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Date:	Fri, 23 Apr 1999 21:33:11 -0500 (CDT)
From:	Mumit Khan <khan AT xraylith DOT wisc DOT edu>
To:	cygwin AT sourceware DOT cygnus DOT com
Subject:	gcc -U_WIN32 pitfalls!
Message-ID:	<Pine.SUN.3.93.990423213143.2983A-200000@modi.xraylith.wisc.edu>
MIME-Version:	1.0

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Just for kicks, I tried to build a small analysis program with -U_WIN32;
this tool is essentially a filter and doesn't use any win32 specific 
features, so it should be pretty safe, right?

Looks like certain typedefs are *WRONG* when you undefine _WIN32 and it
causes amazingly subtle bugs! Any code using stat for example will be
subtly but surely broken.

I'm attaching a small trivial program that should illustrate this. Here's
the header comments from the file. 

This is with stock B20.1. Compiler version is no relevant here.

//
// A simple program to show the pitfall of using -U_WIN32 in your code
// under Cygwin b20.1!
//
// To build:
//  $ c++ -U_WIN32 -o cyg-stat-bug cyg-stat.cc
//  $ c++ -o cyg-stat-ok cyg-stat.cc
//
// Now run it giving a filename on command line:
//
//  $ ./cyg-stat-bug ./cyg-stat.cc
//  $ ./cyg-stat-ok ./cyg-stat.cc
//
// To find the cause of the problem (after you notice it in the output
// of course!), you need to look at the preprocessed files.
//
//  $ c++ -save-temps -U_WIN32 -o cyg-stat-bug cyg-stat.cc
//  $ mv cyg-stat.ii cyg-stat-bug.ii
//  $ c++ -save-temps -o cyg-stat-ok cyg-stat.cc
//  $ mv cyg-stat.ii cyg-stat-ok.ii
//  $ diff -u3p cyg-stat-bug.ii cyg-stat-ok.ii
//
//  Look for ino_t.
// 

Regards,
Mumit


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Content-Description: Test program to show pitfall.

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