This removes the need to install any specific version of Python or
figure out how to configure it by instead asking users to install `uv`
and letting it manage Python. Among other advantages, `uv` is designed
to be fast enough to embed directly into our scripts.
We were already using this in `bench_runner.py` so that the script could
import non standard library dependencies. Moving to it for the rest of
our Python unifies the approach and will also enable dependencies
whenever needed.
I've left `github_tools` alone as it has special handling with its own
Bazel setup.
I've updated the contributing tools to explain the approach here.
`@` refers to the current workspace's working copy, but if we want the
command to respect the working copies of other workspaces, we should use
`working_copies()` instead; see
https://docs.jj-vcs.dev/latest/revsets/#functions .
Also remove `all() &` while here, since it is always redundant.
Assisted-by: Google Antigravity
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Update the syntax for class (and interface/`impl`) methods to move
`self` into
the parameter parentheses `()` and make the type in its binding optional
(defaulting to `Self`). Introduce the `static` keyword for non-instance
member
variables to indicate static storage. Reflects the decision in leads
issue
[#6931](https://github.com/carbon-language/carbon-lang/issues/6931).
Updates the directly relevant design, but leaves a systematic update of
examples
to a future PR.
Assisted-by: Antigravity with Gemini
---------
Co-authored-by: Geoff Romer <gromer@google.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
jj moved the repo config outside the repo. The config.toml might exist
as a symlink in older repos (probably migration), but not clean repos.
So, overall, just switching the advice setup to make it a bit more
robust with config locations.
Also adding "trunk" to the repo config.
Assisted-by: Google Antigravity with Gemini
This gives a setup where `jj b a` / `jj bookmark advance` can reliably
be used to advance a bookmark for a github pull request, without
advancing other bookmarks such as `trunk` or pointing the bookmark at an
empty commit.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Also increases the default optimization to `-Og` which is likely to give
faster turn-around time which is what we want to optimize for here. This
should also _substantially_ shrink binary sizes, etc.
ASan is still available via `--config=asan`, and is added to the CI
infrastructure. However, my current thought is to only run it after push
rather than in PRs and in the merge queue.
Allow partially identifying a named constraint inside its definition,
and allow the query self in an impl lookup with a non-identified facet
type to be used to provide witnesses from that facet type. This allows
impl lookup on `Self` to find `require` decls that have been written
earlier in the named constraint, so that the named constraint to be used
to provide witnesses from inside its definition.
But disallow an incomplete named constraint from being part of an
identified facet type, to prevent forming facet values that store a
witness set that can be invalidated as the named constraint adds
interfaces to its identified facet type.
This was discussed in open discussion [on
2026-03-12](https://docs.google.com/document/d/1mjllGO3ZCL4qGt9uJHUtcxKoHAGEY7Y999ie4EtBWB8/edit?tab=t.0#heading=h.1dvbbrp5a6t3).
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
In addition to the general updates, this switches to a required python
3.10 for pre-commit (3.9 is losing support from black).
Note endpoints for build actions are expanding significantly: see
https://app.stepsecurity.io/github/carbon-language/carbon-lang/actions/runs/22779388360?tab=recommendations&jobId=66080970460
for example, I think just the sources are being increased as a
side-effect of updates (and possibly also things not performing as well
as they should have before).
Similarly allowing sudo in pre-commit because it was actually causing
errors in part of build setup, which used sudo to remove files.
Assisted-by: Google Antigravity with Gemini
Giving both of these their own sections under optional tools because I'm
mainly doing this to share example configs.
Assisted-by: Google Antigravity with Gemini
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This proposal defines the concrete technical mechanisms for C++
interoperability. It specifies the precise syntax and semantics for
importing
C++ APIs. This includes the `import Cpp library "..."` and implicitly
importing
C++ built-in entities, and the establishment of the `Cpp` package as the
dedicated namespace for all imported entities.
This PR also includes high level language C++ Interop design and the
basics of importing C++ APIs and function calling.
