--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/lib/Parse/ParseInit.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,594 @@
+//===--- ParseInit.cpp - Initializer Parsing ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements initializer parsing as specified by C99 6.7.8.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/TokenKinds.h"
+#include "clang/Parse/ParseDiagnostic.h"
+#include "clang/Parse/Parser.h"
+#include "clang/Parse/RAIIObjectsForParser.h"
+#include "clang/Sema/Designator.h"
+#include "clang/Sema/Ownership.h"
+#include "clang/Sema/Scope.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+using namespace clang;
+
+
+/// MayBeDesignationStart - Return true if the current token might be the start
+/// of a designator.  If we can tell it is impossible that it is a designator,
+/// return false.
+bool Parser::MayBeDesignationStart() {
+  switch (Tok.getKind()) {
+  default:
+    return false;
+
+  case tok::period:      // designator: '.' identifier
+    return true;
+
+  case tok::l_square: {  // designator: array-designator
+    if (!PP.getLangOpts().CPlusPlus11)
+      return true;
+
+    // C++11 lambda expressions and C99 designators can be ambiguous all the
+    // way through the closing ']' and to the next character. Handle the easy
+    // cases here, and fall back to tentative parsing if those fail.
+    switch (PP.LookAhead(0).getKind()) {
+    case tok::equal:
+    case tok::ellipsis:
+    case tok::r_square:
+      // Definitely starts a lambda expression.
+      return false;
+
+    case tok::amp:
+    case tok::kw_this:
+    case tok::star:
+    case tok::identifier:
+      // We have to do additional analysis, because these could be the
+      // start of a constant expression or a lambda capture list.
+      break;
+
+    default:
+      // Anything not mentioned above cannot occur following a '[' in a
+      // lambda expression.
+      return true;
+    }
+
+    // Handle the complicated case below.
+    break;
+  }
+  case tok::identifier:  // designation: identifier ':'
+    return PP.LookAhead(0).is(tok::colon);
+  }
+
+  // Parse up to (at most) the token after the closing ']' to determine
+  // whether this is a C99 designator or a lambda.
+  RevertingTentativeParsingAction Tentative(*this);
+
+  LambdaIntroducer Intro;
+  LambdaIntroducerTentativeParse ParseResult;
+  if (ParseLambdaIntroducer(Intro, &ParseResult)) {
+    // Hit and diagnosed an error in a lambda.
+    // FIXME: Tell the caller this happened so they can recover.
+    return true;
+  }
+
+  switch (ParseResult) {
+  case LambdaIntroducerTentativeParse::Success:
+  case LambdaIntroducerTentativeParse::Incomplete:
+    // Might be a lambda-expression. Keep looking.
+    // FIXME: If our tentative parse was not incomplete, parse the lambda from
+    // here rather than throwing away then reparsing the LambdaIntroducer.
+    break;
+
+  case LambdaIntroducerTentativeParse::MessageSend:
+  case LambdaIntroducerTentativeParse::Invalid:
+    // Can't be a lambda-expression. Treat it as a designator.
+    // FIXME: Should we disambiguate against a message-send?
+    return true;
+  }
+
+  // Once we hit the closing square bracket, we look at the next
+  // token. If it's an '=', this is a designator. Otherwise, it's a
+  // lambda expression. This decision favors lambdas over the older
+  // GNU designator syntax, which allows one to omit the '=', but is
+  // consistent with GCC.
+  return Tok.is(tok::equal);
+}
+
+static void CheckArrayDesignatorSyntax(Parser &P, SourceLocation Loc,
+                                       Designation &Desig) {
+  // If we have exactly one array designator, this used the GNU
+  // 'designation: array-designator' extension, otherwise there should be no
+  // designators at all!
+  if (Desig.getNumDesignators() == 1 &&
+      (Desig.getDesignator(0).isArrayDesignator() ||
+       Desig.getDesignator(0).isArrayRangeDesignator()))
+    P.Diag(Loc, diag::ext_gnu_missing_equal_designator);
+  else if (Desig.getNumDesignators() > 0)
+    P.Diag(Loc, diag::err_expected_equal_designator);
+}
+
+/// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production
+/// checking to see if the token stream starts with a designator.
