From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@hurl.cygnus.com>
To: Zack Weinberg <zack@rabi.columbia.edu>
Cc: egcs@egcs.cygnus.com
Subject: Re: added: tests for uninit variable warnings 
Date: Wed, 31 Mar 1999 23:46:00 -0000
Message-ID: <4108.921199337@hurl.cygnus.com>
References: <199903120010.TAA03507@blastula.phys.columbia.edu>
X-SW-Source: 1999-03n/msg00438.html
Message-ID: <19990331234600.FV6LKmBc3Ik584IpCcz9RyZI1W6wHnSFeN1D1ujvMJg@z>

  In message < 199903120010.TAA03507@blastula.phys.columbia.edu >you write:
  > uninit-4.c is bizarre: the warning goes away if you remove the '1'
  > case, or if you replace 'struct operation' by an int, or even if you
  > make 'struct operation' smaller!  Also, if you take out the default
  > case _and_ the '1' case, the warning goes away, but it shouldn't (what
  > if cpp_lex returns 3?)
Not weird at all.  Changing the numberof cases or density of the switch may
cause the compiler to emit it as a series of cascaded if/else statements which
the compiler is better able to analyze.

Structures also present some interesting problems to the uninitialized
variable analysis.  It's quite a bit more difficult for the compiler to
determine that an entire structure has been initialized as opposed to a simple
integer or floating point variable.


  > The tests are marked XFAIL - all systems.  I'm interested to know if
  > they pass on anyone's machine.
They probably will pass on some machines because of differences in switch
table density threshholds (at least uninit-4)

jeff