Path: utzoo!telly!attcan!uunet!mcvax!ukc!warwick!geoff
From: geoff@cs.warwick.ac.uk (Geoff Rimmer)
Newsgroups: gnu.gcc.bug
Subject: Re: gcc 1.34 -ansi -strict -pedantic
Message-ID: <1601@ubu.warwick.UUCP>
Date: 14 Mar 89 03:22:09 GMT
References: <8903061953.AA25822@hector.homer.nj.att.com>
Sender: news@warwick.UUCP
Distribution: gnu
Organization: Computer Science, Warwick University, UK
Lines: 86
In-reply-to: ulysses!north@RESEARCH.ATT.COM's message of 8 Mar 89 20:55:31 GMT

In article <8903061953.AA25822@hector.homer.nj.att.com> ulysses!north@RESEARCH.ATT.COM writes:

> gcc 1.34 -ansi -strict -pedantic
> doesn't warn about functions that fail
> to return a value, as in
> 
> 	   hector> cat t.c
> 
> 	   typedef struct x_t {
> 		   int i;
> 	   } x_t;
> 
> 	   x_t f() {
> 	   }
> 
> 	   hector> gcc -c -ansi -strict -pedantic t.c
> 	   hector> 
> 
> an x_t could just as well be an int.
> i know many programmers are sloppy about this
> but i'd think this combination of command
> line options would trigger a warning at least.

I don't believe there *is* a -strict switch to gcc v1.34.  I just had
a quick glance at gcc.c and the info file, and still couldn't find any
mention of it.  The switches that you should use are the -W flags, in
particular, the -Wreturn-type switch.  If you use -Wall (as I always
do now!), you get all the warnings that GCC can find (except for one).

`-Wimplicit'
     Warn whenever a function is implicitly declared.

`-Wreturn-type'
     Warn whenever a function is defined with a return-type that
     defaults to `int'.  Also warn about any `return' statement with
     no return-value in a function whose return-type is not `void'.

`-Wunused'
     Warn whenever a local variable is unused aside from its
     declaration.

`-Wcomment'
     Warn whenever a comment-start sequence `/*' appears in a comment.

`-Wall'
     All of the above `-W' options combined.

`-Wwrite-strings'
     Give string constants the type `const char[LENGTH]' so that
     copying the address of one into a non-`const' `char *' pointer
     will get a warning.  These warnings will help you find at
     compile time code that can try to write into a string constant,
     but only if you have been very careful about using `const' in
     declarations and prototypes.  Otherwise, it will just be a
     nuisance; this is why we did not make `-Wall' request these
     warnings.

geoff%   cat t.c

	typedef struct x_t
	{
		int i;
	} x_t;
 
	x_t f()
	{

	}

geoff%   gcc -c -ansi -pedantic t.c
		[ no warnings ]
geoff%   gcc -c -Wreturn-type -ansi -pedantic t.c
t.c: In function f:
t.c:10: warning: control reaches end of non-void function

Geoff

	------------------------------------------------------------
	Geoff Rimmer, Computer Science, Warwick University, England.
			geoff@uk.ac.warwick.emerald

	"You can't eat a canvus or a piece of rock."
	"I dunno, you could if you were drunk enough and had enough
	 ketchup"
			- Filthy, Rich and Catflap, 1986.
	------------------------------------------------------------