This is a small simplification of the control flow surrounding these cases. It should make it more obvious when each case happens, and also explicitly defines the current behaviour of --replace.
stdenv.cc may throw, e.g. in the case of pkgsCross.ghcjs where we must
not force it for the purpose of attribute accessing (`or` doesn't
implicitly tryEval…).
Regression introduced in 1a5bd697ad.
Aka `checkMeta` goes brrr.
Using the module system type checking works OK & generates good error messages.
The performance of using it however is terrible because of the value merging it does being very allocation heavy.
By implementing a very minimal type checker we can drastically improve the performance when nixpkgs is evaluated with `checkMeta = true`.
this makes it a lot easier to create a modified stdenv with a
different set of defaultHardeningFlags and as a bonus allows us
to inject the correct defaultHardeningFlags into toolchain wrapper
scripts, reducing repetition.
while most hardening flags are arguably more of a compiler thing,
it works better to put them in bintools-wrapper because cc-wrapper
can easily refer to bintools but not vice-versa.
mkDerivation can still easily refer to either when it is constructed.
this also switches fortran-hook.sh to use the same defaults for
NIX_HARDENING_ENABLE as for C. previously NIX_HARDENING_ENABLE
defaults were apparently used to avoid passing problematic flags
to a fortran compiler, but this falls apart as soon as mkDerivation
sets its own NIX_HARDENING_ENABLE - cc.hardeningUnsupportedFlags
is a more appropriate mechanism for this as it actively filters
out flags from being used by the wrapper, so switch to using that
instead.
this is still an imperfect mechanism because it doesn't handle a
compiler which has both langFortran *and* langC very well - applying
the superset of the two's hardeningUnsupportedFlags to either
compiler's invocation. however this is nothing new - cc-wrapper
already poorly handles a langFortran+langC compiler, applying two
setup hooks that have contradictory options.
If a CMake target has a non-default LINKER_LANGUAGE set, CMake will
manually add the libraries it has detected that language's compiler as
linking implicitly. When it does this, it'll pass -Bstatic and
-Bdynamic options based on the vibes it gets from each such detected
library. This in itself isn't a problem, because the compiler
toolchain, or our wrapper, or something, seems to be smart enough to
ignore -Bdynamic for those libraries. But it does create a problem if
the compiler adds extra libraries to the linker command line after
that final -Bdynamic, because those will be linked dynamically. Since
our compiler is static by default, CMake should reset to -Bstatic
after it's done manually specifying libraries, but CMake didn't
actually know that our compiler is static by default. The fix for
that is to tell it, like so.
Until recently, this problem was difficult to notice, because it would
result binaries that worked, but that were dynamically linked. Since
e08ce498f0 ("cc-wrapper: Account for NIX_LDFLAGS and NIX_CFLAGS_LINK
in linkType"), though, -Wl,-dynamic-linker is no longer mistakenly
passed for executables that are supposed to be static, so they end up
created with a /lib interpreter path, and so don't run at all on
NixOS.
This fixes pkgsStatic.graphite2.
Provide a `runPhase` function which wraps the phase running action of
genericBuild. The new function can be used as an interface by `nix
develop`, i.e. `nix develop some#flake --build` may just call `runPhase
build`, which makes its behavior more consistent with `nix build`.
In preparation of fixing https://github.com/NixOS/nix/issues/6202
- These new-cli commands can be used with `-f`, in which case they're
evaluated with pure evaluation disabled.
- Nix 2.4+ is not part of the condition; "flakes" is fully descriptive
and more relatable.
- Don't suggest that it only enables this variable.
- Just don't say too much.
While there is no fetcher or builder (in nixpkgs) that takes an `md5` parameter,
for some inscrutable reason the nix interpreter accepts the following:
```nix
fetchurl {
url = "https://www.perdu.com";
hash = "md5-rrdBU2a35b2PM2ZO+n/zGw==";
}
```
Note that neither MD5 nor SHA1 are allowed by the syntax of SRI hashes.
When specifying the `builder` attribute in `stdenv.mkDerivation`, this
will be effectively transformed into
builtins.derivation {
builder = stdenv.shell;
args = [ "-e" builder ];
}
This also means that `default-builder.sh` is never sourced and as a
result it's not guaranteed that `$NIX_ATTRS_SH_FILE` is set to a correct
location[1].
Also, we need to source `.attrs.sh` to source `$stdenv`. So, the
following is done now:
* If `$NIX_ATTRS_SH_FILE` points to a correct location, then use it.
Directly using `.attrs.sh` is problematic for `nix-shell(1)` usage
(see previous commit for more context), so prefer the environment
variable if possible.
* Otherwise, if `.attrs.sh` exists, then use it. See [1] for when this
can happen.
* If neither applies, it can be assumed that `__structuredAttrs` is
turned off and thus nothing needs to be done.
[1] It's possible that it doesn't exist at all - in case of Nix 2.3 or
it can point to a wrong location on older Nix versions with a bug in
`__structuredAttrs`.
