Integrate fileprivate

The majority of changes here are just plumbing needed to get the
compiler to look at the (new!) FilePrivate as the (old!) Private and
the (new!) Private as an even more closed-off form the of (old!)
Private.

The interesting changes are in `lib/AST/NameLookup.cpp` where (new!)
private is defined as a declaration where our declcontext and their
declcontext have to match or nest.  (new!) Private predictably causes
quite a lot more dead code elimination to fire in places which has lead
to some interesting bugs that I will see about patches for (or at least
SRs).

Author: CodaFi

docs/AccessControl.rst

@@ -7,16 +7,18 @@ The general guiding principle of Swift access control:
   **No entity can be defined in terms of another entity that has a lower
   access level.**
 
-There are three levels of access: "private", "internal", and "public".
-Private entities can only be accessed from within the source file where they
-are defined. Internal entities can be accessed anywhere within the module they
-are defined. Public entities can be accessed from anywhere within the module
-and from any other context that imports the current module.
+There are four levels of access: "private", "fileprivate", "internal", and
+"public". Private entities can only be accessed from within the current
+declaration where they are defined. FilePrivate entities can only be accessed
+from within the source file where they are defined. Internal entities can be
+accessed anywhere within the module they are defined. Public entities can be
+accessed from anywhere within the module and from any other context that imports
+the current module.
 
 The names ``public`` and ``private`` have precedent in many languages;
-``internal`` comes from C#. In the future, ``public`` may be used for both API
-and SPI, at which point we may design additional annotations to distinguish the
-two.
+``internal`` comes from C# and ``fileprivate`` from the Swift community. In the
+future, ``public`` may be used for both API and SPI, at which point we may
+design additional annotations to distinguish the two.
 
 By default, most entities in a source file have ``internal`` access.
 This optimizes for the most common case—a single-target application

docs/OptimizationTips.rst

@@ -134,17 +134,17 @@ in the following ``C.array1`` and ``D.array1`` will be accessed directly
      d.array2[i] = ... // Will access D.array2 through dynamic dispatch.
   }
 
-Advice: Use 'private' when declaration does not need to be accessed outside of file
------------------------------------------------------------------------------------
-
-Applying the ``private`` keyword to a declaration restricts the visibility of
-the declaration to the file in which it is declared. This allows the compiler to
-be able to ascertain all other potentially overriding declarations. Thus the
-absence of any such declarations enables the compiler to infer the ``final``
-keyword automatically and remove indirect calls for methods and field accesses
-accordingly. For instance in the following, ``e.doSomething()`` and
-``f.myPrivateVar``, will be able to be accessed directly assuming ``E``, ``F``
-do not have any overriding declarations in the same file:
+Advice: Use 'private' and 'fileprivate' when declaration does not need to be accessed outside of file
+-----------------------------------------------------------------------------------------------------
+
+Applying the ``private`` or ``fileprivate`` keywords to a declaration restricts
+the visibility of the declaration to the file in which it is declared. This
+allows the compiler to be able to ascertain all other potentially overriding
+declarations. Thus the absence of any such declarations enables the compiler to
+infer the ``final`` keyword automatically and remove indirect calls for methods
+and field accesses accordingly. For instance in the following,
+``e.doSomething()`` and ``f.myPrivateVar``, will be able to be accessed directly
+assuming ``E``, ``F`` do not have any overriding declarations in the same file:
 
 ::
 

include/swift/AST/Attr.def

@@ -192,6 +192,7 @@ DECL_ATTR(private, Accessibility,
           OnClass | OnProtocol | OnVar | OnSubscript | OnConstructor |
           DeclModifier | NotSerialized,
           /* Not serialized */ 46)
+DECL_ATTR_ALIAS(fileprivate, Accessibility)
 DECL_ATTR_ALIAS(internal, Accessibility)
 DECL_ATTR_ALIAS(public, Accessibility)
 

include/swift/AST/AttrKind.h

@@ -48,8 +48,10 @@ enum class UnaryOperatorKind : uint8_t {
 /// Access control levels.
 // These are used in diagnostics, so please do not reorder existing values.
 enum class Accessibility : uint8_t {
-  /// Private access is limited to the current file.
+  /// Private access is limited to the current declaration.
   Private = 0,
+  /// FilePrivate access is limited to the current file.
+  FilePrivate,
   /// Internal access is limited to the current module.
   Internal,
   /// Public access is not limited.

