Module selectors (formerly module qualifiers)

include/swift/AST/Decl.h

@@ -2467,11 +2467,10 @@ class ValueDecl : public Decl {
   /// names.
   DeclBaseName getBaseName() const { return Name.getBaseName(); }
 
-  /// Generates a DeclNameRef referring to this declaration with as much
-  /// specificity as possible.
-  DeclNameRef createNameRef() const {
-    return DeclNameRef(getFullName());
-  }
+  /// Generates a DeclNameRef referring to this declaration.
+  ///
+  /// \param moduleSelector If true, the name ref includes the module name.
+  DeclNameRef createNameRef(bool moduleSelector = false) const;
 
   /// Retrieve the name to use for this declaration when interoperating
   /// with the Objective-C runtime.

include/swift/AST/DeclNameLoc.h

@@ -29,45 +29,63 @@ class ASTContext;
 class DeclNameLoc {
   /// Source location information.
   ///
-  /// If \c NumArgumentLabels == 0, this is the SourceLoc for the base name.
-  /// Otherwise, it points to an array of SourceLocs, which contains:
+  /// If \c NumArgumentLabels == 0 and \c !HasModuleSelectorLoc, this is the
+  /// SourceLoc for the base name. Otherwise, it points to an array of
+  /// SourceLocs, which contains:
+  /// * The module selector location
   /// * The base name location
   /// * The left parentheses location
   /// * The right parentheses location
   /// * The locations of each of the argument labels.
   const void *LocationInfo;
 
   /// The number of argument labels stored in the name.
-  unsigned NumArgumentLabels;
+  uint32_t NumArgumentLabels;
+  bool HasModuleSelectorLoc;
 
   enum {
     BaseNameIndex = 0,
-    LParenIndex = 1,
-    RParenIndex = 2,
-    FirstArgumentLabelIndex = 3,
+    ModuleSelectorIndex = 1,
+    LParenIndex = 2,
+    RParenIndex = 3,
+    FirstArgumentLabelIndex = 4,
   };
 
   /// Retrieve a pointer to either the only source location that was
   /// stored or to the array of source locations that was stored.
   SourceLoc const * getSourceLocs() const {
-    if (NumArgumentLabels == 0) 
+    if (NumArgumentLabels == 0 && !HasModuleSelectorLoc)
       return reinterpret_cast<SourceLoc const *>(&LocationInfo);
 
     return reinterpret_cast<SourceLoc const *>(LocationInfo);
   }
 
 public:
   /// Create an invalid declaration name location.
-  DeclNameLoc() : LocationInfo(0), NumArgumentLabels(0) { }
+  DeclNameLoc()
+      : LocationInfo(0), NumArgumentLabels(0), HasModuleSelectorLoc(false) { }
 
   /// Create declaration name location information for a base name.
   explicit DeclNameLoc(SourceLoc baseNameLoc)
     : LocationInfo(baseNameLoc.getOpaquePointerValue()),
-      NumArgumentLabels(0) { }
+      NumArgumentLabels(0), HasModuleSelectorLoc(false) { }
+
+  explicit DeclNameLoc(ASTContext &ctx, SourceLoc moduleSelectorLoc,
+                       SourceLoc baseNameLoc)
+    : DeclNameLoc(ctx, moduleSelectorLoc, baseNameLoc,
+                  SourceLoc(), {}, SourceLoc()) { }
 
   /// Create declaration name location information for a compound
   /// name.
   DeclNameLoc(ASTContext &ctx, SourceLoc baseNameLoc,
+              SourceLoc lParenLoc,
+              ArrayRef<SourceLoc> argumentLabelLocs,
+              SourceLoc rParenLoc)
+    : DeclNameLoc(ctx, SourceLoc(), baseNameLoc,
+                  lParenLoc, argumentLabelLocs, rParenLoc) { }
+
+  DeclNameLoc(ASTContext &ctx, SourceLoc moduleSelectorLoc,
+              SourceLoc baseNameLoc,
               SourceLoc lParenLoc,
               ArrayRef<SourceLoc> argumentLabelLocs,
               SourceLoc rParenLoc);
@@ -105,8 +123,13 @@ class DeclNameLoc {
     return getSourceLocs()[FirstArgumentLabelIndex + index];
   }
 
