C++ Sema::Diag方法代码示例

static void HandleDLLImportAttr(Decl *D, const AttributeList &Attr, Sema &S) {
  // Attribute can be applied only to functions or variables.
  FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
  if (!FD && !isa<VarDecl>(D)) {
    // Apparently Visual C++ thinks it is okay to not emit a warning
    // in this case, so only emit a warning when -fms-extensions is not
    // specified.
    if (!S.getLangOpts().MicrosoftExt)
      S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
        << Attr.getName() << 2 /*variable and function*/;
    return;
  }

  // Currently, the dllimport attribute is ignored for inlined functions.
  // Warning is emitted.
  if (FD && FD->isInlineSpecified()) {
    S.Diag(Attr.getLoc(), diag::warn_attribute_ignored) << Attr.getName();
    return;
  }

  unsigned Index = Attr.getAttributeSpellingListIndex();
  DLLImportAttr *NewAttr = S.mergeDLLImportAttr(D, Attr.getRange(), Index);
  if (NewAttr)
    D->addAttr(NewAttr);
}

/// TryStaticMemberPointerUpcast - Tests whether a conversion according to
/// C++ 5.2.9p9 is valid:
///
///   An rvalue of type "pointer to member of D of type cv1 T" can be
///   converted to an rvalue of type "pointer to member of B of type cv2 T",
///   where B is a base class of D [...].
///
TryCastResult
TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType,
                             bool CStyle, const SourceRange &OpRange,
                             unsigned &msg)
{
  const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
  if (!DestMemPtr)
    return TC_NotApplicable;
  const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
  if (!SrcMemPtr) {
    msg = diag::err_bad_static_cast_member_pointer_nonmp;
    return TC_NotApplicable;
  }

  // T == T, modulo cv
  if (Self.Context.getCanonicalType(
        SrcMemPtr->getPointeeType().getUnqualifiedType()) !=
      Self.Context.getCanonicalType(DestMemPtr->getPointeeType().
                                    getUnqualifiedType()))
    return TC_NotApplicable;

  // B base of D
  QualType SrcClass(SrcMemPtr->getClass(), 0);
  QualType DestClass(DestMemPtr->getClass(), 0);
  BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle,
                  /*DetectVirtual=*/true);
  if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) {
    return TC_NotApplicable;
  }

  // B is a base of D. But is it an allowed base? If not, it's a hard error.
  if (Paths.isAmbiguous(DestClass)) {
    Paths.clear();
    Paths.setRecordingPaths(true);
    bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths);
    assert(StillOkay);
    StillOkay = StillOkay;
    std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
    Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
      << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
    msg = 0;
    return TC_Failed;
  }

  if (const RecordType *VBase = Paths.getDetectedVirtual()) {
    Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
      << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
    msg = 0;
    return TC_Failed;
  }

  if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType,
                          diag::err_downcast_from_inaccessible_base, Paths,
                          OpRange.getBegin(), DeclarationName())) {
    msg = 0;
    return TC_Failed;
  }

  return TC_Success;
}

static void HandleMSP430InterruptAttr(Decl *d,
                                      const AttributeList &Attr, Sema &S) {
  if (Attr.getNumArgs() != 1) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments)
      << Attr.getName() << 1;
    return;
  }

  if (!Attr.isArgExpr(0)) {
    S.Diag(Attr.getLoc(), diag::err_attribute_argument_type) << Attr.getName()
      << AANT_ArgumentIntegerConstant;
    return;
  }

  // FIXME: Check for decl - it should be void ()(void).
  Expr *NumParamsExpr = Attr.getArgAsExpr(0);
  llvm::APSInt NumParams(32);
  if (!NumParamsExpr->isIntegerConstantExpr(NumParams, S.Context)) {
    S.Diag(Attr.getLoc(), diag::err_attribute_argument_type)
      << Attr.getName() << AANT_ArgumentIntegerConstant
      << NumParamsExpr->getSourceRange();
    return;
  }

  unsigned Num = NumParams.getLimitedValue(255);
  if ((Num & 1) || Num > 30) {
    S.Diag(Attr.getLoc(), diag::err_attribute_argument_out_of_bounds)
      << "interrupt" << (int)NumParams.getSExtValue()
      << NumParamsExpr->getSourceRange();
    return;
  }

  d->addAttr(::new (S.Context) MSP430InterruptAttr(Attr.getLoc(), S.Context, Num));
  d->addAttr(::new (S.Context) UsedAttr(Attr.getLoc(), S.Context));
}

/// checkUndefinedInternals - Check for undefined objects with internal linkage.
static void checkUndefinedInternals(Sema &S) {
  if (S.UndefinedInternals.empty()) return;

