Existentials don't always conform to a protocol via an abstract confo…

include/swift/AST/GenericSignatureBuilder.h

@@ -519,11 +519,7 @@ class GenericSignatureBuilder {
 
     ProtocolConformanceRef operator()(CanType dependentType,
                                       Type conformingReplacementType,
-                                      ProtocolDecl *conformedProtocol) const {
-      return builder->lookupConformance(dependentType,
-                                        conformingReplacementType,
-                                        conformedProtocol);
-    }
+                                      ProtocolDecl *conformedProtocol) const;
   };
 
   /// Retrieve a function that can perform conformance lookup for this

include/swift/AST/Type.h

@@ -147,10 +147,7 @@ enum class SubstFlags {
   /// Map member types to their desugared witness type.
   DesugarMemberTypes = 0x02,
   /// Substitute types involving opaque type archetypes.
-  SubstituteOpaqueArchetypes = 0x04,
-  /// Force substitution of opened archetypes. Normally -- without these flag --
-  /// opened archetype conformances are not substituted.
-  ForceSubstituteOpenedExistentials = 0x08,
+  SubstituteOpaqueArchetypes = 0x04
 };
 
 /// Options for performing substitutions into a type.

lib/AST/GenericSignatureBuilder.cpp

@@ -3501,6 +3501,19 @@ GenericSignatureBuilder::getLookupConformanceFn()
   return LookUpConformanceInBuilder(this);
 }
 
+ProtocolConformanceRef
+GenericSignatureBuilder::LookUpConformanceInBuilder::operator()(
+    CanType dependentType, Type conformingReplacementType,
+    ProtocolDecl *conformedProtocol) const {
+  // Lookup conformances for opened existential.
+  if (conformingReplacementType->isOpenedExistential()) {
+    return conformedProtocol->getModuleContext()->lookupConformance(
+        conformingReplacementType, conformedProtocol);
+  }
+  return builder->lookupConformance(dependentType, conformingReplacementType,
+                                    conformedProtocol);
+}
+
 ProtocolConformanceRef
 GenericSignatureBuilder::lookupConformance(CanType dependentType,
                                            Type conformingReplacementType,

lib/AST/ProtocolConformance.cpp

@@ -120,12 +120,6 @@ ProtocolConformanceRef::subst(Type origType,
   // Otherwise, compute the substituted type.
   auto substType = origType.subst(subs, conformances, options);
 
-  // Opened existentials trivially conform and do not need to go through
-  // substitution map lookup.
-  if (substType->isOpenedExistential() &&
-      !options.contains(SubstFlags::ForceSubstituteOpenedExistentials))
-    return *this;
-
   auto *proto = getRequirement();
 
   // If the type is an existential, it must be self-conforming.

lib/AST/Type.cpp

@@ -3547,6 +3547,11 @@ operator()(CanType dependentType, Type conformingReplacementType,
 ProtocolConformanceRef LookUpConformanceInSubstitutionMap::
 operator()(CanType dependentType, Type conformingReplacementType,
            ProtocolDecl *conformedProtocol) const {
+  // Lookup conformances for opened existential.
+  if (conformingReplacementType->isOpenedExistential()) {
+    return conformedProtocol->getModuleContext()->lookupConformance(
+        conformingReplacementType, conformedProtocol);
+  }
   return Subs.lookupConformance(dependentType, conformedProtocol);
 }
 
@@ -3558,12 +3563,23 @@ operator()(CanType dependentType, Type conformingReplacementType,
           || conformingReplacementType->is<DependentMemberType>()
           || conformingReplacementType->is<TypeVariableType>())
          && "replacement requires looking up a concrete conformance");
+  // Lookup conformances for opened existential.
+  if (conformingReplacementType->isOpenedExistential()) {
+    return conformedProtocol->getModuleContext()->lookupConformance(
+        conformingReplacementType, conformedProtocol);
+  }
   return ProtocolConformanceRef(conformedProtocol);
 }
 