+///
+/// C99:
+///
+///       designation:
+///         designator-list '='
+/// [GNU]   array-designator
+/// [GNU]   identifier ':'
+///
+///       designator-list:
+///         designator
+///         designator-list designator
+///
+///       designator:
+///         array-designator
+///         '.' identifier
+///
+///       array-designator:
+///         '[' constant-expression ']'
+/// [GNU]   '[' constant-expression '...' constant-expression ']'
+///
+/// C++20:
+///
+///       designated-initializer-list:
+///         designated-initializer-clause
+///         designated-initializer-list ',' designated-initializer-clause
+///
+///       designated-initializer-clause:
+///         designator brace-or-equal-initializer
+///
+///       designator:
+///         '.' identifier
+///
+/// We allow the C99 syntax extensions in C++20, but do not allow the C++20
+/// extension (a braced-init-list after the designator with no '=') in C99.
+///
+/// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an
+/// initializer (because it is an expression).  We need to consider this case
+/// when parsing array designators.
+///
+/// \p CodeCompleteCB is called with Designation parsed so far.
+ExprResult Parser::ParseInitializerWithPotentialDesignator(
+    llvm::function_ref<void(const Designation &)> CodeCompleteCB) {
+
+  // If this is the old-style GNU extension:
+  //   designation ::= identifier ':'
+  // Handle it as a field designator.  Otherwise, this must be the start of a
+  // normal expression.
+  if (Tok.is(tok::identifier)) {
+    const IdentifierInfo *FieldName = Tok.getIdentifierInfo();
+
+    SmallString<256> NewSyntax;
+    llvm::raw_svector_ostream(NewSyntax) << '.' << FieldName->getName()
+                                         << " = ";
+
+    SourceLocation NameLoc = ConsumeToken(); // Eat the identifier.
+
+    assert(Tok.is(tok::colon) && "MayBeDesignationStart not working properly!");
+    SourceLocation ColonLoc = ConsumeToken();
+
+    Diag(NameLoc, diag::ext_gnu_old_style_field_designator)
+      << FixItHint::CreateReplacement(SourceRange(NameLoc, ColonLoc),
+                                      NewSyntax);
+
+    Designation D;
+    D.AddDesignator(Designator::getField(FieldName, SourceLocation(), NameLoc));
+    return Actions.ActOnDesignatedInitializer(D, ColonLoc, true,
+                                              ParseInitializer());
+  }
+
+  // Desig - This is initialized when we see our first designator.  We may have
+  // an objc message send with no designator, so we don't want to create this
+  // eagerly.
+  Designation Desig;
+
+  // Parse each designator in the designator list until we find an initializer.
+  while (Tok.is(tok::period) || Tok.is(tok::l_square)) {
+    if (Tok.is(tok::period)) {
+      // designator: '.' identifier
+      SourceLocation DotLoc = ConsumeToken();
+
+      if (Tok.is(tok::code_completion)) {
+        CodeCompleteCB(Desig);
+        cutOffParsing();
+        return ExprError();
+      }
+      if (Tok.isNot(tok::identifier)) {
+        Diag(Tok.getLocation(), diag::err_expected_field_designator);
+        return ExprError();
+      }
+
+      Desig.AddDesignator(Designator::getField(Tok.getIdentifierInfo(), DotLoc,
+                                               Tok.getLocation()));
+      ConsumeToken(); // Eat the identifier.
+      continue;
+    }
+
+    // We must have either an array designator now or an objc message send.
+    assert(Tok.is(tok::l_square) && "Unexpected token!");
+
+    // Handle the two forms of array designator:
+    //   array-designator: '[' constant-expression ']'
+    //   array-designator: '[' constant-expression '...' constant-expression ']'
+    //
+    // Also, we have to handle the case where the expression after the
+    // designator an an objc message send: '[' objc-message-expr ']'.
+    // Interesting cases are:
+    //   [foo bar]         -> objc message send
+    //   [foo]             -> array designator
+    //   [foo ... bar]     -> array designator
+    //   [4][foo bar]      -> obsolete GNU designation with objc message send.
+    //
+    // We do not need to check for an expression starting with [[ here. If it
+    // contains an Objective-C message send, then it is not an ill-formed
+    // attribute. If it is a lambda-expression within an array-designator, then
+    // it will be rejected because a constant-expression cannot begin with a
+    // lambda-expression.
+    InMessageExpressionRAIIObject InMessage(*this, true);
+
+    BalancedDelimiterTracker T(*this, tok::l_square);
+    T.consumeOpen();
+    SourceLocation StartLoc = T.getOpenLocation();
+
+    ExprResult Idx;
+
+    // If Objective-C is enabled and this is a typename (class message
+    // send) or send to 'super', parse this as a message send
+    // expression.  We handle C++ and C separately, since C++ requires
+    // much more complicated parsing.
