And probably many other distributions.
Until now, ./configure would fail silently printing a warning
./configure: line 4621: AX_CXX_COMPILE_STDCXX_17: command not found
and then continuing, later failing with a C++ #error saying that some C++11
feature isn't supported (it didn't even get to the C++17 features).
This is because older distributions don't come with the
`AX_CXX_COMPILE_STDCXX_17` m4 macro.
This commit vendors that macro accordingly.
Now ./configure complains correctly:
configure: error: *** A compiler with support for C++17 language features is required.
On Ubuntu 16.04, ./configure completes if a newer compiler is used, e.g. with
gcc-7 from https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test
using:
./bootstrap.sh
./configure CXX=g++-7 --disable-doc-gen --with-boost=$(nix-build --no-link '<nixpkgs>' -A boost.dev)
And probably other Linux distributions with long-term support releases.
Also update manual stating what version is needed;
I checked that 1.14 is the oldest version with which current nix compiles,
and added autoconf feature checks for some functions added in that release
that nix uses.
In `args@{ a ? 1 }: /* ... */` the value `a` won't be a part of `args`
unless it's specified when calling the function, the default value will
be ignored in this case.
My personal point of view is that this behavior is a matter of taste, at
least I was pretty sure that unmatched arguments will be a part of
`args@` while debugging some Nix code last week.
I decided to add a warning to the docs which hopefully reduces the
confusion of further Nix developers who thought the same about `args@`.
For text files it is possible to do it like so:
`builtins.hashString "sha256" (builtins.readFile /tmp/a)`
but that doesn't work for binary files.
With builtins.hashFile any kind of file can be conveniently hashed.
Inside a derivation, exportReferencesGraph already provides a way to
dump the Nix database for a specific closure. On the command line,
--dump-db gave us the same information, but only for the entire Nix
database at once.
With this change, one can now pass a list of paths to --dump-db to get
the Nix database dumped for just those paths. (The user is responsible
for ensuring this is a closure, like for --export).
Among other things, this is useful for deploying a closure to a new
host without using --import/--export; one can use tar to transfer the
store paths, and --dump-db/--load-db to transfer the validity
information. This is useful if the new host doesn't actually have Nix
yet, and the closure that is being deployed itself contains Nix.
- The instructions for using nix-shell as an interpreter has a Haskell script
example that doesn't work on more recent versions of Nix. Update the
instructions with a working command
Maximilian Bosch
Jonas Chevalier
Linus Heckemann