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From: santosh on 19 Jul 2007 14:47 On Thursday 19 Jul 2007 11:05 pm, Herbert Kleebauer <klee(a)unibwm.de> wrote in message <469FA0D6.7B942A11(a)unibwm.de>: > santosh wrote: > > >> Just don't post the source to comp.lang.c. ;-) > > What's wrong with comp.lang.c? Many folks in clc are what one might call "pedants". They also believe in writing C code that, if possible, emits no diagnostics even when compiled under strictest diagnostic and Standard conformance checking. If windela.c is compiled with the command line: gcc -Wall -Wextra -std=c99 -pedantic -o lindela windela.c gcc emits the following diagnostics before successful compilation: santosh(a)sapphire:~/tmp/windela$ gcc -Wall -Wextra -std=c99 -pedantic -o lindela windela.c windela.c:152: warning: return type defaults to ?int? windela.c: In function ?main?: windela.c:168: warning: implicit declaration of function ?print_string? windela.c:216: warning: implicit declaration of function ?ende? windela.c:222: warning: implicit declaration of function ?ins_lab? windela.c:263: warning: implicit declaration of function ?get_opcode? windela.c:264: warning: implicit declaration of function ?cmps? windela.c:267: warning: implicit declaration of function ?skip_line? windela.c:311: warning: implicit declaration of function ?read_eol? windela.c:317: warning: implicit declaration of function ?list_label? windela.c:324: warning: implicit declaration of function ?get_operand? windela.c:328: warning: implicit declaration of function ?get_w? windela.c:347: warning: implicit declaration of function ?dec_boperand? windela.c:353: warning: implicit declaration of function ?aus_byte? windela.c:361: warning: implicit declaration of function ?adr_pre? windela.c:362: warning: implicit declaration of function ?seg_pre? windela.c:364: warning: implicit declaration of function ?mod__sib? windela.c:374: warning: implicit declaration of function ?mod_sib? windela.c:395: warning: implicit declaration of function ?dec_operand? windela.c:403: warning: implicit declaration of function ?aus_word? windela.c:403: warning: implicit declaration of function ?aus_long? windela.c:979: warning: implicit declaration of function ?get_wert? windela.c:1470: warning: implicit declaration of function ?trans? windela.c:1649: warning: suggest parentheses around && within || windela.c:1715: warning: suggest parentheses around && within || windela.c:2000: warning: suggest parentheses around assignment used as truth value windela.c:2043: warning: suggest parentheses around assignment used as truth value windela.c:2203: warning: suggest parentheses around assignment used as truth value windela.c:2226: warning: suggest parentheses around assignment used as truth value windela.c:3257: warning: suggest parentheses around && within || windela.c:3399: warning: suggest parentheses around && within || windela.c: In function ?adr_pre?: windela.c:5142: warning: suggest parentheses around && within || windela.c:5144: warning: suggest parentheses around && within || windela.c:5145: warning: suggest parentheses around && within || windela.c:5146: warning: control reaches end of non-void function windela.c: In function ?seg_pre?: windela.c:5156: warning: ?return? with no value, in function returning non-void windela.c:5157: warning: ?return? with no value, in function returning non-void windela.c:5158: warning: ?return? with no value, in function returning non-void windela.c: In function ?out_byte?: windela.c:5184: warning: implicit declaration of function ?print_dec? windela.c:5178: warning: unused variable ?p? windela.c:5188: warning: control reaches end of non-void function windela.c: In function ?aus_byte?: windela.c:5196: warning: implicit declaration of function ?list_char? windela.c:5197: warning: implicit declaration of function ?list_byte? windela.c:5204: warning: control reaches end of non-void function windela.c: In function ?aus_word?: windela.c:5223: warning: control reaches end of non-void function windela.c: In function ?aus_long?: windela.c:5245: warning: control reaches end of non-void function windela.c: In function ?list_byte?: windela.c:5278: warning: control reaches end of non-void function windela.c: In function ?list_char?: windela.c:5288: warning: control reaches end of non-void function windela.c: