Commit Graph
43 Commits
Author SHA1 Message Date
Dana Jansens ea227be0fe Apply min-preludes to more tests (part 6) (#5691)
This drops file_test runtime from about 3.5s to 3s on my machine.
2025-06-23 21:33:17 +00:00
Jon Ross-Perkinsandjosh11b ed82f7ef3f Add ranges to where_expr tests (#5630)
Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
2025-06-17 21:04:49 +00:00
Jon Ross-Perkins c70f23408d Add range flag settings to where_expr files (#5582)
Where `--no-dump-sem-ir` is used, change to `--dump-sem-ir-ranges=only`.
Otherwise, add `--dump-sem-ir-ranges=if-present` with a TODO to change
to `only`.

Note, SemIR is affected just because the extra comments change line
numbers in files where splits aren't in use.
2025-05-31 01:42:10 +00:00
a23631f360 Support for lowering references to imported vars. (#5513)
Previously we walked the global variables defined by the current file
and emitted an LLVM global variable definition for each of them. Now
instead, when emitting a constant reference to a global variable, we
emit an LLVM global variable declaration, and we then subsequently walk
the global variables defined by the current file and convert each of
them from a declaration to a definition.

In order to make import of names of global variables work, add support
for import of `var`, as well as support for importing `tuple_access` and
`tuple_pattern` in the case where the `var` has a tuple pattern in its
declaration. Also treat `bind_name`s that are reference bindings to
`var`s as having the same constant reference value as their `var` so
that we can properly import and lower them.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
2025-05-29 19:48:16 +00:00
Richard Smith 5b884ae14d Improve lowering for global variables. (#5492)
- Track the `VarPattern` instruction on the `VarStorage` instruction so
that it's available for name mangling.
- Mangle global variables based on the first binding name within their
pattern.
- Give global variables external rather than internal linkage, except if
they have no bindings whatsoever in their pattern.
- To support lowering references to bindings nested within a global var,
such as for `var (x: i32, b: i32)`, add some basic initial support for
reference constant expressions. Treat a global `var` as a reference
constant, and treat an aggregate access into a reference constant as a
reference constant.
2025-05-21 00:09:10 +00:00
Richard Smith 797b14eb8e Import ImplWitnessTable into the imports block instead of the constants block. (#5374)
Don't import `ImplWitnessTable` into the `constants` block, because we
generally don't put `Unique` constants there. This matches the handling
of the other kinds of `Unique` constants. In order to keep the
instruction visible in formatted SemIR, add it to the `imports` block
instead.

Also fix a bug in the instruction formatter that resulted in
instructions in the `imports` block being omitted from the output if
they were only referenced by earlier instructions in the `imports` block
and by instructions in the `constants` block. This was already resulting
in some referenced instructions being omitted from the output, but also
occurred frequently for `impl_witness_table` instructions after this
change because it is common for the only reference to those instructions
to be from `impl_witness` instructions in the `constants` block.
2025-05-01 00:08:43 +00:00
Geoff Romer 34887403ab Model patterns as constant values (#5385)
This will enable us to simplify support for parameter and return
patterns in import, which operates primarily on constants.
2025-04-30 22:32:41 +00:00
Geoff Romer 7c85397f8b Stop treating symbolic binding patterns as constants (#5361)
This was originally needed to support constant evaluation of name
expressions, but that's now done in a different way.

This is actually a step toward treating all patterns as constants. The
upcoming change will do so in a slightly different way, and so it will
simplify the review to start from a baseline where patterns are never
constant.
2025-04-28 23:45:15 +00:00
Richard Smith ca8df34d0d Format the call parameters of a function, not the patterns. (#5342)
This makes the parameters printed in a SemIR `fn` declaration match the
arguments printed in a SemIR `call` instruction.
2025-04-22 18:52:21 +00:00
Richard Smith 265968b396 Make evaluation of symbolic bindings simpler and more uniform (#5215)
Factor out logic to evaluate `EntityNameId` instead of duplicating it
between `BindSymbolicName` and `SymbolicBindingPattern`. Remove support
in `SymbolicBindingPattern` for evaluating a pattern to the constant
value of the corresponding binding, which doesn't really make any sense
given that patterns don't generally evaluate to the value that they
matched.

