ASTScope: Remove old implementation of 'selfDC' computation

slavapestov · slavapestov · commit 7cb809bf1dfc · 2020-09-18T16:11:06.000-04:00
diff --git a/include/swift/AST/ASTScope.h b/include/swift/AST/ASTScope.h
@@ -474,16 +474,6 @@ class ASTScopeImpl {
               NullablePtr<const GenericParamList> lastListSearched,
               DeclConsumer consumer) const;
 
-public:
-  /// Returns the SelfDC for parent (and possibly ancestor) scopes.
-  /// A return of None indicates that the previous child (in history) should be
-  /// asked.
-  virtual Optional<NullablePtr<DeclContext>> computeSelfDCForParent() const;
-
-  /// Returns the context that should be used when a nested scope (e.g. a
-  /// closure) captures self explicitly.
-  virtual NullablePtr<DeclContext> capturedSelfDC() const;
-
 protected:
   /// Find either locals or members (no scope has both)
   /// \param history The scopes visited since the start of lookup (including
@@ -691,27 +681,6 @@ class Portion {
     bool lookupMembersOf(const GenericTypeOrExtensionScope *scope,
                          ArrayRef<const ASTScopeImpl *>,
                          ASTScopeImpl::DeclConsumer consumer) const override;
-
-  private:
-    /// A client needs to know if a lookup result required the dynamic implicit
-    /// self value. It is required if the lookup originates from a method body
-    /// or a lazy pattern initializer. So, one approach would be to call the
-    /// consumer to find members right from those scopes. However, because
-    /// members aren't the first things searched, generics are, that approache
-    /// ends up duplicating code from the \c GenericTypeOrExtensionScope. So we
-    /// take the approach of doing those lookups there, and using this function
-    /// to compute the selfDC from the history.
-    static NullablePtr<DeclContext>
-    computeSelfDC(ArrayRef<const ASTScopeImpl *> history);
-    
-    /// If we find a lookup result that requires the dynamic implict self value,
-    /// we need to check the nested scopes to see if any closures explicitly
-    /// captured \c self. In that case, the appropriate selfDC is that of the
-    /// innermost closure which captures a \c self value from one of this type's
-    /// methods.
-    static NullablePtr<DeclContext>
-    checkNestedScopesForSelfCapture(ArrayRef<const ASTScopeImpl *> history,
-                                    size_t start);
 };
 
 /// Behavior specific to representing the trailing where clause of a
@@ -810,7 +779,6 @@ class GenericTypeOrExtensionScope : public ASTScopeImpl {
   virtual std::string declKindName() const = 0;
   virtual bool doesDeclHaveABody() const;
   const char *portionName() const { return portion->portionName; }
-  Optional<NullablePtr<DeclContext>> computeSelfDCForParent() const override;
 
 protected:
   Optional<bool> resolveIsCascadingUseForThisScope(
@@ -1135,7 +1103,6 @@ class FunctionBodyScope final : public AbstractFunctionBodyScope {
   std::string getClassName() const override;
   bool lookupLocalsOrMembers(ArrayRef<const ASTScopeImpl *>,
                              DeclConsumer consumer) const override;
-  Optional<NullablePtr<DeclContext>> computeSelfDCForParent() const override;
 };
 
 class DefaultArgumentInitializerScope final : public ASTScopeImpl {
@@ -1304,8 +1271,6 @@ class PatternEntryInitializerScope final : public AbstractPatternEntryScope {
   getSourceRangeOfThisASTNode(bool omitAssertions = false) const override;
   virtual NullablePtr<DeclContext> getDeclContext() const override;
 
-  Optional<NullablePtr<DeclContext>> computeSelfDCForParent() const override;
-
 protected:
   bool lookupLocalsOrMembers(ArrayRef<const ASTScopeImpl *>,
                              DeclConsumer) const override;
@@ -1417,13 +1382,6 @@ class ClosureParametersScope final : public ASTScopeImpl {
   std::string getClassName() const override;
   SourceRange
   getSourceRangeOfThisASTNode(bool omitAssertions = false) const override;
-  
-  /// Since explicit captures of \c self by closures enable the use of implicit
-  /// \c self, we need to make sure that the appropriate \c self is used as the
-  /// base decl for these uses (otherwise, the capture would be marked as
-  /// unused. \c ClosureParametersScope::capturedSelfDC() checks if we have such
-  ///  a capture of self.
-  NullablePtr<DeclContext> capturedSelfDC() const override;
 
   NullablePtr<ClosureExpr> getClosureIfClosureScope() const override {
     return closureExpr;
diff --git a/include/swift/AST/Expr.h b/include/swift/AST/Expr.h
@@ -3941,12 +3941,6 @@ class ClosureExpr : public AbstractClosureExpr {
   VarDecl *getCapturedSelfDecl() const {
     return CapturedSelfDecl;
   }
-  
-  /// Whether this closure captures the \c self param in its body in such a
-  /// way that implicit \c self is enabled within its body (i.e. \c self is
-  /// captured non-weakly).
-  bool capturesSelfEnablingImplictSelf() const;
-
 
