Just just ./configure CC=gcc CFLAGS=-std=c89 No patching needed. Simple. -- Evgeny On 5 October 2023 23:31:58 GMT+03:00, "Niels Möller" <nisse@xxxxxxxxxxxxxx> wrote: >Hi, > >I still intend GNU Nettle to work with a c89 compiler, and I've been >testing for that by configuring with > > ./configure CC='gcc -std=c89' > >This used to catch accidental use of more recent C language features, >like declarations not at the start of a block. > >However, I just realized that with recent autoconf (I'm now using >autoconf-2.71), AC_PROG_CC has become more helpful, and in this >configuration it automatically changes CC to 'gcc -std=c89 -std=gnu11'. >It's documented at >https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.71/html_node/C-Compiler.html#index-AC_005fPROG_005fCC-1, > > If necessary, options are added to CC to enable support for ISO > Standard C features with extensions, preferring the newest edition of > the C standard that is supported. > >I'm sure that is a very useful feature in most cases, and a natural >extension of the ancient autoconf feature of automatically adding flags >needed to enable c89 aka ANSI-C. > >However, it completely defeats this way of testing that the project can >be built with a c89 ompiler. > >Is there some way of telling autoconf to be less helpful, and attempt to >add options only when needed to enable some particular version (in my >case c89, less conservative projects might want to target c99 in the >same way), but not add anything to enable even later language features? > >An alternative but less general approach would be some hack to skip this >magic in the specific case that the compiler is gcc and CC already >includes some -std=* argument. > >I think similar concerns apply to AC_PROG_CXX, and maybe this kind of >testing is more important there due to higher speed of C++ language >changes. > >BTW, I suspect that there's a typo in the corresponding docs for >AC_PROG_CXX, it says > > After calling this macro, you can check whether the C++ compiler has > been set to accept standard C++ by inspecting the shell variable > ac_prog_cc_stdc. > >"ac_prog_cc_stdc" looks wrong, since that's for AC_PROG_CC, not AC_PROG_CXX? > >Regards, >/Niels >