  // Collect all the still-undefined entities with internal linkage.
  SmallVector<UndefinedInternal, 16> undefined;
  for (llvm::MapVector<NamedDecl*,SourceLocation>::iterator
         i = S.UndefinedInternals.begin(), e = S.UndefinedInternals.end();
       i != e; ++i) {
    NamedDecl *decl = i->first;

    // Ignore attributes that have become invalid.
    if (decl->isInvalidDecl()) continue;

    // If we found out that the decl is external, don't warn.
    if (decl->getLinkage() == ExternalLinkage) continue;

    // __attribute__((weakref)) is basically a definition.
    if (decl->hasAttr<WeakRefAttr>()) continue;

    if (FunctionDecl *fn = dyn_cast<FunctionDecl>(decl)) {
      if (fn->isPure() || fn->hasBody())
        continue;
    } else {
      if (cast<VarDecl>(decl)->hasDefinition() != VarDecl::DeclarationOnly)
        continue;
    }

    S.Diag(decl->getLocation(), diag::warn_undefined_internal)
      << isa<VarDecl>(decl) << decl;
    S.Diag(i->second, diag::note_used_here);
  }
}

static bool CheckNakedParmReference(Expr *E, Sema &S) {
  FunctionDecl *Func = dyn_cast<FunctionDecl>(S.CurContext);
  if (!Func)
    return false;
  if (!Func->hasAttr<NakedAttr>())
    return false;

  SmallVector<Expr*, 4> WorkList;
  WorkList.push_back(E);
  while (WorkList.size()) {
    Expr *E = WorkList.pop_back_val();
    if (isa<CXXThisExpr>(E)) {
      S.Diag(E->getLocStart(), diag::err_asm_naked_this_ref);
      S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
      return true;
    }
    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
      if (isa<ParmVarDecl>(DRE->getDecl())) {
        S.Diag(DRE->getLocStart(), diag::err_asm_naked_parm_ref);
        S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
        return true;
      }
    }
    for (Stmt *Child : E->children()) {
      if (Expr *E = dyn_cast_or_null<Expr>(Child))
        WorkList.push_back(E);
    }
  }
  return false;
}

/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
/// ignore "noop" casts in places where an lvalue is required by an inline asm.
/// We emulate this behavior when -fheinous-gnu-extensions is specified, but
/// provide a strong guidance to not use it.
///
/// This method checks to see if the argument is an acceptable l-value and
/// returns false if it is a case we can handle.
static bool CheckAsmLValue(const Expr *E, Sema &S) {
  // Type dependent expressions will be checked during instantiation.
  if (E->isTypeDependent())
    return false;

  if (E->isLValue())
    return false;  // Cool, this is an lvalue.

  // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
  // are supposed to allow.
  const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
  if (E != E2 && E2->isLValue()) {
    if (!S.getLangOpts().HeinousExtensions)
      S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
        << E->getSourceRange();
    else
      S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
        << E->getSourceRange();
    // Accept, even if we emitted an error diagnostic.
    return false;
  }

  // None of the above, just randomly invalid non-lvalue.
  return true;
}

static void HandleX86ForceAlignArgPointerAttr(Decl *D,
                                              const AttributeList& Attr,
                                              Sema &S) {
  // Check the attribute arguments.
  if (Attr.getNumArgs() != 0) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
    return;
  }

  // If we try to apply it to a function pointer, don't warn, but don't
  // do anything, either. It doesn't matter anyway, because there's nothing
  // special about calling a force_align_arg_pointer function.
  ValueDecl *VD = dyn_cast<ValueDecl>(D);
  if (VD && VD->getType()->isFunctionPointerType())
    return;
  // Also don't warn on function pointer typedefs.
  TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D);
  if (TD && (TD->getUnderlyingType()->isFunctionPointerType() ||
             TD->getUnderlyingType()->isFunctionType()))
    return;
  // Attribute can only be applied to function types.
  if (!isa<FunctionDecl>(D)) {
    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
      << Attr.getName() << /* function */0;
    return;
  }

  D->addAttr(::new (S.Context) X86ForceAlignArgPointerAttr(Attr.getRange(),
                                                           S.Context));
}

static void HandleDLLExportAttr(Decl *D, const AttributeList &Attr, Sema &S) {
  // check the attribute arguments.
  if (Attr.getNumArgs() != 0) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
    return;
  }

  // Attribute can be applied only to functions or variables.
  FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
  if (!FD && !isa<VarDecl>(D)) {
    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
      << Attr.getName() << 2 /*variable and function*/;
    return;
  }

  // Currently, the dllexport attribute is ignored for inlined functions, unless
  // the -fkeep-inline-functions flag has been used. Warning is emitted;
  if (FD && FD->isInlineSpecified()) {
    // FIXME: ... unless the -fkeep-inline-functions flag has been used.
    S.Diag(Attr.getLoc(), diag::warn_attribute_ignored) << "dllexport";
    return;
  }

  unsigned Index = Attr.getAttributeSpellingListIndex();
  DLLExportAttr *NewAttr = S.mergeDLLExportAttr(D, Attr.getRange(), Index);
  if (NewAttr)
    D->addAttr(NewAttr);
}