 ProtocolConformanceRef LookUpConformanceInSignature::
 operator()(CanType dependentType, Type conformingReplacementType,
            ProtocolDecl *conformedProtocol) const {
+  // Lookup conformances for opened existential.
+  if (conformingReplacementType->isOpenedExistential()) {
+    return conformedProtocol->getModuleContext()->lookupConformance(
+        conformingReplacementType, conformedProtocol);
+  }
+
   // FIXME: Should pass dependentType instead, once
   // GenericSignature::lookupConformance() does the right thing
   return Sig->lookupConformance(conformingReplacementType->getCanonicalType(),

lib/SILOptimizer/SILCombiner/SILCombinerApplyVisitors.cpp

@@ -952,8 +952,7 @@ SILInstruction *SILCombiner::createApplyWithConcreteType(
             return CEI.lookupExistentialConformance(proto);
           }
           return ProtocolConformanceRef(proto);
-        },
-        SubstFlags::ForceSubstituteOpenedExistentials);
+        });
   }
 
   // We need to make sure that we can a) update Apply to use the new args and b)

test/SILOptimizer/inline_generics.sil

@@ -1,5 +1,6 @@
-// RUN: %target-sil-opt -enable-sil-verify-all %s -inline -sil-inline-generics=true | %FileCheck %s
+// RUN: %target-sil-opt -enable-sil-verify-all %s -inline -sil-inline-generics=true -sil-print-generic-specialization-info | %FileCheck %s
 // RUN: %target-sil-opt -enable-sil-verify-all %s -inline -sil-inline-generics=false | %FileCheck --check-prefix=DISABLED-GENERIC-INLINING-CHECK %s
+// RUN: %target-swift-frontend -O -emit-ir %s
 
 sil_stage canonical
 
@@ -178,3 +179,48 @@ bb0(%0 : $*T, %1 : $*T):
 sil_default_witness_table P {
   no_default
 }
+
+protocol SomeProto : class {}
+protocol OtherProto {}
+
+class MyObject {}
+extension MyObject : OtherProto {}
+
+class MyNumber : MyObject {}
+extension MyNumber : SomeProto {}
+
+sil_vtable MyObject {}
+sil_vtable MyNumber {}
+
+// Make sure we subsitute the correct conformance when inlining. When
+// substituting we need to pick up the normal_conformance.
+
+// CHECK-LABEL: sil @test_inlining : $@convention(objc_method) (@owned MyNumber) -> () {
+// CHECK-NOT: Generic specialization information for call-site dootherstuff <MyNumber & SomeProto> conformances <(abstract_conformance protocol=OtherProto)>
+// CHECK: Generic specialization information
+// CHECK: (normal_conformance type=MyObject protocol=OtherProto)
+// CHECK: end sil function 'test_inlining'
+
+sil @test_inlining : $@convention(objc_method) (@owned MyNumber) -> () {
+bb0(%0 : $MyNumber):
+  %12 = init_existential_ref %0 : $MyNumber : $MyNumber, $MyNumber & SomeProto
+  %14 = open_existential_ref %12 : $MyNumber & SomeProto to $@opened("B9711AE4-946E-11EA-A871-ACDE48001122") MyNumber & SomeProto
+  %15 = alloc_stack $OtherProto
+  %16 = init_existential_addr %15 : $*OtherProto, $@opened("B9711AE4-946E-11EA-A871-ACDE48001122") MyNumber & SomeProto
+  store %14 to %16 : $*@opened("B9711AE4-946E-11EA-A871-ACDE48001122") MyNumber & SomeProto
+  %18 = function_ref @doStuff : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> ()
+  %20 = apply %18<@opened("B9711AE4-946E-11EA-A871-ACDE48001122") MyNumber & SomeProto>(%16) : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> ()
+  destroy_addr %15 : $*OtherProto
+  dealloc_stack %15 : $*OtherProto
+  %27 = tuple ()
+  return %27 : $()
+}
+
+sil @dootherstuff : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> ()
+
+sil shared [signature_optimized_thunk] [always_inline] @doStuff : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> () {
+bb0(%0 : $*τ_0_0):
+  %2 = function_ref @dootherstuff : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> ()
+  %3 = apply %2<τ_0_0>(%0) : $@convention(thin) <τ_0_0 where τ_0_0 : OtherProto> (@in_guaranteed τ_0_0) -> ()
+  return %3 : $()
+}