Leaving plenty of TODOs to make it easier to fill in more details in
followups.
Part of #4666.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
This proposal introduces the concept of a _form_, which is a
generalization of
"type" that encompasses all of the information about an expression
that's
visible to the type system, including type and expression category.
Forms can be
composed into _tuple forms_ and _struct forms_, which lets us track the
categories of individual tuple and struct literal elements.
The proposal PR also adds `ref` bindings to the pattern matching
documentation,
but that is not part of the proposal itself; it's just bringing the
documentation
up to date with proposal
[#5434](https://github.com/carbon-language/carbon-lang/pull/5434).
---------
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
Adding the note about recursion because it occasionally comes up, and
I'm thinking it'd be helpful to document why we prefer iterative
algorithms.
Also moves a few long style points to headers so that they're easier to
link (I wasn't sure it makes sense to do to all of "syntax and
formatting", but either way what's remaining is shorter if that _is_
linked for reference).
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
This proposal removes the definition of the term "value binding" as a
primitive
category conversion from reference to value, replacing it with the term
"value
acquisition". The other meaning of "value binding", a binding declared
by a
value binding pattern, is unchanged.
Proposal [p5337](https://docs.carbon-lang.dev/proposals/p5337.html)
renamed and introduced new syntax for extending an interface or named
constraint with another.
- The `require` keyword can now be modified by `extend`, instead of it
being a separate thing altogether.
- Interfaces can `extend impl as I` to gain the members of `I` and
implicitly use them to implement `I`. Named constraints can not.
The `Identity` example is meant to not know anything about the type of
the object its passing through, but it ends up making a copy of it. Fix
the example to not by using a pointer.
~~Added explanatory comment about math package usage~~
Changed Main() entry point to Run() as per design and toolchain
This small update of front page code snippets will add
explanatory comment to highlight that provided Carbon code
is hypothetical and meant to show the look and feel of the language.
Also it delivers change of Main() to Run() to
highlight correct entry point for Carbon lang.
Updates the documentation under `docs/design/` to use `ref` instead of
`addr` after their removal in #5434. Care was taken to manually clean up
edge cases and, in a couple cases, surrounding text (see
3d72c49bb75c0f40ca7e8114b6a1369b941e1697). After this change, there are
no matches for `addr(?!ess)` in `docs/design/`.
Closes#6032
Require language design proposals to either update the design documents
to
reflect the proposed changes, or add "TODO" comments to mark where those
changes
will be needed, with links back to the proposal. This is intended to
ensure that
the design documentation accurately informs readers about the current
language
design, without excessively burdening the proposal process.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
# Changes
## Terminology Updates
This PR updates documentation to align with the expression phase
terminology changes introduced in
[#2964](https://github.com/carbon-language/carbon-lang/pull/2964):
* **"symbolic value" → "symbolic constant"**: Updated all remaining
instances using find-and-replace
## Scope of Changes
* Focused on documentation that predates the July 2023 terminology
change
* Used git blame history to identify instances likely using the old
"constant" definition
* Manually reviewed each "constant" usage to distinguish between:
- New definition (unchanged): the broader category including symbolic
constants
Closes
[#5599](https://github.com/carbon-language/carbon-lang/issues/5599)
---------
Co-authored-by: Hitesh Joshi <hitesh@mitsu.care>
I wasn't sure exactly in what way it was problematic, so I was a bit
vague in the justification (though justifications aren't generally
needed/provided here anyway - so I'm not sure it'd be net helpful to add
one anyway).
This proposal renames the syntax used to mark an overriding definition
of a virtual method from `impl fn` to `override fn` to avoid ambiguity:
besides indicating an overriding virtual function, it can be parsed as
an "impl" declaration when the construct following "impl" begins with a
lambda introduced by "fn".
Closes#5711
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Carbon is accelerating and adjusting its safety strategy, specifically
to flesh out its memory safety strategy and reflect simplifying
developments in the safety space.