+  SourceLoc getModuleSelectorLoc() const {
+    if (!HasModuleSelectorLoc) return SourceLoc();
+    return getSourceLocs()[ModuleSelectorIndex];
+  }
+
   SourceLoc getStartLoc() const {
-    return getBaseNameLoc();
+    return HasModuleSelectorLoc ? getModuleSelectorLoc() : getBaseNameLoc();
   }
 
   SourceLoc getEndLoc() const {
@@ -115,9 +138,7 @@ class DeclNameLoc {
 
   /// Retrieve the complete source range for this declaration name.
   SourceRange getSourceRange() const {
-    if (NumArgumentLabels == 0) return getBaseNameLoc();
-
-    return SourceRange(getBaseNameLoc(), getRParenLoc());
+    return SourceRange(getStartLoc(), getEndLoc());
   }
 };
 

include/swift/AST/DiagnosticsParse.def

@@ -111,6 +111,14 @@ ERROR(forbidden_interpolated_string,none,
 ERROR(forbidden_extended_escaping_string,none,
       "%0 cannot be an extended escaping string literal", (StringRef))
 
+ERROR(expected_identifier_in_module_selector,none,
+      "expected identifier in module selector", ())
+ERROR(module_selector_not_allowed_here,none,
+      "name cannot be qualified with module selector here", ())
+ERROR(module_selector_not_allowed_in_decl,none,
+      "%select{%1|name of %1 declaration}0 cannot be qualified with module "
+      "selector", (bool, StringRef))
+
 //------------------------------------------------------------------------------
 // MARK: Lexer diagnostics
 //------------------------------------------------------------------------------

include/swift/AST/DiagnosticsSema.def

@@ -832,6 +832,16 @@ ERROR(use_undeclared_type,none,
       "use of undeclared type %0", (DeclNameRef))
 ERROR(use_undeclared_type_did_you_mean,none,
       "use of undeclared type %0; did you mean to use '%1'?", (DeclNameRef, StringRef))
+ERROR(type_not_in_module,none,
+      "type %0 is not imported through module %1", (DeclName, Identifier))
+ERROR(decl_not_in_module,none,
+      "declaration %0 is not imported through module %1", (DeclName, Identifier))
+NOTE(note_change_module_selector,none,
+     "did you mean module %0?", (Identifier))
+NOTE(note_remove_module_selector,none,
+     "did you mean the local declaration?", ())
+NOTE(note_add_explicit_self_with_module_selector,none,
+     "did you mean the member of 'self'?", ())
 NOTE(note_typo_candidate_implicit_member,none,
      "did you mean the implicitly-synthesized %1 '%0'?", (StringRef, StringRef))
 NOTE(note_remapped_type,none,

include/swift/AST/Identifier.h

@@ -615,74 +615,127 @@ void simple_display(llvm::raw_ostream &out, DeclName name);
 /// An in-source reference to another declaration, including qualification
 /// information.
 class DeclNameRef {
-  DeclName FullName;
+  friend class ASTContext;
+
+  /// Contains the name and module for a DeclNameRef with a module selector.
+  struct alignas(Identifier) SelectiveDeclNameRef : llvm::FoldingSetNode {
+    Identifier moduleSelector;   // Note: currently can never be empty().
+    DeclName fullName;
+
+    SelectiveDeclNameRef(Identifier moduleSelector, DeclName fullName)
+      : moduleSelector(moduleSelector), fullName(fullName) { }
+
+    /// Uniquing for the ASTContext.
+    static void Profile(llvm::FoldingSetNodeID &id, Identifier moduleSelector,
+                        DeclName fullName);
+
+    void Profile(llvm::FoldingSetNodeID &id) {
+      Profile(id, moduleSelector, fullName);
+    }
+
+    // Make vanilla new/delete illegal for SelectiveDeclNameRef.
+    void *operator new(size_t Bytes) = delete;
+    void operator delete(void *Data) = delete;
+
+    // Only allow allocation of SelectiveDeclNameRef using the allocator
+    // in ASTContext or by doing a placement new.
+    void *operator new(size_t Bytes, const ASTContext &C,
+                       unsigned Alignment = alignof(SelectiveDeclNameRef));
+    void *operator new(size_t Bytes, void *Mem) {
+      assert(Mem);
+      return Mem;
+    }
+  };
+
+  llvm::PointerUnion<DeclName, SelectiveDeclNameRef *> storage;
+
+  explicit DeclNameRef(void *Opaque)
+    : storage(decltype(storage)::getFromOpaqueValue(Opaque)) { }
+
+  void initialize(ASTContext &C, Identifier moduleScope, DeclName fullName);
 
