Carbon currently requires a comment to be the only non-whitespace on its
line. A `//` comment that follows other content on a line, called a
_trailing comment_, is a lexer error. This proposal removes that
restriction, allowing a comment to follow other content on a line.
Everything else about comments is unchanged: a comment still begins with
`//`, still requires whitespace after the `//`, and still runs to the
end of the line. Carbon continues to provide only line comments; no
block or intra-line comments are added.
Three observations motivate the change. First, trailing comments are
well suited to short _annotations_ attached to a specific entity or
value on a line. Second, the lexer design now makes it trivial to lex
trailing comments, and in fact requires extra logic and potentially cost
to reject them. Third, C++ code routinely uses trailing comments, so
allowing them lets Carbon carry the layout of migrated code over
directly, rather than reworking each comment to read well in a different
structure.
Implementation notes (beyond the proposal's design):
Keeping trailing comments cheap to lex required a few supporting
changes, all of which keep the cost off the lexer's hot path:
- The lexer already dispatches `//` to comment lexing wherever it
appears, so classifying a comment as trailing is a single O(1) check of
whether the `//` is the line's first non-whitespace (`start + indent`).
The hot comment path is otherwise unchanged.
- That check relies on each line's recorded indentation being its real
leading whitespace. Multi-line string literals previously recorded the
column where the literal opened for the lines they span; they now record
the true (closing-delimiter) indentation instead.
- Parser error recovery (`SkipPastLikelyEnd`) had relied on that
opening-column indentation to keep tokens following a multi-line string
literal attached to the same construct. It now reconstructs that
relationship directly by consulting the line on which the literal
opened, including when other tokens follow the closing delimiter (such
as `''' + "more"`). This is on the cold recovery path.
- `CommentData` records the trailing bit in the high bit of its length
field, keeping it at 8 bytes.
Assisted-by: Claude Code
Mainly because "sorting_diagnostic_consumer" is legacy, since
`SortingDiagnosticConsumer` became `SortingConsumer`. Also better
reflecting contents of these files.
Where I'm not renaming, I'm less positive about dropping "diagnostics"
from "file_diagnostics" and "null_diagnostics" (which contain both a
consumer and emitter, and "null.h" seems like poor naming), so not doing
that here. Also "diagnostic.h" contains `struct Diagnostic`, so is a
decent fit.
Assisted-by: Google Antigravity with Gemini 3 Flash
This adds the necessary parser infrastructure to recognize and parse
lambda expressions in Carbon.
Key changes:
- Added and Parse Node Kinds.
- Updated to use to accommodate the growing number of node kinds.
- Implemented parser states and handlers for lambda syntax ( or ).
- Added structure to .
- Added diagnostics for missing lambda bodies.
- Added a stub in phase to defer semantic analysis using .
- Added parser tests for lambdas.
Decouples associated constants from being special cased in let handlers.
Enforces associated constant grammar restrictions in parsing instead of
checking.
Closes#5411
Also renames variables of that type to match. A follow-up PR will rename
`Parse::StateStackEntry` to `Parse::State`. This is more consistent with
the naming of similar enums elsewhere in the toolchain, and with the
prevailing practice of using `state` rather than e.g. `entry` as the
name of a `StateStackEntry`.
See also discussion
[here](https://discord.com/channels/655572317891461132/963846118964350976/1326280585592700990)
What this really does is avoids shadowing names, so that we can
comfortable have things like `Check::DiagnosticEmitter` or
`Check::DiagnosticLoc` without shadowing being a concern.
Note, down this path I'm also thinking about:
- Renaming misc DiagnosticConsumer/DiagnosticEmitter classes, possibly
just to DiagnosticConsumer/DiagnosticEmitter (so
`Check::DiagnosticEmitter` instead of `SemIRLocDiagnosticEmitter`).
- Dropping `Diagnostic` from `Emitter::DiagnosticBuilder`.
- But not for `Check::DiagnosticBuilder`, because `Check::Builder` would
be ambiguous.