This proposal replaces the previous directional safety strategy with a
new concrete and updated framework for the safety design. It includes a
specific framework for memory safety, simplified build modes, specific
"safety modes", and terminology.
This proposal also provides a _directional_ suggestion for temporal and
data-race safety specifically.
In addition to fully building out the above directional component, there
are several other aspects of our safety design that will follow in
subsequent proposals. The hope is to establish the initial framework
here.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Co-authored-by: Mike Forster <michael@forster.pro>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
- A parameter binding can be marked `ref` instead of `var` or the
default. It will bind to reference argument expressions in the caller
and produces a reference expression in the callee.
- Unlike pointers, a `ref` binding can't be rebound to a different
object.
- This replaces `addr`, and is not restricted to the `self` parameter.
- A `ref` binding, like a value binding, can't be used in fields of
classes or structs.
- When calling functions, arguments to non-`self` `ref` parameters are
also marked with `ref`.
- The return of a function can optionally be marked `ref`, `val`, or
`var`. These control the category of the call expression invoking the
function, and how the return expression is returned.
- These may be mixed for functions returning tuple or struct forms.
- The address of a `ref` binding is `nocapture` and `noalias`.
- We mark parameters of a function that may be referenced by the return
value with `bound`.
---------
Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Geoff Romer <gromer@google.com>
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
In open discussion[1] we decided that "identical" rewrites would mean
that for a given LHS value, all RHS have the same value (after
evaluation), rather than requiring the RHS to all have the same
syntactic value. This means the following is valid, since the value of
`.Y` is known to be `()` while resolving the rewrite constraints of `T`.
So both rewrites of `.X` are resolved to `.X = ()`:
```
fn Identical(T:! I where .X = () and .X = .Y and .Y = ()) {}
```
The implementation of this clarification, along with test cases encoding
it, is done in https://github.com/carbon-language/carbon-lang/pull/5686.
Clarify this in the language design documents, and improve some other
clarity while we're there:
- The prose talks about a facet `T`, but the examples were using `A` as
its name. Change the facet to be `T`. This means changing the `.T`
associated constant (and `.U` and `.V`) to be `.X` (and `.Y` and `.Z`).
While doing this, use `I` for the interface name instead of `C`, which
we use more commonly for a class type name.
- Correct the comments in the cycle example that claim we find `.Y then
.Y* then .Y**`. In this example `.Y = .Z* and .Z = .Y*` which adds _two_
levels of pointers when evaluating `.Y`: `.Y => .Z* => (.Y*)* => .Y**`
[1]
https://docs.google.com/document/d/1Yt-i5AmF76LSvD4TrWRIAE_92kii6j5yFiW-S7ahzlg/edit?tab=t.0#heading=h.qti4vn50zwy
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
The command is:
```
dump <context> [<ID>|<TYPE><ID>|<TYPE> <ID>|-- <ID>]
TYPE can be "inst", "entity_name", etc.
```
This saves a lot of typing of `SemIR::MakeInstId()` in a debugger, and
allows copy-pasting ids from dump output, as they take the form
`inst33`, etc.
This proposal codifies our preference for designs that support
"progressive
disclosure", meaning that programmers can ignore a given language
concept (or
even be unaware of it) until it is directly relevant to the task they're
doing.
This script runs benchmarks written using Google Benchmark repeatedly,
and collects the results from JSON to render them nicely and provide
statistical information across the runs.
Because this runs the binaries repeatedly, this can help account for
run-to-run variations that are pervasive in many of Carbon's benchmarks,
such as ASLR and other process-specific differences.
It's most basic mode runs a benchmark multiple times and shows both
median and confidence intervals.
It also supports two comparison modes:
1) Regular expressions can be provided that describe collections of
related benchmarks where one is the "main" benchmark and the others
are comparable. For example, Carbon's data structure vs. data
structures from LLVM or Abseil. These will be rendered with the main
benchmark first, followed by a comparison relative to a "baseline" of
each comparable benchmark.
2) A baseline benchmark binary, and potentially different command line
flags, can be provided to run two benchmark binaries and compute
a comparison for each benchmark within them.
