Path: utzoo!telly!ddsw1!lll-winken!killer!mit-eddie!bloom-beacon!tut.cis.ohio-state.edu!MCC.COM!rfg
From: rfg@MCC.COM (Ron Guilmette)
Newsgroups: gnu.g++.bug
Subject: BUG in GCC & G++ 1.32 using -O & inline & narrowing implicit casts
Message-ID: <8901312032.AA24614@riunite.aca.mcc.com>
Date: 31 Jan 89 20:32:38 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 58


The following short program prints FAILED when compiled using either
GCC 1.32 or G++ 1.32.0 and (only) when the -O option is used.  This
occurs on a Sun3 with the following links:

	tm-sun3.h	=>	tm.h
	xm-m68k.h	=>	config.h
	m68k.md		=>	md
	output-m68k.c	=>	aux-output.c

I believe that this program also illustrates the need for warnings
(in both G++ and GCC) whenever a value of a given width is implicitly
cast to a value of a smaller width (e.g. int to short int).  Such
implicit casts can cause a loss of information, and they should be
flagged as dangerous via warnings.  It appears that even with -Wall,
such situations are not being flagged with warnings.

// Ron Guilmette  -  MCC  -  Experimental (parallel) Systems Kit Project
// 3500 West Balcones Center Drive,  Austin, TX  78759  -  (512)338-3740
// ARPA: rfg@mcc.com
// UUCP: {rutgers,uunet,gatech,ames,pyramid}!cs.utexas.edu!pp!rfg

/* ------------------------------------------------------------------------- */
/*
Description - check that when an int value is assigned to a short int,
		the proper half of the int (i.e. the low order half) ends
		up in the short.

		This fails with 1.32.0 if -O is used and f1() is inline.

		Workaround - declare "f1_arg" as type "short int".
*/

short int v2;

int v1 = 0x11117777;

inline void f1 (int f1_arg)
{
	v2 = f1_arg;
}

void test()
{
	f1 (v1);
	if (v2 != 0x00007777) {
		printf ("v2 = 0x%08x\n", v2);
		printf ("FAILED - assignment of int to short does not work right\n");
		exit (0);
	}
}

main()
{
	test ();
	printf ("PASSED\n");
	exit (0);
}