This implements the leads decision made in #6821, proposal #6910. The
proposal is pending, but I figured it's relatively safe to just do given
the decision.
Assisted-by: Google Antigravity with Gemini
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
This moves the LValue path code from macros.cpp to constant.cpp, so that
it can be called from `MapAPValueToConstant`. TODO messages are updated
accordingly to avoid referring to macros. Added a constexpr pointer test
to `constexpr.carbon` to show the result of this change.
Add a clang::ExternalASTSource to begin exposing Carbon entities to
Clang - initially only a single `Carbon` top level namespace.
Subsequent work will add Carbon entities to this namespace.
Likely this CarbonExternalASTSource will be refactored into another
file, tie into/reference SemIR::File and CppFile, etc eventually - but
that'll wait for future patches.
If there's mechanical problems with the current implementation - how I'm
creating the new NamespaceDecl, etc - I'm all ears. It's very much in
the "it seems to work" state, not much more than that.
This does break Clang Modules (header modules, C++20 modules,
precompiled headers, etc) since they're implemented as an
ExternalASTSource as well, and Clang's ASTContext only supports one
ExternalASTSource at a time. To fix that regression we'll need to
implement some kind of ExternalASTSource multiplexing support - either
in Clang or Carbon (unclear which).
This regression of modules support can be observed by the following:
`A.h`
```
inline void f1() { }
```
`module.modulemap`
```
module A {
header "A.h"
export *
}
```
`test.carbon`
```
import Cpp inline '''
// Hardcode the pragma to ensure this isn't silently falling back to
// textual inclusion.
void f2() {
f1();
}
''';
```
```
carbon compile test.carbon -- -I . -fmodules -fimplicit-modules -fmodules-cache-path=module_cache
```
I wrote a `file_test` test for this, but it doesn't /quite/ work because
`file_test` provides an in-memory filesystem for tests to make them more
hermetic, but Clang's Filesystem abstrtaction is for reading only - so
the module that's written out successfully can't be found when it needs
to be read back in - so the test doesn't pass as a baseline. Clang does
have support for `llvm::vfs::OutputBackend` which allows virtualizing
output - which I guess we could tie together with the InMemoryFilesystem
we use for input to make such a test work. But I guess that's not worth
the effort here?
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Right now I think everyone has the habit of doing an autoupdate then
using source control for a diff. This is offering an option of better
diff output from the test.
For example:
```
TEST: toolchain/driver/testdata/fail_flush_errors.carbon !
Ran 1 tests in 81 ms wall time, 8 ms across threads
testing/file_test/file_test_base.cpp:264: Failure
Value of: SplitOutput(test_file.actual_stderr)
Expected: matches elements with union diff
Actual: { "fail_flush_errors.carbon:22:3: error: name `undeclared1` not found [NameNotFound]", " undeclared1;", " ^~~~~~~~~~~", "", "fail_flush_errors.carbon:31:3: error: `Core.String` implicitly referenced here, but package `Core` not found [CoreNotFound]", " \"undec\\x6Cared2\";", " ^~~~~~~~~~~~~~~~", "", "fail_flush_errors.carbon:35:3: error: name `undeclared2` not found [NameNotFound]", " undeclared2;", " ^~~~~~~~~~~", "", "fail_flush_errors.carbon:43:3: error: name `undeclared3` not found [NameNotFound]", " undeclared3;", " ^~~~~~~~~~~", "", "" }, union diff (- expected, + actual):
=== diff in expected elements 0 to 2:
+ fail_flush_errors.carbon:22:3: error: name `undeclared1` not found [NameNotFound]
undeclared1;
^~~~~~~~~~~
=== diff in expected elements 4 to 9:
"undec\x6Cared2";
^~~~~~~~~~~~~~~~
+ fail_flush_errors.carbon:35:3: error: name `undeclared2` not found [NameNotFound]
undeclared2;
^~~~~~~~~~~
=== diff end
Stack trace:
0x55e476d29efd: Carbon::Testing::FileTestCase::TestBody()
0x55e476dbd1f2: testing::internal::HandleExceptionsInMethodIfSupported<>()
0x55e476dbcf57: testing::Test::Run()
0x55e476dbf0bf: testing::TestInfo::Run()
... Google Test internal frames ...
