I am in the process of updating a template library I made several years ago. The purpose of the update was more as an experiment in using variadic templates. The prior template library was not variadic, the updated version is.
Note, I realize that I am still debugging the templates.
The templates are used in files inside a static library file (a handful of .objs).
Then I have a test program that runs through permutations of template arguments.
The library builds with warnings of duplicate functions (due to different sources expanding the same template).
These are warning (should be hushed up).
The test program compiles fine (no warnings, probably because I've #if 0'd all tests but the first two).
The problem comes in with the Link phase of linking the app against the library. In this case, the duplicate entries cause an error.
I thought (and my prior experience was) that template expanded code, when identical, was permitted to have a pass at duplicate functions.
1>------ Rebuild All started: Project: QuickThread, Configuration: Debug x64 ------ 1> Performing Custom Build Tools ... 1>parallel_pipeline.obj : : warning LNK4006: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in QuickThread.obj; second definition ignored 1>parallel_manifold.obj : : warning LNK4006: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in QuickThread.obj; second definition ignored 1>parallel_list.obj : : warning LNK4006: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in QuickThread.obj; second definition ignored 1>parallel_allocator.obj : : warning LNK4006: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in QuickThread.obj; second definition ignored 1> QuickThread.vcxproj -> C:\QuickThread\QuickThread_v4\x64\Debug\QuickThread.lib 2>------ Rebuild All started: Project: TemplateTestSuite, Configuration: Debug x64 ------ 2> stdafx.cpp 2> TemplateTestSuite.cpp ... 2>QuickThread.lib(QuickThread.obj) : error LNK2005: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in TemplateTestSuite.obj 2>QuickThread.lib(parallel_allocator.obj) : error LNK2005: "void __cdecl qt::qt_unwrap_fn_args(struct qt::unwrap_struct_t<void (__cdecl*)(void)> *)" (?qt_unwrap_fn_args@qt@@YAXPEAU?$unwrap_struct_t@P6AXXZ@1@@Z) already defined in TemplateTestSuite.obj ... 2>C:\QuickThread\QuickThread_v4\x64\Debug\TemplateTestSuite.exe : fatal error LNK1169: one or more multiply defined symbols found ========== Rebuild All: 1 succeeded, 1 failed, 0 skipped ==========
Using VS 2013 with PS 2016 Update 2
Is there a linker option to have it check the duplicately named functions for same content, then ignore the second one?
Jim Dempsey