[SE-0491] Parse and ASTGen module selectors

include/swift/AST/ASTBridging.h

@@ -146,14 +146,19 @@ class BridgedDeclNameRef {
   BRIDGED_INLINE swift::DeclNameRef unbridged() const;
 };
 
-SWIFT_NAME("BridgedDeclNameRef.createParsed(_:baseName:argumentLabels:)")
-BridgedDeclNameRef BridgedDeclNameRef_createParsed(BridgedASTContext cContext,
-                                                   swift::DeclBaseName baseName,
-                                                   BridgedArrayRef cLabels);
+SWIFT_NAME("BridgedDeclNameRef.createParsed(_:moduleSelector:baseName:"
+           "argumentLabels:)")
+BridgedDeclNameRef
+BridgedDeclNameRef_createParsed(BridgedASTContext cContext,
+                                swift::Identifier cModuleSelector,
+                                swift::DeclBaseName cBaseName,
+                                BridgedArrayRef cLabels);
 
-SWIFT_NAME("BridgedDeclNameRef.createParsed(_:)")
+SWIFT_NAME("BridgedDeclNameRef.createParsed(_:moduleSelector:baseName:)")
 BridgedDeclNameRef
-BridgedDeclNameRef_createParsed(swift::DeclBaseName baseName);
+BridgedDeclNameRef_createParsed(BridgedASTContext cContext,
+                                swift::Identifier cModuleSelector,
+                                swift::DeclBaseName cBaseName);
 
 class BridgedDeclNameLoc {
   const void *_Nullable LocationInfo;
@@ -941,11 +946,12 @@ BridgedDocumentationAttr BridgedDocumentationAttr_createParsed(
 
 SWIFT_NAME(
     "BridgedDynamicReplacementAttr.createParsed(_:atLoc:attrNameLoc:lParenLoc:"
-    "replacedFunction:rParenLoc:)")
+    "replacedFunction:replacedFunctionLoc:rParenLoc:)")
 BridgedDynamicReplacementAttr BridgedDynamicReplacementAttr_createParsed(
-    BridgedASTContext cContext, swift::SourceLoc atLoc,
-    swift::SourceLoc attrNameLoc, swift::SourceLoc lParenLoc,
-    BridgedDeclNameRef cReplacedFunction, swift::SourceLoc rParenLoc);
+    BridgedASTContext cContext, swift::SourceLoc cAtLoc,
+    swift::SourceLoc cAttrNameLoc, swift::SourceLoc cLParenLoc,
+    BridgedDeclNameRef cReplacedFunction,
+    BridgedDeclNameLoc cReplacedFunctionLoc, swift::SourceLoc cRParenLoc);
 
 SWIFT_NAME("BridgedEffectsAttr.createParsed(_:atLoc:range:effectKind:)")
 BridgedEffectsAttr BridgedEffectsAttr_createParsed(
@@ -1276,22 +1282,24 @@ enum ENUM_EXTENSIBILITY_ATTR(closed) BridgedSpecializationKind : uint8_t {
 };
 
 SWIFT_NAME("BridgedSpecializeAttr.createParsed(_:atLoc:range:whereClause:"
-           "exported:kind:taretFunction:spiGroups:availableAttrs:)")
+           "exported:kind:targetFunction:targetFunctionLoc:spiGroups:"
+           "availableAttrs:)")
 BridgedSpecializeAttr BridgedSpecializeAttr_createParsed(
     BridgedASTContext cContext, swift::SourceLoc atLoc,
     swift::SourceRange range, BridgedNullableTrailingWhereClause cWhereClause,
     bool exported, BridgedSpecializationKind cKind,
-    BridgedDeclNameRef cTargetFunction, BridgedArrayRef cSPIGroups,
-    BridgedArrayRef cAvailableAttrs);
+    BridgedDeclNameRef cTargetFunction, BridgedDeclNameLoc cTargetFunctionLoc,
+    BridgedArrayRef cSPIGroups, BridgedArrayRef cAvailableAttrs);
 
