[Bug]: Multiple Definition Linker Error for IID_IUnknown #193

chapterjason · 2024-03-04T14:58:06Z

bit7z version

4.0.x

Compilation options

No response

7-zip version

v23.01

7-zip shared library used

7z.dll / 7z.so

Compilers

MinGW

Compiler versions

MinGW 11.0 w64, bundles in CLion IDE, GCC 13.1.0

Architecture

x86_64

Operating system

Windows

Operating system versions

Windows 11

Bug description

The linker fails with a "multiple definition" error for IID_IUnknown. This symbol conflict arises because IID_IUnknown is defined both in the bit7z library (libbit7z64_d.a) and MinGW's libuuid.a.

Steps to reproduce

Nothing special, just added as following in CMake:

CPMAddPackage(
    NAME bit7z
    GIT_REPOSITORY "[email protected]:rikyoz/bit7z.git"
    GIT_TAG master
    OPTIONS
        "BIT7Z_BUILD_TESTS false"
        "BIT7Z_BUILD_DOCS false"
)

target_link_libraries(${PROJECT_NAME} [...] bit7z)

Expected behavior

No response

Relevant compilation output

-- CPM: Adding package bit7z@ (master)
-- Standard filesystem: NO (using ghc::filesystem)
-- Target Version: 1.0.0
-- Compiler ID: GNU
-- Compiler Version: 13.1.0
-- Architecture: x64
-- Build Type: Debug
-- Language Standard for bit7z: C++14
-- Auto format detection: OFF
-- Regex matching extraction: OFF
-- Use std::byte: OFF
-- Use native string: OFF
-- Generate Position Independent Code: OFF
-- Disable Zip ASCII password check: OFF
-- Disable using std::filesystem: OFF
-- 7-zip version: 23.01
-- Build tests: false
-- Build docs: false
-- Auto prefix long paths: OFF
-- Use the default codepage: OFF
-- Path sanitization: OFF
-- CPM: bit7z: Adding package [email protected] (v23.01)
-- 7-zip source code available at [...]/cmake-build-debug/_deps/7-zip-src
-- CPM: bit7z: Adding package ghc_filesystem@0 (c0dcd0b090da7dffc74b124a6f164f54dbbb5ccb)
-- ghc::filesystem source code available at [...]/cmake-build-debug/_deps/ghc_filesystem-src
-- Enable sanitizers: OFF

[...]mingw\bin/ld.exe:
[...]mingw/bin/../lib/gcc/x86_64-w64-mingw32/13.1.0/../../../../x86_64-w64-mingw32/lib/../lib/libuuid.a(lib64_libuuid_a-uuid.o):uuid.c:(.rdata$IID_IUnknown[IID_IUnknown]+0x0):
multiple definition of `IID_IUnknown'; _deps/bit7z-src/lib/x64/libbit7z64_d.a(guids.cpp.obj):
[...]/cmake-build-debug/_deps/bit7z-src/src/internal/guids.cpp:19: first defined here



### Code of Conduct

- [X] By submitting this issue, I agree to follow bit7z's [Code of Conduct](https://github.com/rikyoz/bit7z/blob/master/CODE_OF_CONDUCT.md)

The text was updated successfully, but these errors were encountered:

chapterjason · 2024-03-04T16:53:55Z

This fixes the issue for me.

File guids.hpp

 #ifndef _MSC_VER
+#ifndef __MINGW32__
 extern const GUID IID_IUnknown;
+#endif
 #endif

File guids.cpp

 #ifndef _MSC_VER
+#ifndef __MINGW32__
 const GUID IID_IUnknown = {
     0x00000000, 0x0000, 0x0000, { 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46 }
 };
+#endif
 #endif

rikyoz · 2024-03-04T20:09:31Z

Hi!
This is actually quite strange, as I cannot replicate the issue:

Toolchain (MinGW bundled with CLion 2024.1 EAP, still MinGW 11.0 and GCC 13.1.0):
CMakeLists.txt:

cmake_minimum_required( VERSION 3.28 )
project( test_uuid_mingw )

set( CMAKE_CXX_STANDARD 17 )

add_executable( test_uuid_mingw main.cpp )

include( cmake/Dependencies.cmake )

CPMAddPackage(
        NAME bit7z
        GIT_REPOSITORY "https://github.com/rikyoz/bit7z.git"
        GIT_TAG master
        OPTIONS
            "BIT7Z_BUILD_TESTS false"
            "BIT7Z_BUILD_DOCS false"
)

target_link_libraries(${PROJECT_NAME} PRIVATE bit7z)

CMake output:

-- CPM: Adding package bit7z@ (master)
-- Standard filesystem: NO (using ghc::filesystem)
-- Target Version: 
-- Compiler ID: GNU
-- Compiler Version: 13.1.0
-- Architecture: x64
-- Build Type: Debug
-- Language Standard for bit7z: C++14
-- Auto format detection: OFF
-- Regex matching extraction: OFF
-- Use std::byte: OFF
-- Use native string: OFF
-- Generate Position Independent Code: OFF
-- Disable Zip ASCII password check: OFF
-- Disable using std::filesystem: OFF
-- 7-zip version: 23.01
-- Build tests: false
-- Build docs: false
-- Auto prefix long paths: OFF
-- Use the default codepage: OFF
-- Path sanitization: OFF
-- CPM: bit7z: Adding package [email protected] (v23.01)
-- 7-zip source code available at [...]/test_uuid_mingw/cmake-build-debug-mingw-bundled/_deps/7-zip-src
-- CPM: bit7z: Adding package ghc_filesystem@0 (c0dcd0b090da7dffc74b124a6f164f54dbbb5ccb)
-- ghc::filesystem source code available at [...]/test_uuid_mingw/cmake-build-debug-mingw-bundled/_deps/ghc_filesystem-src
-- Enable sanitizers: OFF
-- Configuring done (5.2s)
-- Generating done (0.0s)
-- Build files have been written to: [...]/test_uuid_mingw/cmake-build-debug-mingw-bundled