include/swift/AST/Decl.h

@@ -544,7 +544,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     /// This is encoded as (1 << maxAccess) | (1 << defaultAccess), which
     /// works because the maximum is always greater than or equal to the
     /// default. 0 represents an uncomputed value.
-    unsigned DefaultAndMaxAccessLevel : 3;
+    unsigned DefaultAndMaxAccessLevel : 4;
 
     /// Whether there is an active conformance loader for this
     /// extension.
@@ -1701,6 +1701,9 @@ class ExtensionDecl final : public Decl, public DeclContext,
     if (ExtensionDeclBits.DefaultAndMaxAccessLevel &
         (1 << static_cast<unsigned>(Accessibility::Private)))
       return Accessibility::Private;
+    if (ExtensionDeclBits.DefaultAndMaxAccessLevel &
+        (1 << static_cast<unsigned>(Accessibility::FilePrivate)))
+      return Accessibility::FilePrivate;
     if (ExtensionDeclBits.DefaultAndMaxAccessLevel &
         (1 << static_cast<unsigned>(Accessibility::Internal)))
       return Accessibility::Internal;
@@ -1715,6 +1718,9 @@ class ExtensionDecl final : public Decl, public DeclContext,
     if (ExtensionDeclBits.DefaultAndMaxAccessLevel &
         (1 << static_cast<unsigned>(Accessibility::Internal)))
       return Accessibility::Internal;
+    if (ExtensionDeclBits.DefaultAndMaxAccessLevel &
+        (1 << static_cast<unsigned>(Accessibility::FilePrivate)))
+      return Accessibility::FilePrivate;
     return Accessibility::Private;
   }
 
@@ -2084,7 +2090,7 @@ class IfConfigDecl : public Decl {
 class ValueDecl : public Decl {
   DeclName Name;
   SourceLoc NameLoc;
-  llvm::PointerIntPair<Type, 2, OptionalEnum<Accessibility>> TypeAndAccess;
+  llvm::PointerIntPair<Type, 3, OptionalEnum<Accessibility>> TypeAndAccess;
 
 protected:
   ValueDecl(DeclKind K,
@@ -3823,8 +3829,8 @@ class AbstractStorageDecl : public ValueDecl {
   void configureObservingRecord(ObservingRecord *record,
                                 FuncDecl *willSet, FuncDecl *didSet);
 
-  llvm::PointerIntPair<GetSetRecord*, 2, OptionalEnum<Accessibility>> GetSetInfo;
-  llvm::PointerIntPair<BehaviorRecord*, 2, OptionalEnum<Accessibility>>
+  llvm::PointerIntPair<GetSetRecord*, 3, OptionalEnum<Accessibility>> GetSetInfo;
+  llvm::PointerIntPair<BehaviorRecord*, 3, OptionalEnum<Accessibility>>
     BehaviorInfo;
 
   ObservingRecord &getDidSetInfo() const {
@@ -5926,6 +5932,8 @@ inline Accessibility ValueDecl::getEffectiveAccess() const {
       return Accessibility::Public;
     }
     return Accessibility::Internal;
+  case Accessibility::FilePrivate:
+    return Accessibility::FilePrivate;
   case Accessibility::Private:
     return Accessibility::Private;
   }

include/swift/AST/DiagnosticsSema.def

@@ -105,11 +105,11 @@ ERROR(could_not_use_member_on_existential,none,
       (Type, DeclName))
 
 ERROR(candidate_inaccessible,none,
-      "%0 is inaccessible due to '%select{private|internal|PUBLIC}1' "
+      "%0 is inaccessible due to '%select{private|fileprivate|internal|PUBLIC}1' "
       "protection level", (DeclName, Accessibility))
 
 ERROR(init_candidate_inaccessible,none,
-    "%0 initializer is inaccessible due to '%select{private|internal|PUBLIC}1' "
+    "%0 initializer is inaccessible due to '%select{private|fileprivate|internal|PUBLIC}1' "
       "protection level", (Type, Accessibility))
 