 SWIFT_NAME("BridgedSpecializedAttr.createParsed(_:atLoc:range:whereClause:"
-           "exported:kind:taretFunction:spiGroups:availableAttrs:)")
+           "exported:kind:targetFunction:targetFunctionLoc:spiGroups:"
+           "availableAttrs:)")
 BridgedSpecializedAttr BridgedSpecializedAttr_createParsed(
     BridgedASTContext cContext, swift::SourceLoc atLoc,
     swift::SourceRange range, BridgedNullableTrailingWhereClause cWhereClause,
     bool exported, BridgedSpecializationKind cKind,
-    BridgedDeclNameRef cTargetFunction, BridgedArrayRef cSPIGroups,
-    BridgedArrayRef cAvailableAttrs);
+    BridgedDeclNameRef cTargetFunction, BridgedDeclNameLoc cTargetFunctionLoc,
+    BridgedArrayRef cSPIGroups, BridgedArrayRef cAvailableAttrs);
 
 SWIFT_NAME(
     "BridgedSPIAccessControlAttr.createParsed(_:atLoc:range:spiGroupName:)")
@@ -2544,9 +2552,10 @@ BridgedOpaqueReturnTypeOfTypeAttr_createParsed(
 // MARK: TypeReprs
 //===----------------------------------------------------------------------===//
 
-SWIFT_NAME("BridgedUnqualifiedIdentTypeRepr.createParsed(_:loc:name:)")
+SWIFT_NAME("BridgedUnqualifiedIdentTypeRepr.createParsed(_:name:loc:)")
 BridgedUnqualifiedIdentTypeRepr BridgedUnqualifiedIdentTypeRepr_createParsed(
-    BridgedASTContext cContext, swift::SourceLoc loc, swift::Identifier id);
+    BridgedASTContext cContext, BridgedDeclNameRef cName,
+    BridgedDeclNameLoc cLoc);
 
 SWIFT_NAME(
     "BridgedArrayTypeRepr.createParsed(_:base:leftSquareLoc:rightSquareLoc:)")
@@ -2580,8 +2589,8 @@ BridgedCompileTimeLiteralTypeRepr_createParsed(BridgedASTContext cContext,
 SWIFT_NAME("BridgedDeclRefTypeRepr.createParsed(_:base:name:nameLoc:"
            "genericArguments:angleRange:)")
 BridgedDeclRefTypeRepr BridgedDeclRefTypeRepr_createParsed(
-    BridgedASTContext cContext, BridgedTypeRepr cBase, swift::Identifier name,
-    swift::SourceLoc loc, BridgedArrayRef cGenericArguments,
+    BridgedASTContext cContext, BridgedTypeRepr cBase, BridgedDeclNameRef cName,
+    BridgedDeclNameLoc cLoc, BridgedArrayRef cGenericArguments,
     swift::SourceRange angleRange);
 
 SWIFT_NAME("BridgedDictionaryTypeRepr.createParsed(_:leftSquareLoc:keyType:"
@@ -2606,8 +2615,8 @@ BridgedFunctionTypeRepr BridgedFunctionTypeRepr_createParsed(
 SWIFT_NAME("BridgedUnqualifiedIdentTypeRepr.createParsed(_:name:nameLoc:"
            "genericArgs:leftAngleLoc:rightAngleLoc:)")
 BridgedUnqualifiedIdentTypeRepr BridgedUnqualifiedIdentTypeRepr_createParsed(
-    BridgedASTContext cContext, swift::Identifier name,
-    swift::SourceLoc nameLoc, BridgedArrayRef genericArgs,
+    BridgedASTContext cContext, BridgedDeclNameRef cName,
+    BridgedDeclNameLoc cNameLoc, BridgedArrayRef genericArgs,
     swift::SourceLoc lAngleLoc, swift::SourceLoc rAngleLoc);
 
 SWIFT_NAME("BridgedOptionalTypeRepr.createParsed(_:base:questionLoc:)")

include/swift/AST/Attr.h

@@ -1253,19 +1253,22 @@ class DynamicReplacementAttr final
   friend class DynamicallyReplacedDeclRequest;
 
   DeclNameRef ReplacedFunctionName;
+  DeclNameLoc ReplacedFunctionNameLoc;
   LazyMemberLoader *Resolver = nullptr;
   uint64_t ResolverContextData;
 
   /// Create an @_dynamicReplacement(for:) attribute written in the source.
   DynamicReplacementAttr(SourceLoc atLoc, SourceRange baseRange,
                          DeclNameRef replacedFunctionName,
+                         DeclNameLoc replacedFunctionNameLoc,
                          SourceRange parenRange);
 