/// HandleObjCGCTypeAttribute - Process an objc's gc attribute on the
/// specified type.  The attribute contains 1 argument, weak or strong.
static void HandleObjCGCTypeAttribute(QualType &Type, 
                                      const AttributeList &Attr, Sema &S) {
  if (Type.getObjCGCAttr() != QualType::GCNone) {
    S.Diag(Attr.getLoc(), diag::err_attribute_multiple_objc_gc);
    return;
  }
  
  // Check the attribute arguments.
  if (!Attr.getParameterName()) {    
    S.Diag(Attr.getLoc(), diag::err_attribute_argument_n_not_string)
      << "objc_gc" << 1;
    return;
  }
  QualType::GCAttrTypes GCAttr;
  if (Attr.getNumArgs() != 0) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 1;
    return;
  }
  if (Attr.getParameterName()->isStr("weak")) 
    GCAttr = QualType::Weak;
  else if (Attr.getParameterName()->isStr("strong"))
    GCAttr = QualType::Strong;
  else {
    S.Diag(Attr.getLoc(), diag::warn_attribute_type_not_supported)
      << "objc_gc" << Attr.getParameterName();
    return;
  }
  
  Type = S.Context.getObjCGCQualType(Type, GCAttr);
}

static void HandleDLLExportAttr(Decl *D, const AttributeList &Attr, Sema &S) {
  // check the attribute arguments.
  if (Attr.getNumArgs() != 0) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
    return;
  }

  // Attribute can be applied only to functions or variables.
  if (isa<VarDecl>(D)) {
    D->addAttr(::new (S.Context) DLLExportAttr(Attr.getLoc(), S.Context));
    return;
  }

  FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
  if (!FD) {
    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
      << Attr.getName() << 2 /*variable and function*/;
    return;
  }

  // Currently, the dllexport attribute is ignored for inlined functions, unless
  // the -fkeep-inline-functions flag has been used. Warning is emitted;
  if (FD->isInlineSpecified()) {
    // FIXME: ... unless the -fkeep-inline-functions flag has been used.
    S.Diag(Attr.getLoc(), diag::warn_attribute_ignored) << "dllexport";
    return;
  }

  D->addAttr(::new (S.Context) DLLExportAttr(Attr.getLoc(), S.Context));
}

static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
                                    StringRef Keyword) {
  // 'co_await' and 'co_yield' are not permitted in unevaluated operands.
  if (S.isUnevaluatedContext()) {
    S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
    return false;
  }

  // Any other usage must be within a function.
  auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
  if (!FD) {
    S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
                    ? diag::err_coroutine_objc_method
                    : diag::err_coroutine_outside_function) << Keyword;
    return false;
  }

  // An enumeration for mapping the diagnostic type to the correct diagnostic
  // selection index.
  enum InvalidFuncDiag {
    DiagCtor = 0,
    DiagDtor,
    DiagCopyAssign,
    DiagMoveAssign,
    DiagMain,
    DiagConstexpr,
    DiagAutoRet,
    DiagVarargs,
  };
  bool Diagnosed = false;
  auto DiagInvalid = [&](InvalidFuncDiag ID) {
    S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
    Diagnosed = true;
    return false;
  };

  // Diagnose when a constructor, destructor, copy/move assignment operator,
  // or the function 'main' are declared as a coroutine.
  auto *MD = dyn_cast<CXXMethodDecl>(FD);
  if (MD && isa<CXXConstructorDecl>(MD))
    return DiagInvalid(DiagCtor);
  else if (MD && isa<CXXDestructorDecl>(MD))
    return DiagInvalid(DiagDtor);
  else if (MD && MD->isCopyAssignmentOperator())
    return DiagInvalid(DiagCopyAssign);
  else if (MD && MD->isMoveAssignmentOperator())
    return DiagInvalid(DiagMoveAssign);
  else if (FD->isMain())
    return DiagInvalid(DiagMain);

  // Emit a diagnostics for each of the following conditions which is not met.
  if (FD->isConstexpr())
    DiagInvalid(DiagConstexpr);
  if (FD->getReturnType()->isUndeducedType())
    DiagInvalid(DiagAutoRet);
  if (FD->isVariadic())
    DiagInvalid(DiagVarargs);

  return !Diagnosed;
}

/// HandleAddressSpaceTypeAttribute - Process an address_space attribute on the
/// specified type.  The attribute contains 1 argument, the id of the address
/// space for the type.
static void HandleAddressSpaceTypeAttribute(QualType &Type, 
                                            const AttributeList &Attr, Sema &S){
  // If this type is already address space qualified, reject it.
  // Clause 6.7.3 - Type qualifiers: "No type shall be qualified by qualifiers
  // for two or more different address spaces."
  if (Type.getAddressSpace()) {
    S.Diag(Attr.getLoc(), diag::err_attribute_address_multiple_qualifiers);
    return;
  }
  
