问题
I'm developing a Python binding for a C++ library using Boost Python. To avoid having issues distributing the Boost libraries, I'm using the static versions. It works fine in Linux and MacOSX, but in Windows, a dependency to Python is still required. My CMakeLists.txt is set as:
if((${CMAKE_SYSTEM_NAME} STREQUAL "Linux") OR APPLE)
target_link_libraries(my_python_module ${Boost_LIBRARIES})
elseif(WIN32 AND MSVC)
add_definitions(/DBOOST_PYTHON_STATIC_LIB) # This is also required to force the usage of libboost_python37-vc141-mt-x64-1_70.lib instead of boost_python37-vc141-mt-x64-1_70.lib
target_link_libraries(my_python_module ${Boost_LIBRARIES}) # This includes the Boost Python library
# Even though Boost Python library is included statically, in Windows it has a dependency to the Python library.
target_link_libraries(my_python_module ${Python_LIBRARIES})
endif()
Thus because in Windows, if I remove the target_link_libraries(my_python_module ${Python_LIBRARIES}) line, I get a:
LINK : fatal error LNK1104: Can't open file 'python37.lib'
My resulting DLL has indeed Python as a dependency:
C:\PythonModule\bin\Release\Release>"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx64\x64\dumpbin.exe" /DEPENDENTS my_python_module.dll
Microsoft (R) COFF/PE Dumper Version 14.16.27031.1
Copyright (C) Microsoft Corporation. All rights reserved.
Dump of file my_python_module.dll
File Type: DLL
Image has the following dependencies:
python37.dll <------- HERE
MSVCP140.dll
VCRUNTIME140.dll
api-ms-win-crt-runtime-l1-1-0.dll
api-ms-win-crt-heap-l1-1-0.dll
KERNEL32.dll
Summary
B000 .data
3000 .pdata
18000 .rdata
1000 .reloc
1000 .rsrc
27000 .text
Since I'm using Boost static libraries, the process is linking against libboost_python37-vc141-mt-x64-1_70.lib, not boost_python37-vc141-mt-x64-1_70.lib (which is the library module associated to the dynamic library, boost_python37-vc141-mt-x64-1_70.dll). I can check this on the command line passed to Visual Studio (thanks to -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON):
Link:
C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\HostX86\x64\link.exe /ERRORREPORT:QUEUE /OUT:"C:\PythonModule\bin\Release\Release\my_python_module.dll" /INCREMENTAL:NO /NOLOGO "C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_filesystem-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_program_options-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_python37-vc141-mt-x64-1_70.lib" <------- HERE
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_thread-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_system-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_stacktrace_windbg-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_chrono-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_date_time-vc141-mt-x64-1_70.lib"
"C:\local\boost_1_70_0\lib64-msvc-14.1\libboost_atomic-vc141-mt-x64-1_70.lib"
"C:\Program Files\Python37\libs\python37.lib"
kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /manifest:embed /PDB:"C:/PythonModule/lib/Release/Release/my_python_module.pdb" /SUBSYSTEM:CONSOLE /TLBID:1 /DYNAMICBASE /NXCOMPAT /IMPLIB:"C:/PythonModule/lib/Release/Release/my_python_module.lib" /MACHINE:X64 /machine:x64 /IGNORE:4049,4217 /DLL my_python_module.dir\Release\my_python_module.obj
Creating library C:/PythonModule/lib/Release/Release/my_python_module.lib and object C:/PythonModule/lib/Release/Release/my_python_module.exp
my_python_module.vcxproj -> C:\PythonModule\bin\Release\Release\my_python_module.dll
BTW, these are the Boost officially provided binaries, by the way, obtained from https://dl.bintray.com/boostorg/release/1.70.0/binaries/boost_1_70_0-msvc-14.1-64.exe
The static Boost Python library DOESN'T have a dependency to Python, as far as I can check:
C:\local\boost_1_70_0\lib64-msvc-14.1>"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx64\x64\dumpbin.exe" /DEPENDENTS libboost_python37-vc141-mt-x64-1_70.lib
Microsoft (R) COFF/PE Dumper Version 14.16.27031.1
Copyright (C) Microsoft Corporation. All rights reserved.
Dump of file libboost_python37-vc141-mt-x64-1_70.lib
File Type: LIBRARY
Summary
100 .CRT$XCU
35A .bss
17EF8 .chks64
DD0 .data
CFE .data$r
1804 .debug$S
23B5 .drectve
5B20 .pdata
9FD3 .rdata
EF8 .rdata$r
4DB .text$di
32D89 .text$mn
3F59 .text$x
608 .text$yd
11C10 .xdata
4C0 .xdata$x
While the shared one does:
C:\local\boost_1_70_0\lib64-msvc-14.1>"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx64\x64\dumpbin.exe" /DEPENDENTS boost_python37-vc141-mt-x64-1_70.dll
Microsoft (R) COFF/PE Dumper Version 14.16.27031.1
Copyright (C) Microsoft Corporation. All rights reserved.
Dump of file boost_python37-vc141-mt-x64-1_70.dll
File Type: DLL
Image has the following dependencies:
python37.dll <------- HERE
MSVCP140.dll
KERNEL32.dll
VCRUNTIME140.dll
api-ms-win-crt-runtime-l1-1-0.dll
api-ms-win-crt-heap-l1-1-0.dll
Summary
3000 .data
3000 .pdata
18000 .rdata
1000 .reloc
1000 .rsrc
1D000 .text
So, my main question is:
Why, if I'm using the static version of the Boost Python library, I still have that Python dependency?
I'm not using Python directly in the module in any other way, and in Linux, such dependency doesn't exist.
Thanks a lot for your help.
来源：https://stackoverflow.com/questions/56797584/why-does-static-version-of-the-boost-python-library-has-a-dependency-to-python-i