Commit 6d928ab684 changed this to not
preserve timestamps. However, that results in non-determinism; in
particular, it gives us a broken $SOURCE_DATE_EPOCH (especially for
everything using fetchFromGitHub). Builds affected by timestamps <
1980 should be fixed in some other way (e.g. changing the timestamp to
some fixed date > 1980).
The ld-wrapper.sh script calls `readlink` in some circumstances. We need
to ensure that this is the `readlink` from the `coreutils` package so
that flag support is as expected.
This is accomplished by explicitly setting PATH at the top of each shell
script.
Without doing this, the following happens with a trivial `main.c`:
```
nix-env -f "<nixpkgs>" -iA pkgs.clang
$ clang main.c -L /nix/../nix/store/2ankvagznq062x1gifpxwkk7fp3xwy63-xnu-2422.115.4/Library -o a.out
readlink: illegal option -- f
usage: readlink [-n] [file ...]
```
The key element is the `..` in the path supplied to the linker via a
`-L` flag. With this patch, the above invocation works correctly on
darwin, whose native `/usr/bin/readlink` does not support the `-f` flag.
The explicit path also ensures that the `grep` called by `cc-wrapper.sh`
is the one from Nix.
Fixes#6447
This is used by some build tools to provide reproducible builds. See
https://reproducible-builds.org/specs/source-date-epoch/
for more info.
Later, we'll want to set this to a more intelligent value (such as the
most recent mtime of any source file).
So far if no configure script is found or no makefile,
the rest of the phase is skipped, *including* post-hooks.
I find that behavior unexpected/unintuitive.
Earlier version of this patch had problems due to me assuming
that $configureScript is always a simple path, but that turned out
to be false in many cases, e.g. perl.
This un-hardcodes the bootstrap tools passed into the Darwin stdenv and
thus allows us to quickly iterate on improving the design of the full
bootstrap process. We can easily change the contents of the bootstrap
tools and evaluate an entire bootstrap all the way up to real packages.
The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.