- Renaming diagnostics/diagnostic_* to drop "diagnostic".
[Discussion about SemIRLoc ->
DiagnosticLoc](https://discord.com/channels/655572317891461132/655578254970716160/1353771570463768698)
reminded me of this (in particular the older [Check::DiagnosticBuilder
discussion](https://discord.com/channels/655572317891461132/655578254970716160/1344363562608627763)),
but I'd only do that rename if there's matching consensus about a path
forward where we keep SemIRLoc, and in a way that it's only ever used
for diagnostics (the divergence from which is at the root of current
LocId discussion).
I'm trying to keep that separate from a namespace addition for clarity.
Building on #5120, make a variant of `AddNode` that returns typed nodes,
and replace `UnsafeMake` uses with it. This switches to templating in
import parsing so that we can get type validation.
With this change, `UnsafeMake` ends up used in three places: `Tree::As`,
`Tree::TryAs`, and `Context::AddNode`. That should mean that all typed
nodes are verified.
This doesn't change functionality, but I was seeing better diagnostics
in VS Code.
This also changes the NodeId constructors for related types (also
NodeCategory and NodeIdForKind) to use UnsafeMake for construction. That
originated from avoiding ambiguity coming from `requires`, but the
constructor mode is also one we should typically avoid (e.g., preferring
`Parse::Tree::As`).
At present, we typically define a DiagnosticConverter, then store an
instance of it and a DiagnosticEmitter that wraps it. This is relatively
minor in general, but I've been trying to create more self-contained
DiagnosticEmitter classes (which hold their own DiagnosticConverter,
similar to NullDiagnosticEmitter), and there it just gets in the way.
Since we don't reuse DiagnosticConverter instances, this combines the
definition into DiagnosticEmitter. Mainly this means we don't have a
separate object in play, and less to carry around.
The most impact is probably to SemIRDiagnosticConverter, which was also
the most complex. Now `SemIRLocDiagnosticEmitter`, this gets some
different construction flow. Note in the PR I've split the file rename
to its own commit, to try to help delta views. However, the most
substantial parts of the refactoring are split into #4876, which this
depends upon.
High level, replacing `Id::Invalid` with `Id::None` and `Id::is_valid`
with `Id::has_value` for clarity, as discussed
[here](https://discord.com/channels/655572317891461132/655578254970716160/1331664574545395794).
The `IntId` refactoring is needed together with `AnyIdBase` because it's
also used with `ValueStore`.
Note, trying to be careful not to rewrite `EnumBase::InvalidIndex`, or
`is_valid` in general (e.g., `IdKind::is_valid`).
I've tried to sequence commits here:
1. Automatic replacements:
- `((?:Id|Index)(?: |::|\(|Base(?:\(|::)))Invalid((?:Index)?\W)` ->
`$1None$2`
- `<invalid>` -> `<none>`
- `InvalidNodeId` -> `NoneNodeId`
- `/\*invalid\*/` -> `/*none*/`
- `id((?:_|\(\))(?:\.|->))is_valid` -> `id$1has_value`
2. Manual edits:
- In `int.h` and `int_test.cpp`
- `IntT` has `is_value`, which I'm renaming to `is_embedded_value`.
- Manual edits to comments in this file.
- `AnyIdBase` and `IdBase`
- Declaration of `is_valid` -> `has_value`, `InvalidIndex` ->
`NoneIndex`.
- In `ids.h` and `ids.cpp`
- `is_valid` -> `has_value`
- `// An explicitly invalid ID.` -> `// An ID with no value.`; similar
for index
- Various math on `InvalidIndex` -> `NoneIndex`
- Various mentions of "valid" in comments
- In `value_store.h`, for `IdT::Invalid`, plus one comment
- In `impl.h` and `tokenized_buffer.h`, we had different initialization
of `::None` values (versus `ids.h` syntax) that I fixed manually.
- Spot checks to compile
- Particularly where `is_valid` replacements didn't catch spots due to
different naming.