   /// Get the type checking state of this closure's body.
   BodyState getBodyState() const {
diff --git a/include/swift/AST/NameLookup.h b/include/swift/AST/NameLookup.h
@@ -633,7 +633,7 @@ class AbstractASTScopeDeclConsumer {
 
   /// Eventually this functionality should move into ASTScopeLookup
   virtual bool
-  lookInMembers(NullablePtr<DeclContext> selfDC, DeclContext *const scopeDC,
+  lookInMembers(DeclContext *const scopeDC,
                 NominalTypeDecl *const nominal,
                 function_ref<bool(Optional<bool>)> calculateIsCascadingUse) = 0;
 
@@ -656,7 +656,7 @@ class ASTScopeDeclGatherer : public AbstractASTScopeDeclConsumer {
                NullablePtr<DeclContext> baseDC = nullptr) override;
 
   /// Eventually this functionality should move into ASTScopeLookup
-  bool lookInMembers(NullablePtr<DeclContext>, DeclContext *const,
+  bool lookInMembers(DeclContext *const,
                      NominalTypeDecl *const,
                      function_ref<bool(Optional<bool>)>) override {
     return false;
diff --git a/lib/AST/ASTScopeLookup.cpp b/lib/AST/ASTScopeLookup.cpp
@@ -264,8 +264,7 @@ bool GenericTypeOrExtensionWhereOrBodyPortion::lookupMembersOf(
   auto nt = scope->getCorrespondingNominalTypeDecl().getPtrOrNull();
   if (!nt)
     return false;
-  auto selfDC = computeSelfDC(history);
-  return consumer.lookInMembers(selfDC, scope->getDeclContext().get(), nt,
+  return consumer.lookInMembers(scope->getDeclContext().get(), nt,
                                 [&](Optional<bool> initialIsCascadingUse) {
                                   return ASTScopeImpl::computeIsCascadingUse(
                                              history, initialIsCascadingUse)
@@ -456,69 +455,6 @@ bool ASTScopeImpl::lookupLocalBindingsInPattern(const Pattern *p,
   return isDone;
 }
 
-#pragma mark computeSelfDC
-
-NullablePtr<DeclContext>
-GenericTypeOrExtensionWhereOrBodyPortion::computeSelfDC(
-    ArrayRef<const ASTScopeImpl *> history) {
-  ASTScopeAssert(history.size() != 0, "includes current scope");
-  size_t i = history.size() - 1; // skip last entry (this scope)
-  while (i != 0) {
-    Optional<NullablePtr<DeclContext>> maybeSelfDC =
-        history[--i]->computeSelfDCForParent();
-    if (maybeSelfDC) {
-      // If we've found a selfDC, we'll definitely be returning something.
-      // However, we may have captured 'self' somewhere down the tree, so we
-      // can't return outright without checking the nested scopes.
-      NullablePtr<DeclContext> nestedCapturedSelfDC =
-          checkNestedScopesForSelfCapture(history, i);
-      return nestedCapturedSelfDC ? nestedCapturedSelfDC : *maybeSelfDC;
-    }
-  }
-  return nullptr;
-}
-
-#pragma mark checkNestedScopesForSelfCapture
-
-NullablePtr<DeclContext>
-GenericTypeOrExtensionWhereOrBodyPortion::checkNestedScopesForSelfCapture(
-    ArrayRef<const ASTScopeImpl *> history, size_t start) {
-  NullablePtr<DeclContext> innerCapturedSelfDC;
-  // Start with the next scope down the tree.
-  size_t j = start;
-
-  // Note: even though having this loop nested inside the while loop from
-  // GenericTypeOrExtensionWhereOrBodyPortion::computeSelfDC may appear to
-  // result in quadratic blowup, complexity actually remains linear with respect
-  // to the size of history. This relies on the fact that
-  // GenericTypeOrExtensionScope::computeSelfDCForParent returns a null pointer,
-  // which will cause this method to bail out of the search early. Thus, this
-  // method is called once per type body in the lookup history, and will not
-  // end up re-checking the bodies of nested types that have already been
-  // covered by earlier calls, so the total impact of this method across all
-  // calls in a single lookup is O(n).
-  while (j != 0) {
-      auto *entry = history[--j];
-    Optional<NullablePtr<DeclContext>> selfDCForParent =
-      entry->computeSelfDCForParent();
-
-    // If we encounter a scope that should cause us to forget the self
-    // context (such as a nested type), bail out and use whatever the
-    // the last inner captured context was.
-    if (selfDCForParent && (*selfDCForParent).isNull())
-      break;
-
-    // Otherwise, if we have a captured self context for this scope, then
-    // remember it since it is now the innermost scope we have encountered.
-    NullablePtr<DeclContext> capturedSelfDC = entry->capturedSelfDC();
-    if (!capturedSelfDC.isNull())
-      innerCapturedSelfDC = entry->capturedSelfDC();
-
-    // Continue searching in the next scope down.
-  }
-  return innerCapturedSelfDC;
-}
-
 #pragma mark compute isCascadingUse
 
