Age | Commit message (Collapse) | Author | Files | Lines |
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This test case checks two things:
* A sanity check that "pointer equality for functions" means not
just the lambda, but also the upvalues.
* To be pointer-equal, it is not enough for the upvalues to be
normal-form equal (i.e. `nix_eq()`-equal); the upvalues must be
*pointer*-equal. The second part of the test case checks for
this.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I4e59327a6f199b8212e97197b212e3c3934bb3f0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7372
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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The "dep:" syntax in Cargo.toml is very new; crate2nix master has
support for it, but they have not yet made a release with this
update, and therefore the crate2nix in nixpkgs does not yet support
it.
Could we avoid using "dep:" for a few weeks to give crate2nix a
chance to release so I can bump the version in nixpkgs? I've opened
an issue asking crate2nix to make a release:
https://github.com/kolloch/crate2nix/issues/264
I propose that if they haven't acted within a month we stop waiting
and revert this at that time.
Change-Id: I999a72429db667bedf4b2cdba27cb63b3f3d9657
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7350
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Change-Id: I6dfc9108220762ef3372cd2739e91d79c01a55e1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7366
Tested-by: BuildkiteCI
Autosubmit: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <tazjin@tvl.su>
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Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Ia373eb30d8516a056f1349f9011dee9816593d6f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7357
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Change-Id: I3b1284e28c350bfed84d643ae7f922f3487e1f2a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7355
Autosubmit: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Ib813d794177c623bf2f12fc2e6a6f304089607d1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7356
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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When we start unrecursivifying (sp?) things, Rust's borrow checker
is going to be a headache; its magic only works when you use the CPU
stack as your call stack.
Fixing the borrow checker issues usually involves adding lots of
`clone()`s. Right now `NixList` is the only variant of `Value` that
isn't cheap to clone() -- all the others are either a wrapper around
Rc or else are of bounded size.
Note that this requires dropping the `DerefMut for NixList` instance
and using `Vec<Value>` instead in those situations.
Change-Id: I5a47df66855342aa2064f8f3cb7934ff422d26bd
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7359
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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When comparing Nix values for equality, an issue can occur where
recursive values contain thunks to themselves which causes borrow
errors when forcing them for comparison later down the line.
To work around this we clone the values for now. There might be some
optimisations possible like checking for thunk equality directly and
short-circuiting on that (we have to check what Nix does).
Change-Id: I7e75c992ea68f100058f52b4b46168da7d671994
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7314
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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Change-Id: Ief9ebc2285a0c50654c2edd3351432dc1588f9fc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7313
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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When passing multiple arguments, every intermediate callable needs to
be forced as this is expected by the VM's call_value function.
Also adds a debug assertion for this which makes it easier to spot
exactly what went wrong.
Change-Id: I3aa519cb6cdaab713bd18282bef901c4cd77c535
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7312
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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This function covers builtins.genericClosure, seemingly including
weird behaviour around the order in which the work set is processed.
For some reason, in C++ Nix the test expectation is written in XML
which we do not yet support, so I have created a new expectation file
using `nix-instantiate --eval --strict` on the file (yes, using C++
Nix).
Change-Id: Id90e7117d120dc66d963a51083c4d8e8f2d9f181
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7311
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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This implementation closely follows the original implementation in
Nix, including the use of an equality-based "set" structure to track
keys that have already been processed.
Note that this test does not yet enable the `notyetpassing` test for
builtins.genericClosure because (for as of yet unknown reasons) this
test compares against XML output (however, evaluating the test case
actually does work).
This takes us one step closer to nixpkgs eval.
This commit was written somewhere in the North Sea.
Co-Authored-By: Griffin Smith <root@gws.fyi>
Change-Id: I450a866e6f2888b27c2fe7c7f77ce0f79bfe3e6c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7310
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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Change-Id: Ic52159141b2346dd580215566056aca7110f0a10
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7253
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
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Both //tvix/eval and //tvix/nix_cli have need to for rust tooling available
in $PATH.
Move this one level up, so it's accessible in all subdirectories.
