Microsoft Compatibility

Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

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ID 767253

Date 9/08/2022

Version

Public

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Microsoft Compatibility

The Intel® oneAPI DPC++/C++ Compiler is fully source- and binary-compatible (native code only) with Microsoft Visual C++ (MSVC). You can debug binaries built with the Intel® oneAPI DPC++/C++ Compiler from within the Microsoft Visual Studio environment.

The compiler supports security checks with the /GS option. You can control this option in the Microsoft Visual Studio IDE by using C/C++ > Code Generation > Buffer Security Check.

Microsoft Visual Studio Integration

The compiler is compatible with Microsoft Visual Studio 2017, 2019, and 2022 projects.

NOTE:

Support for Microsoft Visual Studio 2017 is deprecated as of the Intel® oneAPI 2022.1 release, and will be removed in a future release.

Unsupported Features

Unsupported project types:

.NET-based CLR C++ project types are not supported by the Intel® oneAPI DPC++/C++ Compiler. The specific project types will vary depending on your version of Visual Studio, for example:
- CLR Class Library
- CLR Console App
- CLR Empty Project

Unsupported major features:

COM Attributes
C++ Accelerated Massive Parallelism (C++ AMP)
Managed extensions for C++ (new pragmas, keywords, and command-line options)
Event handling (new keywords)
Select keywords:
- __abstract
- __box
- __delegate
- __gc
- __identifier
- __nogc
- __pin
- __property
- __sealed
- __try_cast
- __w64

Unsupported preprocessor features:

#import directive changes for attributed code
#using directive
managed, unmanaged pragmas
_MANAGED macro
runtime_checks pragma

Mix Managed and Unmanaged Code

If you use the managed extensions to the C++ language in Microsoft Visual Studio .NET, you can use the compiler for your non-managed code for better application performance. Make sure managed keywords do not appear in your non-managed code.

For information on how to mix managed and unmanaged code, refer to the article, An Overview of Managed/Unmanaged Code Interoperability, on the Microsoft Web site.

Precompiled Header Support

There are some differences in how precompiled header (PCH) files are supported between the Intel® oneAPI DPC++/C++ Compiler and the Microsoft Visual C++ Compiler:

The PCH information generated by the Intel oneAPI DPC++/C++ Compiler is not compatible with the PCH information generated by the Microsoft Visual Studio Compiler.
The Intel oneAPI DPC++/C++ Compiler does not support PCH generation and use in the same translation unit.

Compilation and Execution Differences

While the Intel® oneAPI DPC++/C++ Compiler is compatible with the Microsoft Visual C++ Compiler, some differences can prevent successful compilation. There can also be some incompatible generated-code behavior of some source files with the Intel oneAPI DPC++/C++ Compiler. In most cases, a modification of the user source file enables successful compilation with both the Intel oneAPI DPC++/C++ Compiler and the Microsoft Visual C++ Compiler. The differences between the compilers are:

Inlining Functions Marked for dllimport

The Intel oneAPI DPC++/C++ Compiler will attempt to inline any functions that are marked dllimport but Microsoft will not. Therefore, any calls or variables used inside a dllimport routine need to be available at link time or the result will be an unresolved symbol.

The following example contains two files: header.h and bug.cpp.

header.h:

#ifndef _HEADER_H
#define _HEADER_H
namespace Foo_NS { 

        class Foo2 { 
        public: 
                Foo2(){}; 
                ~Foo2(); 
                static int test(int m_i); 
        }; 
} 
#endif

bug.cpp:

#include “header.h”
struct Foo2 { 
  static void test(); 
}; 

struct __declspec(dllimport) Foo 
{ 
   void getI() { Foo2::test(); }; 
}; 

struct C  { 
  virtual void test(); 
}; 

void C::test() { Foo p;  p->getI(); } 

int main() { 
   return 0; 
}

Enum Bit-field Signedness

The Intel® oneAPI DPC++/C++ Compiler and Microsoft Visual C++ differ in how they attribute signedness to bit fields declared with an enum type. Microsoft Visual C++ always considers enum bit fields to be signed, even if not all values of the enum type can be represented by the bit field.

The Intel oneAPI DPC++/C++ Compiler considers an enum bit field to be unsigned, unless the enum type has at least one enum constant with a negative value. In any case, the Intel oneAPI DPC++/C++ Compiler produces a warning if the bit field is declared with too few bits to represent all the values of the enum type.

Parent topic: Compatibility and Portability

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