 Optional<bool> ASTScopeImpl::computeIsCascadingUse(
@@ -587,65 +523,6 @@ NullablePtr<const ASTScopeImpl> ASTScopeImpl::ancestorWithDeclSatisfying(
   return nullptr;
 }
 
-#pragma mark computeSelfDCForParent
-
-// If the lookup depends on implicit self, selfDC is its context.
-// (Names in extensions never depend on self.)
-// Lookup can propagate it up from, say a method to the enclosing type body.
-
-// By default, propagate the selfDC up to a NomExt decl, body,
-// or where clause
-Optional<NullablePtr<DeclContext>>
-ASTScopeImpl::computeSelfDCForParent() const {
-  return None;
-}
-
-// Forget the "self" declaration:
-Optional<NullablePtr<DeclContext>>
-GenericTypeOrExtensionScope::computeSelfDCForParent() const {
-  return NullablePtr<DeclContext>();
-}
-
-Optional<NullablePtr<DeclContext>>
-PatternEntryInitializerScope::computeSelfDCForParent() const {
-  // Pattern binding initializers are only interesting insofar as they
-  // affect lookup in an enclosing nominal type or extension thereof.
-  if (auto *ic = getPatternEntry().getInitContext()) {
-    if (auto *bindingInit = dyn_cast<PatternBindingInitializer>(ic)) {
-      // Lazy variable initializer contexts have a 'self' parameter for
-      // instance member lookup.
-      if (bindingInit->getImplicitSelfDecl()) {
-        return NullablePtr<DeclContext>(bindingInit);
-      }
-    }
-  }
-  return None;
-}
-
-Optional<NullablePtr<DeclContext>>
-FunctionBodyScope::computeSelfDCForParent() const {
-  if (decl->getDeclContext()->isTypeContext())
-    return NullablePtr<DeclContext>(decl);
-  return None;
-}
-
-#pragma mark capturedSelfDC
-
-// Closures may explicitly capture the self param, in which case the lookup
-// should use the closure as the context for implicit self lookups.
-
-// By default, there is no such context to return.
-NullablePtr<DeclContext> ASTScopeImpl::capturedSelfDC() const {
-  return NullablePtr<DeclContext>();
-}
-
-// Closures track this information explicitly.
-NullablePtr<DeclContext> ClosureParametersScope::capturedSelfDC() const {
-  if (closureExpr->capturesSelfEnablingImplictSelf())
-    return NullablePtr<DeclContext>(closureExpr);
-  return NullablePtr<DeclContext>();
-}
-
 #pragma mark ifUnknownIsCascadingUseAccordingTo
 
 static bool isCascadingUseAccordingTo(const DeclContext *const dc) {
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
@@ -1955,19 +1955,6 @@ bool ClosureExpr::hasEmptyBody() const {
   return getBody()->empty();
 }
 
-bool ClosureExpr::capturesSelfEnablingImplictSelf() const {
-  if (auto *VD = getCapturedSelfDecl()) {
-    if (!VD->isSelfParamCapture())
-      return false;
-
-    if (auto *attr = VD->getAttrs().getAttribute<ReferenceOwnershipAttr>())
-      return attr->get() != ReferenceOwnership::Weak;
-
-    return true;
-  }
-  return false;
-}
-
 void ClosureExpr::setExplicitResultType(Type ty) {
   assert(ty && !ty->hasTypeVariable() && !ty->hasHole());
   ExplicitResultTypeAndBodyState.getPointer()
diff --git a/lib/AST/UnqualifiedLookup.cpp b/lib/AST/UnqualifiedLookup.cpp
@@ -248,8 +248,7 @@ class ASTScopeDeclConsumerForUnqualifiedLookup
                NullablePtr<DeclContext> baseDC = nullptr) override;
 
   /// returns true if finished and new value for isCascadingUse
-  bool lookInMembers(NullablePtr<DeclContext> selfDC,
-                     DeclContext *const scopeDC, NominalTypeDecl *const nominal,
+  bool lookInMembers(DeclContext *const scopeDC, NominalTypeDecl *const nominal,
                      function_ref<bool(Optional<bool>)>) override;
 
 #ifndef NDEBUG
@@ -642,7 +641,7 @@ bool ASTScopeDeclGatherer::consume(ArrayRef<ValueDecl *> valuesArg,
 
 // TODO: in future, migrate this functionality into ASTScopes
 bool ASTScopeDeclConsumerForUnqualifiedLookup::lookInMembers(
-    NullablePtr<DeclContext> selfDC, DeclContext *const scopeDC,
+    DeclContext *const scopeDC,
     NominalTypeDecl *const nominal,
     function_ref<bool(Optional<bool>)> calculateIsCascadingUse) {
   if (candidateSelfDC) {