3. Autoupdate tests
4. verbose.carbon (NOAUTOUPDATE)
5. Comment spot checks
Note there are probably other mentions of "Invalid" that should be swept
up, but I'd like to argue for merging and separating out remaining
cleanup since this is so sweeping (and likely to hit merge conflicts
from churn). We'll probably have lingering mentions of "invalid" for a
bit regardless, just because there are uses of "invalid" in non-Id APIs.
This change deliberately breaks away from the line/column ordering, and
instead focuses on a last byte offset corresponding to the final token
processed as part of producing the message. Where that's equal, this
maintains stable ordering in order to reflect the order that diagnostics
were produced.
The intent of this approach is that lex, parse, and check diagnostics
are interleaved based on where they are produced, but that
subexpressions still have diagnostics emitted prior to containing
expressions. In particular, the prior line/column sort essentially
sorted on the _start_ of where a diagnostic was associated, and this is
closer to sorting based on the _end_. As a consequence, something like
`F(1 2)` will have the error for `1 2` emitted _before_ a diagnostic for
`F(1 2)` not matching parameters, instead of _after_.
In check, we track the last handled node. This provides a
last_byte_offset _separate_ from where a diagnostic is associated. The
intent is that this creates an ordering of diagnostics which may be
associated with earlier code, to cause the diagnostics to be emitted
later. An example consequence of this is the change in ordering of
modifier diagnostics: we are diagnosing those from the same place, but
they have the same last_byte_offset, so we print them out in the order
produced.
I've added similar tracking to parse, but cannot identify any test which
is affected by it (note the separate commit, I thought about this late).
I'm not sure whether we have good out-of-order errors we could produce
for this.
A significant number of tests have reordered diagnostics as a
consequence of this change, so this change does not add further testing.
Just a small packing optimization. We currently have 222 `NodeKinds`, so
this reduces us to just 30ish more we can add without needing to pack
more. However, if we did, there would be a couple options for bringing
the count down by reusing `NodeKinds` and disambiguating based on the
token kind (the 29 infix operators as an example). Or we could just undo
this.
I'm expecting this to yield a small improvement. I'll see if I can get
better numbers since my machine's not really reliable, but here are some
basic values.
Also suggesting to draw the use of `::RawEnumType` for `TokenKind`,
since bit packing appears to work without it. Hoping the `static_assert`
is easier for people to understand the size of the field.
With the change:
```
----------------------------------------------------------------------------------------------------------------------------
Benchmark Time CPU Iterations Bytes Lines Tokens
----------------------------------------------------------------------------------------------------------------------------
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 50399 ns 50359 ns 14336 104.588M/s 3.87217M/s 21.8629M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 237823 ns 237629 ns 3072 136.721M/s 4.11986M/s 24.2058M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 997645 ns 996771 ns 768 142.343M/s 4.04105M/s 23.9363M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 4020308 ns 4018319 ns 192 152.041M/s 4.05966M/s 24.0874M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 16691390 ns 16683058 ns 48 151.317M/s 3.92374M/s 23.2936M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 75265735 ns 75233476 ns 8 135.842M/s 3.48421M/s 20.6862M/s
```
Without the change:
```
----------------------------------------------------------------------------------------------------------------------------
Benchmark Time CPU Iterations Bytes Lines Tokens
----------------------------------------------------------------------------------------------------------------------------
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 51515 ns 51480 ns 13312 102.312M/s 3.78789M/s 21.387M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 241040 ns 240900 ns 3072 134.865M/s 4.06392M/s 23.8771M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 985593 ns 984657 ns 768 144.094M/s 4.09077M/s 24.2308M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 4109327 ns 4105496 ns 192 148.813M/s 3.97345M/s 23.576M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 17459655 ns 17446006 ns 48 144.7M/s 3.75215M/s 22.275M/s
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 80802815 ns 80737489 ns 8 126.581M/s 3.24668M/s 19.276M/s
```
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
- Provide `Check::Dump(context, arg)` and similar.
