This commit adds a derivation `gcc-stageCompare` to
`pkgs/test/stdenv/default.nix`.
It is important to always build this derivation whenever building
`stdenv`! Because we are using a Nix-driven bootstrap instead of
gcc's built-in `--enable-bootstrap`, the `gcc` derivation no longer
performs the post-self-compilation sanity check. You must build
this derivation in order to perform that sanity check.
The major benefit of this new approach is that the sanity check
(which involves a third compilation of gcc) can be performed
*concurrently* with all packages that depend on `stdenv`, rather
than serially. Since `stdenv` has very little derivation-level
parallelism it cannot take advantage of more than one or perhaps two
builders. If you have three or more builders this commit will
reduce the time-to-rebuild-stdenv by around 20% (one of three gcc
rebuilds is removed from the critical path, and stdenv's build time
is dominated by roughly 3*gcc + 1*binutils + 1*bison-test-suite).
Co-authored-by: Sandro <sandro.jaeckel@gmail.com>
with structuredAttrs lists will be bash arrays which cannot be exported
which will be a issue with some patches and some wrappers like cc-wrapper
this makes it clearer that NIX_CFLAGS_COMPILE must be a string as lists
in env cause a eval failure
Closes#16182
This improves the error message
Error: _assignFirst found no valid variant!
which occurred when the set of outputs was not sufficient to set
the various outputDev, outputBin, etc variables. Specifically, this
would mean that "out" is not among the outputs, which is valid for
a derivation.
This changes the message to something like
error: _assignFirst: could not find a non-empty variable to assign to outputDev. The following variables were all unset or empty: dev out.
If you did not define an "out" output, make sure to define all the specific required outputs: define an output for one of the unset variables.
While this isn't a full explanation of what stdenv can and can not do,
I think it's vast improvement over the 0 bits of information that it
used to provide. This at least gives a clue as to what's going on, and
even suggests a fix, although probably multiple such fixes are required
in an instance where someone starts with a no-out derivation from scratch
(and decide to persist).
Derivations not using `__structuredAttrs` should not attempt to set
environment variables from `env`.
Derivations using `__structuredAttrs` should fail if `env` is not
exportable.