+    if  (getLangOpts().ObjC && getLangOpts().CPlusPlus) {
+      // Send to 'super'.
+      if (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_super &&
+          NextToken().isNot(tok::period) &&
+          getCurScope()->isInObjcMethodScope()) {
+        CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
+        return ParseAssignmentExprWithObjCMessageExprStart(
+            StartLoc, ConsumeToken(), nullptr, nullptr);
+      }
+
+      // Parse the receiver, which is either a type or an expression.
+      bool IsExpr;
+      void *TypeOrExpr;
+      if (ParseObjCXXMessageReceiver(IsExpr, TypeOrExpr)) {
+        SkipUntil(tok::r_square, StopAtSemi);
+        return ExprError();
+      }
+
+      // If the receiver was a type, we have a class message; parse
+      // the rest of it.
+      if (!IsExpr) {
+        CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
+        return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
+                                                           SourceLocation(),
+                                   ParsedType::getFromOpaquePtr(TypeOrExpr),
+                                                           nullptr);
+      }
+
+      // If the receiver was an expression, we still don't know
+      // whether we have a message send or an array designator; just
+      // adopt the expression for further analysis below.
+      // FIXME: potentially-potentially evaluated expression above?
+      Idx = ExprResult(static_cast<Expr*>(TypeOrExpr));
+    } else if (getLangOpts().ObjC && Tok.is(tok::identifier)) {
+      IdentifierInfo *II = Tok.getIdentifierInfo();
+      SourceLocation IILoc = Tok.getLocation();
+      ParsedType ReceiverType;
+      // Three cases. This is a message send to a type: [type foo]
+      // This is a message send to super:  [super foo]
+      // This is a message sent to an expr:  [super.bar foo]
+      switch (Actions.getObjCMessageKind(
+          getCurScope(), II, IILoc, II == Ident_super,
+          NextToken().is(tok::period), ReceiverType)) {
+      case Sema::ObjCSuperMessage:
+        CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
+        return ParseAssignmentExprWithObjCMessageExprStart(
+            StartLoc, ConsumeToken(), nullptr, nullptr);
+
+      case Sema::ObjCClassMessage:
+        CheckArrayDesignatorSyntax(*this, StartLoc, Desig);
+        ConsumeToken(); // the identifier
+        if (!ReceiverType) {
+          SkipUntil(tok::r_square, StopAtSemi);
+          return ExprError();
+        }
+
+        // Parse type arguments and protocol qualifiers.
+        if (Tok.is(tok::less)) {
+          SourceLocation NewEndLoc;
+          TypeResult NewReceiverType
+            = parseObjCTypeArgsAndProtocolQualifiers(IILoc, ReceiverType,
+                                                     /*consumeLastToken=*/true,
+                                                     NewEndLoc);
+          if (!NewReceiverType.isUsable()) {
+            SkipUntil(tok::r_square, StopAtSemi);
+            return ExprError();
+          }
+
+          ReceiverType = NewReceiverType.get();
+        }
+
+        return ParseAssignmentExprWithObjCMessageExprStart(StartLoc,
+                                                           SourceLocation(),
+                                                           ReceiverType,
+                                                           nullptr);
+
+      case Sema::ObjCInstanceMessage:
+        // Fall through; we'll just parse the expression and
+        // (possibly) treat this like an Objective-C message send
+        // later.
+        break;
+      }
+    }
+
+    // Parse the index expression, if we haven't already gotten one
+    // above (which can only happen in Objective-C++).
+    // Note that we parse this as an assignment expression, not a constant
+    // expression (allowing *=, =, etc) to handle the objc case.  Sema needs
+    // to validate that the expression is a constant.
+    // FIXME: We also need to tell Sema that we're in a
+    // potentially-potentially evaluated context.
+    if (!Idx.get()) {
+      Idx = ParseAssignmentExpression();
+      if (Idx.isInvalid()) {
+        SkipUntil(tok::r_square, StopAtSemi);
+        return Idx;
+      }
+    }
+
+    // Given an expression, we could either have a designator (if the next
+    // tokens are '...' or ']' or an objc message send.  If this is an objc
+    // message send, handle it now.  An objc-message send is the start of
+    // an assignment-expression production.
+    if (getLangOpts().ObjC && Tok.isNot(tok::ellipsis) &&
+        Tok.isNot(tok::r_square)) {
+      CheckArrayDesignatorSyntax(*this, Tok.getLocation(), Desig);
+      return ParseAssignmentExprWithObjCMessageExprStart(
+          StartLoc, SourceLocation(), nullptr, Idx.get());
+    }
+
+    // If this is a normal array designator, remember it.