   DynamicReplacementAttr(DeclNameRef name, AbstractFunctionDecl *f)
       : DeclAttribute(DeclAttrKind::DynamicReplacement, SourceLoc(),
                       SourceRange(),
                       /*Implicit=*/false),
-        ReplacedFunctionName(name), Resolver(nullptr), ResolverContextData(0) {
+        ReplacedFunctionName(name), ReplacedFunctionNameLoc(),
+        Resolver(nullptr), ResolverContextData(0) {
     Bits.DynamicReplacementAttr.HasTrailingLocationInfo = false;
   }
 
@@ -1274,8 +1277,8 @@ class DynamicReplacementAttr final
       : DeclAttribute(DeclAttrKind::DynamicReplacement, SourceLoc(),
                       SourceRange(),
                       /*Implicit=*/false),
-        ReplacedFunctionName(name), Resolver(Resolver),
-        ResolverContextData(Data) {
+        ReplacedFunctionName(name), ReplacedFunctionNameLoc(),
+        Resolver(Resolver), ResolverContextData(Data) {
     Bits.DynamicReplacementAttr.HasTrailingLocationInfo = false;
   }
 
@@ -1296,7 +1299,8 @@ class DynamicReplacementAttr final
 public:
   static DynamicReplacementAttr *
   create(ASTContext &Context, SourceLoc AtLoc, SourceLoc DynReplLoc,
-         SourceLoc LParenLoc, DeclNameRef replacedFunction, SourceLoc RParenLoc);
+         SourceLoc LParenLoc, DeclNameRef replacedFunction,
+         DeclNameLoc replacedFunctionNameLoc, SourceLoc RParenLoc);
 
   static DynamicReplacementAttr *create(ASTContext &ctx,
                                         DeclNameRef replacedFunction,
@@ -1311,6 +1315,10 @@ class DynamicReplacementAttr final
     return ReplacedFunctionName;
   }
 
+  DeclNameLoc getReplacedFunctionNameLoc() const {
+    return ReplacedFunctionNameLoc;
+  }
+
   /// Retrieve the location of the opening parentheses, if there is one.
   SourceLoc getLParenLoc() const;
 
@@ -1800,6 +1808,7 @@ class AbstractSpecializeAttr
   GenericSignature specializedSignature;
 
   DeclNameRef targetFunctionName;
+  DeclNameLoc targetFunctionNameLoc;
   LazyMemberLoader *resolver = nullptr;
   uint64_t resolverContextData;
   size_t numSPIGroups;
@@ -1812,7 +1821,9 @@ class AbstractSpecializeAttr
                  TrailingWhereClause *clause,
                  bool exported,
                  SpecializationKind kind, GenericSignature specializedSignature,
-                 DeclNameRef targetFunctionName, ArrayRef<Identifier> spiGroups,
+                 DeclNameRef targetFunctionName,
+                 DeclNameLoc targetFunctionNameLoc,
+                 ArrayRef<Identifier> spiGroups,
                  ArrayRef<AvailableAttr *> availabilityAttrs,
                  size_t typeErasedParamsCount);
 
@@ -1896,6 +1907,10 @@ class AbstractSpecializeAttr
     return targetFunctionName;
   }
 
+  DeclNameLoc getTargetFunctionNameLoc() const {
+    return targetFunctionNameLoc;
+  }
+
   /// \p forDecl is the value decl that the attribute belongs to.
   ValueDecl *getTargetFunctionDecl(const ValueDecl *forDecl) const;
 
@@ -1925,19 +1940,23 @@ class SpecializeAttr final : public AbstractSpecializeAttr,
                  TrailingWhereClause *clause,
                  bool exported,
                  SpecializationKind kind, GenericSignature specializedSignature,
-                 DeclNameRef targetFunctionName, ArrayRef<Identifier> spiGroups,
+                 DeclNameRef targetFunctionName,
+                 DeclNameLoc targetFunctionNameLoc,
+                 ArrayRef<Identifier> spiGroups,
                  ArrayRef<AvailableAttr *> availabilityAttrs,
                  size_t typeErasedParamsCount) :
     AbstractSpecializeAttr(DeclAttrKind::Specialize, atLoc, Range, clause,
                    exported, kind, specializedSignature, targetFunctionName,
-                   spiGroups, availabilityAttrs, typeErasedParamsCount) {}
+                   targetFunctionNameLoc, spiGroups, availabilityAttrs,
+                   typeErasedParamsCount) {}
 
 public:
   static SpecializeAttr *
   create(ASTContext &Ctx, SourceLoc atLoc, SourceRange Range,
          TrailingWhereClause *clause, bool exported,
          SpecializationKind kind,
-         DeclNameRef targetFunctionName, ArrayRef<Identifier> spiGroups,
+         DeclNameRef targetFunctionName, DeclNameLoc targetFunctionNameLoc,
+         ArrayRef<Identifier> spiGroups,
          ArrayRef<AvailableAttr *> availabilityAttrs,
          GenericSignature specializedSignature = nullptr);
 
