vfork confers a large performance advantage over fork, measured locally
at 16µs per vfork agains 90µs per fork. however nix *almost always*
follows a vfork up with an execve-family call, melting the performance
advantage from 6x to only 15%. in most of those cases it's doing things
that are undefined behavior (like manipulating the heap, or even
throwing exceptions and trashing the parent process stack).
most notably the one place that could benefit from the vfork performance
improvement is linux derivation sandbox setup—which doesn't use vfork.
Change-Id: I2037b7384d5a4ca24da219a569e1b1f39531410e
This builtin is only going to cause us problems because we are not Nix,
so let's just falsify being in the 2.18 series, since that is the
closest target that has any meaning.
In future we might want to have a better feature detection mechanism,
for when we actually add stuff to some builtin's attr set argument. But
builtins.nixVersion is just going to be hopelessly broken and it should
be stubbed out.
Fixes #144
Change-Id: Id7390b32a29c6147f2977737d81846320de5d67e
diagnose attr duplication at the path the duplication was detected, not
at the path the current attribute wanted to place. doing the latter is
only correct if a leaf attribute was duplicated, not if an attrpath was
set to a non-attrset in one binding and a (potentially implied) attrset
in another binding.
fixes#124
Change-Id: Ic4aa9cc12a9874d4e7897c6f64408f10aa36fc82
It happens with some frequency that plugins that might be unimportant to
the evaluation at hand mismatch with the nix version, leading to
spurious load failures. Let's make these non fatal.
Change-Id: Iba10e951d171725ccf1a121bcd9be1e1d6ad69eb
using the total-attrs-printed and total-list-items-printed counters to
calculate how many attrs were elided only works properly if no nesting
is involved. once things do nest the global counter can exceed the size
of the currently printed object, leading to unsigned wrapping and great
overestimation of elided counts. counting locally in addition to global
counts fixes this.
these are functional tests because creating these objects requires the
evaluator to not be a huge amount of code, and we also want defaults to
be tested for cli usage.
fixes#14
Change-Id: Icb9a0cb21b2f4bacbc5e9dcdd8c0b9055b4088a7
This is definitely not a stable thing, but it does feel slightly crimes
to put it as an experimental feature. Shrug, up for bikeshedding.
Change-Id: I6ef176e3dee6fb1cac9c0a7a60d553a2c63ea728
This solves the problem of collections of boxed subclasses with virtual
dispatch, which should still be treated as values, since the
indirection is only there due to the virtual dispatch.
Change-Id: I368daedd3f31298e99c6e56a15606337a55494c6
it's no longer widely used and has a rather confusing meaning now that
inherit-from is handled very differently.
(cherry picked from commit 1cd87b7042d14aae1fafa47b1c28db4c5bd20de7)
Change-Id: I90bbebddf06762960d8ca4f621cf042ce8ae83f9
desugaring inherit-from to syntactic duplication of the source expr also
duplicates side effects of the source expr (such as trace calls) and
expensive computations (such as derivationStrict).
(cherry picked from commit cefd0302b55b3360dbca59cfcb4bf6a750d6cdcf)
Change-Id: Iff519f991adef2e51683ba2c552d37a3df7a179e
deduplication does not currently work fully, showing derivations
multiple times if they have different underlying values. this can happen
by selecting the same derivation twice for two different attributes of a
set, using inherit-from (which reduces to the previous), importing
nixpkgs twice, or any other number of things.
since users already have to deal with duplicates for this reason it
won't hurt to add *more* duplicates. the alternative would be to
deduplicate fully, which would drop derivations that are currently
returned and those pose a regression risk.
Change-Id: I64b397351237e10375d270f1bddecb71f62aa131
for plain inherits this is really just a stylistic choice, but for
inherit-from it actually fixes an exponential size increase problem
during expr printing (as may happen during assertion failure reporting,
on during duplicate attr detection in the parser)
(cherry picked from commit ecf8b12d60ad2929f9998666cf0966475b91e291)
Change-Id: Ie55f0cb01a37e766414c31f8d40f51c2c7d106b0
this also has the effect of sorting let bindings lexicographically
rather than by symbol creation order as was previously done, giving a
better canonicalization in the process.
(cherry picked from commit 6c08fba533ef31cad2bdc03ba72ecf58dc8ee5a0)
Change-Id: Ia887f629305645bb8a165fbbc0d32e620912595a
in place of inherited() — not quite useful yet since we don't
distinguish plain and inheritFrom attr kinds so far.