+    if (Tok.isNot(tok::ellipsis)) {
+      Desig.AddDesignator(Designator::getArray(Idx.get(), StartLoc));
+    } else {
+      // Handle the gnu array range extension.
+      Diag(Tok, diag::ext_gnu_array_range);
+      SourceLocation EllipsisLoc = ConsumeToken();
+
+      ExprResult RHS(ParseConstantExpression());
+      if (RHS.isInvalid()) {
+        SkipUntil(tok::r_square, StopAtSemi);
+        return RHS;
+      }
+      Desig.AddDesignator(Designator::getArrayRange(Idx.get(),
+                                                    RHS.get(),
+                                                    StartLoc, EllipsisLoc));
+    }
+
+    T.consumeClose();
+    Desig.getDesignator(Desig.getNumDesignators() - 1).setRBracketLoc(
+                                                        T.getCloseLocation());
+  }
+
+  // Okay, we're done with the designator sequence.  We know that there must be
+  // at least one designator, because the only case we can get into this method
+  // without a designator is when we have an objc message send.  That case is
+  // handled and returned from above.
+  assert(!Desig.empty() && "Designator is empty?");
+
+  // Handle a normal designator sequence end, which is an equal.
+  if (Tok.is(tok::equal)) {
+    SourceLocation EqualLoc = ConsumeToken();
+    return Actions.ActOnDesignatedInitializer(Desig, EqualLoc, false,
+                                              ParseInitializer());
+  }
+
+  // Handle a C++20 braced designated initialization, which results in
+  // direct-list-initialization of the aggregate element. We allow this as an
+  // extension from C++11 onwards (when direct-list-initialization was added).
+  if (Tok.is(tok::l_brace) && getLangOpts().CPlusPlus11) {
+    return Actions.ActOnDesignatedInitializer(Desig, SourceLocation(), false,
+                                              ParseBraceInitializer());
+  }
+
+  // We read some number of designators and found something that isn't an = or
+  // an initializer.  If we have exactly one array designator, this
+  // is the GNU 'designation: array-designator' extension.  Otherwise, it is a
+  // parse error.
+  if (Desig.getNumDesignators() == 1 &&
+      (Desig.getDesignator(0).isArrayDesignator() ||
+       Desig.getDesignator(0).isArrayRangeDesignator())) {
+    Diag(Tok, diag::ext_gnu_missing_equal_designator)
+      << FixItHint::CreateInsertion(Tok.getLocation(), "= ");
+    return Actions.ActOnDesignatedInitializer(Desig, Tok.getLocation(),
+                                              true, ParseInitializer());
+  }
+
+  Diag(Tok, diag::err_expected_equal_designator);
+  return ExprError();
+}
+
+/// ParseBraceInitializer - Called when parsing an initializer that has a
+/// leading open brace.
+///
+///       initializer: [C99 6.7.8]
+///         '{' initializer-list '}'
+///         '{' initializer-list ',' '}'
+/// [GNU]   '{' '}'
+///
+///       initializer-list:
+///         designation[opt] initializer ...[opt]
+///         initializer-list ',' designation[opt] initializer ...[opt]
+///
+ExprResult Parser::ParseBraceInitializer() {
+  InMessageExpressionRAIIObject InMessage(*this, false);
+
+  BalancedDelimiterTracker T(*this, tok::l_brace);
+  T.consumeOpen();
+  SourceLocation LBraceLoc = T.getOpenLocation();
+
+  /// InitExprs - This is the actual list of expressions contained in the
+  /// initializer.
+  ExprVector InitExprs;
+
+  if (Tok.is(tok::r_brace)) {
+    // Empty initializers are a C++ feature and a GNU extension to C.
+    if (!getLangOpts().CPlusPlus)
+      Diag(LBraceLoc, diag::ext_gnu_empty_initializer);
+    // Match the '}'.
+    return Actions.ActOnInitList(LBraceLoc, None, ConsumeBrace());
+  }
+
+  // Enter an appropriate expression evaluation context for an initializer list.
+  EnterExpressionEvaluationContext EnterContext(
+      Actions, EnterExpressionEvaluationContext::InitList);
+
+  bool InitExprsOk = true;
+  auto CodeCompleteDesignation = [&](const Designation &D) {
+    Actions.CodeCompleteDesignator(PreferredType.get(T.getOpenLocation()),
+                                   InitExprs, D);
+  };
+
+  while (1) {
+    // Handle Microsoft __if_exists/if_not_exists if necessary.
