Merge pull request swiftlang#23734 from slavapestov/subscript-default-arguments

Subscript default arguments

Author: slavapestov

include/swift/AST/Decl.h

@@ -393,16 +393,11 @@ class alignas(1 << DeclAlignInBits) Decl {
     /// Information about a symbolic default argument, like #file.
     defaultArgumentKind : NumDefaultArgumentKindBits
   );
-  
+
   SWIFT_INLINE_BITFIELD(SubscriptDecl, VarDecl, 2,
     StaticSpelling : 2
   );
 
-  SWIFT_INLINE_BITFIELD(EnumElementDecl, ValueDecl, 1,
-    /// The ResilienceExpansion to use for default arguments.
-    DefaultArgumentResilienceExpansion : 1
-  );
-  
   SWIFT_INLINE_BITFIELD(AbstractFunctionDecl, ValueDecl, 3+8+1+1+1+1+1+1+1,
     /// \see AbstractFunctionDecl::BodyKind
     BodyKind : 3,
@@ -425,9 +420,6 @@ class alignas(1 << DeclAlignInBits) Decl {
     /// Whether NeedsNewVTableEntry is valid.
     HasComputedNeedsNewVTableEntry : 1,
 
-    /// The ResilienceExpansion to use for default arguments.
-    DefaultArgumentResilienceExpansion : 1,
-
     /// Whether this member was synthesized as part of a derived
     /// protocol conformance.
     Synthesized : 1
@@ -5307,8 +5299,6 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
     Bits.AbstractFunctionDecl.Throws = Throws;
     Bits.AbstractFunctionDecl.NeedsNewVTableEntry = false;
     Bits.AbstractFunctionDecl.HasComputedNeedsNewVTableEntry = false;
-    Bits.AbstractFunctionDecl.DefaultArgumentResilienceExpansion =
-        unsigned(ResilienceExpansion::Maximal);
     Bits.AbstractFunctionDecl.Synthesized = false;
   }
 
@@ -5556,21 +5546,6 @@ class AbstractFunctionDecl : public GenericContext, public ValueDecl {
   /// Resolved during type checking
   void setIsOverridden() { Bits.AbstractFunctionDecl.Overridden = true; }
 
-  /// The ResilienceExpansion for default arguments.
-  ///
-  /// In Swift 4 mode, default argument expressions are serialized, and must
-  /// obey the restrictions imposed upon inlinable function bodies.
-  ResilienceExpansion getDefaultArgumentResilienceExpansion() const {
-    return ResilienceExpansion(
-        Bits.AbstractFunctionDecl.DefaultArgumentResilienceExpansion);
-  }
-
-  /// Set the ResilienceExpansion for default arguments.
-  void setDefaultArgumentResilienceExpansion(ResilienceExpansion expansion) {
-    Bits.AbstractFunctionDecl.DefaultArgumentResilienceExpansion =
-        unsigned(expansion);
-  }
-
   /// Set information about the foreign error convention used by this
   /// declaration.
   void setForeignErrorConvention(const ForeignErrorConvention &convention);
@@ -6025,10 +6000,7 @@ class EnumElementDecl : public DeclContext, public ValueDecl {
     Params(Params),
     EqualsLoc(EqualsLoc),
     RawValueExpr(RawValueExpr)
-  {
-    Bits.EnumElementDecl.DefaultArgumentResilienceExpansion =
-        static_cast<unsigned>(ResilienceExpansion::Maximal);
-  }
+  {}
 
   Identifier getName() const { return getFullName().getBaseIdentifier(); }
 
@@ -6057,21 +6029,6 @@ class EnumElementDecl : public DeclContext, public ValueDecl {
     TypeCheckedRawValueExpr = e;
   }
 
-  /// The ResilienceExpansion for default arguments.
-  ///
-  /// In Swift 4 mode, default argument expressions are serialized, and must
-  /// obey the restrictions imposed upon inlinable function bodies.
-  ResilienceExpansion getDefaultArgumentResilienceExpansion() const {
-    return ResilienceExpansion(
-        Bits.EnumElementDecl.DefaultArgumentResilienceExpansion);
-  }
-
-  /// Set the ResilienceExpansion for default arguments.
-  void setDefaultArgumentResilienceExpansion(ResilienceExpansion expansion) {
-    Bits.EnumElementDecl.DefaultArgumentResilienceExpansion =
-        unsigned(expansion);
-  }
-  
   /// Return the containing EnumDecl.
   EnumDecl *getParentEnum() const {
     return cast<EnumDecl>(getDeclContext());

