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* [Bug c/78155] missing warning on invalid isalpha et al. [not found] <bug-78155-4@http.gcc.gnu.org/bugzilla/> @ 2020-05-04 11:51 ` bruno at clisp dot org 2022-04-28 11:57 ` [Bug c/78155] missing warning on invalid usage of functions/macros from <ctype.h> (isalpha et al.) egallager at gcc dot gnu.org 2022-06-08 17:39 ` egallager at gcc dot gnu.org 2 siblings, 0 replies; 3+ messages in thread From: bruno at clisp dot org @ 2020-05-04 11:51 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78155 Bruno Haible <bruno at clisp dot org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bruno at clisp dot org --- Comment #6 from Bruno Haible <bruno at clisp dot org> --- Created attachment 48440 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48440&action=edit Test case Another test case is the attached program, alpha.c. When run on glibc systems on x86, x86_64, and other CPUs (not powerpc), it sign-extends the 'char' argument; so the character 'ÿ' (in ISO-8859-1 encoding) becomes EOF, and the <ctype.h> function returns 0. $ LC_ALL=de_DE.ISO-8859-1 xterm $ ./a.out ÿ not alphabetic The corrected program (with a cast to 'unsigned char' in the isalpha() argument) behaves as expected: $ LC_ALL=de_DE.ISO-8859-1 xterm $ ./a.out ÿ alphabetic ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/78155] missing warning on invalid usage of functions/macros from <ctype.h> (isalpha et al.) [not found] <bug-78155-4@http.gcc.gnu.org/bugzilla/> 2020-05-04 11:51 ` [Bug c/78155] missing warning on invalid isalpha et al bruno at clisp dot org @ 2022-04-28 11:57 ` egallager at gcc dot gnu.org 2022-06-08 17:39 ` egallager at gcc dot gnu.org 2 siblings, 0 replies; 3+ messages in thread From: egallager at gcc dot gnu.org @ 2022-04-28 11:57 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78155 Eric Gallager <egallager at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|missing warning on invalid |missing warning on invalid |isalpha et al. |usage of functions/macros | |from <ctype.h> (isalpha et | |al.) --- Comment #7 from Eric Gallager <egallager at gcc dot gnu.org> --- retitling to help me find it more easily again later ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/78155] missing warning on invalid usage of functions/macros from <ctype.h> (isalpha et al.) [not found] <bug-78155-4@http.gcc.gnu.org/bugzilla/> 2020-05-04 11:51 ` [Bug c/78155] missing warning on invalid isalpha et al bruno at clisp dot org 2022-04-28 11:57 ` [Bug c/78155] missing warning on invalid usage of functions/macros from <ctype.h> (isalpha et al.) egallager at gcc dot gnu.org @ 2022-06-08 17:39 ` egallager at gcc dot gnu.org 2 siblings, 0 replies; 3+ messages in thread From: egallager at gcc dot gnu.org @ 2022-06-08 17:39 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78155 --- Comment #8 from Eric Gallager <egallager at gcc dot gnu.org> --- (In reply to Martin Sebor from comment #4) > I don't really see what existing warning this might fall under, except > perhaps -Wchar-subscripts because isalpha and friend use the argument as an > index into an array of 257 characters, but that seems like a stretch. > > I think maybe adding a more general warning option, say something like > -Wargument-range, and using it to diagnose all such problems, might be the > way to go. To generalize the solution I would even consider adding a new > function attribute, let's call it range, to specify the range of valid > values of a function argument. Then isalpha (or any other such function) > could be declared like so: > > __attribute__ ((range (/* position = */1, -1, UCHAR_MAX))) > int isalpha (int); > > GCC would then check every call to the function to see if its argument is in > the expected range and, if not, issue a warning. The attribute could even > be applied multiple times to specify disjoint ranges. Position zero could > denote the return value so that toupper could be declared like so > > __attribute__ ((range (/* returns = */ 0, -1, UCHAR_MAX), > range (/* position = */ 1, -1, UCHAR_MAX))) > int toupper (int); There's been an attempt to add an attribute like this recently on the mailing lists: https://gcc.gnu.org/pipermail/gcc/2022-June/238819.html ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-06-08 17:39 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <bug-78155-4@http.gcc.gnu.org/bugzilla/> 2020-05-04 11:51 ` [Bug c/78155] missing warning on invalid isalpha et al bruno at clisp dot org 2022-04-28 11:57 ` [Bug c/78155] missing warning on invalid usage of functions/macros from <ctype.h> (isalpha et al.) egallager at gcc dot gnu.org 2022-06-08 17:39 ` egallager at gcc dot gnu.org
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