In some cases `$pkgs_src` can be a path. For example with `FSharp.Core` when it comes with dotnet SDK.
In these cases we need to fallback on default URL otherwise curl fails.
A function to generate pkg-config files for Nix packages that need to create them ad hoc,
like blas and lapack.
Inspiration taken from `makeDesktopItem`.
Currently when cross compiling the `buildPackages.libredirect` has the wrong dynamic library extension.
To reproduce the issue run something like:
```
file $(nix-build -A pkgsCross.mingwW64.buildPackages.libredirect)/lib/libredirect.dll
/nix/store/80llmqa9lkabg3qnmglngzz22fwf739q-libredirect-0/lib/libredirect.dll: Mach-O 64-bit dynamically linked shared library x86_64
```
or
```
nix-diff $(nix-instantiate -A libredirect) $(nix-instantiate -A pkgsCross.mingwW64.buildPackages.libredirect)
```
By default, Cargo will only enable line tables. -g enables full debug
info. The RUSTFLAGS environment variable is examined by Cargo,
similar to how the NIX_*FLAGS* variables are examined by our compiler
wrappers.
Before this change `srcOnly git` gives:
duplicate derivation output 'debug', at pkgs/stdenv/generic/make-derivation.nix:270:7
This was because separateDebugInfo = true was passed on to the srcOnly
mkDerivation as well as the outputs list _including_ the debug output.
Luckily we don't need to untangle this mess since srcOnly is only
supposed to have a single output anyways.
Some haskell code starts silently hanging when not built with a
threaded runtime, so let’s assume people using `writeHaskell` don’t
care about micro-optimizations like this and do the expected thing.
Some architectures don’t support a threaded runtime, for these we
provide the `threadedRuntime` option to turn it off (it should fail at
build time in that case, easy to detect).
If somebody already passed `"-threaded"` before via ghcArgs, this
will not add the flag a second time. Thus it’s backward-compatible in
this regard.
I tested out both branches (with `-threaded` set and not set before),
on an example I had where the runtime would hang when not compiled
with `-threaded`.
Sometimes I want to pass a different implementation of `mkNugetDeps`.
For example in private repos, it can be handy to use `__noChroot = true`
and bypass the deps.nix generation altogether. Or some Nuget packages
ship with ELF binaries that need to be patched, and that's best done as
soon as possible.
If the package was not restored from nuget.org (determinted by checking
the "source" field of ".nupkg.metadata"), query the custom source for
the package endpoint (the way nuget api is built we can't determine it
without an API query) and build a custom package URL to save in the
generated deps file.