In function ?trans?: windela.c:5305: warning: control reaches end of non-void function windela.c: In function ?mod_sib?: windela.c:5313: warning: control reaches end of non-void function windela.c: In function ?mod__sib?: windela.c:5484: warning: control reaches end of non-void function windela.c: In function ?get_wert?: windela.c:5493: warning: suggest parentheses around assignment used as truth value windela.c:5496: warning: control reaches end of non-void function windela.c: In function ?get_w?: windela.c:5568: warning: implicit declaration of function ?buchzahl? windela.c:5569: warning: implicit declaration of function ?get_zahl? windela.c:5611: warning: operation on ?j? may be undefined windela.c:5611: warning: operation on ?j? may be undefined windela.c:5612: warning: operation on ?j? may be undefined windela.c:5612: warning: operation on ?j? may be undefined windela.c:5613: warning: operation on ?j? may be undefined windela.c:5613: warning: operation on ?j? may be undefined windela.c:5614: warning: operation on ?j? may be undefined windela.c:5614: warning: operation on ?j? may be undefined windela.c:5615: warning: operation on ?j? may be undefined windela.c:5615: warning: operation on ?j? may be undefined windela.c:5616: warning: operation on ?j? may be undefined windela.c:5616: warning: operation on ?j? may be undefined windela.c:5617: warning: operation on ?j? may be undefined windela.c:5617: warning: operation on ?j? may be undefined windela.c:5618: warning: operation on ?j? may be undefined windela.c:5618: warning: operation on ?j? may be undefined windela.c:5619: warning: operation on ?j? may be undefined windela.c:5619: warning: operation on ?j? may be undefined windela.c:5620: warning: operation on ?j? may be undefined windela.c:5620: warning: operation on ?j? may be undefined windela.c:5621: warning: operation on ?j? may be undefined windela.c:5621: warning: operation on ?j? may be undefined windela.c:5622: warning: operation on ?j? may be undefined windela.c:5622: warning: operation on ?j? may be undefined windela.c:5623: warning: operation on ?j? may be undefined windela.c:5623: warning: operation on ?j? may be undefined windela.c:5624: warning: operation on ?j? may be undefined windela.c:5624: warning: operation on ?j? may be undefined windela.c:5625: warning: operation on ?j? may be undefined windela.c:5625: warning: operation on ?j? may be undefined windela.c:5626: warning: operation on ?j? may be undefined windela.c:5626: warning: operation on ?j? may be undefined windela.c:5627: warning: operation on ?j? may be undefined windela.c:5628: warning: operation on ?j? may be undefined windela.c: In function ?get_zahl?: windela.c:5692: warning: implicit declaration of function ?buchst? windela.c:5696: warning: implicit declaration of function ?get_lab? windela.c: In function ?get_operand?: windela.c:5710: warning: implicit declaration of function ?read_char? windela.c:5711: warning: ?return? with no value, in function returning non-void windela.c:5714: warning: implicit declaration of function ?del_blank? windela.c:5708: warning: unused variable ?j? windela.c: In function ?del_blank?: windela.c:5737: warning: suggest parentheses around && within || windela.c:5737: warning: suggest parentheses around && within || windela.c:5740: warning: control reaches end of non-void function windela.c: In function ?dec_boperand?: windela.c:5752: warning: ?return? with no value, in function returning non-void windela.c: In function ?dec_operand?: windela.c:5765: warning: ?return? with no value, in function returning non-void windela.c:5776: warning: ?return? with no value, in function returning non-void windela.c:5782: warning: ?return? with no value, in function returning non-void windela.c:5785: warning: implicit declaration of function ?finds? windela.c:5791: warning: ?return? with no value, in function returning non-void windela.c:5801: warning: ?return? with no value, in function returning non-void windela.c:5812: warning: ?return? with no value, in function returning non-void windela.c:5821: warning: ?return? with no value, in function returning non-void windela.c:5833: warning: ?return? with no value, in function returning non-void windela.c:5846: warning: ?return? with no value, in function returning non-void windela.c:5857: warning: ?return? with no