IRGen: Fix capture descriptor emission for @pseudogeneric functions

Pseudogeneric functions do not have runtime type metadata in
their closure context, so don't try to emit metadata sources
in the capture descriptor for reflection.

Also, erase generic type parameters in capture types down to
AnyObject, since the reflection library won't be able to
substitute them.

Author: slavapestov

lib/IRGen/GenReflection.cpp

@@ -633,7 +633,10 @@ class CaptureDescriptorBuilder : public ReflectionMetadataBuilder {
   MetadataSourceMap getMetadataSourceMap() {
     MetadataSourceMap SourceMap;
 
-    if (!OrigCalleeType->isPolymorphic())
+    // Generic parameters of pseudogeneric functions do not have
+    // runtime metadata.
+    if (!OrigCalleeType->isPolymorphic() ||
+        OrigCalleeType->isPseudogeneric())
       return SourceMap;
 
     // Any generic parameters that are not fulfilled are passed in via the
@@ -702,6 +705,19 @@ class CaptureDescriptorBuilder : public ReflectionMetadataBuilder {
 
     for (auto ElementType : getElementTypes()) {
       auto SwiftType = ElementType.getSwiftRValueType();
+
+      // Erase pseudogeneric captures down to AnyObject.
+      if (OrigCalleeType->isPseudogeneric()) {
+        SwiftType = SwiftType.transform([&](Type t) -> Type {
+          if (auto *archetype = t->getAs<ArchetypeType>()) {
+            assert(archetype->requiresClass() && "don't know what to do");
+            return IGM.Context.getProtocol(KnownProtocolKind::AnyObject)
+                ->getDeclaredType();
+          }
+          return t;
+        })->getCanonicalType();
+      }
+
       auto InterfaceType = Caller.mapTypeOutOfContext(SwiftType);
       CaptureTypes.push_back(InterfaceType->getCanonicalType());
     }

test/Reflection/capture_descriptors.sil

@@ -192,6 +192,28 @@ sil_vtable GenericClass {}
 // CHECK-NEXT:   (reference_capture index=0))
 
 
+// Pseudogeneric caller and pseudogeneric callee -- type parameters are
+// erased at runtime.
+
+sil @pseudogeneric_callee : $@convention(thin) @pseudogeneric <T : AnyObject, U : AnyObject> (@owned T, @owned U) -> () {
+bb0(%t: $T, %u: $U):
+  %12 = tuple ()
+  return %12 : $()
+}
+
+sil @pseudogeneric_caller : $@convention(thin) @pseudogeneric <A : AnyObject, B : AnyObject, C : AnyObject> (@owned A, @owned B) -> @owned @pseudogeneric @callee_owned () -> () {
+bb0(%a: $A, %b: $B):
+  %f = function_ref @pseudogeneric_callee : $@convention(thin) @pseudogeneric <T : AnyObject, U : AnyObject> (@owned T, @owned U) -> ()
+  %c = partial_apply %f<A, B>(%a, %b) : $@convention(thin) @pseudogeneric <A : AnyObject, B : AnyObject> (@owned A, @owned B) -> ()
+  return %c : $@pseudogeneric @callee_owned () -> ()
+}
+
+// CHECK:      - Capture types:
+// CHECK-NEXT:   (protocol Swift.AnyObject)
+// CHECK-NEXT:   (protocol Swift.AnyObject)
+// CHECK-NEXT: - Metadata sources:
+
+
 // Capturing lowered function types
 
 sil @function_callee : $@convention(thin) (@convention(thin) () -> (), @convention(c) () -> (), @convention(block) () -> (), @convention(thick) () -> (), @convention(method) () -> (), @convention(witness_method) () -> ()) -> () {