To test this file alone, run:
bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/driver/testdata/fail_flush_errors.carbon
testing/file_test/file_test_base.cpp:277: Failure
Failed
Autoupdate would make changes to the file content. Run:
bazel run //toolchain/testing:file_test -- --autoupdate --file_tests=toolchain/driver/testdata/fail_flush_errors.carbon
Stack trace:
0x55e476d2a5f0: Carbon::Testing::FileTestCase::TestBody()
0x55e476dbd1f2: testing::internal::HandleExceptionsInMethodIfSupported<>()
0x55e476dbcf57: testing::Test::Run()
0x55e476dbf0bf: testing::TestInfo::Run()
... Google Test internal frames ...
[ FAILED ] ToolchainFileTest.toolchain/driver/testdata/fail_flush_errors.carbon, where GetParam() = toolchain/driver/testdata/fail_flush_errors.carbon (93 ms)
```
Assisted-by: Google Antigravity with Gemini
Using a named constraint inside itself is problematic:
- If there were not require decls written above, it identifies as an
empty set. This makes `Z(Self)` essentially disappear in the identified
facet type, which produces "no use of Self" diagnostics while the user
can see a use of Self in the code.
- It won't include require decls that are written after, and so `require
T impls Z` won't actually enforce that `T` impls all of `Z`.
Previously this was an error because using the named constraint would
require it to be identified, and it's not identified until it is
complete. But this will change in proposal #6902. So that proposal also
includes changes to preserve diagnostics for incorrect use of a named
constraint before it's complete, which is implemented here.
Discussed in open discussion [on
2026-03-12](https://docs.google.com/document/d/1mjllGO3ZCL4qGt9uJHUtcxKoHAGEY7Y999ie4EtBWB8/edit?tab=t.0#heading=h.1dvbbrp5a6t3).
The new tests exposed a bug where we're not copying named constraints in
a facet type on the RHS of `where .Self impls` into the facet type on
the left, which is now fixed. The
`fail_require_impls_incomplete_self_in_period_self_impls.carbon` test
would not diagnose its error without this fix.
Fixes#6895
Note this is just a short-term fix to avoid confusion, as the compile
structure needs to change on the whole.
Assisted-by: Google Antigravity with Gemini
We discussed whether associated functions should be processed in a
general manner. Since many associated functions will have some amount of
unique processing, we're probably better off not having a general
utility, and we can return to the original `CoreInterface`, which was
much simpler in design.
This reverts commit 4d0003765d.
This is so that the last file is more likely what we're trying to
compile in tests. Just splitting out the churn-y change of reordering.
Assisted-by: Google Antigravity with Gemini
Iterators, smart pointers, optional, and expected types depend on
`operator*`. This commit adds `CppUnsafeDeref` as a core interface, with
an associated function, so that the compiler can dereference
user-defined C++ types.
Things not implemented in this commit:
* `operator*` overload resolution
* SemIR lowering
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This is making it consistent with other places we set a Python version:
- contribution_tools.md
- .python-version
- bench_runner.py
- build-setup-common/action.yml
Assisted-by: Google Antigravity with Gemini
This shifts the Bazel toolchain configuration of our installation to
build all of the Clang runtimes Carbon uses on-demand natively in Bazel.
We export the information about how to build into a generated Starlark
file, and emit BUILD files and Starlark logic into the installation to
orchestrate the build.
This requires some complex management of Bazel toolchains -- we need to
first set-up a "runtimes toolchain" that doesn't have runtimes of its
own, but can be used to _build_ runtimes. Then we build the runtimes
using that toolchain, and assemble them into the standard layout for a
Carbon runtimes tree. Finally we configure the _actual_ toolchain with
this built tree.
Currently, this is only setup for the installed toolchain, but I plan to
factor this runtimes build into one that can be used directly as well to
break up the monolithic runtimes build step into Bazel-integrated build
of the runtimes. This will also serve as the foundation for adding
bootstrapping support directly to our Bazel build.
---------
Co-authored-by: Dana Jansens <danakj@orodu.net>
Use the object parameter type when creating a reference to the thunk
parameter so that we create an xvalue rather than an lvalue for the
`*this` expression in the thunk.
