Cannot define placement new in any project where another file #includes <new> directly or indirectly

Cannot define placement new in any project where another file #includes <new> directly or indirectly by David Librik

Active

Type:	Bug
ID:	768788
Opened:	10/25/2012 10:24:07 PM
Access Restriction:	Public

Workaround(s)

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User(s) can reproduce this bug

If you have a C++ file in your program which defines a placement new function, and another C++ file which #includes <new> either directly or indirectly (i.e. a different C++ header that happens to #include <new>), you will get multiple LNK2005 errors.

This only happens with the Visual Studio 2012 toolchain. The older toolchains (Visual Studio 2008, 2010) compile and link it just fine.

Details (expand)

Visual Studio 2012

1. Download the attached .zip file, placement-new-error.zip, and unzip it into a working directory.
2. Get a command prompt with Visual Studio 2012 tools (for instance, by running VCVARS32.BAT, or opening "VS 2012 Native Tools Command Prompt"), and CD to the working directory in step 1.
3. Compile and link the two files, file1.cpp and file2.cpp, as follows. (The switch /EHsc is only used to quiet an unrelated warning message.)
cl /EHsc file1.cpp file2.cpp
4. Notice the error messages:
file2.obj : error LNK2005: "void * __cdecl operator new(unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
libcpmt.lib(xthrow.obj) : error LNK2005: "void * __cdecl operator new (unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
libcpmt.lib(syserror.obj) : error LNK2005: "void * __cdecl operator new (unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
file1.exe : fatal error LNK1169: one or more multiply defined symbols found
5. Repeat steps 1-4 with a Visual Studio 2010 command prompt. The files will compile and link with no errors.

English

Windows 7 SP1

English

/out:file1.exe
file1.obj
file2.obj
file2.obj : error LNK2005: "void * __cdecl operator new(unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
libcpmt.lib(xthrow.obj) : error LNK2005: "void * __cdecl operator new (unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
libcpmt.lib(syserror.obj) : error LNK2005: "void * __cdecl operator new (unsigned int,void *)" (??2@YAPAXIPAX@Z) already defined in file1.obj
file1.exe : fatal error LNK1169: one or more multiply defined symbols found

/out:file1.exe
file1.obj
file2.obj

File Name	Submitted By	Submitted On	File Size
placement-new-error.zip	David Librik	10/25/2012	325 bytes
placement-new-error.zip	David Librik	10/25/2012	325 bytes

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