I have just noticed that CFLAGS suggested by Config also include -D_FORTIFY_SOURCE=2 which causes the compiler to warn me that because of this it needs -O! So the question now is whether I need to use -D_FORTIFY_SOURCE=2 in compiling my perl-embed C programs or I can safely ignore it, at least when I need to debug.

-D_REENTRANT -D_GNU_SOURCE -O2 -g -pipe -Wall -Werror=format-security 
+-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param
+=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/r
+edhat-hardened-cc1 -m64 -mtune=generic -fasynchronous-unwind-tables -
+fwrapv -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE 
+-D_FILE_OFFSET_BITS=64
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