path: root/lib/Sema/SemaChecking.cpp

//===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements extra semantic analysis beyond what is enforced 
//  by the C type system.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/Lex/Preprocessor.h"
using namespace clang;

/// CheckFunctionCall - Check a direct function call for various correctness
/// and safety properties not strictly enforced by the C type system.
Action::OwningExprResult
Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
  OwningExprResult TheCallResult(Owned(TheCall));
  // Get the IdentifierInfo* for the called function.
  IdentifierInfo *FnInfo = FDecl->getIdentifier();

  // None of the checks below are needed for functions that don't have
  // simple names (e.g., C++ conversion functions).
  if (!FnInfo)
    return move(TheCallResult);

  switch (FDecl->getBuiltinID(Context)) {
  case Builtin::BI__builtin___CFStringMakeConstantString:
    assert(TheCall->getNumArgs() == 1 &&
           "Wrong # arguments to builtin CFStringMakeConstantString");
    if (CheckBuiltinCFStringArgument(TheCall->getArg(0)))
      return ExprError();
    return move(TheCallResult);
  case Builtin::BI__builtin_stdarg_start:
  case Builtin::BI__builtin_va_start:
    if (SemaBuiltinVAStart(TheCall))
      return ExprError();
    return move(TheCallResult);
  case Builtin::BI__builtin_isgreater:
  case Builtin::BI__builtin_isgreaterequal:
  case Builtin::BI__builtin_isless:
  case Builtin::BI__builtin_islessequal:
  case Builtin::BI__builtin_islessgreater:
  case Builtin::BI__builtin_isunordered:
    if (SemaBuiltinUnorderedCompare(TheCall))
      return ExprError();
    return move(TheCallResult);
  case Builtin::BI__builtin_return_address:
  case Builtin::BI__builtin_frame_address:
    if (SemaBuiltinStackAddress(TheCall))
      return ExprError();
    return move(TheCallResult);
  case Builtin::BI__builtin_shufflevector:
    return SemaBuiltinShuffleVector(TheCall);
    // TheCall will be freed by the smart pointer here, but that's fine, since
    // SemaBuiltinShuffleVector guts it, but then doesn't release it.
  case Builtin::BI__builtin_prefetch:
    if (SemaBuiltinPrefetch(TheCall))
      return ExprError();
    return move(TheCallResult);
  case Builtin::BI__builtin_object_size:
    if (SemaBuiltinObjectSize(TheCall))
      return ExprError();
  }

  // FIXME: This mechanism should be abstracted to be less fragile and
  // more efficient. For example, just map function ids to custom
  // handlers.

  // Printf checking.
  if (const FormatAttr *Format = FDecl->getAttr<FormatAttr>()) {
    if (Format->getType() == "printf") {
      bool HasVAListArg = false;
      if (const FunctionTypeProto *Proto 
          = FDecl->getType()->getAsFunctionTypeProto())
        HasVAListArg = !Proto->isVariadic();
      CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
                           Format->getFirstArg() - 1);
    }
  }

  return move(TheCallResult);
}

/// CheckBuiltinCFStringArgument - Checks that the argument to the builtin
/// CFString constructor is correct
bool Sema::CheckBuiltinCFStringArgument(Expr* Arg) {
  Arg = Arg->IgnoreParenCasts();
  
  StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);

  if (!Literal || Literal->isWide()) {
    Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
      << Arg->getSourceRange();
    return true;
  }
  
  const char *Data = Literal->getStrData();
  unsigned Length = Literal->getByteLength();
  
  for (unsigned i = 0; i < Length; ++i) {
    if (!isascii(Data[i])) {
      Diag(PP.AdvanceToTokenCharacter(Arg->getLocStart(), i + 1),
           diag::warn_cfstring_literal_contains_non_ascii_character)
        << Arg->getSourceRange();
      break;
    }
    
    if (!Data[i]) {
      Diag(PP.AdvanceToTokenCharacter(Arg->getLocStart(), i + 1),
           diag::warn_cfstring_literal_contains_nul_character)
        << Arg->getSourceRange();
      break;
    }
  }
  
  return false;
}

/// SemaBuiltinVAStart - Check the arguments to __builtin_va_start for validity.
/// Emit an error and return true on failure, return false on success.
bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
  Expr *Fn = TheCall->getCall