linking dilemma (undefined reference) between MinGW and MSVC. MinGW fails MSVC works

问题:

I'm trying to port an old C .dll library originally done with MSVC that uses BEA Tuxedo library to use MinGW.

I have encountered a situation where MSVC compiles and links one file but MinGW fails. The actual problem is in linking stage. There comes 'undefined reference' error.

Here's the minimal example to create a dll: (tpsetunsol_test.c)

#include   void __stdcall msghandler(char *pszMessage, long lMessageLen, long lFlags) {  }     int Inittpsetunsol() {                int ret = 0;      tpsetunsol(msghandler);      return ret;                      }    

This compiles without errors:

gcc -Wall -fexceptions -g -O2 -DWIN32 -DNDEBUG -D_WINDOWS -ID:/dev/tuxedo/include   -o   tpsetunsol_test.o -c tpsetunsol_test.c 

Here comes the error:

dllwrap --export-all-symbols -LD:/dev/tuxedo/lib -k --output-lib test.lib --output-def test.def --enable-stdcall-fixup --add-stdcall-alias -o IAWS.dll tpsetunsol_test.o -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lwtuxws32  C:\MinGW\bin\dllwrap.exe: no export definition file provided. Creating one, but that may not be what you want tpsetunsol_test.o: In function `Inittpsetunsol': d:\dev\tpsetunsol_test.c:13: undefined reference to `tpsetunsol' collect2.exe: error: ld returned 1 exit status C:\MinGW\bin\dllwrap.exe: C:\MinGW\bin\gcc exited with status 1 

function declaration in atmi.h:

extern void (_TMDLLENTRY * _TMDLLENTRY tpsetunsol _((void (_TMDLLENTRY *)(char _TM_FAR *, long, long)))) _((char _TM_FAR *, long, long));  #define _TMDLLENTRY __stdcall #define _TM_FAR 

Version:

$ gcc -v Using built-in specs. COLLECT_GCC=C:\MinGW\bin\gcc.exe COLLECT_LTO_WRAPPER=c:/mingw/bin/../libexec/gcc/mingw32/4.7.2/lto-wrapper.exe Target: mingw32 Configured with: ../gcc-4.7.2/configure --enable-    languages=c,c++,ada,fortran,objc,obj-c++ --disable-sjlj-exceptions --with-dwarf2 --enable-shared --enable-libgomp --disable-win32-registry --enable-libstdcxx-debug --disable-build-poststage1-with-cxx --enable-version-specific-runtime-libs     --build=ming w32 --prefix=/mingw Thread model: win32 gcc version 4.7.2 (GCC) 

Edit: I found out using nm on object files created by MSVC and GCC that symbol tpsetunsol is different

Looking at _tpsetunsol symbol it is quite evident that MSVC and GCC produce different symbols.

GCC produces: U _tpsetunsol and MSVC: U _tpsetunsol@4

Edit: nm output after build with Haroogan's suggestion:

$ dllwrap --export-all-symbols -LD:/dev/tuxedo.64/lib --output-lib test.lib --output-def test.def -o IAWS.dll tpsetunsol_test.o -lwtuxws32_new C:\MinGW\bin\dllwrap.exe: no export definition file provided. Creating one, but that may not be what you want tpsetunsol_test.o: In function `Inittpsetunsol': d:\dev\IA/tpsetunsol_test.c:13: undefined reference to `tpsetunsol' collect2.exe: error: ld returned 1 exit status C:\MinGW\bin\dllwrap.exe: C:\MinGW\bin\gcc exited with status 1   $ nm tpsetunsol_test.o 00000000 b .bss 00000000 d .data 00000000 N .debug_abbrev 00000000 N .debug_aranges 00000000 N .debug_info 00000000 N .debug_line 00000000 N .debug_loc 00000000 r .eh_frame 00000000 t .text 00000004 T _Inittpsetunsol 00000000 T _msghandler@12          U _tpsetunsol  $ nm ../tuxedo.64/lib/libwtuxws32.a  | grep -i tpsetuns 00000000 I __imp__tpsetunsol@4 00000000 T _tpsetunsol@4 

output from gcc preprocessor (-E) (only the line tpsetunsol is declared)

extern void (__attribute__((__stdcall__)) * __attribute__((__stdcall__)) tpsetunsol (void (__attribute__((__stdcall__)) *)(char *, long, long))) (char *, long, long); 

回答1:

Change the declaration of tpsetunsol() in the atmi.h header from:

extern void (_TMDLLENTRY * _TMDLLENTRY tpsetunsol _((void (_TMDLLENTRY *)(char _TM_FAR *, long, long)))) _((char _TM_FAR *, long, long)); 

to:

extern  void (_TMDLLENTRY * (_TMDLLENTRY tpsetunsol) _((void (_TMDLLENTRY *)(char _TM_FAR *, long, long)))) _((char _TM_FAR *, long, long)); //                          ^                      ^ 

so the function will be properly declared to be a stdcall function as it is in the library (as indicated by the @4 suffix on the name in the library).

回答2:

As you have already discovered yourself - name mangling may be different across compilers. To solve your problem follow the instructions:

1. Download and install (can build from source) gendef utility:

   • If you have usual MinGW (targeting 32-bit), then obtain it here;
   • If you have MinGW-w64 (targeting 64-bit), then obtain it here.

2. Run gendef wtuxws32.dll (will generate wtuxws32.def);

3. Run dlltool -D wtuxws32.dll -d wtuxws32.def -l libwtuxws32.a (will generate libwtuxws32.a);

4. Put libwtuxws32.a to D:/dev/tuxedo/lib;

5. Now link against it.

文章来源: linking dilemma (undefined reference) between MinGW and MSVC. MinGW fails MSVC works