value, in function returning non-void windela.c:5866: warning: ?return? with no value, in function returning non-void windela.c:5879: warning: ?return? with no value, in function returning non-void windela.c:5884: warning: ?return? with no value, in function returning non-void windela.c:5895: warning: ?return? with no value, in function returning non-void windela.c:5905: warning: ?return? with no value, in function returning non-void windela.c:5915: warning: ?return? with no value, in function returning non-void windela.c:5931: warning: ?return? with no value, in function returning non-void windela.c:5942: warning: ?return? with no value, in function returning non-void windela.c:5953: warning: ?return? with no value, in function returning non-void windela.c:5964: warning: ?return? with no value, in function returning non-void windela.c:5980: warning: ?return? with no value, in function returning non-void windela.c:5986: warning: ?return? with no value, in function returning non-void windela.c:5998: warning: ?return? with no value, in function returning non-void windela.c:6004: warning: ?return? with no value, in function returning non-void windela.c:6017: warning: ?return? with no value, in function returning non-void windela.c:6023: warning: ?return? with no value, in function returning non-void windela.c:6036: warning: ?return? with no value, in function returning non-void windela.c:6042: warning: ?return? with no value, in function returning non-void windela.c:6049: warning: ?return? with no value, in function returning non-void windela.c:6055: warning: ?return? with no value, in function returning non-void windela.c:6060: warning: ?return? with no value, in function returning non-void windela.c:6067: warning: ?return? with no value, in function returning non-void windela.c:6072: warning: ?return? with no value, in function returning non-void windela.c:6078: warning: ?return? with no value, in function returning non-void windela.c:6084: warning: ?return? with no value, in function returning non-void windela.c:6090: warning: ?return? with no value, in function returning non-void windela.c:6095: warning: ?return? with no value, in function returning non-void windela.c:6100: warning: ?return? with no value, in function returning non-void windela.c:6105: warning: ?return? with no value, in function returning non-void windela.c:6110: warning: ?return? with no value, in function returning non-void windela.c:6115: warning: ?return? with no value, in function returning non-void windela.c:6120: warning: ?return? with no value, in function returning non-void windela.c:6128: warning: ?return? with no value, in function returning non-void windela.c:6136: warning: ?return? with no value, in function returning non-void windela.c:6141: warning: ?return? with no value, in function returning non-void windela.c:6146: warning: ?return? with no value, in function returning non-void windela.c:6154: warning: ?return? with no value, in function returning non-void windela.c:6162: warning: ?return? with no value, in function returning non-void windela.c:6170: warning: ?return? with no value, in function returning non-void windela.c:6177: warning: ?return? with no value, in function returning non-void windela.c:6178: warning: ?return? with no value, in function returning non-void windela.c:6179: warning: ?return? with no value, in function returning non-void windela.c:6180: warning: ?return? with no value, in function returning non-void windela.c:6181: warning: ?return? with no value, in function returning non-void windela.c:6182: warning: ?return? with no value, in function returning non-void windela.c:6188: warning: suggest parentheses around assignment used as truth value windela.c:6194: warning: ?return? with no value, in function returning non-void windela.c: In function ?finds?: windela.c:6217: warning: suggest explicit braces to avoid ambiguous ?else? windela.c: In function ?ins_lab?: windela.c:6340: warning: suggest explicit braces to avoid ambiguous ?else? windela.c:6351: warning: suggest parentheses around assignment used as truth value windela.c:6358: warning: control reaches end of non-void function windela.c: In function ?list_label?: windela.c:6405: warning: control reaches end of non-void function windela.c: In function ?skip_line?: windela.c:6435: warning: control