@@ -1981,19 +2000,23 @@ class SpecializedAttr final : public AbstractSpecializeAttr ,
                  TrailingWhereClause *clause,
                  bool exported,
                  SpecializationKind kind, GenericSignature specializedSignature,
-                 DeclNameRef targetFunctionName, ArrayRef<Identifier> spiGroups,
+                 DeclNameRef targetFunctionName,
+                 DeclNameLoc targetFunctionNameLoc,
+                 ArrayRef<Identifier> spiGroups,
                  ArrayRef<AvailableAttr *> availabilityAttrs,
                  size_t typeErasedParamsCount) :
     AbstractSpecializeAttr(DeclAttrKind::Specialized, atLoc, Range, clause,
                    exported, kind, specializedSignature, targetFunctionName,
-                   spiGroups, availabilityAttrs, typeErasedParamsCount) {}
+                   targetFunctionNameLoc, spiGroups, availabilityAttrs,
+                   typeErasedParamsCount) {}
 
 public:
   static SpecializedAttr *
   create(ASTContext &Ctx, SourceLoc atLoc, SourceRange Range,
          TrailingWhereClause *clause, bool exported,
          SpecializationKind kind,
-         DeclNameRef targetFunctionName, ArrayRef<Identifier> spiGroups,
+         DeclNameRef targetFunctionName, DeclNameLoc targetFunctionNameLoc,
+         ArrayRef<Identifier> spiGroups,
          ArrayRef<AvailableAttr *> availabilityAttrs,
          GenericSignature specializedSignature = nullptr);
 

include/swift/AST/DiagnosticsParse.def

@@ -93,6 +93,17 @@ 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 module name in module selector", ())
+ERROR(expected_identifier_after_module_selector,none,
+      "expected identifier after module selector", ())
+NOTE(extra_whitespace_module_selector,none,
+     "remove extraneous whitespace after '::'", ())
+ERROR(module_selector_submodule_not_allowed,none,
+      "module selector cannot specify a submodule", ())
+NOTE(replace_module_selector_with_member_lookup,none,
+     "replace '::' with '.'", ())
+
 //------------------------------------------------------------------------------
 // MARK: Lexer diagnostics
 //------------------------------------------------------------------------------
@@ -2199,5 +2210,9 @@ ERROR(using_decl_invalid_specifier,PointsToFirstBadToken,
 ERROR(experimental_using_decl_disabled,PointsToFirstBadToken,
       "'using' is an experimental feature that is currently disabled", ())
 
+ERROR(impossible_parse,none,
+      "parser entered impossible state; please file a bug report with this "
+      "source file", ())
+
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"

include/swift/AST/TokenKinds.def

@@ -203,6 +203,7 @@ PUNCTUATOR(period_prefix, ".")
 PUNCTUATOR(comma, ",")
 PUNCTUATOR(ellipsis, "...")
 PUNCTUATOR(colon, ":")
+PUNCTUATOR(colon_colon, "::")
 PUNCTUATOR(semi, ";")
 PUNCTUATOR(equal, "=")
 PUNCTUATOR(at_sign, "@")

include/swift/Parse/Parser.h

@@ -487,9 +487,8 @@ class Parser {
   /// \returns the value returned by \c f
   /// \note When calling, you may need to specify the \c Val type
   ///       explicitly as a type parameter.
-  template <typename Val>
-  Val lookahead(unsigned char K,
-                llvm::function_ref<Val(CancellableBacktrackingScope &)> f) {
+  template <typename Fn>
+  decltype(auto) lookahead(unsigned char K, Fn f) {
     CancellableBacktrackingScope backtrackScope(*this);
 
     for (unsigned char i = 0; i < K; ++i)
@@ -772,6 +771,17 @@ class Parser {
   consumeStartingCharacterOfCurrentToken(tok Kind = tok::oper_binary_unspaced,
                                          size_t Len = 1);
 