 
@@ -924,34 +924,34 @@ ERROR(attr_methods_only,none,
 ERROR(access_control_in_protocol,none,
       "%0 modifier cannot be used in protocols", (DeclAttribute))
 ERROR(access_control_setter,none,
-      "'%select{private|internal|public}0(set)' modifier can only be applied "
+      "'%select{private|fileprivate|internal|public}0(set)' modifier can only be applied "
       "to variables and subscripts",
       (Accessibility))
 ERROR(access_control_setter_read_only,none,
-      "'%select{private|internal|public}0(set)' modifier cannot be applied to "
+      "'%select{private|fileprivate|internal|public}0(set)' modifier cannot be applied to "
       "%select{constants|read-only variables|read-only properties"
       "|read-only subscripts}1",
       (Accessibility, unsigned))
 ERROR(access_control_setter_more,none,
-      "%select{private|internal|PUBLIC}0 "
+      "%select{private|fileprivate|internal|PUBLIC}0 "
       "%select{variable|property|subscript}1 cannot have "
-      "%select{PRIVATE|an internal|a public}2 setter",
+      "%select{PRIVATE|a fileprivate|an internal|a public}2 setter",
       (Accessibility, unsigned, Accessibility))
 WARNING(access_control_member_more,none,
-    "declaring %select{PRIVATE|an internal|a public}0 %1 for "
-    "%select{a private|an internal|PUBLIC}2 %3",
+    "declaring %select{PRIVATE|a fileprivate|an internal|a public}0 %1 for "
+    "%select{a private|a fileprivate|an internal|PUBLIC}2 %3",
     (Accessibility, DescriptiveDeclKind, Accessibility, DescriptiveDeclKind))
 WARNING(access_control_ext_member_more,none,
-    "declaring %select{PRIVATE|an internal|a public}0 %1 in "
-    "%select{a private|an internal|PUBLIC}2 extension",
+    "declaring %select{PRIVATE|a fileprivate|an internal|a public}0 %1 in "
+    "%select{a private|a fileprivate|an internal|PUBLIC}2 extension",
     (Accessibility, DescriptiveDeclKind, Accessibility))
 ERROR(access_control_ext_requirement_member_more,none,
-    "cannot declare %select{PRIVATE|an internal|a public}0 %1 in "
-    "an extension with %select{private|internal|PUBLIC}2 requirements",
+    "cannot declare %select{PRIVATE|a fileprivate|an internal|a public}0 %1 in "
+    "an extension with %select{private|fileprivate|internal|PUBLIC}2 requirements",
     (Accessibility, DescriptiveDeclKind, Accessibility))
 ERROR(access_control_extension_more,none,
-      "extension of %select{private|internal|PUBLIC}0 %1 cannot be "
-      "declared %select{PRIVATE|internal|public}2",
+      "extension of %select{private|fileprivate|internal|PUBLIC}0 %1 cannot be "
+      "declared %select{PRIVATE|fileprivate|internal|public}2",
       (Accessibility, DescriptiveDeclKind, Accessibility))
 
 ERROR(invalid_decl_attribute_simple,none,
@@ -1039,15 +1039,15 @@ ERROR(static_requires_initializer,none,
       "expression or getter/setter specifier", (StaticSpellingKind))
 ERROR(pattern_type_access,none,
       "%select{%select{variable|constant}0|property}1 "
-      "%select{must be declared %select{private|internal|PUBLIC}4"
-      "|cannot be declared %select{PRIVATE|internal|public}3}2 because its "
-      "type uses %select{a private|an internal|PUBLIC}4 type",
+      "%select{must be declared %select{private|fileprivate|internal|PUBLIC}4"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}3}2 because its "
+      "type uses %select{a private|a fileprivate|an internal|PUBLIC}4 type",
       (bool, bool, bool, Accessibility, Accessibility))
 ERROR(pattern_type_access_inferred,none,
       "%select{%select{variable|constant}0|property}1 "
-      "%select{must be declared %select{private|internal|PUBLIC}4"
-      "|cannot be declared %select{PRIVATE|internal|public}3}2 because its "
-      "type %5 uses %select{a private|an internal|PUBLIC}4 type",
+      "%select{must be declared %select{private|fileprivate|internal|PUBLIC}4"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}3}2 because its "
+      "type %5 uses %select{a private|a fileprivate|an internal|PUBLIC}4 type",
       (bool, bool, bool, Accessibility, Accessibility, Type))
 ERROR(pattern_binds_no_variables,none,
       "%select{property|global variable}0 declaration does not bind any "
@@ -1070,26 +1070,26 @@ ERROR(unsupported_type_nested_in_generic_function,none,
 ERROR(circular_type_alias,none,
       "type alias %0 circularly references itself", (Identifier))
 ERROR(type_alias_underlying_type_access,none,
-      "type alias %select{must be declared %select{private|internal|PUBLIC}2"
-      "|cannot be declared %select{PRIVATE|internal|public}1}0 because its "
-      "underlying type uses %select{a private|an internal|PUBLIC}2 type",
+      "type alias %select{must be declared %select{private|fileprivate|internal|PUBLIC}2"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}1}0 because its "
+      "underlying type uses %select{a private|a fileprivate|an internal|PUBLIC}2 type",
       (bool, Accessibility, Accessibility))
 