reaches end of non-void function windela.c: In function ?read_eol?: windela.c:6457: warning: ?return? with no value, in function returning non-void windela.c: In function ?read_char?: windela.c:6469: warning: implicit declaration of function ?get_char? windela.c: In function ?get_char?: windela.c:6498: warning: suggest explicit braces to avoid ambiguous ?else? windela.c: In function ?ende?: windela.c:6570: warning: implicit declaration of function ?exit? windela.c:6570: warning: incompatible implicit declaration of built-in function ?exit? windela.c:6516: warning: unused variable ?p? windela.c: In function ?print_dec?: windela.c:6588: warning: control reaches end of non-void function windela.c: In function ?print_string?: windela.c:6597: warning: control reaches end of non-void function santosh(a)sapphire:~/tmp/windela$ This will be considered simply *awful* in clc. :)
From: Herbert Kleebauer on 19 Jul 2007 17:06 santosh wrote: > If windela.c is compiled with the command line: > > gcc -Wall -Wextra -std=c99 -pedantic -o lindela windela.c > > gcc emits the following diagnostics before successful compilation: Very funny warnings. I always use int instead of void (because then you can use the implicit declaration) and just return nothing. There is only one real warning: > windela.c:5611: warning: operation on ?j? may be undefined But this shouldn't be flaged as a warning but as an error. case 0x05: {la[--j] = la[j] / la[j+1]; break;} With this code, Windela shouldn't work properly when compiled with GCC on a SUN (but this was my first C program and you only learn by making errors). > This will be considered simply *awful* in clc. :) I would consider the warning-system of GCC *awful*.
From: santosh on 19 Jul 2007 17:24 On Friday 20 Jul 2007 2:36 am, Herbert Kleebauer <klee(a)unibwm.de> wrote in message <469FD26C.18F2A0F3(a)unibwm.de>: > santosh wrote: > >> If windela.c is compiled with the command line: >> >> gcc -Wall -Wextra -std=c99 -pedantic -o lindela windela.c >> >> gcc emits the following diagnostics before successful compilation: > > Very funny warnings. I always use int instead of void (because > then you can use the implicit declaration) and just return nothing. > > There is only one real warning: > >> windela.c:5611: warning: operation on ?j? may be undefined > > But this shouldn't be flaged as a warning but as an error. > > case 0x05: {la[--j] = la[j] / la[j+1]; break;} Why should this be an error? This exhibits undefined behaviour, but that doesn't mean compilation should be stopped. > With this code, Windela shouldn't work properly when compiled > with GCC on a SUN (but this was my first C program and you only > learn by making errors). Why only on the SUN? This code should invoke undefined behaviour on all implementations, since 'j' is modified more than once between sequence points. >> This will be considered simply *awful* in clc. :) > > I would consider the warning-system of GCC *awful*. Well just don't say this clc. You'll never hear the end of the story. :)
From: T.M. Sommers on 19 Jul 2007 19:26 santosh wrote: > On Friday 20 Jul 2007 2:36 am, Herbert Kleebauer <klee(a)unibwm.de> > wrote in message <469FD26C.18F2A0F3(a)unibwm.de>: > >>But this shouldn't be flaged as a warning but as an error. >> >> case 0x05: {la[--j] = la[j] / la[j+1]; break;} > > Why should this be an error? This exhibits undefined behaviour, but > that doesn't mean compilation should be stopped. > >>With this code, Windela shouldn't work properly when compiled >>with GCC on a SUN (but this was my first C program and you only >>learn by making errors). > > Why only on the SUN? This code should invoke undefined behaviour on > all implementations, since 'j' is modified more than once between > sequence points. I only see j being modified once. -- Thomas M. Sommers -- tms(a)nj.net -- AB2SB
From: T.M. Sommers on 19 Jul 2007 19:51
Herbert Kleebauer wrote: > > Very funny warnings. I always use int instead of void (because > then you can use the implicit declaration) and just return nothing. Just because you always do it does not mean that it is conforming C. Just because you get away with it today does not mean that you will tomorrow. Implicit int is no longer a part of the language. Neither is a non-void function not having a return. -- Thomas M. Sommers -- tms(a)nj.net -- AB2SB |