  // Check the attribute arguments.
  if (Attr.getNumArgs() != 1) {
    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 1;
    return;
  }
  Expr *ASArgExpr = static_cast<Expr *>(Attr.getArg(0));
  llvm::APSInt addrSpace(32);
  if (!ASArgExpr->isIntegerConstantExpr(addrSpace, S.Context)) {
    S.Diag(Attr.getLoc(), diag::err_attribute_address_space_not_int)
      << ASArgExpr->getSourceRange();
    return;
  }

  unsigned ASIdx = static_cast<unsigned>(addrSpace.getZExtValue()); 
  Type = S.Context.getAddrSpaceQualType(Type, ASIdx);
}

static void HandleARMInterruptAttr(Decl *d,
                                   const AttributeList &Attr, Sema &S) {
  // Check the attribute arguments.
  if (Attr.getNumArgs() > 1) {
    S.Diag(Attr.getLoc(), diag::err_attribute_too_many_arguments)
        << 1;
    return;
  }

  StringRef Str;
  SourceLocation ArgLoc;

  if (Attr.getNumArgs() == 0)
    Str = "";
  else if (!S.checkStringLiteralArgumentAttr(Attr, 0, Str, &ArgLoc))
    return;

  ARMInterruptAttr::InterruptType Kind;
  if (!ARMInterruptAttr::ConvertStrToInterruptType(Str, Kind)) {
    S.Diag(Attr.getLoc(), diag::warn_attribute_type_not_supported)
        << Attr.getName() << Str << ArgLoc;
    return;
  }

  unsigned Index = Attr.getAttributeSpellingListIndex();
  d->addAttr(::new (S.Context)
             ARMInterruptAttr(Attr.getLoc(), S.Context, Kind, Index));
}

/// Build calls to await_ready, await_suspend, and await_resume for a co_await
/// expression.
static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
                                                  SourceLocation Loc, Expr *E) {
  OpaqueValueExpr *Operand = new (S.Context)
      OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);

  // Assume invalid until we see otherwise.
  ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};

  ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
  if (CoroHandleRes.isInvalid())
    return Calls;
  Expr *CoroHandle = CoroHandleRes.get();

  const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
  MultiExprArg Args[] = {None, CoroHandle, None};
  for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
    ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
    if (Result.isInvalid())
      return Calls;
    Calls.Results[I] = Result.get();
  }

  // Assume the calls are valid; all further checking should make them invalid.
  Calls.IsInvalid = false;

  using ACT = ReadySuspendResumeResult::AwaitCallType;
  CallExpr *AwaitReady = cast<CallExpr>(Calls.Results[ACT::ACT_Ready]);
  if (!AwaitReady->getType()->isDependentType()) {
    // [expr.await]p3 [...]
    // — await-ready is the expression e.await_ready(), contextually converted
    // to bool.
    ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
    if (Conv.isInvalid()) {
      S.Diag(AwaitReady->getDirectCallee()->getLocStart(),
             diag::note_await_ready_no_bool_conversion);
      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
          << AwaitReady->getDirectCallee() << E->getSourceRange();
      Calls.IsInvalid = true;
    }
    Calls.Results[ACT::ACT_Ready] = Conv.get();
  }
  CallExpr *AwaitSuspend = cast<CallExpr>(Calls.Results[ACT::ACT_Suspend]);
  if (!AwaitSuspend->getType()->isDependentType()) {
    // [expr.await]p3 [...]
    //   - await-suspend is the expression e.await_suspend(h), which shall be
    //     a prvalue of type void or bool.
    QualType RetType = AwaitSuspend->getType();
    if (RetType != S.Context.BoolTy && RetType != S.Context.VoidTy) {
      S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
             diag::err_await_suspend_invalid_return_type)
          << RetType;
      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
          << AwaitSuspend->getDirectCallee();
      Calls.IsInvalid = true;
    }
  }

  return Calls;
}

/// Produce primary diagnostic for an indirect jump statement.
static void DiagnoseIndirectJumpStmt(Sema &S, IndirectGotoStmt *Jump,
                                     LabelDecl *Target, bool &Diagnosed) {
  if (Diagnosed)
    return;
  S.Diag(Jump->getGotoLoc(), diag::err_indirect_goto_in_protected_scope);
  S.Diag(Target->getStmt()->getIdentLoc(), diag::note_indirect_goto_target);
  Diagnosed = true;
}