[Bug bootstrap/61797] [4.10 regression] 'bool decl_in_symtab_p(const_tree)' defined but not used error breaks x86_64-linux bootstrap

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61797

--- Comment #1 from Mikael Pettersson <mikpelinux at gmail dot com> ---
decl_in_symtab_p is used under #ifdef ENABLE_CHECKING by symtab_get_node (also
in craph.h), and unconditionally by fold-const.c:tree_single_nonzero_warnv_p.

Sticking an __attribute__((__used__)) on decl_in_symtab_p allows bootstrap to
continue, until it hits

build/genmodes: config/i386/i386-modes.def:25: (TF) field format must not be
set
build/genmodes: config/i386/i386-modes.def:24: (XF) field format must not be
set
build/genmodes: machmode.def:203: (DF) field format must not be set
build/genmodes: machmode.def:202: (SF) field format must not be set
build/genmodes: machmode.def:244: (TD) field format must not be set
build/genmodes: machmode.def:243: (DD) field format must not be set
build/genmodes: machmode.def:242: (SD) field format must not be set
make[3]: *** [s-modes-m] Error 1

in stage 3, i.e. PR61757.