Unresolvable linking error E2065 with XXH32 (xxHash and lz4)

Question

I am currently updating/writing a delphi binding for lz4 & xxHash.

Project state with compiler error is available here.

Not working line of xxHash.pas

function XXH32 (const AInput: Pointer; ALength: Integer; ASeed: Cardinal):  Cardinal; cdecl; external name '_XXH32';

When trying to bind function XXH32 from xxHash.o, it results in the error E2065.

[dcc32 Fehler] xxHash.pas(122): E2065 Ungenügende Forward- oder External-Deklaration: 'XXH32'

What i do not understand, all other functions are bound and working without problems.

When i analyze xxHash.o by creating a dumpfile, the function is present like every other of xxHash.o

Objdump command:

objdump -D xxhash.o > xxhash.o.txt

Dumpfile part of xxH32:

xxhash.o:     file format pe-i386
Disassembly of section .text:
00000000 <_XXH32>:
   0:   55                      push   %ebp
   1:   57                      push   %edi
   2:   56                      push   %esi
   3:   53                      push   %ebx
   4:   83 ec 14                sub    $0x14,%esp
   7:   8b 44 24 28             mov    0x28(%esp),%eax
   b:   8b 4c 24 2c             mov    0x2c(%esp),%ecx
...

Any suggestions?

Minimal Implementation:

program lz4_minimal;

{$APPTYPE CONSOLE}

{$L xxhash.o}

function XXH32 (const AInput: Pointer; ALength: Integer; ASeed: Cardinal):  Cardinal; cdecl; external name '_XXH32';
function XXH64 (const AInput: Pointer; ALength: Integer; ASeed: UInt64):    UInt64;   cdecl; external name '_XXH64';

//necessary dependencies
function  _malloc(size: cardinal): Pointer; cdecl;
begin
  GetMem(Result, size);
end;

procedure _memcpy(dest, source: Pointer;  count: Integer); cdecl;
begin
  Move(source^, dest^, count);
end;

procedure _free(P: Pointer); cdecl;
begin
 FreeMem(P);
end;

begin
end.

xxHash.o is 32bit for windows, build using MinGW 4.8.1. and the original sourcecode by Yann Collet in revision r36, included in lz4. Makefile is included.

Objectfile can be found on github here

Answer 1

A Workaround, also suggested by David Heffernan, is to add a dummy function to xxHash.c as first function.

The new dumpfile looks like this:

xxhash.o:     file format pe-i386
Disassembly of section .text:
00000000 <_XXDUMMY>:
   0:   b8 2a 00 00 00          mov    $0x2a,%eax
   5:   c3                      ret    
   6:   8d 76 00                lea    0x0(%esi),%esi
   9:   8d bc 27 00 00 00 00    lea    0x0(%edi,%eiz,1),%edi

00000010 <_XXH32>:
  10:   55                      push   %ebp
  11:   57                      push   %edi
  12:   56                      push   %esi
....

The project compiles with this hack, the error is gone.

Analyzing the other object files and trying to bind the first referenced functions always results in an error E2065.

There seems to be a general problem with using MinGW and gcc compiled .o files with Delphi.