(cherry picked from commit 1f542adb3e18e7078e6a589182a53a47d971748a)
Change-Id: If948c9d43e875de18f213a73a06a36f7c335b536
Do not skip any stack frames when `--show-trace` is given
(cherry picked from commit 0b47783d0a879875d558f0b56e49584f25ceb2d0)
Change-Id: Ia0f18266dbcf97543110110c655c219c7a3e3270
Enter debugger on `builtins.trace` with an option
(cherry picked from commit 774e7ca5847ebc392eac2a124a8f12b24da4f65a)
Change-Id: If01e2110b3a128e639b05143227e365227d149f1
Pretty-print values in the REPL by printing each item in a list or
attrset on a separate line. When possible, single-item lists and
attrsets are printed on one line, as long as they don't contain a nested
list, attrset, or thunk.
Before:
```
{ attrs = { a = { b = { c = { }; }; }; }; list = [ 1 ]; list' = [ 1 2 3 ]; }
```
After:
```
{
attrs = {
a = {
b = {
c = { };
};
};
};
list = [ 1 ];
list' = [
1
2
3
];
}
```
(cherry picked from commit c0a15fb7d03dfb8f53bc6726c414bc88aa362592)
Change-Id: Ia2b41849165a5ddb63f7a8c272a2476b3e4292df
While preparing PRs like #9753, I've had to change error messages in
dozens of code paths. It would be nice if instead of
EvalError("expected 'boolean' but found '%1%'", showType(v))
we could write
TypeError(v, "boolean")
or similar. Then, changing the error message could be a mechanical
refactor with the compiler pointing out places the constructor needs to
be changed, rather than the error-prone process of grepping through the
codebase. Structured errors would also help prevent the "same" error
from having multiple slightly different messages, and could be a first
step towards error codes / an error index.
This PR reworks the exception infrastructure in `libexpr` to
support exception types with different constructor signatures than
`BaseError`. Actually refactoring the exceptions to use structured data
will come in a future PR (this one is big enough already, as it has to
touch every exception in `libexpr`).
The core design is in `eval-error.hh`. Generally, errors like this:
state.error("'%s' is not a string", getAttrPathStr())
.debugThrow<TypeError>()
are transformed like this:
state.error<TypeError>("'%s' is not a string", getAttrPathStr())
.debugThrow()
The type annotation has moved from `ErrorBuilder::debugThrow` to
`EvalState::error`.
(cherry picked from commit c6a89c1a1659b31694c0fbcd21d78a6dd521c732)
Change-Id: Iced91ba4e00ca9e801518071fb43798936cbd05a
Don't print the first bracket in values in magenta in error messages
(cherry picked from commit 46a0625a40aef6946a35f92fdacf0e6b4a14414f)
Change-Id: I8435565c87db182116140eaeea9df1243e67ea94
Enter debugger more reliably in `let` expressions and function calls
(cherry picked from commit c4ed92fa6f836d3d8eb354a48c37a2f9eeecc3aa)
Change-Id: I16d0cad7e898feecd2399723b92ba8df67222fb4
Catch `Error`, not `BaseError` in `ValuePrinter`
BaseError includes Interrupt. We probably don't want the value printer to tell you Ctrl-C was pressed while it was printing.
(cherry picked from commit c291d2d8dda38aa88b004e2ed05b28653c07e342)
Change-Id: I70b105bfb2f52a8f345ae0281d12f022aa36b14e
`nix eval` forces values and prints derivations as attribute sets, so
commands that print derivations (e.g. `nix eval nixpkgs#bash`) will
infinitely loop and segfault.
Printing derivations as `.drv` paths makes `nix eval` complete as
expected. Further work is needed, but this is better than a segfault.
(cherry picked from commit 4910d74086a85876e093136a0e8ebc547b467af7)
Change-Id: I8e1cb39c05db812080759ec183ee7a131760e6ea
these symbols are used a *lot*, so it makes sense to cache them. this
mostly increases clarity of the code (however clear one may wish to call
the parser desugaring here), but it also provides a small performance
benefit.
(cherry picked from commit 09a1128d9e2ff0ae6176784938047350d6f8a782)
Change-Id: I73d9f66be4555168e048cb2d542277251580c2d1
eldritch horrors
jade
Rebecca Turner