Antonin Décimo <antonin@xxxxxxxxxxx> writes: > Le mar. 30 avr. 2024 à 15:01, Sam James <sam@xxxxxxxxxx> a écrit : >> >> Paul Eggert <eggert@xxxxxxxxxxx> writes: >> >> > On 2024-04-26 08:10, Zack Weinberg wrote: >> > >> >> I think what we should do here is fold AC_C_VARARRAYS into AC_PROG_CC. >> >> Take the test for VLAs completely out of _AC_C_C99_TEST_MAIN, but >> >> unconditionally *run* a test for VLAs as part of AC_PROG_CC. If that >> >> test fails, and __STDC_NO_VLA__ was not defined by the compiler, >> >> then AC_DEFINE([__STDC_NO_VLA__], 1) >> > >> > Although the basic strategy sounds reasonable, AC_PROG_CC is >> > documented to operate by setting compiler options not via AC_DEFINE, >> > so presumably this should put -D__STDC_NO_VLA__ into $CC rather than >> > use AC_DEFINE. >> > >> > I installed the attached patch, which is less ambitious but should >> > address the original problem report. The attached patch doesn't >> > preclude your suggestion, which can be done later as needed. >> > >> > [2. text/x-patch; 0001-Port-better-to-MSVC.patch]... >> >> Note that "or later" isn't right -- C23 makes VLAs mandatory again. > > I don't think that's true… Wikipedia links to the paper modifying the > standard: > >> For these reasons, we propose to make variably-modified types >> mandatory in C23. VLAs with automatic storage duration remain an >> optional language feature due to their higher implementation >> overhead and security concerns on some implementations (i.e. when >> allocated on the stack and not using stack probing). > > https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2778.pdf You're right - I confused VLAs with VMTs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896#c13. Thanks! > > Best regards, > Antonin
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