Fixes#204051. I have tried this on the reproducer stated in the ticket.
```
[nix-develop]$ $(nix-build -I nixpkgs=/home/shana/programming/nixpkgs --no-out-link)/tests/foo
running 1 test
test check_module_name ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
```
nixpkgs-release-checks> Nixpkgs is not allowed to use <nixpkgs> to refer to itself.
nixpkgs-release-checks> The offending files: /nix/store/mpwvmd4mr2nx1ymw1b2r44lm34ff2vs7-source/pkgs/build-support/deterministic-uname/default.nix
Gcc does not allow `-march=` on PowerPC:
https://gcc.gnu.org/onlinedocs/gcc-12.2.0/gcc/RS_002f6000-and-PowerPC-Options.html#RS_002f6000-and-PowerPC-Options
Instead, `-mcpu=` should be used to set the minimum instruction set
and `-mtune=` is used to optimize instruction scheduling for a
specific processor. Both flags take the same set of valid values,
which includes `native`.
This commit causes `isGccArchSupported` to return `false` for PowerPC
targets so we never pass an `-march=` flag, since that will always be
rejected by gcc.
Inside `nix-shell`, `TMPDIR` (used by `mktemp`) is set to
`/run/user/<uid>` which is usually a tmpfs stored in RAM.
When fetching a large dotnet deps tree to this tmpdir from a
nix-shell (e.g. via `btcpayserver/update.sh`), this can easily exceed
system RAM and `fetch-deps` fails.
mktemp arg `-t` is deprecated and can be omitted.
Switches that gnatmake needs to pass to gcc must be given as
"-cargs <gcc_switches>" after at least the files to compile (see the
gnatmake docs for all the subtleties). This commit makes that happen,
in a way that triggers rebuilds only for things that actually depend on
GNAT, and not the other compilers contained in GCC.
For reasons explained in the commit contents, in order to build the
native gnat package for x86_64-darwin, the native gnatboot package for
x86_64-darwin must have access to both the Clang integrated assembler
and the cctools GNU assembler for that platform. This commit creates a
package with both of those assemblers that x86_64-darwin gnatboot can
then be wrapped with.
Previously srcOnly would not work for e.g.
`srcOnly haskell.compiler.ghcjs`, as the custom `installPhase` would be
skipped if `dontInstall` is set. Consequently, we need to ensure that
the two skippable phases we need will always be executed.
This change switches to using GCC 11 by default on aarch64-linux, as well as passing `-lgcc` to the linker, per #201485.
See #201254 and #208412 for wider context on the issue.