 // Subscripts
 ERROR(subscript_type_access,none,
-      "subscript %select{must be declared %select{private|internal|PUBLIC}2"
-      "|cannot be declared %select{PRIVATE|internal|public}1}0 because its "
+      "subscript %select{must be declared %select{private|fileprivate|internal|PUBLIC}2"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}1}0 because its "
       "%select{index|element type}3 uses "
-      "%select{a private|an internal|PUBLIC}2 type",
+      "%select{a private|a fileprivate|an internal|PUBLIC}2 type",
       (bool, Accessibility, Accessibility, bool))
 
 // Functions
 ERROR(function_type_access,none,
       "%select{function|method|initializer}3 "
-      "%select{must be declared %select{private|internal|PUBLIC}2"
-      "|cannot be declared %select{PRIVATE|internal|public}1}0 because its "
+      "%select{must be declared %select{private|fileprivate|internal|PUBLIC}2"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}1}0 because its "
       "%select{parameter|result}4 uses "
-      "%select{a private|an internal|PUBLIC}2 type",
+      "%select{a private|a fileprivate|an internal|PUBLIC}2 type",
       (bool, Accessibility, Accessibility, unsigned, bool))
 WARNING(non_trailing_closure_before_default_args,none,
         "closure parameter prior to parameters with default arguments will "
@@ -1191,28 +1191,28 @@ ERROR(witness_requires_dynamic_self,none,
 ERROR(witness_not_accessible_proto,none,
       "%select{initializer %1|method %1|%select{|setter for }2property %1"
       "|subscript%select{| setter}2}0 must be declared "
-      "%select{PRIVATE|internal|public}3 because it matches a requirement "
-      "in %select{PRIVATE|internal|public}3 protocol %4",
+      "%select{PRIVATE|fileprivate|internal|public}3 because it matches a requirement "
+      "in %select{PRIVATE|fileprivate|internal|public}3 protocol %4",
       (RequirementKind, DeclName, bool, Accessibility, DeclName))
 ERROR(witness_not_accessible_type,none,
       "%select{initializer %1|method %1|%select{|setter for }2property %1"
       "|subscript%select{| setter}2}0 must be as accessible as its enclosing "
       "type because it matches a requirement in protocol %4",
       (RequirementKind, DeclName, bool, Accessibility, DeclName))
 ERROR(type_witness_not_accessible_proto,none,
-      "%0 %1 must be declared %select{PRIVATE|internal|public}2 because it "
-      "matches a requirement in %select{PRIVATE|internal|public}2 protocol %3",
+      "%0 %1 must be declared %select{PRIVATE|fileprivate|internal|public}2 because it "
+      "matches a requirement in %select{PRIVATE|fileprivate|internal|public}2 protocol %3",
       (DescriptiveDeclKind, DeclName, Accessibility, DeclName))
 ERROR(type_witness_not_accessible_type,none,
       "%0 %1 must be as accessible as its enclosing type because it "
       "matches a requirement in protocol %3",
       (DescriptiveDeclKind, DeclName, Accessibility, DeclName))
 