+  /// If the next token is \c tok::colon, consume it; if the next token is
+  /// \c tok::colon_colon, split it into two \c tok::colons and consume the
+  /// first; otherwise, do nothing and return false.
+  bool consumeIfColonSplittingDoubles() {
+    if (!Tok.isAny(tok::colon, tok::colon_colon))
+      return false;
+
+    consumeStartingCharacterOfCurrentToken(tok::colon);
+    return true;
+  }
+
   //===--------------------------------------------------------------------===//
   // Primitive Parsing
 
@@ -1063,7 +1073,7 @@ class Parser {
       std::optional<bool> &Exported,
       std::optional<SpecializeAttr::SpecializationKind> &Kind,
       TrailingWhereClause *&TrailingWhereClause, DeclNameRef &targetFunction,
-      AvailabilityRange *SILAvailability,
+      DeclNameLoc &targetFunctionLoc, AvailabilityRange *SILAvailability,
       SmallVectorImpl<Identifier> &spiGroups,
       SmallVectorImpl<AvailableAttr *> &availableAttrs,
       llvm::function_ref<bool(Parser &)> parseSILTargetName,
@@ -1807,6 +1817,19 @@ class Parser {
   void parseOptionalArgumentLabel(Identifier &name, SourceLoc &loc,
                                   bool isAttr = false);
 
+  /// Attempts to parse a \c module-selector if one is present.
+  ///
+  /// \verbatim
+  ///   module-selector: identifier '::'
+  /// \endverbatim
+  ///
+  /// \return \c None if no selector is present or a selector is present but
+  ///         is not allowed; an instance with an empty \c Identifier if a
+  ///         selector is present but has no valid identifier; an instance with
+  ///         a valid \c Identifier if a selector is present and includes a
+  ///         module name.
+  std::optional<Located<Identifier>> parseModuleSelector();
+
   enum class DeclNameFlag : uint8_t {
     /// If passed, operator basenames are allowed.
     AllowOperators = 1 << 0,
@@ -1819,6 +1842,9 @@ class Parser {
     /// not ordinary identifiers.
     AllowKeywordsUsingSpecialNames = AllowKeywords | 1 << 2,
 
+    /// If passed, module selectors are not permitted on this declaration name.
+    ModuleSelectorUnsupported = 1 << 3,
+
     /// If passed, compound names with argument lists are allowed, unless they
     /// have empty argument lists.
     AllowCompoundNames = 1 << 4,
@@ -1830,13 +1856,19 @@ class Parser {
     /// cases this doesn't actually make sense but we need to accept them for
     /// backwards compatibility.
     AllowLowercaseAndUppercaseSelf = 1 << 6,
+
+    /// If passed, `$0` etc. are allowed.
+    AllowAnonymousParamNames = 1 << 7,
   };
   using DeclNameOptions = OptionSet<DeclNameFlag>;
 
   friend DeclNameOptions operator|(DeclNameFlag flag1, DeclNameFlag flag2) {
     return DeclNameOptions(flag1) | flag2;
   }
 
+  /// Parse a declaration name that results in a `DeclNameRef` in the syntax
+  /// tree.
+  /// 
   /// Without \c DeclNameFlag::AllowCompoundNames, parse an
   /// unqualified-decl-base-name.
   ///
@@ -1860,7 +1892,8 @@ class Parser {
       SourceLoc &rightAngleLoc, ArgumentList *&argList, bool isExprBasic,
       DiagRef diag);
 
-  ParserResult<Expr> parseExprIdentifier(bool allowKeyword);
+  ParserResult<Expr> parseExprIdentifier(bool allowKeyword,
+                                         bool allowModuleSelector = true);
   Expr *parseExprEditorPlaceholder(Token PlaceholderTok,
                                    Identifier PlaceholderId);
 

lib/AST/ASTDumper.cpp

@@ -1970,7 +1970,8 @@ namespace {
 
       printFlag(!ABIRoleInfo(D).providesAPI(), "abi_only");
 
-      printSourceRange(D->getSourceRange(), &D->getASTContext());
+      if (D->getStartLoc().isValid() && D->getEndLoc().isValid())
+        printSourceRange(D->getSourceRange(), &D->getASTContext());
       printFlag(D->TrailingSemiLoc.isValid(), "trailing_semi",
                 DeclModifierColor);