include/swift/AST/DiagnosticsParse.def

@@ -821,8 +821,6 @@ ERROR(untyped_pattern_ellipsis,none,
       "'...' cannot be applied to a subpattern which is not explicitly typed", ())
 ERROR(no_default_arg_closure,none,
       "default arguments are not allowed in closures", ())
-ERROR(no_default_arg_subscript,none,
-      "default arguments are not allowed in subscripts", ())
 ERROR(no_default_arg_curried,none,
       "default arguments are not allowed in curried parameter lists", ())
 ERROR(var_pattern_in_var,none,

include/swift/Parse/Parser.h

@@ -1098,8 +1098,8 @@ class Parser {
     /// all the arguments, not just those that have default arguments.
     unsigned claimNextIndex() { return NextIndex++; }
 
-    /// Set the parsed context for all the initializers to the given
-    /// function.
+    /// Set the parsed context of all default argument initializers to
+    /// the given function, enum case or subscript.
     void setFunctionContext(DeclContext *DC, ParameterList *paramList);
 
     DefaultArgumentInfo() {

include/swift/Serialization/ModuleFormat.h

@@ -52,7 +52,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 482; // static subscripts
+const uint16_t SWIFTMODULE_VERSION_MINOR = 483; // Remove default arg expansion
 
 using DeclIDField = BCFixed<31>;
 
@@ -1002,7 +1002,6 @@ namespace decls_block {
     DeclIDField, // overridden decl
     AccessLevelField, // access level
     BCFixed<1>,   // requires a new vtable slot
-    BCFixed<1>,   // default argument resilience expansion
     BCFixed<1>,   // 'required' but overridden is not (used for recovery)
     BCVBR<5>,     // number of parameter name components
     BCArray<IdentifierIDField> // name components,
@@ -1069,7 +1068,6 @@ namespace decls_block {
                   // components plus one
     AccessLevelField, // access level
     BCFixed<1>,   // requires a new vtable slot
-    BCFixed<1>,   // default argument resilience expansion
     BCArray<IdentifierIDField> // name components,
                                // followed by TypeID dependencies
     // The record is trailed by:
@@ -1099,7 +1097,6 @@ namespace decls_block {
     AccessorKindField, // accessor kind
     AccessLevelField, // access level
     BCFixed<1>,   // requires a new vtable slot
-    BCFixed<1>,   // default argument resilience expansion
     BCArray<IdentifierIDField> // name components,
                                // followed by TypeID dependencies
     // The record is trailed by:
@@ -1158,7 +1155,6 @@ namespace decls_block {
     EnumElementRawValueKindField,  // raw value kind
     BCFixed<1>,  // negative raw value?
     IdentifierIDField, // raw value
-    BCFixed<1>,   // default argument resilience expansion
     BCVBR<5>, // number of parameter name components
     BCArray<IdentifierIDField> // name components,
 

lib/AST/ASTVerifier.cpp

@@ -761,6 +761,7 @@ class Verifier : public ASTWalker {
     FUNCTION_LIKE(DestructorDecl)
     FUNCTION_LIKE(FuncDecl)
     FUNCTION_LIKE(EnumElementDecl)
+    FUNCTION_LIKE(SubscriptDecl)
     SCOPE_LIKE(NominalTypeDecl)
     SCOPE_LIKE(ExtensionDecl)
 

lib/AST/Decl.cpp

@@ -5551,8 +5551,10 @@ const ParamDecl *swift::getParameterAt(ValueDecl *source, unsigned index) {
   const ParameterList *paramList;
   if (auto *AFD = dyn_cast<AbstractFunctionDecl>(source)) {
     paramList = AFD->getParameters();
+  } else if (auto *EED = dyn_cast<EnumElementDecl>(source)) {
+    paramList = EED->getParameterList();
   } else {
-    paramList = cast<EnumElementDecl>(source)->getParameterList();
+    paramList = cast<SubscriptDecl>(source)->getIndices();
   }
 
   return paramList->get(index);

