PRB: LNK4022 & LNK4006 Warnings When Build PowerStation 32 DLL (123668)

SYMPTOMS

The following errors are generated when building a DLL using a module definition (.DEF) file that does not use the fully decorated name of a function named testing:

warning LNK4022: cannot find unique match for symbol "TESTING"
warning LNK4006: _TESTING already defined in test.obj; second definition ignored
warning LNK4006: _TESTING@4 already defined in test.obj; second definition ignored
LINK : error LNK1141: failure during build of exports file

MORE INFORMATION

There may be times when it is desirable not to modify the Fortran source code to add the DLLEXPORT attribute to a function. For example, you might want to maintain a common code base for several computer platforms. In this case, the exports must be identified in the EXPORTS section of a .DEF file or the LINK command line. In either case, if the name specified is not the fully decorated name, the errors described above will be generated by the linker.

Steps to Reproduce Problem

Use the sample code listed at the end of this article and this definitions file:
library test
EXPORTS TESTING
Use the following LINK command to generate the error messages:
```
   link test.obj /dll /def:test.def msfrt.lib msvcrt.lib
```

NOTE: The second LNK4006 error generated by the linker gives the correct fully decorated name "_TESTING@4". The @4 in the name indicates the number of bytes in the function parameters.

Example Resolution

To successfully link and produce a DLL, include the fully decorated name in the .DEF file:

library test
EXPORTS _TESTING@4

or in the EXPORT LINK option:

   link test.obj /dll /export:_TESTING@4 msfrt.lib msvcrt.lib

Sample Code

C Compile options needed: none
        subroutine testing(i)
        integer i
        i = i*2
        end