=?utf-8?B?0J3QuNC60L7Qu9Cw0Lkg0KfQsNC00LDQtdCy?= <nick-ch58@yandex.ru> writes:
PG>make PG_CONFIG=/usr/pgsql-12/bin/pg_config
. . . . . .
$>make PG_CONFIG=/usr/pgsql-12/bin/pg_config
/opt/rh/llvm-toolset-7/root/usr/bin/clang -Wno-ignored-attributes -fno-strict-aliasing -fwrapv -O2 -I. -I./ -I/usr/pgsql-12/include/server -I/usr/pgsql-12/include/internal -D_GNU_SOURCE -I/usr/include/libxml2 -I/usr/include -flto=thin -emit-llvm -c -o pg_hashids.bc pg_hashids.c
clang: error: unknown argument: '-flto=thin'

Hm. I'm guessing that that version of clang is too old. Are you
perhaps overriding the value of CLANG that our Makefile.global
tries to set?

                        regards, tom lane