Change-Id: I0763bbe9cefdc962f3a8f86c51e8f67cde8b4b04
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7248
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
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This detects if the second argument of a division is a zero (either as integer
or as float). If so, an error message is displayed.
This fixes b/219.
Change-Id: I50203d14a71482bc757832a2c8dee08eb7d35c49
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7258
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
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Add a new `documentation: Option<&'static str>` field to Builtin, and
populate it in the `#[builtins]` macro with the docstring of the builtin
function, if any.
Change-Id: Ic68fdf9b314d15a780731974234e2ae43f6a44b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7205
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Refactor the arguments of a Builtin to be a vec of a new BuiltinArgument
struct, which contains the old strictness boolean and also a static
`name` str - this is automatically determined via the ident for the
corresponding function argument in the proc-macro case, and passed in in
the cases where we're still manually calling Builtin::new.
Currently this name is unused, but in the future this can be used as
part of a documentation system for builtins.
Change-Id: Ib9dadb15b69bf8c9ea1983a4f4f197294a2394a6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7204
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Some new top-level re-exports (specifically VM, Builtin, and ErrorKind)
were added to lib.rs in tvix/eval to allow the builtin-macros tests to
work - we should be clear which of these are part of the public
interface (I think it's reasonable for ErrorKind to be) and which
aren't (specifically I'm not sure VM and Builtin necessarily should be,
at least yet).
Change-Id: I3bbeaa63cdda9227224cd3bc298a9bb8da4deb7c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7203
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Similar to what we did with pure builtins, define the impure builtins
within a module at the top-level using the new #[builtins] attribute
macro
Change-Id: Ie5d5135d00bb65e651531df6eadba642cd4eb08e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7202
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Break out all pure builtin functions to top-level functions defined
within the `pure_builtins` module in `builtins/mod.rs`.
Change-Id: I9a10660446d557b1a86da4c45a463e9a1a9b4f2d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7201
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
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Mostly as a proof-of-concept of the new proc-macros for defining
builtins, define a single builtin (the first in the list, `abort`) at
the top-level of a child module within builtins/mod.rs, and add it to
the list of builtins returned from `pure_builtins`.
If this works nicely, we can start breaking out the rest of the builtins
into the top-level too, in addition to introducing additional sets of
builtins (to differentiate between pure and impure builtins).
Change-Id: I5bdd57c57fecf8d63c9fed4fc6b1460f533b20f2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7199
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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Add a single new proc macro to a new proc-macro crate,
`tvix-eval-proc-macros` for defining an inline module containing nix
builtins, and automatically generating a function within that module
which returns a list of those builtins as `tvix_eval::value::Builtin`.
Change-Id: Ie4afae438914d2af93d15637151a49b4c68aa352
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7198
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
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Change-Id: Idd4ae78ef55891d89b72b5c2f3afc8b697b4b26e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7189
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
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This commit adds a markdown document which explains how the
thread-local VM infrastructure works, in case it is useful in the
future.
Change-Id: Id10e32a9e3c5fa38a15d4bec9800f7234c59234a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7193
Tested-by: BuildkiteCI
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
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Adds initial placeholders for builtins.{derivation,
unsafeDiscardStringContext}.
Change-Id: I67a126c9b9f9f4f11e2256e69b9a32ebd9eb1b0e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7187
Autosubmit: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
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This is more generally useful than just inside the VM, until it is
stabilised in Rust itself.
Change-Id: Id9aa3d5b533ff38e3d2c6b85ad484394fdd05dcf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7186
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: grfn <grfn@gws.fyi>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
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This fixes a mistake I made in d978b556e6.
Change-Id: I88db697105a7149e9785f6aface03bff68566d2b
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7085
Reviewed-by: grfn <grfn@gws.fyi>
Tested-by: BuildkiteCI
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Scope_depth and with_stack_depth were being reset to zero for nested
function abstractions. Fortunately nothing depends on them being
computed correctly in these cases, but it sure was confusing.
Change-Id: I59980b6a5aff043f60079f97211220b0086eb97d
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7091
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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It is very confusing that this opcode is called DataLocalIdx, but it
carries a StackIdx rather than a LocalIdx. It seems like this
really ought to be called DataStackIdx, but maybe I've
misunderstood; if so please explain it to me.
