Merge pull request swiftlang#27435 from davidungar/A-9-29-recursion-assert

[ASTScopes] Use RequestEvaluator for ASTScope expansion to detect recursion

Author: David Ungar

include/swift/AST/ASTScope.h

@@ -30,6 +30,7 @@
 
 #include "swift/AST/ASTNode.h"
 #include "swift/AST/NameLookup.h" // for DeclVisibilityKind
+#include "swift/AST/SimpleRequest.h"
 #include "swift/Basic/Compiler.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/Basic/NullablePtr.h"
@@ -88,6 +89,14 @@ struct AnnotatedInsertionPoint {
   ASTScopeImpl *insertionPoint;
   const char *explanation;
 };
+} // namespace ast_scope
+
+namespace ast_scope {
+
+void simple_display(llvm::raw_ostream &out, const ASTScopeImpl *);
+void simple_display(llvm::raw_ostream &out, const ScopeCreator *);
+
+SourceLoc extractNearestSourceLoc(std::tuple<ASTScopeImpl *, ScopeCreator *>);
 
 #pragma mark the root ASTScopeImpl class
 
@@ -333,6 +342,11 @@ class ASTScopeImpl {
 public:
   /// expandScope me, sending deferred nodes to my descendants.
   /// Return the scope into which to place subsequent decls
+  ASTScopeImpl *expandAndBeCurrentDetectingRecursion(ScopeCreator &);
+
+  /// Expand or reexpand the scope if unexpanded or if not current.
+  /// There are several places in the compiler that mutate the AST after the
+  /// fact, above and beyond adding Decls to the SourceFile.
   ASTScopeImpl *expandAndBeCurrent(ScopeCreator &);
 
   unsigned getASTAncestorScopeCount() const { return astAncestorScopeCount; }
@@ -344,6 +358,12 @@ class ASTScopeImpl {
   void setWasExpanded() { wasExpanded = true; }
   virtual ASTScopeImpl *expandSpecifically(ScopeCreator &) = 0;
   virtual void beCurrent();
+  virtual bool doesExpansionOnlyAddNewDeclsAtEnd() const;
+
+public:
+  bool isExpansionNeeded(const ScopeCreator &) const;
+
+protected:
   bool isCurrent() const;
   virtual bool isCurrentIfWasExpanded() const;
 
@@ -374,16 +394,7 @@ class ASTScopeImpl {
 
   bool isATypeDeclScope() const;
 
-  /// There are several places in the compiler that mutate the AST after the
-  /// fact, above and beyond adding Decls to the SourceFile. These are
-  /// documented in: rdar://53018839, rdar://53027266, rdar://53027733,
-  /// rdar://53028050
-  /// Return true if did reexpand
-  bool reexpandIfObsolete(ScopeCreator &);
-
 private:
-  void reexpand(ScopeCreator &);
-
   virtual ScopeCreator &getScopeCreator();
 
 #pragma mark - - creation queries
@@ -533,8 +544,8 @@ class ASTSourceFileScope final : public ASTScopeImpl {
   /// The number of \c Decls in the \c SourceFile that were already seen.
   /// Since parsing can be interleaved with type-checking, on every
   /// lookup, look at creating scopes for any \c Decls beyond this number.
-  /// rdar://55562483 Unify with numberOfChildrenWhenLastExpanded
-  int numberOfDeclsAlreadySeen = 0;
+  /// TODO: Unify with numberOfChildrenWhenLastExpanded
+  size_t numberOfDeclsAlreadySeen = 0;
 
   ASTSourceFileScope(SourceFile *SF, ScopeCreator *scopeCreator);
 
@@ -548,7 +559,6 @@ class ASTSourceFileScope final : public ASTScopeImpl {
 public:
   NullablePtr<DeclContext> getDeclContext() const override;
 
