Building a static library that depends on wxWidgets

[damateem]

I've built a static library that utilizes wxWidgets. It built without
errors, but I'm having linking issues when I link the library into my
application. When the application links, the linker reports that there
are multiple definitions of wxWidgets classes and functions.

What might I be doing wrong? Is there documentation somewhere that will
step me through this process?

Thanks,
David

wxWidgets 2.8.11
MS Windows
MinGW

[Lluís Batlle i Rossell]

On Fri, Jun 15, 2012 at 11:09:47PM -0400, damateem wrote:
> I've built a static library that utilizes wxWidgets. It built
> without errors, but I'm having linking issues when I link the
> library into my application. When the application links, the linker
> reports that there are multiple definitions of wxWidgets classes and
> functions.
>
> What might I be doing wrong? Is there documentation somewhere that
> will step me through this process?

I don't think there is any difference whether it is wxWidgets, or any other
library, in this your linking process.

The linker will tell you where are the multiple definitions.

Regards,
Lluís.

[damateem]

True, but how do I prevent the multiple definitions? Since my library
uses wxWidgets, MinGW is including it in my library.

It seems that I need a way to tell MinGW to exclude wxWidgets from my
library.

How do I do that?

[Nathan Ridge]

----------------------------------------
> Date: Sat, 16 Jun 2012 09:31:57 -0400
> From: dama...@gmail.com
> To: wx-u...@googlegroups.com
> Subject: Re: Building a static library that depends on wxWidgets

MinGW should not include wxWidgets in your library unless you tell it to.

What commands do you use to build your library?

Regards,
Nate

[damateem]

On 6/16/2012 4:00 PM, Nathan Ridge wrote:
> ----------------------------------------
>> Date: Sat, 16 Jun 2012 09:31:57 -0400
>> From: dama...@gmail.com
>> To: wx-u...@googlegroups.com
>> Subject: Re: Building a static library that depends on wxWidgets
>>

>> On 6/16/2012 5:03 AM, Llu�s Batlle i Rossell wrote:
>>> On Fri, Jun 15, 2012 at 11:09:47PM -0400, damateem wrote:
>>>> I've built a static library that utilizes wxWidgets. It built
>>>> without errors, but I'm having linking issues when I link the
>>>> library into my application. When the application links, the linker
>>>> reports that there are multiple definitions of wxWidgets classes and
>>>> functions.
>>>>
>>>> What might I be doing wrong? Is there documentation somewhere that
>>>> will step me through this process?
>>> I don't think there is any difference whether it is wxWidgets, or any other
>>> library, in this your linking process.
>>>
>>> The linker will tell you where are the multiple definitions.
>> True, but how do I prevent the multiple definitions? Since my library
>> uses wxWidgets, MinGW is including it in my library.
>>
>> It seems that I need a way to tell MinGW to exclude wxWidgets from my
>> library.
>>
>> How do I do that?
> MinGW should not include wxWidgets in your library unless you tell it to.
>
> What commands do you use to build your library?

Just to prove I could get this to work at the simplest level, I created
two very small example projects. One a static library that utilizes
wxWidgets and another, a wxWidgets application that utilizes the library.

The library contains only one function,

void Dummy( wxString &Param )
{
Param =_T("Dummy string");
}

which it called from a button click handler in the application.

void test_appFrame::OnbtnTestClick(wxCommandEvent& event)
{
wxString s;

Dummy( s );

wxMessageBox( s );
}

The library builds fine.

mingw32-g++.exe -Wall -g
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\contrib\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib\mswud
-c C:\user_data\david\code\test_lib\test_lib.cpp -o obj\Debug\test_lib.o
ar.exe -r -s libtest_lib.a obj\Debug\test_lib.o
ar.exe: creating libtest_lib.a

However, the application does not.

