Why doesn't $^E work with Borland builds on Win32?

I have a problem with a Borland build of perl on Win32 not setting $^E, 
e.g.:

 >perl -e "open F, 'nothere' or die $^E"
Died at -e line 1.

whereas a VC++ build says:

 >perl -e "open F, 'nothere' or die $^E"
The system cannot find the file specified at -e line 1.

Looking at Perl_magic_get() in mg.c, it appears that getting $^E 
actually calls GetLastError(), so I changed win32/win32.c as follows:

==========
@@ -3122,6 +3122,7 @@
      dTHX;
      va_list ap;
      int pmode;
+    int retval;

      va_start(ap, flag);
      pmode = va_arg(ap, int);
@@ -3130,7 +3131,10 @@
      if (stricmp(path, "/dev/null")==0)
         path = "NUL";

-    return open(PerlDir_mapA(path), flag, pmode);
+    printf("open(%s, %d, %d)\n", PerlDir_mapA(path), flag, pmode);
+    retval = open(PerlDir_mapA(path), flag, pmode);
+    printf("last error=%lu\n", GetLastError());
+    return retval;
  }

  /* close() that understands socket */
==========

and now the command:

perl -e "open F, 'nothere' or die $^E"

outputs:

[...]
open(C:\p5p\bleadperl\nothere, 32768, 438)
last error=0
Died at -e line 1.

So then I tried a standalone C program that calls open() with the same 
arguments:

#include <fcntl.h>
#include <io.h>
#include <stdio.h>
#include <windows.h>
void main(void) {
   char *path = "C:\\p5p\\bleadperl\\nothere";
   int flag = 32768;
   int pmode = 438;
   printf("open(%s, %d, %d)\n", path, flag, pmode);
   open(path, flag, pmode);
   printf("last error=%lu\n", GetLastError());
}

but when I run this (also built with Borland, of course) it works fine:

open(C:\p5p\bleadperl\nothere, 32768, 438)
last error=2

Why doesn't open() set the Windows last error code when called inside 
perl, but does normally?  What weirdness does perl do that stops it from 
working?


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• Why doesn't $^E work with Borland builds on Win32? by Steve Hay
• RE: Why doesn't $^E work with Borland builds on Win32? by Jan Dubois
• Re: Why doesn't $^E work with Borland builds on Win32? by Steve Hay