Previously we forced a temporary materialization, resulting in it being
treated as an ephemeral reference expression. This change allows
```carbon
var x: Class = {} as Class;
```
even when `Class` is not copyable.
In C++ overload resolution, when mapping a Carbon value expression into
a C++ argument, produce a const-qualified argument where possible. This
has two effects:
* Overload resolution does not consider non-const-qualified member
functions to be viable for a prvalue self any more. This is desirable
since such functions are not actually callable with a prvalue self, and
permits overload resolution to pick a const-qualified overload instead.
* Overload resolution does not allow a Carbon value expression to be
passed to a C++ `T&&` parameter any more. This is desirable since it's
not correct to move from a value expression. Previously we allowed this
and moved from the value!
This case is redundant: when deducing against a runtime parameter
pattern, the type is all that matters, and the type is added to the
deduction earlier. Additionally deducing the same argument against
parameter's subpattern just creates duplicate work, because the
subpattern has the same type.
When lexing a hash-prefixed character literal, the lexer assumed that
the hash level of escape sequences inside the literal was zero, which
allowed unclosed escape sequences inside the literal which crashed the
compiler.
Closes#6799
Use the same node kind for the body of `case` and `default` handlers. We
don't need to distinguish these in check, so don't create extra node
kinds for them.
In order to make the nodes properly delimited, make the label (`case
...` or `default`) nodes be children of the `=>` node rather than
siblings. This allows us to use the node kind of the `=>` as the
bracketing node for the complete handler, rather than having two
different bracketing node kinds, one for each kind of label.
Add an `IntFitsIn` interface with a custom witness, such that `T impls
IntFitsIn(U)` if `T` is an integer type all of whose values fit
losslessly into the integer type `U`. Use it to constrain implicit
conversions between integer types.
So far, this has not been extended to the
`CppCompat.[U]{Long32,LongLong64}` types, only to `Core.Int(N)` and
`Core.UInt(N)`.
Assisted-by: Gemini 3 Pro via Antigravity
This includes checking and lowering for concrete form literals. Support
for symbolic forms is future work.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This moves the most complex of the logic fully into Starlark: both the
many different platform sources list, and the overriding of generic
files with architecture specific files.
This also fixes significant bugs in the AArch64 build where we were
skipping numerous files: all of the outlined atomics and `emupac.cpp`.
This PR forcibly disables `emupac.cpp` as fixing that will require a
more significant change.
Noticed this in bazel central registry, I'm interested in trying it out.
It's using a faster approach, but leaving the other around for the
moment in case it doesn't work out well.
Assisted-by: Google Antigravity with Gemini
Roll LLVM to `6811a83c81500ee373adfc0d9978ff9625a4cf1c`.
This includes https://github.com/llvm/llvm-project/pull/183831 which
moved the functionality of `finish()` on `DiagnosticConsumer`s into the
destructors, and removed the `finish()` method. So, our callers to
`finish()` are migrated to cause the destructor to run at that time
instead.
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Trying to work on some behaviors:
- Using `black` to format Python files (using `pre-commit` makes better
use of allow-listed commands)
- Writing Python code over 80 columns (adding more style notes)
- Running `bazel` (being more emphatic about `bazelisk`, splitting tool
usage out to its own skill to try making clear it's not
toolchain-specific)
Assisted-by: Google Antigravity with Gemini
Missed in #6848 (had it sitting in my workspace uncommitted, apparently
have gotten too used to jj; using git here)
Assisted-by: Google Antigravity with Gemini
By using git_override, we get some validation from the sha, while
removing the sha256 on the .tar.gz which has been brittle lately. Note
the difference between downloading via sha is this still locally
validates content.
Versus something like #6844, this doesn't update the llvm version, just
how we get it.
Assisted-by: Google Antigravity with Gemini
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>
We may want to split some out to skills, I'm just trying to merge in
some info of my own now.
Assisted-by: Google Antigravity with Gemini 3 Flash
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Jon Ross-PerkinsandChandler Carruth
Nicholas Bishop
dependabot[bot]
Dana Jansens
Christopher Di Bella
Geoff Romer
Ilya