- gdb and lldb should do contextual lookup, and `call Dump(*this,
Lex::TokenIndex::Invalid)` has been tested with gdb.
- Since this is only for debug, keeps the functions fully separated from
code.
- Uses alwayslink to ensure objects are correctly linked, even though
there are no calls.
- `-Wno-missing-prototypes` is needed when we don't have forward
declarations.
- Code is not linked in opt builds, using `#ifndef NDEBUG`.
- This probably could be doing something in BUILD files with a
`select()`, but the `#ifndef` seemed easier.
This is based on #4620, but uses free functions instead of member
functions.
Co-authored-by: Dana Jansens <danakj@orodu.net>
---------
Co-authored-by: danakj <danakj@orodu.net>
Building on #4411, avoid using StringLiteral in format strings. This
includes a diagnostic check to prevent regressions (which is also how I
gathered issues).
Note, I haven't looked at `std::string` uses yet, but we might need
things like that to be able to pass strings in code back to the user.
StringLiteral though means that it's literally written down in the
toolchain, at which point it should probably be written in the format
string instead of separately.
---------
Co-authored-by: Geoff Romer <gromer@google.com>
Note, this supports plurals, but doesn't apply it anywhere. I'm mainly
doing that to demonstrate the approach regarding syntax. See
format_providers.h for details.
This is a primarily automated change:
- Search & replace for capitalization
-
`(CARBON_DIAGNOSTIC\((?:\n\s+)?\w+,(?:\n\s+)?\s\w+,(?:\n\s+)?\s")([A-Z])`
- `$1\L$2`
- Search & replace for period
-
`(CARBON_DIAGNOSTIC\((?:\n\s+)?\w+,(?:\n\s+)?\s\w+,(?:\n\s+)?\s"(?:[^)]|\n)+)\.("[,)])`
- `$1$2`
- Limited search & replace for `ERROR: ` -> `error: ` in streamed things
- Leaving a TODO for command_line because there's more cleanup that can
be done there
- Modify diagnostic_consumer.cpp
- ERROR -> error
- WARNING -> warning
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This switches `DCHECK` and `FATAL` as well.
The goal is to reduce the code size impact of these assertions so that
we can keep more of them enabled. Currently, the largest cost I see from
`CHECK` is not the actual check or the cold code itself, but actually
the failure to inline trivial functions due to the presence of the cold
code. This means that our goal isn't to reduce apparent code size in the
final binary but the LLVM IR cost assessed for these routines in the
inliner, which closely correlates with code size but is a bit different.
As discussed in #4283, experimentation shows that a single function call
with a minimal number of arguments is the lowest cost model for these.
This is easily achieved with a format-string API that internally uses
`llvm::formatv`. This PR is essentially the `CHECK` version of #4283.
However, the check macros are substantially harder to make work with
both format strings and streaming because they also take a condition.
Also, unexpectedly, I was very successful at devising a regular
expression based automated rewrite from the streaming to the format
string form with only low 10s of manual fixes. This includes compacting
strings broken up across lines, etc. Given how well that went, I've
prepared this PR which just directly switches to the format string API
and migrate everything to use it.
One nice side-effect is that the format string approach ends up greatly
simplifying the implementation here as well.
This is ... *shockingly* effective. Parsing speeds up by more than 3%
with just this change. And checking speeds up by **8%** with this change
alone:
```
BM_CompileAPIFileDenseDecls<Phase::Parse>/256 86.3µs ± 1% 82.9µs ± 1% -3.94% (p=0.000 n=17+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 431µs ± 1% 415µs ± 1% -3.76% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 1.77ms ± 1% 1.71ms ± 1% -3.18% (p=0.000 n=18+19)
BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 7.44ms ± 1% 7.17ms ± 2% -3.56% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 30.7ms ± 1% 29.7ms ± 1% -3.15% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 131ms ± 1% 127ms ± 1% -2.81% (p=0.000 n=18+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/256 878µs ± 2% 800µs ± 1% -8.91% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1.88ms ± 2% 1.72ms ± 1% -8.56% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5.78ms ± 2% 5.28ms ± 1% -8.70% (p=0.000 n=20+18)
BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21.9ms ± 1% 20.1ms ± 1% -8.02% (p=0.000 n=18+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/65536 90.4ms ± 2% 83.1ms ± 1% -8.04% (p=0.000 n=19+20)
BM_CompileAPIFileDenseDecls<Phase::Check>/262144 381ms ± 2% 352ms ± 1% -7.79% (p=0.000 n=19+19)
```
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
Move subtree sizes over to TreeAndSubtrees, using the different
structure to represent the additional parse work that occurs, as well as
making it clear which functions require the extra information. My intent
is to make it hard to use this by accident.
