[Bug c/42457] New: AVR fails to build unless LTO is disabled

[hutchinsonandy at gcc dot gnu dot org]

AVR will fail to build with (default) LTO enabled.

LTO becomes enabled when a working libelf implementation is found.

Mike Stein brought this to my attention and I have been able to replicate it
now I have loaded libelf.

The undefined symbol `builtin_define_std' is defined in c-cppbuiltin.c. It
would appear this is not linked for some of lto compilations - yet target avr.c
is.

The root cause seems to be that avr target uses `builtin_define_std' inside a
staic function `avr_cpu_cpp_builtins' (avr.c) - whereas is used to be used
inside a macro (avr.h). On most (all?) other targets it is used inside a macro
When the macro is not used, there is no definition needed and no link error.

A relevant change on avr target was made 149519

2009-07-11  Anatoly Sokolov  <aesok@post.ru>

        * config/avr/avr.h (TARGET_CPU_CPP_BUILTINS): Redefine.
        (avr_extra_arch_macro) Remove declatation.
        * config/avr/avr.c (avr_cpu_cpp_builtins): New function.
        (avr_extra_arch_macro) Declare as static.
        * config/avr/avr-protos.h (avr_cpu_cpp_builtins): Dclare.


Using --disable-lto switch for configure allows build to complete.


-- 
           Summary: AVR fails to build unless  LTO is disabled
           Product: gcc
           Version: lto
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hutchinsonandy at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: avr-unknown-none


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42457