(Sending this a 2nd time, after I joined the list.) For the Nettle crypto library:
If the C compiler lacks __builtin_bswap64, then Nettle may call a function named __builtin_bswap64 and get a link error. The problem is that ./configure doesn't check for link errors. I append a small diff to switch from AC_TRY_COMPILE to AC_TRY_LINK. OpenBSD, on some unusual hardware platforms, still uses GCC 4.2.1, which doesn't have __builtin_bswap64. Manphiz reported to OpenBSD that the build of Nettle 3.5.1 failed on mips64el/longsoon hardware: https://marc.info/?l=openbsd-ports&m=157510504817444&w=2 The error was "undefined reference to `__builtin_bswap64'". Nettle only uses __builtin_bswap64 (in ctr.c) on little-endian hardware. The error didn't happen when OpenBSD built Nettle with GCC 4.2.1 on big-endian platforms, like powerpc/macppc. In traditional C, you never needed to declare functions if their return type was int. C code like `whatever(11, "a string")` would implicitly declare `int whatever();`. Likewise, if __builtin_bswap64 isn't a built-in, then `__builtin_bswap64(x)` in ./configure does implicitly declare `int __builtin_bswap64();` as a function. AC_TRY_COMPILE can compile this function call, but AC_TRY_LINK can't link it. OpenBSD decided to patch ./configure to do a link test: https://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/security/libnettle/patches/patch-configure?rev=1.9&content-type=text/x-cvsweb-markup The below diff is for configure.ac in Nettle git master cdbbe64. After I made this change, I ran ./.bootstrap and checked the build on my OpenBSD powerpc/macppc machine with GCC 4.2.1: $ ../configure --disable-documentation \ > CPPFLAGS=-I/usr/local/include LDFLAGS=-L/usr/local/lib $ gmake $ gmake check (The --disable-documentation prevents an error from makeinfo 4.8, which seems too old. The FLAGS find gmp in /usr/local, because OpenBSD's compilers don't look there by default. gmake is GNU make.) The build got "All 99 tests passed", then "All 3 tests passed". config.log shows that "checking for __builtin_bswap64" failed with the "undefined reference" error. --George diff --git a/configure.ac b/configure.ac index 3547cae4..7ac84f2e 100644 --- a/configure.ac +++ b/configure.ac @@ -213,7 +213,7 @@ AC_C_BIGENDIAN([AC_DEFINE([WORDS_BIGENDIAN], 1) AC_CACHE_CHECK([for __builtin_bswap64], nettle_cv_c_builtin_bswap64, -[AC_TRY_COMPILE([ +[AC_TRY_LINK([ #include <stdint.h> ],[ uint64_t x = 17; _______________________________________________ nettle-bugs mailing list [email protected] http://lists.lysator.liu.se/mailman/listinfo/nettle-bugs