The subtree size is still tracked during Parse::Tree construction. I
think a lot of that can be cleaned up, although we use it during
placeholder assignment so it may take some work. I wanted to see what
people thought about this before taking action on such a change.
I'm using a 1m line source file generated by #4124 for testing. Command
is `time bazel-bin/toolchain/install/prefix_root/bin/carbon compile
--phase=check --dump-mem-usage ~/tmp/data.carbon`
At head, what I'm seeing is:
```
...
parse_tree_.node_impls_:
used_bytes: 61516116
reserved_bytes: 61516116
...
Total:
used_bytes: 447814230
reserved_bytes: 551663894
...
1.43s user 0.14s system 99% cpu 1.565 total
```
With `Tree::Verify` disabled completely, it looks like:
```
parse_tree_.node_impls_:
used_bytes: 41010744
reserved_bytes: 41010744
...
Total:
used_bytes: 427308858
reserved_bytes: 531158522
...
1.20s user 0.13s system 99% cpu 1.332 total
```
Re-enabling just the basic verification (what is now `Tree::Verify`),
I'm seeing maybe 0.05s slower, but that's within noise for my system. I
do see variability in my timing results, and overall I think this is a
0.2s +/- 0.1s improvement versus the earlier (always testing `Extract`
code) implementation. That's opt; debug builds will be unaffected,
because the same checking occurs as before.
Note, the subtree size is a third of the node representation, which is
why I'm showing the decrease in memory usage here.
Following up on discussion from #3948, doing a general rename of
"enclosing scope" to "parent scope" (and "enclosing scopes" to "ancestor
scopes"). The intent is to improve understandability and collide less
with C++ terminology for "enclosing scope". Note this changes most uses
of "enclosing", but leaves behind a few like "enclosing function" and
"enclosing block".
Note this does create some "parent class" mentions for "adapt" and "var"
(the class they're within), which is maybe unfortunate, but we'd
probably say "base class" if we meant inheritance so perhaps that's
okay. Along the same lines, these are the only `parent_class` uses I see
now, and we do have a few `base_class`.
Instead of tracking the token associated with a parse node in the `.def`
file macro, track it on the typed node instead. List the token as a
field inside the node structure to show the order of the token relative
to the other components of the grammar production, and to allow the
token index to be accessed when the node is extracted.
Remove the corresponding information from the `.def` file, leaving
behind just a list of parse node kinds in the majority of cases.
This also removes the checking of the token kind associated with a parse
node in the case where the parse node has errors. Previously we had a
flag on the node kind to indicate whether we should check this, but per
[discord
discussion](https://discord.com/channels/655572317891461132/655578254970716160/1246214418979881052),
we have decided to remove this.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
When we expect a semicolon, we should be able to provide more standard
recovery.
Note this affects a test of `base`, but it looks like a partial
improvement (the prior line was moving too far). Still, it looks like
recovery isn't handling `{}` quite right. I'm not trying to address that
here though -- leaving a TODO.
This is something I noticed working on
https://github.com/carbon-language/carbon-lang/pull/3884; I think we
have more functions named Diagnose* at present than Emit* or Report*, so
just trying to consolidate. Note a couple Diagnose* functions do a
little more validation, but maybe those should actually be renamed away
(zygoloid had mentioned wanting to generally split out diagnostics to
their own function, and then we'd have it be a more common pattern).
