do the right thing and I map the
relevant type into the function's generic context and then do the check. This
ensures that when isAnyActorType() performs the conformance check,
ModuleDecl::lookupConformance() has a generic signature to work with.

(cherry picked from commit 4412fff)

Author: gottesmm

lib/SIL/Verifier/SILVerifier.cpp

@@ -6578,36 +6578,6 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
                               })),
             "transferring result means all results are transferring");
 
-    // We should only ever have a single sil_isolated parameter.
-    bool foundIsolatedParameter = false;
-    for (const auto &parameterInfo : FTy->getParameters()) {
-      if (parameterInfo.hasOption(SILParameterInfo::Isolated)) {
-        auto argType = parameterInfo.getArgumentType(F.getModule(),
-                                                     FTy,
-                                                     F.getTypeExpansionContext());
-        if (argType->isOptional())
-          argType = argType->lookThroughAllOptionalTypes()->getCanonicalType();
-
-        auto genericSig = FTy->getInvocationGenericSignature();
-        auto &ctx = F.getASTContext();
-        auto *actorProtocol = ctx.getProtocol(KnownProtocolKind::Actor);
-        auto *anyActorProtocol = ctx.getProtocol(KnownProtocolKind::AnyActor);
-        bool genericTypeWithActorRequirement = llvm::any_of(
-            genericSig.getRequirements(), [&](const Requirement &other) {
-              if (other.getKind() != RequirementKind::Conformance)
-                return false;
-              if (other.getFirstType()->getCanonicalType() != argType)
-                return false;
-              auto *otherProtocol = other.getProtocolDecl();
-              return otherProtocol->inheritsFrom(actorProtocol) ||
-                     otherProtocol->inheritsFrom(anyActorProtocol);
-            });
-        require(argType->isAnyActorType() || genericTypeWithActorRequirement,
-                "Only any actor types can be isolated");
-        require(!foundIsolatedParameter, "Two isolated parameters");
-        foundIsolatedParameter = true;
-      }
-    }
     require(1 >= std::count_if(FTy->getParameters().begin(), FTy->getParameters().end(),
                                [](const SILParameterInfo &parameterInfo) {
                                  return parameterInfo.hasOption(SILParameterInfo::Isolated);
@@ -7015,11 +6985,37 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
     }
   }
 
+  void verifyParentFunctionSILFunctionType(CanSILFunctionType FTy) {
+    bool foundIsolatedParameter = false;
+    for (const auto &parameterInfo : FTy->getParameters()) {
+      if (parameterInfo.hasOption(SILParameterInfo::Isolated)) {
+           auto argType = parameterInfo.getArgumentType(F.getModule(),
+                                                     FTy,
+                                                     F.getTypeExpansionContext());
+
+        if (argType->isOptional())
+          argType = argType->lookThroughAllOptionalTypes()->getCanonicalType();
+
+        auto genericSig = FTy->getInvocationGenericSignature();
+        auto &ctx = F.getASTContext();
+        auto *actorProtocol = ctx.getProtocol(KnownProtocolKind::Actor);
+        auto *anyActorProtocol = ctx.getProtocol(KnownProtocolKind::AnyActor);
+        require(argType->isAnyActorType() ||
+                    genericSig->requiresProtocol(argType, actorProtocol) ||
+                    genericSig->requiresProtocol(argType, anyActorProtocol),
+                "Only any actor types can be isolated");
+        require(!foundIsolatedParameter, "Two isolated parameters");
+        foundIsolatedParameter = true;
+      }
+    }
+  }
+
   void visitSILFunction(SILFunction *F) {
     PrettyStackTraceSILFunction stackTrace("verifying", F);
 
     CanSILFunctionType FTy = F->getLoweredFunctionType();
     verifySILFunctionType(FTy);
+    verifyParentFunctionSILFunctionType(FTy);
 
     SILModule &mod = F->getModule();
     bool embedded = mod.getASTContext().LangOpts.hasFeature(Feature::Embedded);