lib/AST/DeclContext.cpp

@@ -313,11 +313,25 @@ ResilienceExpansion DeclContext::getResilienceExpansion() const {
     // Default argument initializer contexts have their resilience expansion
     // set when they're type checked.
     if (isa<DefaultArgumentInitializer>(dc)) {
-      if (auto *EED = dyn_cast<EnumElementDecl>(dc->getParent())) {
-        return EED->getDefaultArgumentResilienceExpansion();
+      dc = dc->getParent();
+
+      const ValueDecl *VD;
+      if (auto *FD = dyn_cast<AbstractFunctionDecl>(dc)) {
+        VD = FD;
+      } else if (auto *EED = dyn_cast<EnumElementDecl>(dc)) {
+        VD = EED;
+      } else {
+        VD = cast<SubscriptDecl>(dc);
       }
-      return cast<AbstractFunctionDecl>(dc->getParent())
-          ->getDefaultArgumentResilienceExpansion();
+
+      auto access =
+        VD->getFormalAccessScope(/*useDC=*/nullptr,
+                                 /*treatUsableFromInlineAsPublic=*/true);
+
+      if (access.isPublic())
+        return ResilienceExpansion::Minimal;
+
+      return ResilienceExpansion::Maximal;
     }
 
     // Stored property initializer contexts use minimal resilience expansion

lib/Parse/ParseDecl.cpp

@@ -6364,10 +6364,11 @@ Parser::parseDeclSubscript(ParseDeclOptions Flags,
     return makeParserCodeCompletionStatus();
 
   // Parse the parameter list.
+  DefaultArgumentInfo DefaultArgs;
   SmallVector<Identifier, 4> argumentNames;
   ParserResult<ParameterList> Indices
     = parseSingleParameterClause(ParameterContextKind::Subscript,
-                                 &argumentNames);
+                                 &argumentNames, &DefaultArgs);
   Status |= Indices;
 
   SignatureHasCodeCompletion |= Indices.hasCodeCompletion();
@@ -6419,6 +6420,8 @@ Parser::parseDeclSubscript(ParseDeclOptions Flags,
                                                 nullptr);
   Subscript->getAttrs() = Attributes;
 
+  DefaultArgs.setFunctionContext(Subscript, Subscript->getIndices());
+
   // Parse a 'where' clause if present, adding it to our GenericParamList.
   if (Tok.is(tok::kw_where)) {
     ContextChange CC(*this, Subscript);

lib/Parse/ParsePattern.cpp

@@ -92,13 +92,11 @@ static ParserStatus parseDefaultArgument(
   case Parser::ParameterContextKind::Operator:
   case Parser::ParameterContextKind::Initializer:
   case Parser::ParameterContextKind::EnumElement:
+  case Parser::ParameterContextKind::Subscript:
     break;
   case Parser::ParameterContextKind::Closure:
     diagID = diag::no_default_arg_closure;
     break;
-  case Parser::ParameterContextKind::Subscript:
-    diagID = diag::no_default_arg_subscript;
-    break;
   case Parser::ParameterContextKind::Curried:
     diagID = diag::no_default_arg_curried;
     break;
@@ -609,7 +607,8 @@ mapParsedParameters(Parser &parser,
       assert((paramContext == Parser::ParameterContextKind::Function ||
               paramContext == Parser::ParameterContextKind::Operator ||
               paramContext == Parser::ParameterContextKind::Initializer ||
-              paramContext == Parser::ParameterContextKind::EnumElement) &&
+              paramContext == Parser::ParameterContextKind::EnumElement ||
+              paramContext == Parser::ParameterContextKind::Subscript) &&
              "Default arguments are only permitted on the first param clause");
       DefaultArgumentKind kind = getDefaultArgKind(param.DefaultArg);
       result->setDefaultArgumentKind(kind);

lib/SIL/SILDeclRef.cpp

@@ -476,19 +476,13 @@ IsSerialized_t SILDeclRef::isSerialized() const {
   // Default argument generators are serialized if the containing
   // declaration is public.
   if (isDefaultArgGenerator()) {
-    ResilienceExpansion expansion;
-    if (auto *EED = dyn_cast<EnumElementDecl>(d)) {
-      expansion = EED->getDefaultArgumentResilienceExpansion();
-    } else {
-      expansion = cast<AbstractFunctionDecl>(d)
-                    ->getDefaultArgumentResilienceExpansion();
-    }
-    switch (expansion) {
-    case ResilienceExpansion::Minimal:
+    auto scope =
+      d->getFormalAccessScope(/*useDC=*/nullptr,
+                              /*treatUsableFromInlineAsPublic=*/true);
+
+    if (scope.isPublic())
       return IsSerialized;
-    case ResilienceExpansion::Maximal:
-      return IsNotSerialized;
-    }
+    return IsNotSerialized;
   }
 
   // Stored property initializers are inlinable if the type is explicitly