Across all of these, the script works to present the best text UI it can
in the console. I may have gotten a bit obsessed with rendering the
benchmark results in a way that is really pretty. There are lots of
fancy color coding and progress bars, etc., when run in in the terminal.
For the basic mode without any comparisons, the results look like:
```
Computing statistically significant deltas only wherethe P-value < 𝛂 of 0.05
Metric key:
BenchmarkName... <median> ± <% at 95th conf>
Benchmark ┃ CPU Time ┃ bytes_per_second
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━
BM_LatencyHash<RandValues<uint8_t>, CarbonHashBench>. │ 3.051 ns ± 2.721% │ 327.8 M ± 2.765%
BM_LatencyHash<RandValues<uint8_t>, AbseilHashBench>. │ 3.395 ns ± 4.377% │ 294.6 M ± 4.572%
BM_LatencyHash<RandValues<uint8_t>, LLVMHashBench>... │ 6.125 ns ± 2.662% │ 163.3 M ± 2.726%
BM_LatencyHash<RandValues<uint16_t>, CarbonHashBench> │ 3.105 ns ± 3.947% │ 644.1 M ± 4.109%
BM_LatencyHash<RandValues<uint16_t>, AbseilHashBench> │ 3.433 ns ± 4.308% │ 582.6 M ± 4.502%
BM_LatencyHash<RandValues<uint16_t>, LLVMHashBench>.. │ 6.127 ns ± 2.540% │ 326.5 M ± 2.587%
BM_LatencyHash<RandValues<uint32_t>, CarbonHashBench> │ 3.082 ns ± 2.846% │ 1.298 G ± 2.923%
BM_LatencyHash<RandValues<uint32_t>, AbseilHashBench> │ 3.401 ns ± 3.611% │ 1.176 G ± 3.739%
BM_LatencyHash<RandValues<uint32_t>, LLVMHashBench>.. │ 6.209 ns ± 4.064% │ 644.3 M ± 4.236%
BM_LatencyHash<RandValues<uint64_t>, CarbonHashBench> │ 3.122 ns ± 2.871% │ 2.563 G ± 2.956%
BM_LatencyHash<RandValues<uint64_t>, AbseilHashBench> │ 3.426 ns ± 2.811% │ 2.335 G ± 2.892%
BM_LatencyHash<RandValues<uint64_t>, LLVMHashBench>.. │ 6.497 ns ± 3.081% │ 1.231 G ± 3.179%
```
For the first comparison mode on one of Carbon's benchmarks, the results
look like:
```
Computing statistically significant deltas only wherethe P-value < 𝛂 of 0.05
Metric key:
BenchmarkName... <median> ± <% at 95th conf>
vs Comparable: 👍 <delta> p=<U-test P-value>
<median> ± <% at 95th conf>
Benchmark ┃ CPU Time ┃ bytes_per_second
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━
BM_LatencyHash<RandValues<uint8_t>, CarbonHashBench>. │ 3.037 ns ± 1.781% │ 329.2 M ± 1.813%
vs Abseil: │ 👍 -8.200% p=0.000183 │ 👍 8.933% p=0.000183
│ 3.309 ns ± 2.064% │ 302.2 M ± 2.022%
vs LLVM: │ 👍 -49.401% p=0.000183 │ 👍 97.632% p=0.000183
│ 6.003 ns ± 1.502% │ 166.6 M ± 1.480%
│ │
BM_LatencyHash<RandValues<uint16_t>, CarbonHashBench> │ 3.026 ns ± 1.816% │ 661 M ± 1.784%
vs Abseil: │ 👍 -8.599% p=0.000183 │ 👍 9.408% p=0.000183
│ 3.311 ns ± 1.873% │ 604.1 M ± 1.839%
vs LLVM: │ 👍 -49.829% p=0.000183 │ 👍 99.319% p=0.000183
│ 6.031 ns ± 2.806% │ 331.6 M ± 2.730%
│ │
BM_LatencyHash<RandValues<uint32_t>, CarbonHashBench> │ 3.017 ns ± 2.696% │ 1.326 G ± 2.625%
vs Abseil: │ 👍 -9.754% p=0.000183 │ 👍 10.808% p=0.000183
│ 3.344 ns ± 1.537% │ 1.196 G ± 1.514%
vs LLVM: │ 👍 -49.857% p=0.000183 │ 👍 99.427% p=0.000183