 public:
   static DeclNameRef createSubscript();
   static DeclNameRef createConstructor();
 
-  DeclNameRef() : FullName() { }
+  DeclNameRef() : storage(DeclName()) { }
 
-  void *getOpaqueValue() const { return FullName.getOpaqueValue(); }
+  void *getOpaqueValue() const {
+    return storage.getOpaqueValue();
+  }
   static DeclNameRef getFromOpaqueValue(void *p);
 
+  explicit DeclNameRef(ASTContext &C, Identifier moduleSelector,
+                       DeclName fullName) {
+    initialize(C, moduleSelector, fullName);
+  }
+
+  explicit DeclNameRef(ASTContext &C, Identifier moduleSelector,
+                       DeclBaseName baseName, ArrayRef<Identifier> argLabels) {
+    initialize(C, moduleSelector, DeclName(C, baseName, argLabels));
+  }
+
   explicit DeclNameRef(DeclName FullName)
-    : FullName(FullName) { }
+    : storage(FullName) { }
+
+  bool hasModuleSelector() const {
+    return storage.is<SelectiveDeclNameRef *>();
+  }
 
-  explicit DeclNameRef(DeclBaseName BaseName)
-    : FullName(BaseName) { }
+  Identifier getModuleSelector() const {
+    if (!hasModuleSelector())
+      return Identifier();
 
-  explicit DeclNameRef(Identifier BaseName)
-    : FullName(BaseName) { }
+    return storage.get<SelectiveDeclNameRef *>()->moduleSelector;
+  }
 
   /// The name of the declaration being referenced.
   DeclName getFullName() const {
-    return FullName;
-  }
+    if (!hasModuleSelector())
+      return storage.get<DeclName>();
 
-  DeclName &getFullName() {
-    return FullName;
+    return storage.get<SelectiveDeclNameRef *>()->fullName;
   }
 
   /// The base name of the declaration being referenced.
   DeclBaseName getBaseName() const {
-    return FullName.getBaseName();
+    return getFullName().getBaseName();
   }
 
   Identifier getBaseIdentifier() const {
-    return FullName.getBaseIdentifier();
+    return getFullName().getBaseIdentifier();
   }
 
   ArrayRef<Identifier> getArgumentNames() const {
-    return FullName.getArgumentNames();
+    return getFullName().getArgumentNames();
   }
 
   bool isSimpleName() const {
-    return FullName.isSimpleName();
+    return getFullName().isSimpleName();
   }
 
   bool isSimpleName(DeclBaseName name) const {
-    return FullName.isSimpleName(name);
+    return getFullName().isSimpleName(name);
   }
 
   bool isSimpleName(StringRef name) const {
-    return FullName.isSimpleName(name);
+    return getFullName().isSimpleName(name);
   }
 
   bool isSpecial() const {
-    return FullName.isSpecial();
+    return getFullName().isSpecial();
   }
 
   bool isOperator() const {
-    return FullName.isOperator();
+    return getFullName().isOperator();
   }
 
   bool isCompoundName() const {
-    return FullName.isCompoundName();
+    return getFullName().isCompoundName();
   }
 
   explicit operator bool() const {
-    return (bool)FullName;
+    return (bool)getFullName();
   }
 
   /// Compare two declaration names, producing -1 if \c *this comes before
@@ -722,7 +775,7 @@ class DeclNameRef {
     return lhs.compare(rhs) >= 0;
   }
 