Relying on `.attrs.sh` to exist in `$NIX_BUILD_TOP` is problematic
because that's not compatible with how `nix-shell(1)` behaves. It places
`.attrs.{json,sh}` into a temporary directory and makes them accessible via
`$NIX_ATTRS_{SH,JSON}_FILE` in the environment[1]. The sole reason that
`nix-shell(1)` still works with structured-attrs enabled derivations
is that the contents of `.attrs.sh` are sourced into the
shell before sourcing `$stdenv/setup` (if `$stdenv` exists) by `nix-shell`.
However, the assumption that two files called `.attrs.sh` and
`.attrs.json` exist in `$NIX_BUILD_TOP` is wrong in an interactive shell
session and thus an inconsistency between shell debug session and actual
builds which can lead to unexpected problems.
To be precise, we currently have the following problem: an expression
like
with import ./. {};
runCommand "foo" { __structuredAttrs = true; foo.bar = [ 1 2 3 ]; }
''
echo "''${__structuredAttrs@Q}"
touch $out
''
prints `1` in its build-log. However when building interactively in a
`nix-shell`, it doesn't.
Because of that, I'm considering to propose a full deprecation of
`$NIX_BUILD_TOP/.attrs.{json,sh}`. A first step is to only mention the
environment variables, but not the actual paths anymore in Nix's
manual[2]. The second step - this patch - is to fix nixpkgs' stdenv
accordingly.
Please note that we cannot check for `-e "$NIX_ATTRS_JSON_FILE"` because
certain outdated Nix minors (that are still in the range of supported
Nix versions in `nixpkgs`) have a bug where `NIX_ATTRS_JSON_FILE` points
to the wrong file while building[3].
Also, for compatibility with Nix 2.3 which doesn't provide these
environment variables at all we still need to check for the existence of
.attrs.json/.attrs.sh here. As soon as we bump nixpkgs' minver to 2.4,
this can be dropped.
Finally, dropped the check for ATTRS_SH_FILE because that was never
relevant. In nix#4770 the ATTRS_SH_FILE variable was introduced[4] and
in a review iteration prefixed with NIX_[5]. In other words, these
variables were never part of a release and you'd only have this problem
if you'd use a Nix from a git revision of my branch from back then. In
other words, that's dead code.
[1] https://github.com/nixos/nix/pull/4770#issuecomment-834718851
[2] https://github.com/NixOS/nix/pull/9032
[3] https://github.com/NixOS/nix/issues/6736
[4] 3944a120ec
[5] 27ce722638
Fixes `pkgsCross.musl64.llvmPackages_16.clang.cc` on `x86_64-linux`,
which used to fail with `/bin/sh: clang-tblgen: not found`.
Same hack is used in other projects:
https://github.com/search?q=%2FCMAKE_CROSSCOMPILING_EMULATOR.%2B%5C%2Fusr%5C%2Fbin%5C%2Fenv%2F+NOT+is%3Afork&type=code
Comment from 30435a9d0f/build/cmake/HostLinuxToolchain.cmake (L64)
> Required to run host Linux executables during the build itself.
> An example would be https://gitub.com/KhronosGroup/Vulkan-Loader and
> its "asm_offset" program.
>
> NOTE: Alternatives have been tried unsuccessfully, i.e.:
>
> With $(set CMAKE_CROSSCOMPILING_EMULATOR), the build fails because
> the CMake ninja/Make script tries to find the executable in the current
> path, as in:
>
> [3/16] Generating gen_defines.asm
> FAILED: loader/gen_defines.asm
> cd /tmp/cc/build-Vulkan-Loader/loader && asm_offset GAS
> /bin/sh: asm_offset: command not found
> ninja: build stopped: subcommand failed.
>
> With $(set CMAKE_CROSSCOMPILING_EMULATOR ""), the build fails because
> the shell cannot find the "" program as in:
>
> [3/16] Generating gen_defines.asm
> FAILED: loader/gen_defines.asm
> cd /tmp/cc/build-Vulkan-Loader/loader && "" /tmp/cc/build-Vulkan-Loader/loader/asm_offset GAS
> /bin/sh: : command not found
> ninja: build stopped: subcommand failed.
>
> It seems that the root of the problem comes from how the CMake function
> cmCustomCommandGenerator::GetArgc0Location() computes the target
> executable's location. At this point it's unclear whether this is a CMake
> bug or a feature.
Risicle discovered this hack.
Co-authored-by: Robert Scott <code@humanleg.org.uk>
In the default `fixupPhase` the output of `substituteAllStream` is
streamed to setup-hook.
`stdenv.cc.bintools.overrideAttrs { NIX_DEBUG = 6; }`
With `NIX_DEBUG` contains:
```
@expandResponseParams@ -> /nix/store/yl01rd58vp4m8bbhkihpk132cprfmx6f-expand-response-params/bin/expand-response-params
...
```
