warning in 2.4.1pre10
In file included from /usr/src/linux/include/linux/raid/md.h:51,
from init/main.c:25:
/usr/src/linux/include/linux/raid/md_k.h: In function `pers_to_level':/usr/src/linux/include/linux/raid/md_k.h:39: warning: control reaches end of non-void function
It is harmless, 'cause the last sentence in the funtion is a panic, but it is good to add the 'return 0', just to shut up the compiler.
The same happens in the aic7xxx drivers v 6.0.9b, file aic7xxx_linux.h, line 824.
Signature · 9 lines
J.A. Magallon $> cd pub mailto:[email protected] $> more beer Linux werewolf 2.4.1-pre10 #4 SMP Wed Jan 24 00:20:15 CET 2001 i686 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] Please read the FAQ at http://www.tux.org/lkml/
[J. A. Magallon]
Quoted 2 lines
It is harmless, 'cause the last sentence in the funtion is a panic, but it is good to add the 'return 0', just to shut up the compiler.
The correct fix is __attribute__((noreturn)) in the panic() prototype. As it happens, this has already been done....
Peter
include/linux/raid/md_k.h renamed from include/linux/raid/md_k.h~ +2 -0
@@ -15,6 +15,8 @@#ifndef _MD_K_H#define _MD_K_H +#include <linux/kernel.h> // for panic() +#define MD_RESERVED 0UL#define LINEAR 1UL#define STRIPED 2UL
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Quoted 8 lines · On 01.25 Peter Samuelson wrote:
[J. A. Magallon]
Quoted 2 lines
It is harmless, 'cause the last sentence in the funtion is a panic, but it is good to add the 'return 0', just to shut up the compiler.
The correct fix is __attribute__((noreturn)) in the
panic()prototype. As it happens, this has already been done....
I know Linux will never be compiled with any other thing than gcc. But what I do not understand is why if there is a standard C way of doing something you have to use an strange extension of gcc.
Same happens with 'return' and 'break'. You type the same to add a '/* DO NOT REMEMBER THE PRECISE COMMENT */' to shut up the compiler instead of just writing
case X:
... return xxx; break;
???
Size optimization for the couple of bytes of the jump in return or break ?
Signature · 9 lines
J.A. Magallon $> cd pub mailto:[email protected] $> more beer Linux werewolf 2.4.1-pre10 #4 SMP Wed Jan 24 00:20:15 CET 2001 i686 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] Please read the FAQ at http://www.tux.org/lkml/
[J. A. Magallon]
Quoted 3 lines
I know Linux will never be compiled with any other thing than gcc. But what I do not understand is why if there is a standard C way of doing something you have to use an strange extension of gcc.
__attribute__((noreturn)) may do other things besides suppress the "no return from non-void function" warning. The gcc manual gives two additional reasons for it:
void fatal () __attribute__ ((noreturn));
The noreturn' keyword tells the compiler to assume that fatal' cannot return. It can then optimize without regard to what would happen if `fatal' ever did return. This makes slightly better code. More importantly, it helps avoid spurious warnings of uninitialized variables.
Thus it is not a workaround, it is a way to give the optimizer extra information. Standard C cannot express this assertion, to my knowledge, so if you stick with ISO you get suboptimal code.
Quoted 1 line
From another viewpoint: the 'return 0', though syntactically correct,
would be misleading -- it will never be executed and we know it. Using __attribute__((noreturn)) reflects reality, which is usually a good thing for coding style. (Whoops, I said "coding style".(: )
Quoted 10 lines
Same happens with 'return' and 'break'. You type the same to add a '/* DO NOT REMEMBER THE PRECISE COMMENT */' to shut up the compiler instead of just writing
case X:... return xxx; break;???
Size optimization for the couple of bytes of the jump in return or break ?
Sorry, I don't follow your point here..
Peter
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