+    if (getLangOpts().MicrosoftExt && (Tok.is(tok::kw___if_exists) ||
+        Tok.is(tok::kw___if_not_exists))) {
+      if (ParseMicrosoftIfExistsBraceInitializer(InitExprs, InitExprsOk)) {
+        if (Tok.isNot(tok::comma)) break;
+        ConsumeToken();
+      }
+      if (Tok.is(tok::r_brace)) break;
+      continue;
+    }
+
+    // Parse: designation[opt] initializer
+
+    // If we know that this cannot be a designation, just parse the nested
+    // initializer directly.
+    ExprResult SubElt;
+    if (MayBeDesignationStart())
+      SubElt = ParseInitializerWithPotentialDesignator(CodeCompleteDesignation);
+    else
+      SubElt = ParseInitializer();
+
+    if (Tok.is(tok::ellipsis))
+      SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());
+
+    SubElt = Actions.CorrectDelayedTyposInExpr(SubElt.get());
+
+    // If we couldn't parse the subelement, bail out.
+    if (SubElt.isUsable()) {
+      InitExprs.push_back(SubElt.get());
+    } else {
+      InitExprsOk = false;
+
+      // We have two ways to try to recover from this error: if the code looks
+      // grammatically ok (i.e. we have a comma coming up) try to continue
+      // parsing the rest of the initializer.  This allows us to emit
+      // diagnostics for later elements that we find.  If we don't see a comma,
+      // assume there is a parse error, and just skip to recover.
+      // FIXME: This comment doesn't sound right. If there is a r_brace
+      // immediately, it can't be an error, since there is no other way of
+      // leaving this loop except through this if.
+      if (Tok.isNot(tok::comma)) {
+        SkipUntil(tok::r_brace, StopBeforeMatch);
+        break;
+      }
+    }
+
+    // If we don't have a comma continued list, we're done.
+    if (Tok.isNot(tok::comma)) break;
+
+    // TODO: save comma locations if some client cares.
+    ConsumeToken();
+
+    // Handle trailing comma.
+    if (Tok.is(tok::r_brace)) break;
+  }
+
+  bool closed = !T.consumeClose();
+
+  if (InitExprsOk && closed)
+    return Actions.ActOnInitList(LBraceLoc, InitExprs,
+                                 T.getCloseLocation());
+
+  return ExprError(); // an error occurred.
+}
+
+
+// Return true if a comma (or closing brace) is necessary after the
+// __if_exists/if_not_exists statement.
+bool Parser::ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
+                                                    bool &InitExprsOk) {
+  bool trailingComma = false;
+  IfExistsCondition Result;
+  if (ParseMicrosoftIfExistsCondition(Result))
+    return false;
+
+  BalancedDelimiterTracker Braces(*this, tok::l_brace);
+  if (Braces.consumeOpen()) {
+    Diag(Tok, diag::err_expected) << tok::l_brace;
+    return false;
+  }
+
+  switch (Result.Behavior) {
+  case IEB_Parse:
+    // Parse the declarations below.
+    break;
+
+  case IEB_Dependent:
+    Diag(Result.KeywordLoc, diag::warn_microsoft_dependent_exists)
+      << Result.IsIfExists;
+    // Fall through to skip.
+    LLVM_FALLTHROUGH;
+
+  case IEB_Skip:
+    Braces.skipToEnd();
+    return false;
+  }
+
+  auto CodeCompleteDesignation = [&](const Designation &D) {
+    Actions.CodeCompleteDesignator(PreferredType.get(Braces.getOpenLocation()),
+                                   InitExprs, D);
+  };
+  while (!isEofOrEom()) {
+    trailingComma = false;
+    // If we know that this cannot be a designation, just parse the nested
+    // initializer directly.
+    ExprResult SubElt;
+    if (MayBeDesignationStart())
+      SubElt = ParseInitializerWithPotentialDesignator(CodeCompleteDesignation);
+    else
+      SubElt = ParseInitializer();
+
+    if (Tok.is(tok::ellipsis))
+      SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken());
+
+    // If we couldn't parse the subelement, bail out.
+    if (!SubElt.isInvalid())
+      InitExprs.push_back(SubElt.get());
+    else
+      InitExprsOk = false;
+
+    if (Tok.is(tok::comma)) {
+      ConsumeToken();
+      trailingComma = true;
+    }
+
+    if (Tok.is(tok::r_brace))
+      break;
+  }
+
+  Braces.consumeClose();
+
+  return !trailingComma;
+}