Change-Id: I91f6ffa759412beef0b91d3c19ec0d873fe51b99
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7088
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I8c72405880a9342eb502d92c1e0087f5bb17e03c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7087
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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This implements builtins.split, and passes eval-okay-regex-split.nix
(which is moved out of notyetpassing).
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Ieb0975da2058966c697ee0e2f5b3f26ccabfae57
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7143
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
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We have to be careful implementing `builtins.groupBy`, since the
list may contain thunks, and tvix's to_xxx() functions do not work
on thunks.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I182b6fc2d4296f864ed16744ef70b153e8e6978a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7039
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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The impl Display for NixAttrs needs to wrap double quotes around any
keys which are not valid Nix identifiers. This commit does that,
and adds a test (which fails prior to this commit and passes after
this commit).
Change-Id: Ie31ce91e8637cb27073f23f115db81feefdc6424
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7084
Autosubmit: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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The variable name `local_idx` is used here for a StackIdx, which invites
confusion.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I2e22db90acdc0d29586ee5b72ea18d42d93badcb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7086
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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If self.depth > other.depth then self is deeper than other, so self
is *below* other, not above it. Let's just inline the function.
Change-Id: I8dda3d90cbc86c8a6fa01bc4a5e506a2e403bd20
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7090
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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It isn't possible to implement PartialEq properly for Value, because
any sensible implementation needs to force() thunks, which cannot be
done without a `&mut VM`.
The existing derive(PartialEq) has false negatives, which caused the
bug which cl/7142 fixed. Fortunately that bug was easy to find, but
a silent false negative deep within the bowels of nixpkgs could be a
real nightmare to hunt down.
Let's just remove the PartialEq impl for Value, and the other
derive(PartialEq)'s that depend on it.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Iacd3726fefc7fc1edadcd7e9b586e04cf8466775
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7144
Reviewed-by: kanepyork <rikingcoding@gmail.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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I think we should bring this into $PATH too.
Change-Id: Ie31ac558355b7c4ed9dcd3dd60e1b03f141d1178
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7166
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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The current implementation of nix_eq will force one level of thunks
and then switch to the (non-forcing) rust Eq::eq() method. This
gives incorrect results for lists-of-thunks.
This commit changes nix_eq() to be recursive.
A regression test (which fails prior to this commit) is included.
This fix also causes nix_tests/eval-okay-fromjson.nix to pass, so it
is moved out of notyetpassing.
Change-Id: I655fd7a5294208a7b39df8e2c3c12a8b9768292f
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7142
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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We're getting close to the finish line, folks.
I went through the list of builtins and there are only 33 that
remain unimplemented. I've marked them, and indicated which are
ready to be implemented vs which are waiting for other things.
We can delete this column from the table once everything is
implemented.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Idfaef93283536288b12e59aef5c3e1cd139bd133
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7140
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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I believe that the currentTime, findFile, hashFile, pathExists,
readDir, path (unless ?sha256), and readFile builtins are impure.
This commit marks them as such in docs/builtins.md.
Change-Id: Ib1b59fe643dde73cb2b00050b4ef9d3401ad22eb
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7139
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Change-Id: I59a0756940d1e5360a2ab4e886cf0bc9af7b8901
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7133
Autosubmit: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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This is a bit tricky because the comparator can throw errors, so we
need to propagate them out if they exist and try to avoid sorting
forever by returning a reasonable ordering in this case (as
short-circuiting is not available).
Co-Authored-By: Vincent Ambo <tazjin@tvl.su>
Change-Id: Icae1d30f43ec1ae64b2ba51e73ee467605686792
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7072
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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Lists are compared lexicographically in C++ nix as of [0], and our
updated nix test suites depend on this. This implements comparison of
list values in `Value::nix_cmp` using a very similar algorithm to what
C++ does - similarly to there, this requires passing in the VM so we can
force thunks in the list elements as we go.
