Most Linux distributions are enabling this these days and it does
protect against real world vulnerabilities as demonstrated by
CVE-2018-16864 and CVE-2018-16865.
Fix#53753.
Information on llvm version support gleaned from
6609892a2d68e07da3e5092507a730
Information on gcc version support a lot harder to gather,
but both 32bit and 64bit arm do appear to be supported
based on the test suite.
this equates to -ftrivial-auto-var-init=pattern
clang has removed support for -ftrivial-auto-var-init=zero and
are unlikely to re-add it, so use -ftrivial-auto-var-init=pattern
on both compilers if only to make behaviour more consistent
between the two.
add to pkgsExtraHardening's defaultHardeningFlags.
Patch every `derivation` call in the bootsrap process to add it a
conditional `__contentAddressed` parameter.
That way, passing `contentAddressedByDefault` means that the entire
build closure of a system can be content addressed
On one hand, don't want to pass garbage that affects hash, on the other
hand footguns are bad.
Now, factored out the derivation so only need to pass in what is used.