-  DeclNameRef withoutArgumentLabels() const;
+  DeclNameRef withoutArgumentLabels(ASTContext &C) const;
   DeclNameRef withArgumentLabels(ASTContext &C,
                                  ArrayRef<Identifier> argumentNames) const;
 
@@ -753,19 +806,18 @@ class DeclNameRef {
 };
 
 inline DeclNameRef DeclNameRef::getFromOpaqueValue(void *p) {
-  return DeclNameRef(DeclName::getFromOpaqueValue(p));
+  return DeclNameRef(p);
 }
 
-inline DeclNameRef DeclNameRef::withoutArgumentLabels() const {
-  return DeclNameRef(getBaseName());
+inline DeclNameRef DeclNameRef::withoutArgumentLabels(ASTContext &C) const {
+  return DeclNameRef(C, getModuleSelector(), getBaseName());
 }
 
 inline DeclNameRef DeclNameRef::withArgumentLabels(
     ASTContext &C, ArrayRef<Identifier> argumentNames) const {
-  return DeclNameRef(DeclName(C, getBaseName(), argumentNames));
+  return DeclNameRef(C, getModuleSelector(), getBaseName(), argumentNames);
 }
 
-
 inline DeclNameRef DeclNameRef::createSubscript() {
   return DeclNameRef(DeclBaseName::createSubscript());
 }
@@ -931,7 +983,7 @@ namespace llvm {
     static inline swift::DeclNameRef getFromVoidPointer(void *ptr) {
       return swift::DeclNameRef::getFromOpaqueValue(ptr);
     }
-    enum { NumLowBitsAvailable = PointerLikeTypeTraits<swift::DeclName>::NumLowBitsAvailable };
+    enum { NumLowBitsAvailable = PointerLikeTypeTraits<swift::DeclName>::NumLowBitsAvailable - 1 };
   };
 
   // DeclNameRefs hash just like DeclNames.

include/swift/AST/ModuleNameLookup.h

@@ -41,14 +41,14 @@ enum class ResolutionKind {
 
 void simple_display(llvm::raw_ostream &out, ResolutionKind kind);
 
-/// Performs a lookup into the given module and it's imports.
+/// Performs a lookup into the given module and its imports.
 ///
-/// If 'moduleOrFile' is a ModuleDecl, we search the module and it's
+/// If 'moduleOrFile' is a ModuleDecl, we search the module and its
 /// public imports. If 'moduleOrFile' is a SourceFile, we search the
 /// file's parent module, the module's public imports, and the source
 /// file's private imports.
 ///
-/// \param moduleOrFile The module or file unit whose imports to search.
+/// \param moduleOrFile The module or file unit to search, including imports.
 /// \param name The name to look up.
 /// \param[out] decls Any found decls will be added to this vector.
 /// \param lookupKind Whether this lookup is qualified or unqualified.

include/swift/AST/NameLookup.h

@@ -440,6 +440,14 @@ class AccessFilteringDeclConsumer final : public VisibleDeclConsumer {
 /// \returns true if any declarations were removed, false otherwise.
 bool removeOverriddenDecls(SmallVectorImpl<ValueDecl*> &decls);
 
+/// Remove any declarations in the given set that do not match the
+/// module selector, if it is not empty.
+///
+/// \returns true if any declarations were removed, false otherwise.
+bool removeOutOfModuleDecls(SmallVectorImpl<ValueDecl*> &decls,
+                            Identifier moduleSelector,
+                            const DeclContext *dc);
+
 /// Remove any declarations in the given set that are shadowed by
 /// other declarations in that set.
 ///
@@ -474,6 +482,7 @@ namespace namelookup {
 /// Once name lookup has gathered a set of results, perform any necessary
 /// steps to prune the result set before returning it to the caller.
 void pruneLookupResultSet(const DeclContext *dc, NLOptions options,
+                          Identifier moduleSelector,
                           SmallVectorImpl<ValueDecl *> &decls);
 
 /// Do nothing if debugClient is null.