AST: Resolve inherited types in usesFeatureRethrowsProtocol().

Previously, `usesFeatureRethrowsProtocol()` could mistakenly return false in
lazy typechecking mode since the types in an inheritance clause might not have
been resolved yet.

Author: tshortli

lib/AST/ASTPrinter.cpp

@@ -2955,8 +2955,8 @@ static bool usesFeatureRethrowsProtocol(
 
   // Check an inheritance clause for a marker protocol.
   auto checkInherited = [&](InheritedTypes inherited) -> bool {
-    for (const auto &inheritedEntry : inherited.getEntries()) {
-      if (auto inheritedType = inheritedEntry.getType()) {
+    for (unsigned i : inherited.getIndices()) {
+      if (auto inheritedType = inherited.getResolvedType(i)) {
         if (inheritedType->isExistentialType()) {
           auto layout = inheritedType->getExistentialLayout();
           for (ProtocolDecl *proto : layout.getProtocols()) {

test/Inputs/lazy_typecheck.swift

@@ -53,6 +53,10 @@ public protocol PublicProto {
   func req() -> Int // expected-note 2 {{protocol requires function 'req()' with type '() -> Int'; add a stub for conformance}}
 }
 
+@rethrows public protocol PublicRethrowsProto {
+  func req() throws -> Int
+}
+
 protocol InternalProto {
   func goodReq() -> Int // expected-note 2 {{protocol requires function 'goodReq()' with type '() -> Int'; add a stub for conformance}}
   func badReq() -> DoesNotExist // expected-error {{cannot find type 'DoesNotExist' in scope}}
@@ -139,6 +143,12 @@ extension String: PublicProto {
 
 extension String: InternalProto {} // expected-error {{type 'String' does not conform to protocol 'InternalProto'}}
 
+extension Int: PublicRethrowsProto {
+  public func req() throws -> Int {
+    return true // expected-error {{cannot convert return expression of type 'Bool' to return type 'Int'}}
+  }
+}
+
 struct InternalStructConformingToPublicProto: PublicProto { // expected-error {{type 'InternalStructConformingToPublicProto' does not conform to protocol 'PublicProto'}}
 }
 

test/ModuleInterface/lazy-typecheck.swift

@@ -29,6 +29,11 @@
 // CHECK:       public protocol PublicProto {
 // CHECK:         func req() -> Swift.Int
 // CHECK:       }
+// CHECK:       #if compiler(>=5.3) && $RethrowsProtocol
+// CHECK:       @rethrows public protocol PublicRethrowsProto {
+// CHECK:         func req() throws -> Swift.Int
+// CHECK:       }
+// CHECK:       #endif
 // CHECK:       public struct PublicStruct {
 // CHECK:         public init(x: Swift.Int)
 // CHECK:         public func publicMethod() -> Swift.Int
@@ -52,3 +57,8 @@
 // CHECK:       extension Swift.String : lazy_typecheck.PublicProto {
 // CHECK:         public func req() -> Swift.Int
 // CHECK:       }
+// CHECK:       #if compiler(>=5.3) && $RethrowsProtocol
+// CHECK:       extension Swift.Int : lazy_typecheck.PublicRethrowsProto {
+// CHECK:         public func req() throws -> Swift.Int
+// CHECK:       }
+// CHECK:       #endif

test/TBD/lazy-typecheck.swift

@@ -55,10 +55,13 @@ exports:
                        '_$s14lazy_typecheck12PublicStructV18publicStaticMethodyyFZ',
                        '_$s14lazy_typecheck12PublicStructV1xACSi_tcfC', '_$s14lazy_typecheck12PublicStructVMa',
                        '_$s14lazy_typecheck12PublicStructVMn', '_$s14lazy_typecheck12PublicStructVN',
-                       '_$s14lazy_typecheck13inlinableFuncSiyF', '_$s14lazy_typecheck24publicFuncWithDefaultArgyS2iF',
+                       '_$s14lazy_typecheck13inlinableFuncSiyF', '_$s14lazy_typecheck19PublicRethrowsProtoMp',
+                       '_$s14lazy_typecheck19PublicRethrowsProtoP3reqSiyKFTj', '_$s14lazy_typecheck19PublicRethrowsProtoP3reqSiyKFTq',
+                       '_$s14lazy_typecheck19PublicRethrowsProtoTL', '_$s14lazy_typecheck24publicFuncWithDefaultArgyS2iF',
                        '_$s14lazy_typecheck30publicFuncWithOpaqueReturnTypeQryF',
                        '_$s14lazy_typecheck30publicFuncWithOpaqueReturnTypeQryFQOMQ',
                        '_$s14lazy_typecheck32constrainedGenericPublicFunctionyyxAA0E5ProtoRzlF',
                        '_$sSS14lazy_typecheck11PublicProtoAAMc', '_$sSS14lazy_typecheck11PublicProtoAAWP',
-                       '_$sSS14lazy_typecheckE3reqSiyF' ]
+                       '_$sSS14lazy_typecheckE3reqSiyF', '_$sSi14lazy_typecheck19PublicRethrowsProtoAAMc',
+                       '_$sSi14lazy_typecheck19PublicRethrowsProtoAAWP', '_$sSi14lazy_typecheckE3reqSiyKF' ]
 ...