On 12/31/2012 09:57 AM, Eric Blake wrote: > How do I go about debugging and fixing these errors? I suspect they are > more fallout from Paul's efforts to revamp how 'inline' works; these > were reproduced by temporarily bumping m4 to the latest gnulib.git and > compiling on a RHEL 5.8 machine (kernel 2.6.18, glibc 2.5, gcc 4.6.4):
It looks like the particular machine I tested on was using a non-default gcc (stock RHEL 5 still ships with gcc 4.1.2); this may be a case of the old headers and new compiler not being compatible with one another, and therefore something we don't have to worry about by default. > > gcc -std=gnu99 -g -O2 -o m4 m4.o builtin.o debug.o eval.o format.o > freeze.o input.o macro.o output.o path.o symtab.o ../lib/libm4.a > /usr/local/lib/libsigsegv.a -lc > builtin.o: In function `stpncpy': > /usr/include/bits/string3.h:156: multiple definition of `stpncpy' > m4.o:/usr/include/bits/string3.h:156: first defined here > > It's choking on this, and any other function, where older glibc uses the > following style of declaration: > > extern __always_inline char * > __NTH (stpncpy (char *__dest, __const char *__src, size_t __n)) Looking at the preprocessor output, this expanded to: extern __inline __attribute__ ((__always_inline__)) char * __attribute__ ((__nothrow__)) stpncpy (char *__dest, __const char *__src, size_t __n) But comparing it to a machine with modern gcc _and_ modern glibc, I see a more complex expansion to: extern __inline __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__)) __attribute__ ((__artificial__)) char * __attribute__ ((__nothrow__ , __leaf__)) stpncpy (char *__dest, const char *__src, size_t __n) So I wonder if it is worth trying to have gnulib fix the glibc definition of __always_inline to include '__attribute__ ((__gnu_inline__))' when appropriate. But I'm not sure how easy that would be to detect if the current gcc needs this attribute added to the current glibc definition of the internal __always_inline macro. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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