docs: Add some examples to fetchGit

Print stats in more programs

This is already done by coerceToString(), provided that the argument
is a path (e.g. 'fetchGit ./bla'). It fixes the handling of URLs like
git@github.com:owner/repo.git. It breaks 'fetchGit "./bla"', but that
was never intended to work anyway and is inconsistent with other
builtin functions (e.g. 'readFile "./bla"' fails).

Fixes #2390.

https://hydra.nixos.org/build/80480356

docs: Add IDs to important sections

fix `error: unknown serve command 9`

Also some cosmetic improvements.

E.g.

  $ nix upgrade-nix
  error: directory '/home/eelco/Dev/nix/inst/bin' does not appear to be part of a Nix profile

instead of

  $ nix upgrade-nix
  error: '/home/eelco/Dev/nix/inst' is not a symlink

Docs: Fix install prefix

Fix a 32-bit overflow that resulted in negative numbers being printed;
use fmt() instead of boost::format(); change -H to -h for consistency
with 'ls' and 'du'; make the columns narrower (since they can't be
bigger than 1024.0).

If the user has an object greater than 1024 yottabytes, it'll just display it as
N yottabytes instead of overflowing.

Swaps to use boost::format strings instead of std::setw and std::setprecision.

Unfortunately, -h is already taken as a short option by --help, so we have to
use a different letter or the capitalized version.

Resolves #2363

This reduces the size of the closure by 45 MiB.

repl: don't add trailing spaces to history lines

libexpr: Use int64_t for NixInt

Using a 64bit integer on 32bit systems will come with a bit of a
performance overhead, but given that Nix doesn't use a lot of integers
compared to other types, I think the overhead is negligible also
considering that 32bit systems are in decline.

The biggest advantage however is that when we use a consistent integer
size across all platforms it's less likely that we miss things that we
break due to that. One example would be:

https://github.com/NixOS/nixpkgs/pull/44233

On Hydra it will evaluate, because the evaluator runs on a 64bit
machine, but when evaluating the same on a 32bit machine it will fail,
so using 64bit integers should make that consistent.

While the change of the type in value.hh is rather easy to do, we have a
few more options available for doing the conversion in the lexer:

  * Via an #ifdef on the architecture and using strtol() or strtoll()
    accordingly depending on which architecture we are. For the #ifdef
    we would need another AX_COMPILE_CHECK_SIZEOF in configure.ac.
  * Using istringstream, which would involve copying the value.
  * As we're already using boost, lexical_cast might be a good idea.

Spoiler: I went for the latter, first of all because lexical_cast does
have an overload for const char* and second of all, because it doesn't
involve copying around the input string. Also, because istringstream
seems to come with a bigger overhead than boost::lexical_cast:

https://www.boost.org/doc/libs/release/doc/html/boost_lexical_cast/performance.html



The first method (still using strtol/strtoll) also wasn't something I
pursued further, because it is also locale-aware which I doubt is what
we want, given that the regex for int is [0-9]+.

Signed-off-by: aszlig <aszlig@nix.build>
Fixes: #2339

The profile present in PATH is not necessarily the actual profile
location. User profiles are generally added as $HOME/.nix-profile
in which case the indirect profile link needs to be resolved first.

/home/user/.nix-profile -> /nix/var/nix/profiles/per-user/user/profile
/nix/var/nix/profiles/per-user/user/profile -> profile-15-link
/nix/var/nix/profiles/per-user/user/profile-14-link -> /nix/store/hyi4kkjh3bwi2z3wfljrkfymz9904h62-user-environment
/nix/var/nix/profiles/per-user/user/profile-15-link -> /nix/store/6njpl3qvihz46vj911pwx7hfcvwhifl9-user-environment

To upgrade nix here we want /nix/var/nix/profiles/per-user/user/profile-16-link
instead of /home/user/.nix-profile-1-link. The latter is not a gcroot
and would be garbage collected, resulting in a broken profile.

Fixes #2175

This reverts commit d277442d.

Make sucks.

Drop dead code

shell.nix defines the install prefix as $(pwd)/inst

Ubuntu 17.10 doesn't have libbrotli.

https://hydra.nixos.org/build/79867741