 ERROR(protocol_refine_access,none,
-      "%select{protocol must be declared %select{private|internal|PUBLIC}2 "
+      "%select{protocol must be declared %select{private|fileprivate|internal|PUBLIC}2 "
       "because it refines"
-      "|%select{PRIVATE|internal|public}1 protocol cannot refine}0 "
-      "%select{a private|an internal|PUBLIC}2 protocol",
+      "|%select{PRIVATE|fileprivate|internal|public}1 protocol cannot refine}0 "
+      "%select{a private|a fileprivate|an internal|PUBLIC}2 protocol",
       (bool, Accessibility, Accessibility))
 ERROR(protocol_property_must_be_computed_var,none,
       "immutable property requirement must be declared as 'var' with a "
@@ -1240,8 +1240,8 @@ NOTE(default_associated_type_req_fail,none,
      "does not conform to %3",
      (Type, DeclName, Type, Type))
 ERROR(associated_type_access,none,
-      "associated type in %select{PRIVATE|an internal|a public}0 protocol "
-      "uses %select{a private|an internal|PUBLIC}1 type in its "
+      "associated type in %select{PRIVATE|a fileprivate|an internal|a public}0 protocol "
+      "uses %select{a private|a fileprivate|an internal|PUBLIC}1 type in its "
       "%select{default definition|requirement}2 ",
       (Accessibility, Accessibility, unsigned))
 
@@ -1345,7 +1345,7 @@ NOTE(optional_req_near_match_move,none,
 NOTE(optional_req_near_match_nonobjc,none,
      "add '@nonobjc' to silence this %select{warning|error}0", (bool))
 NOTE(optional_req_near_match_accessibility,none,
-     "make %0 %select{ERROR|private|private or internal}1 to silence this "
+     "make %0 %select{ERROR|ERROR|fileprivate|fileprivate or internal}1 to silence this "
      "warning", (DeclName, Accessibility))
 
 // Protocols and existentials
@@ -1397,10 +1397,10 @@ ERROR(requires_generic_param_same_type_does_not_conform,none,
       (Type, Identifier))
 
 ERROR(generic_param_access,none,
-      "%0 %select{must be declared %select{private|internal|PUBLIC}3"
-      "|cannot be declared %select{PRIVATE|internal|public}2}1 because its "
+      "%0 %select{must be declared %select{private|fileprivate|internal|PUBLIC}3"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}2}1 because its "
       "generic %select{parameter|requirement}4 uses "
-      "%select{a private|an internal|PUBLIC}3 type",
+      "%select{a private|a fileprivate|an internal|PUBLIC}3 type",
       (DescriptiveDeclKind, bool, Accessibility, Accessibility, bool))
 
 ERROR(override_multiple_decls_base,none,
@@ -1576,8 +1576,8 @@ ERROR(inheritance_from_objc_runtime_visible_class,none,
 
 // Enums
 ERROR(enum_case_access,none,
-      "enum case in %select{PRIVATE|an internal|a public}0 enum uses "
-      "%select{a private|an internal|PUBLIC}1 type",
+      "enum case in %select{PRIVATE|a fileprivate|an internal|a public}0 enum uses "
+      "%select{a private|a fileprivate|an internal|PUBLIC}1 type",
       (Accessibility, Accessibility))
 ERROR(enum_stored_property,none,
       "enums may not contain stored properties", ())
@@ -1596,9 +1596,9 @@ ERROR(enum_raw_type_not_equatable,none,
       "RawRepresentable 'init' cannot be synthesized because raw type %0 is not "
       "Equatable", (Type))
 ERROR(enum_raw_type_access,none,
-      "enum %select{must be declared %select{private|internal|PUBLIC}2"
-      "|cannot be declared %select{PRIVATE|internal|public}1}0 because its "
-      "raw type uses %select{a private|an internal|PUBLIC}2 type",
+      "enum %select{must be declared %select{private|fileprivate|internal|PUBLIC}2"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}1}0 because its "
+      "raw type uses %select{a private|a fileprivate|an internal|PUBLIC}2 type",
       (bool, Accessibility, Accessibility))
 
 NOTE(enum_here,none,
@@ -2490,9 +2490,9 @@ ERROR(self_in_nominal,none,
       "'Self' is only available in a protocol or as the result of a "
       "method in a class; did you mean %0?", (Identifier))
 ERROR(class_super_access,none,
-      "class %select{must be declared %select{private|internal|PUBLIC}2"
-      "|cannot be declared %select{PRIVATE|internal|public}1}0 because its "
-      "superclass is %select{private|internal|PUBLIC}2",
+      "class %select{must be declared %select{private|fileprivate|internal|PUBLIC}2"
+      "|cannot be declared %select{PRIVATE|fileprivate|internal|public}1}0 because its "
+      "superclass is %select{private|fileprivate|internal|PUBLIC}2",
       (bool, Accessibility, Accessibility))
 ERROR(dot_protocol_on_non_existential,none,
       "cannot use 'Protocol' with non-protocol type %0", (Type))