mingw32-g++.exe -pipe -mthreads -D__GNUWIN32__ -D__WXMSW__
-DwxUSE_UNICODE -Wno-attributes -Winvalid-pch -include wx_pch.h
-DWX_PRECOMP -Wall -g -D__WXDEBUG__
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\contrib\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib\mswud
-c C:\user_data\david\code\test_lib\wx_pch.h -o
wx_pch.h.gch\Debug_wx_pch_h_gch

mingw32-g++.exe -pipe -mthreads -D__GNUWIN32__ -D__WXMSW__
-DwxUSE_UNICODE -Wno-attributes -Winvalid-pch -include wx_pch.h
-DWX_PRECOMP -Wall -g -D__WXDEBUG__
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\contrib\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib\mswud
-c C:\user_data\david\code\test_lib\test_appMain.cpp -o
obj\Debug\test_appMain.o

mingw32-g++.exe -pipe -mthreads -D__GNUWIN32__ -D__WXMSW__
-DwxUSE_UNICODE -Wno-attributes -Winvalid-pch -include wx_pch.h
-DWX_PRECOMP -Wall -g -D__WXDEBUG__
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\contrib\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib\mswud
-c C:\user_data\david\code\test_lib\test_appApp.cpp -o
obj\Debug\test_appApp.o
windres.exe -i C:\USER_D~1\david\code\test_lib\resource.rc -J rc -o
obj\Debug\resource.res -O coff
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\include
-IC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib\mswud

mingw32-g++.exe
-LC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib -L.
-o bin\Debug\test_app.exe obj\Debug\test_appApp.o
obj\Debug\test_appMain.o obj\Debug\resource.res -mthreads -ltest_lib
-lwxmsw28ud -lwxpngd -lwxjpegd -lwxtiffd -lwxzlibd -lkernel32 -luser32
-lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32
-luuid -lcomctl32 -lwsock32 -lodbc32 -mwindows

./libtest_lib.a(test_lib.o):C:/user_data/david/dajac/source_pool/wxWidgets-2.8.11/include/wx/string.h:965:
undefined reference to `wxStringBase::operator=(char const*)'
collect2: ld returned 1 exit status

Process terminated with status 1 (0 minutes, 7 seconds)
1 errors, 0 warnings


I've tried moving "-ltest_lib" after "-lwxmsw28ud", but I get the same
error.

wxmsw28ud is being linked into the application, so why the undefined
reference error?

Thanks,
David

[Nathan Ridge]

> mingw32-g++.exe
> -LC:\user_data\david\dajac\source_pool\wxWidgets-2.8.11\lib\gcc_lib -L.
> -o bin\Debug\test_app.exe obj\Debug\test_appApp.o
> obj\Debug\test_appMain.o obj\Debug\resource.res -mthreads -ltest_lib
> -lwxmsw28ud -lwxpngd -lwxjpegd -lwxtiffd -lwxzlibd -lkernel32 -luser32
> -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32
> -luuid -lcomctl32 -lwsock32 -lodbc32 -mwindows
>
> ./libtest_lib.a(test_lib.o):C:/user_data/david/dajac/source_pool/wxWidgets-2.8.11/include/wx/string.h:965:
> undefined reference to `wxStringBase::operator=(char const*)'
> collect2: ld returned 1 exit status
>

> [snip]

>
> wxmsw28ud is being linked into the application, so why the undefined
> reference error?

There are other wxWidgets static libraries that you need to link to besides
wxmsw28ud, wxpngd, wxjpegd, wxtiffd, and wxzlibd. In particular, wxString
members should be in a library called "wxbase28ud" or similar.

Check your wxWidgets-2.8.11\lib\gcc_lib folder and make sure you link to *all*
the static libraries in there.

Regards,
Nate

[Kobus Grobler]

You compile the library with different options than the app.
In this case you use -DwxUSE_UNICODE when compiling the app, but not the
test_lib library which is in ascii/utf mode depending on setup.h.

Best
Kobus

[damateem]

I use a monolithic build so only one library is needed.

Thanks,
David

[damateem]

That did the trick! Building the library with the unicode option makes
it all work.

Thank You
David