-  void addNewDeclsToScopeTree();
   void buildFullyExpandedTree();
   void
   buildEnoughOfTreeForTopLevelExpressionsButDontRequestGenericsOrExtendedNominals();
@@ -559,11 +569,15 @@ class ASTSourceFileScope final : public ASTScopeImpl {
 
 protected:
   ASTScopeImpl *expandSpecifically(ScopeCreator &scopeCreator) override;
+  bool isCurrentIfWasExpanded() const override;
+  void beCurrent() override;
+  bool doesExpansionOnlyAddNewDeclsAtEnd() const override;
 
   ScopeCreator &getScopeCreator() override;
 
 private:
-  void expandAScopeThatDoesNotCreateANewInsertionPoint(ScopeCreator &);
+  AnnotatedInsertionPoint
+  expandAScopeThatCreatesANewInsertionPoint(ScopeCreator &);
 };
 
 class Portion {
@@ -1148,7 +1162,6 @@ class AttachedPropertyWrapperScope final : public ASTScopeImpl {
   /// false positives, that that doesn't hurt anything. However, the result of
   /// the conservative source range computation doesn't seem to be stable. So
   /// keep the original here, and use it for source range queries.
-  /// rdar://55263708
 
   const SourceRange sourceRangeWhenCreated;
 
@@ -1251,7 +1264,6 @@ class PatternEntryDeclScope final : public AbstractPatternEntryScope {
 };
 
 class PatternEntryInitializerScope final : public AbstractPatternEntryScope {
-  // Should be able to remove this when rdar://53921703 is accomplished.
   Expr *initAsWrittenWhenCreated;
 
 public:

include/swift/AST/NameLookupRequests.h

@@ -30,6 +30,10 @@ class GenericContext;
 class GenericParamList;
 class TypeAliasDecl;
 class TypeDecl;
+namespace ast_scope {
+class ASTScopeImpl;
+class ScopeCreator;
+} // namespace ast_scope
 
 /// Display a nominal type or extension thereof.
 void simple_display(
@@ -324,6 +328,30 @@ class LookupPrecedenceGroupRequest
   bool isCached() const { return true; }
 };
 
+/// Expand the given ASTScope. Requestified to detect recursion.
+class ExpandASTScopeRequest
+    : public SimpleRequest<ExpandASTScopeRequest,
+                           ast_scope::ASTScopeImpl *(ast_scope::ASTScopeImpl *,
+                                                     ast_scope::ScopeCreator *),
+                           CacheKind::SeparatelyCached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  // Evaluation.
+  llvm::Expected<ast_scope::ASTScopeImpl *>
+  evaluate(Evaluator &evaluator, ast_scope::ASTScopeImpl *,
+           ast_scope::ScopeCreator *) const;
+
+public:
+  // Separate caching.
+  bool isCached() const;
+  Optional<ast_scope::ASTScopeImpl *> getCachedResult() const;
+  void cacheResult(ast_scope::ASTScopeImpl *) const {}
+};
+
 #define SWIFT_TYPEID_ZONE NameLookup
 #define SWIFT_TYPEID_HEADER "swift/AST/NameLookupTypeIDZone.def"
 #include "swift/Basic/DefineTypeIDZone.h"

include/swift/AST/NameLookupTypeIDZone.def

@@ -18,6 +18,10 @@
 SWIFT_REQUEST(NameLookup, CustomAttrNominalRequest,
               NominalTypeDecl *(CustomAttr *, DeclContext *), Cached,
               NoLocationInfo)
+SWIFT_REQUEST(NameLookup, ExpandASTScopeRequest,
+              ast_scope::ASTScopeImpl* (ast_scope::ASTScopeImpl*, ast_scope::ScopeCreator*),
+              SeparatelyCached,
+              NoLocationInfo)
 SWIFT_REQUEST(NameLookup, ExtendedNominalRequest,
               NominalTypeDecl *(ExtensionDecl *), SeparatelyCached,
               NoLocationInfo)