Source code:

#include <bit7z/bit7zlibrary.hpp>
#include <bit7z/bitmemcompressor.hpp>

int main() {
    bit7z::Bit7zLibrary lib{};
    bit7z::BitMemCompressor compressor{lib, bit7z::BitFormat::Zip};
    compressor.compressFile({'h', 'e', 'l', 'l', 'o'}, "hello.zip");
    return 0;
}

Build output:

[...]
[57/61] Building CXX object _deps/bit7z-build/CMakeFiles/bit7z64.dir/src/internal/renameditem.cpp.obj
[58/61] Building CXX object _deps/bit7z-build/CMakeFiles/bit7z64.dir/src/internal/stringutil.cpp.obj
[59/61] Building CXX object _deps/bit7z-build/CMakeFiles/bit7z64.dir/src/internal/updatecallback.cpp.obj
[60/61] Linking CXX static library _deps\bit7z-src\lib\x64\libbit7z64_d.a
[61/61] Linking CXX executable test_uuid_mingw.exe

Build finished

chapterjason · 2024-03-04T20:14:29Z

That is really strange, let me try to create a reproducer.

chapterjason · 2024-03-04T22:04:01Z

This main file fails:

Usage of CLSID_* is the case #include <shobjidl.h> (https://learn.microsoft.com/en-us/windows/win32/api/shobjidl/)

#include <iostream>
#include <bit7z/bit7zlibrary.hpp>
#include <bit7z/bitmemcompressor.hpp>
#include <shobjidl.h>

int main() {
    const auto id = CLSID_FileOpenDialog;

    std::cout << id.Data1 << std::endl;

    bit7z::Bit7zLibrary lib{};
    bit7z::BitMemCompressor compressor{lib, bit7z::BitFormat::Zip};
    compressor.compressFile({'h', 'e', 'l', 'l', 'o'}, "hello.zip");
    return 0;
}

chapterjason · 2024-03-04T22:15:52Z

Looks like this chain: #include <shobjidl.h> -> #include <ole2.h> -> #include <objbase.h> -> #include <combaseapi.h> -> #include <unknwnbase.h> which contains the IID_IUnknown

But I am not sure TBH, couldn't get a smaller reproducer.

rikyoz · 2024-03-05T07:58:04Z

I see. Thank you for the reproducer!
Unfortunately, the obvious fix of using #ifndef _WIN32 instead of #ifndef _MSC_VER breaks linking other programs:

libbit7z64_d.a(bufferextractcallback.cpp.obj):bufferextractcallback.cpp:(.rdata$.refptr.IID_IUnknown[.refptr.IID_IUnknown]+0x0): undefined reference to `IID_IUnknown'
collect2.exe: error: ld returned 1 exit status

I remember fixing this exact issue some years ago (24706ff), but that same fix is causing your issue.
So I'll need to come up with a better fix.
Thank you again for reporting this!

Close issue #193

rikyoz · 2024-03-05T17:34:39Z

I just pushed a fix to the branch hotfix/v4.0.6.
Basically, bit7z now defines IID_IUnknown inside a #ifndef _WIN32 condition, and more importantly, the CMakeLists.txt conditionally specifies the uuid library as a link dependency of bit7z, i.e.,

if( MINGW )
    target_link_libraries( ${LIB_TARGET} PUBLIC uuid )
endif()

This way, a project using bit7z will link against uuid, which will provide the (only) definition of IID_IUnknown.

chapterjason · 2024-03-05T22:12:30Z

@rikyoz Works as expected! Thanks a lot. 👍🏼

rikyoz · 2024-03-06T12:30:10Z

Perfect! You're welcome! 👍🏼

rikyoz · 2024-03-17T15:15:26Z

Released on v4.0.6.

chapterjason added the 🐞 bug label Mar 4, 2024

chapterjason assigned rikyoz Mar 4, 2024

rikyoz added a commit that referenced this issue Mar 5, 2024

Fix linking issue with MinGW

0a60e2f

Close issue #193

rikyoz closed this as completed Mar 17, 2024

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[Bug]: Multiple Definition Linker Error for IID_IUnknown #193

[Bug]: Multiple Definition Linker Error for IID_IUnknown #193

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[Bug]: Multiple Definition Linker Error for IID_IUnknown #193

[Bug]: Multiple Definition Linker Error for IID_IUnknown #193

Comments

chapterjason commented Mar 4, 2024

bit7z version

Compilation options

7-zip version

7-zip shared library used

Compilers

Compiler versions

Architecture

Operating system

Operating system versions

Bug description

Steps to reproduce

Expected behavior

Relevant compilation output

chapterjason commented Mar 4, 2024

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