In parse, form a list of methods that are defined inline, tracking where
they start, where they end, and which other inline methods are nested
within them.
In check, when we reach an inline method body, skip it and add it to a
worklist to be processed later. We also track when we reach the start
and end of a context in which inline method bodies are deferred, so that
we know when to replay the bodies.
When suspending a function definition to be processed later, the
`DeclNameStack` entry is moved to separate storage, including popping
the corresponding scopes from the scope stack and removing the
corresponding lexical names from lexical lookup. Later, when we return
to the function and parse its definition, the `DeclNameStack` entry is
restored. The same is done when we reach the end of a nested context
that can have inline methods, so that we can reenter the nested scope
before processing its members.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This was previously discussed at
https://discord.com/channels/655572317891461132/655578254970716160/1209975051588210729.
I'm initiating this mainly because we typically use "id" suffixes to
indicate an `IdBase` being passed around and the non-id suffix of
`parse_node` suggests at it carrying more data than it actually does.
There used to be more reason for avoiding `node_id` because
`SemIR::InstId` used to be named `NodeId`, but that's no longer
necessary. As a consequence, I'd like to rename `parse_node` to more
precisely reflect its type.
In full, this is doing:
```
parse_node_kind -> node_kind
parse_node -> node_id
ParseNodeCategory -> NodeCategory
ParseNodeKind -> NodeKind
ParseNode -> NodeId
```
This is primarily in check and sem_ir, but with some `parse_node_kind`
references in parse too.
Pluralization is consistent with name forms on both sides, so that
wasn't part of my replacements.
We already do this with things like llvm::DenseMapInfo, I don't know why
I was doing this with format_provider. But this should be more
consistent, and slightly better for not entering another library's
namespace.
This builds on the series of changes to NodeKinds, aiming to simplify
the NodeKind implementation a little, also making it clearer that
there's a single associated token for each parse node (or, for
placeholders/invalid parses, not validated).
Note that prior to the relevant changes, there were nodes with multiple
tokens. This change is also locking in the approach of one token per
parse node, by refactoring macros to stop supporting multiple.
The main difference I'm aiming for is that clangd doesn't complain about
the struct being unused, but it does miss the function's use. But really
these are specific to formatv for diagnostics, so this is more clearly
marking such, and probably makes for a better pattern for the future.
I was suggesting this because `FloatingPoint` is pretty long. `int` and
`float` should be familiar abbreviations. `unsigned` should be familiar
to developers too, but `UnsignedInt` still feels usefully clearer for
the additional chars.
These are manual fixes; mostly from clang-tidy, some from clangd (which
notes unused includes).
In typed_insts, adding inlline due to misc-definitions-in-headers. Per
discussion, clang-tidy is wrong, but inline silences it.
For parameter name skew in definition versus declaration, I'm just using
the name from the definition.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This gets to a lifetime subtlety, particularly with things like the
sorting diagnostic consumer that delay output. In order to reduce the
chance of accidental references, disallow StringRef in the diagnostics.
For example:
```
./toolchain/diagnostics/diagnostic_emitter.h:162:5: error: static_assert failed due to requirement '!std::is_same_v<llvm::StringRef, llvm::StringRef>' "Use std::string or llvm::StringLiteral for diagnostic lifetimes."
static_assert(
^
toolchain/check/convert.cpp:477:11: note: in instantiation of member function 'Carbon::Internal::DiagnosticBase<std::string, std::string, llvm::StringRef>::DiagnosticBase' requested here
CARBON_DIAGNOSTIC(StructInitMissingFieldInConversion, Error,
^
./toolchain/diagnostics/diagnostic_emitter.h:47:7: note: expanded from macro 'CARBON_DIAGNOSTIC'
::Carbon::Internal::DiagnosticBase<__VA_ARGS__>( \
^
```
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Dana Jansens
Chandler Carruth
Geoff Romer
Jon Ross-Perkins
Burak Emir
Elliott Kalt
Thomas Köppe
