Merge pull request swiftlang#35900 from CodaFi/semantic-members-only-club

[5.4] Install Semantic Members for Class-Bound Archetypes and Protocol Compositions

Author: CodaFi

include/swift/AST/Decl.h

@@ -3195,6 +3195,17 @@ class NominalTypeDecl : public GenericTypeDecl, public IterableDeclContext {
   /// declaration, or \c nullptr if it doesn't have one.
   ConstructorDecl *getDefaultInitializer() const;
 
+  /// Force the synthesis of all members named \c member requiring semantic
+  /// analysis and install them in the member list of this nominal type.
+  ///
+  /// \Note The use of this method in the compiler signals an architectural
+  /// problem with the caller. Use \c TypeChecker::lookup* instead of
+  /// introducing new usages.
+  ///
+  /// FIXME: This method presents a problem with respect to the consistency
+  /// and idempotency of lookups in the compiler. If we instead had a model
+  /// where lookup requests would explicitly return semantic members or parsed
+  /// members this function could disappear.
   void synthesizeSemanticMembersIfNeeded(DeclName member);
 
   /// Retrieves the static 'shared' property of a global actor type, which

lib/Sema/TypeCheckNameLookup.cpp

@@ -273,6 +273,32 @@ LookupResult TypeChecker::lookupUnqualified(DeclContext *dc, DeclNameRef name,
   return result;
 }
 
+// An unfortunate hack to kick the decl checker into adding semantic members to
+// the current type before we attempt a semantic lookup. The places this method
+// looks needs to be in sync with \c extractDirectlyReferencedNominalTypes.
+// See the note in \c synthesizeSemanticMembersIfNeeded about a better, more
+// just, and peaceful world.
+static void installSemanticMembersIfNeeded(Type type, DeclNameRef name) {
+  // Look-through class-bound archetypes to ensure we synthesize e.g.
+  // inherited constructors.
+  if (auto archetypeTy = type->getAs<ArchetypeType>()) {
+    if (auto super = archetypeTy->getSuperclass()) {
+      type = super;
+    }
+  }
+
+  if (type->isExistentialType()) {
+    auto layout = type->getExistentialLayout();
+    if (auto super = layout.explicitSuperclass) {
+      type = super;
+    }
+  }
+
+  if (auto *current = type->getAnyNominal()) {
+    current->synthesizeSemanticMembersIfNeeded(name.getFullName());
+  }
+}
+
 LookupResult
 TypeChecker::lookupUnqualifiedType(DeclContext *dc, DeclNameRef name,
                                    SourceLoc loc,
@@ -320,9 +346,7 @@ LookupResult TypeChecker::lookupMember(DeclContext *dc,
   subOptions &= ~NL_RemoveNonVisible;
 
   // Make sure we've resolved implicit members, if we need them.
-  if (auto *current = type->getAnyNominal()) {
-    current->synthesizeSemanticMembersIfNeeded(name.getFullName());
-  }
+  installSemanticMembersIfNeeded(type, name);
 
   LookupResultBuilder builder(result, dc, options);
   SmallVector<ValueDecl *, 4> lookupResults;
@@ -392,9 +416,7 @@ LookupTypeResult TypeChecker::lookupMemberType(DeclContext *dc,
     subOptions |= NL_IncludeUsableFromInline;
 
   // Make sure we've resolved implicit members, if we need them.
-  if (auto *current = type->getAnyNominal()) {
-    current->synthesizeSemanticMembersIfNeeded(name.getFullName());
-  }
+  installSemanticMembersIfNeeded(type, name);
 
   if (!dc->lookupQualified(type, name, subOptions, decls))
     return result;

test/decl/init/Inputs/inherited-init-multifile-other.swift

@@ -0,0 +1,8 @@
+class A {
+  required init(_ x: Int) {}
+}
+
+class B : A {}
+class C : A {}
+
+protocol P {}

test/decl/init/inherited-init-multifile.swift

@@ -0,0 +1,10 @@
+// RUN: %target-swift-frontend -typecheck -verify -primary-file %s %S/Inputs/inherited-init-multifile-other.swift
+// RUN: %target-swift-frontend -typecheck -verify %s -primary-file %S/Inputs/inherited-init-multifile-other.swift
+
+func make<Result: B>(ofClass cls: Result.Type) -> Result {
+    return cls.init(1)
+}
+
+func make(ofClass cls: (C & P).Type) -> C {
+    return cls.init(1)
+}