│ 6.018 ns ± 3.269% │ 664.7 M ± 3.167%
│ │
BM_LatencyHash<RandValues<uint64_t>, CarbonHashBench> │ 3.025 ns ± 3.395% │ 2.644 G ± 3.284%
vs Abseil: │ 👍 -9.812% p=0.000183 │ 👍 10.879% p=0.000183
│ 3.354 ns ± 2.640% │ 2.385 G ± 2.572%
vs LLVM: │ 👍 0.476x p=0.000183 │ 👍 2.101x p=0.000183
│ 6.357 ns ± 2.477% │ 1.258 G ± 2.418%
│ │
```
For the second mode, in this case comparing a baseline build with `-Oz`
vs an experiment with `-Os`, the results look like:
```
Computing statistically significant deltas only wherethe P-value < 𝛂 of 0.05
Metric key:
BenchmarkName... 👍 <delta> p=<U-test P-value>
baseline: <median> ± <% at 95th conf>
experiment: <median> ± <% at 95th conf>
Benchmark ┃ CPU Time ┃ bytes_per_second
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━
BM_LatencyHash<RandValues<std::pair<uint32_t, uint32_t>>, CarbonHashBench> │ 👍 -35.870% p=0.000557 │ 👍 55.930% p=0.000557
baseline: │ 5.704 ns ± 1.877% │ 1.403 G ± 1.911%
experiment: │ 3.658 ns ± 4.209% │ 2.187 G ± 4.039%
│ │
BM_LatencyHash<RandValues<std::pair<uint32_t, uint64_t>>, CarbonHashBench> │ 👍 -19.475% p=0.00119 │ 👍 24.186% p=0.00119
baseline: │ 4.974 ns ± 3.029% │ 3.217 G ± 3.124%
experiment: │ 4.005 ns ± 4.297% │ 3.995 G ± 4.120%
│ │
BM_LatencyHash<RandValues<std::pair<uint32_t, int*>>, CarbonHashBench>.... │ 👍 -11.740% p=0.00153 │ 👍 13.302% p=0.00153
baseline: │ 4.634 ns ± 3.433% │ 3.453 G ± 3.555%
experiment: │ 4.09 ns ± 2.999% │ 3.912 G ± 2.911%
│ │
```
The script itself uses a new tool for managing dependencies called `uv`:
https://docs.astral.sh/uv/ This tool allows for the script to contain an
inline set of dependencies that will be installed and cached for
subsequent runs. This seemed particularly important as dependencies like
SciPy and NumPy can be particularly difficult to manager or keep
installed in other ways, but are essential to this scripts statistical
analysis. So far, the `uv` system has been working remarkably well for
me and been a relatively pleasant experience on the whole.
I have included as much of the Python dependencies as have good type
information into the MyPy configuration to get good type checking in
pre-commit however.
Last but not least, this has been a pet project of mine for a quite a
while and so may be a bit rough around the edges as I added and tweaked
functionality based on specific benchmarks I was looking at. It feels
like its gotten useful enough to contribute somewhere, but totally open
to any refactoring or improvements needed. I tried to take a few passes
over it to organize and document the code before sending it, but I'm
sure there are still some things that could use improvement.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
Chandler Carruth
josh11bandJosh L
Jon Ross-Perkins
Dana JansensandRichard Smith
Nicholas Bishop
Özgür
Burak EmirandDana Jansens
gleb
Calvin
Hitesh JoshiandHitesh Joshi
David Blaikie
Elliott KaltandRichard Smith
pascal754
