AST: Add 'hoisted' flag to Decl

Author: slavapestov

include/swift/AST/Decl.h

@@ -284,7 +284,7 @@ class alignas(1 << DeclAlignInBits) Decl {
 protected:
   union { uint64_t OpaqueBits;
 
-  SWIFT_INLINE_BITFIELD_BASE(Decl, bitmax(NumDeclKindBits,8)+1+1+1+1,
+  SWIFT_INLINE_BITFIELD_BASE(Decl, bitmax(NumDeclKindBits,8)+1+1+1+1+1,
     Kind : bitmax(NumDeclKindBits,8),
 
     /// Whether this declaration is invalid.
@@ -301,7 +301,13 @@ class alignas(1 << DeclAlignInBits) Decl {
 
     /// Whether this declaration was added to the surrounding
     /// DeclContext of an active #if config clause.
-    EscapedFromIfConfig : 1
+    EscapedFromIfConfig : 1,
+
+    /// Whether this declaration is syntactically scoped inside of
+    /// a local context, but should behave like a top-level
+    /// declaration for name lookup purposes. This is used by
+    /// lldb.
+    Hoisted : 1
   );
 
   SWIFT_INLINE_BITFIELD_FULL(PatternBindingDecl, Decl, 1+2+16,
@@ -690,6 +696,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     Bits.Decl.Implicit = false;
     Bits.Decl.FromClang = false;
     Bits.Decl.EscapedFromIfConfig = false;
+    Bits.Decl.Hoisted = false;
   }
 
   /// Get the Clang node associated with this declaration.
@@ -837,6 +844,16 @@ class alignas(1 << DeclAlignInBits) Decl {
   /// Mark this declaration as implicit.
   void setImplicit(bool implicit = true) { Bits.Decl.Implicit = implicit; }
 
+  /// Determine whether this declaration is syntactically scoped inside of
+  /// a local context, but should behave like a top-level declaration
+  /// for name lookup purposes. This is used by lldb.
+  bool isHoisted() const { return Bits.Decl.Hoisted; }
+
+  /// Set whether this declaration should be syntactically scoped inside
+  /// of a local context, but should behave like a top-level declaration,
+  /// but should behave like a top-level declaration. This is used by lldb.
+  void setHoisted(bool hoisted = true) { Bits.Decl.Hoisted = hoisted; }
+
 public:
   bool escapedFromIfConfig() const {
     return Bits.Decl.EscapedFromIfConfig;

include/swift/AST/SourceFile.h

@@ -187,6 +187,10 @@ class SourceFile final : public FileUnit {
   /// have been removed, this can become an optional ArrayRef.
   Optional<std::vector<Decl *>> Decls;
 
+  /// The list of hoisted declarations. See Decl::isHoisted().
+  /// This is only used by lldb.
+  std::vector<Decl *> Hoisted;
+
   using SeparatelyImportedOverlayMap =
     llvm::SmallDenseMap<ModuleDecl *, llvm::SmallPtrSet<ModuleDecl *, 1>>;
 
@@ -231,9 +235,18 @@ class SourceFile final : public FileUnit {
     Decls->insert(Decls->begin(), d);
   }
 
+  /// Add a hoisted declaration. See Decl::isHoisted().
+  void addHoistedDecl(Decl *d) {
+    Hoisted.push_back(d);
+  }
+
   /// Retrieves an immutable view of the list of top-level decls in this file.
   ArrayRef<Decl *> getTopLevelDecls() const;
 
+  /// Retrieves an immutable view of the list of hoisted decls in this file.
+  /// See Decl::isHoisted().
+  ArrayRef<Decl *> getHoistedDecls() const;
+
   /// Retrieves an immutable view of the top-level decls if they have already
   /// been parsed, or \c None if they haven't. Should only be used for dumping.
   Optional<ArrayRef<Decl *>> getCachedTopLevelDecls() const {

lib/AST/ASTDumper.cpp

@@ -585,6 +585,9 @@ namespace {
       if (D->isImplicit())
         PrintWithColorRAII(OS, DeclModifierColor) << " implicit";
 
+      if (D->isHoisted())
+        PrintWithColorRAII(OS, DeclModifierColor) << " hoisted";
+
       auto R = D->getSourceRange();
       if (R.isValid()) {
         PrintWithColorRAII(OS, RangeColor) << " range=";

lib/AST/Module.cpp

@@ -2342,6 +2342,10 @@ ArrayRef<Decl *> SourceFile::getTopLevelDecls() const {
                            {}).TopLevelDecls;
 }
 
+ArrayRef<Decl *> SourceFile::getHoistedDecls() const {
+  return Hoisted;
+}
+
 bool FileUnit::walk(ASTWalker &walker) {
   SmallVector<Decl *, 64> Decls;
   getTopLevelDecls(Decls);