Eliminate the notion of a "bound signature" for opaque type archetypes.

The refactoring that moved the substitution of the outer environment
into an opaque type archeptype into the generic environment eliminated
the need for the bound signature entirely, so remove it.

Author: DougGregor

include/swift/AST/GenericEnvironment.h

@@ -107,12 +107,10 @@ class alignas(1 << DeclAlignInBits) GenericEnvironment final
   /// This is only useful when lazily populating a generic environment.
   Optional<Type> getMappingIfPresent(GenericParamKey key) const;
 
-  /// Get the "raw" generic signature, without substituting into opaque
-  /// type's signature.
-  GenericSignature getRawGenericSignature() const;
-
 public:
-  GenericSignature getGenericSignature() const;
+  GenericSignature getGenericSignature() const {
+    return SignatureAndKind.getPointer();
+  }
 
   Kind getKind() const { return SignatureAndKind.getInt(); }
 

include/swift/AST/Types.h

@@ -5578,12 +5578,6 @@ class OpaqueTypeArchetypeType final : public ArchetypeType,
   /// Retrieve the set of substitutions applied to the opaque type.
   SubstitutionMap getSubstitutions() const;
 
-  /// Get the generic signature used to build out this archetype. This is
-  /// equivalent to the OpaqueTypeDecl's interface generic signature, with
-  /// all of the generic parameters aside from the opaque type's interface
-  /// type same-type-constrained to their substitutions for this type.
-  GenericSignature getBoundSignature() const;
-  
   /// Get a generic environment that has this opaque archetype bound within it.
   GenericEnvironment *getGenericEnvironment() const;
 

lib/AST/ASTContext.cpp

@@ -4592,7 +4592,7 @@ GenericEnvironment *GenericEnvironment::forOpaqueType(
   size_t bytes = totalSizeToAlloc<OpaqueTypeDecl *, SubstitutionMap, Type>(
       1, 1, numGenericParams);
   void *mem = ctx.Allocate(bytes, alignof(GenericEnvironment), arena);
-  auto env = new (mem) GenericEnvironment(GenericSignature(), opaque, subs);
+  auto env = new (mem) GenericEnvironment(signature, opaque, subs);
   return env;
 }
 

lib/AST/ASTMangler.cpp

@@ -3314,7 +3314,8 @@ void ASTMangler::appendAnyProtocolConformance(
                                                      conformance.getAbstract());
     appendDependentProtocolConformance(path, genericSig);
   } else if (auto opaqueType = conformingType->getAs<OpaqueTypeArchetypeType>()) {
-    GenericSignature opaqueSignature = opaqueType->getBoundSignature();
+    GenericSignature opaqueSignature =
+        opaqueType->getDecl()->getOpaqueInterfaceGenericSignature();
     ConformanceAccessPath conformanceAccessPath =
         opaqueSignature->getConformanceAccessPath(
           opaqueType->getInterfaceType(),

lib/AST/GenericEnvironment.cpp

@@ -50,58 +50,6 @@ size_t GenericEnvironment::numTrailingObjects(OverloadToken<Type>) const {
   return getGenericParams().size();
 }
 
-GenericSignature GenericEnvironment::getRawGenericSignature() const {
-  switch (getKind()) {
-  case Kind::Normal:
-  case Kind::OpenedExistential:
-    return SignatureAndKind.getPointer();
-
-  case Kind::Opaque:
-    return getOpaqueTypeDecl()->getOpaqueInterfaceGenericSignature();
-  }
-}
-
-GenericSignature GenericEnvironment::getGenericSignature() const {
-  switch (getKind()) {
-  case Kind::Normal:
-  case Kind::OpenedExistential:
-    return SignatureAndKind.getPointer();
-
-  case Kind::Opaque:
-    if (auto sig = SignatureAndKind.getPointer())
-      return sig;
-
-    // Build signature below.
-    break;
-  }
-
-  // Create a new opaque archetype.
-  // It lives in an environment in which the interface generic arguments of the
-  // decl have all been same-type-bound to the arguments from our substitution
-  // map.
-  SmallVector<Requirement, 2> newRequirements;
-
-  // Same-type-constrain the arguments in the outer signature to their
-  // replacements in the substitution map.
-  auto opaqueDecl = getOpaqueTypeDecl();
-  auto subs = getOpaqueSubstitutions();
-  if (auto outerSig = opaqueDecl->getGenericSignature()) {
-    for (auto outerParam : outerSig.getGenericParams()) {
-      auto boundType = Type(outerParam).subst(subs);
-      newRequirements.push_back(
-          Requirement(RequirementKind::SameType, Type(outerParam), boundType));
-    }
-  }
-
-  auto signature = buildGenericSignature(
-        opaqueDecl->getASTContext(),
-        opaqueDecl->getOpaqueInterfaceGenericSignature(),
-        /*genericParams=*/{ },
-        std::move(newRequirements));
-  SignatureAndKind.setPointer(signature);
-  return signature;
-}
-
 /// Retrieve the array containing the context types associated with the
 /// generic parameters, stored in parallel with the generic parameters of the
 /// generic signature.
@@ -120,7 +68,7 @@ ArrayRef<Type> GenericEnvironment::getContextTypes() const {
 
 TypeArrayView<GenericTypeParamType>
 GenericEnvironment::getGenericParams() const {
-  return getRawGenericSignature().getGenericParams();
+  return getGenericSignature().getGenericParams();
 }
 
 OpaqueTypeDecl *GenericEnvironment::getOpaqueTypeDecl() const {
@@ -272,7 +220,7 @@ Type TypeBase::mapTypeOutOfContext() {
 
 Type
 GenericEnvironment::getOrCreateArchetypeFromInterfaceType(Type depType) {
-  auto genericSig = getRawGenericSignature();
+  auto genericSig = getGenericSignature();
   LookUpConformanceInSignature conformanceLookupFn(genericSig.getPointer());
 
   auto requirements = genericSig->getLocalRequirements(depType);
@@ -425,7 +373,7 @@ Type GenericEnvironment::mapTypeIntoContext(
 }
 
 Type GenericEnvironment::mapTypeIntoContext(Type type) const {
-  auto sig = getRawGenericSignature();
+  auto sig = getGenericSignature();
   return mapTypeIntoContext(type, LookUpConformanceInSignature(sig.getPointer()));
 }
 

lib/AST/Type.cpp

@@ -3320,10 +3320,6 @@ GenericEnvironment *OpaqueTypeArchetypeType::getGenericEnvironment() const {
   return Environment;
 }
 
-GenericSignature OpaqueTypeArchetypeType::getBoundSignature() const {
-  return getGenericEnvironment()->getGenericSignature();
-}
-
 OpaqueTypeDecl *OpaqueTypeArchetypeType::getDecl() const {
   return Environment->getOpaqueTypeDecl();
 }