[0]: https://github.com/NixOS/nix/commit/09471d2680292af48b2788108de56a8da755d661#
Change-Id: I5d8bb07f90647a1fec83f775243e21af856afbb1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7070
Autosubmit: grfn <grfn@gws.fyi>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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CL/7034 looks great, except that for a length-N target string it
will perform N deep copies of each of the from and to-lists. Let's
use references instead of clones.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Icd341213a9f0e728f9c8453cec6d23af5e1dea91
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7095
Reviewed-by: wpcarro <wpcarro@gmail.com>
Reviewed-by: j4m3s <james.landrein@gmail.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Change-Id: I93dcdaeb101364ee2273bcaeb19acb57cf6b9e7d
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7034
Autosubmit: j4m3s <james.landrein@gmail.com>
Reviewed-by: Adam Joseph <adam@westernsemico.com>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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I assumed that AttrsRep::KV represented attrsets with a single
attribute as a Key-Value pair. That is not the case. Let's warn
other people about this.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: Ie3d2765fcc1ab705c153ab94ffe77bbd6d4ab39e
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7093
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I460230863de853ca5248733bc977d4780b216f36
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7096
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
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Rustc uses wasm32-unknown-unknown, which is rejected by config.sub,
for wasm-in-the-browser environments. Rustc should be using
wasm32-unknown-none, which config.sub accepts. Hopefully the rustc
people will change their triple before stabilising this triple. In
the meantime, we fix it here in order to unbreak tvixbolt.
https://doc.rust-lang.org/beta/nightly-rustc/rustc_target/spec/wasm32_unknown_unknown/index.html
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I941fd8d6f3db4e249901772fd79321ad88cd9cc6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7107
Reviewed-by: tazjin <tazjin@tvl.su>
Reviewed-by: sterni <sternenseemann@systemli.org>
Tested-by: BuildkiteCI
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This commit contains two search-and-replace renames which are broken
out from I04131501029772f30e28da8281d864427685097f in order to
reduce the noise in that CL:
- `is_thunk -> is_suspended_thunk`, since there are now
OpThunkClosure and OpThunkSuspended
- `compile_lambda_or_thunk` -> `compile_lambda_or_suspension`
Change-Id: I7cc5bbb75ef6605e3428c7be27e812f41a10c127
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7037
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
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CL/6867 added support for builtins.import, which required a cyclic
reference import->globals->builtins->import. This was implemented
using a RefCell, which makes it possible to mutate the builtins
during evaluation. The commit message for CL/6867 expressed a
desire to eliminate this possibility:
This opens up a potentially dangerous footgun in which we could
mutate the builtins at runtime leading to different compiler
invocations seeing different builtins, so it'd be nice to have
some kind of "finalised" status for them or some such, but I'm not
sure how to represent that atm.
This CL replaces the RefCell with Rc::new_cyclic(), making the
globals/builtins immutable once again. At VM runtime (once opcodes
start executing) everything is the same as before this CL, except
that the Rc<RefCell<>> introduced by CL/6867 is turned into an
rc::Weak<>.
The function passed to Rc::new_cyclic works very similarly to
overlays in nixpkgs: a function takes its own result as an argument.
However instead of laziness "breaking the cycle", Rust's
Rc::new_cyclic() instead uses an rc::Weak. This is done to prevent
memory leaks rather than divergence.
This CL also resolves the following TODO from CL/6867:
// TODO: encapsulate this import weirdness in builtins
The main disadvantage of this CL is the fact that the VM now must
ensure that it holds a strong reference to the globals while a
program is executing; failure to do so will cause a panic when the
weak reference in the builtins is upgrade()d.
In theory it should be possible to create strong reference cycles
the same way Rc::new_cyclic() creates weak cycles, but these cycles
would cause a permanent memory leak -- without either an rc::Weak or
RefCell there is no way to break the cycle. At some point we will
have to implement some form of cycle collection; whatever library we
choose for that purpose is likely to provide an "immutable strong
reference cycle" primitive similar to Rc::new_cyclic(), and we
should be able to simply drop it in.
Signed-off-by: Adam Joseph <adam@westernsemico.com>
Change-Id: I34bb5821628eb97e426bdb880b02e2097402adb7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7097
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>
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