This results in the handling for `SymbolicBindingPattern` being simply
the default handling for an always-constant instruction, so remove the
special case for it entirely and change its constant kind to `Always`.
It's not entirely clear that it makes sense for `SymbolicBindingPattern`
to be treated as a constant when other patterns aren't, but we seem to
be relying on this in various places, so leave it as a constant for now.
Changing it to never be constant will be a smaller change now -- it just
requires changing the `constant_kind`.

The IR changes in the tests are fairly widespread, but mechanical, and
there are two kinds of things changing:

- `symbolic_binding_pattern`s in specifics now evaluate to
`symbolic_binding_pattern`s, not to the argument values. This means in a
few cases we end up with additional `symbolic_binding_pattern`
constants.
- We evaluate the type operand of `symbolic_binding_pattern` now, so an
error in the type will now properly be propagated into an error in the
pattern's constant value.
2025-04-01 20:24:00 +00:00
Geoff Romer d264f14027 Clean up handling of Call params (#5061)
- Explicitly document that `*Param` and `*ParamPattern` insts represent
`Call` parameters.
- Stop wrapping compile-time parameter patterns in `ValueParamPattern`
insts (because they aren't `Call` parameters).
- Document how `MatchContext::results_` relates to the `Call`
parameters, and be more consistent about when it's written to.
- Remove `RuntimeParamIndex::Unknown`: we no longer need to distinguish
"this `Param`'s runtime index is unknown" from "this `Param` isn't a
runtime param", because we no longer use `Param`s at all in the latter
case.
- Rename `RuntimeParamIndex` to `CallParamIndex`.

As a side effect of removing the `ValueParamPattern` insts, this fixes a
minor diagnostic bug where `NoteInitializingParam` didn't identify the
specific parameter that led to a deduction failure, because it expects
generic parameters to only be represented by `SymbolicBindingPattern`s,
but before this change they could be wrapped in `ValueParamPattern`s.
2025-03-04 21:01:59 +00:00
Richard Smith 0d2f364f39 Split evaluation up into one function per instruction kind (#5008)
Replace the large and growing `TryEvalInstInContext` function with one
function per kind. While we still have special-case handling for a small
number of instruction kinds, most instructions are now handled either
fully automatically or use a common codepath that evaluates the
instruction operands and then performs an eval-context-independent
evaluation of the instruction.

To support this, `InstConstantKind` is expanded to describe more
fine-grained details about how each kind of instruction interacts with
constant evaluation. Also, the operand kinds of instructions become
slightly more fine-grained: we now distinguish between operands that
describe the destination of an initializing expression (`DestInstId`)
from other `InstId` operands, because `DestInstId` operands need
different treatment during constant evaluation. In particular, an
initializing expression can have a constant value even if its
destination is non-constant or has not yet been set, because evaluation
of an initializing expression doesn't include the store to the
destination.

Some minor test changes:

- We now more consistently propagate errors into the results of constant
evaluation, so more instructions that depend on errors have a constant
value of `<error>`.
- Diagnostic location for invalid array types now point at the whole
array type rather than the array index expression, because
`EvalConstantinst` doesn't have access to the original expression.
- Diagnostic for failed `RequireCompleteType` doesn't print the original
type any more because `EvalConstantInst` doesn't have access to the
original expression.

As a follow-up, some of this -- in particular, the `EvalConstantInst`
overloads -- will be moved to a separate file, in an effort to split the
overall constant evaluation machinery apart from the logic to evaluate
each individual kind of instruction.
2025-02-27 01:31:26 +00:00
Boaz Brickner 986a2a064c Add poisoned names to the format (#4961)
Part of #4622.
2025-02-14 19:18:51 +00:00
Richard Smith c6d35e1c4a Rename template constant -> concrete constant. (#4939)
This implements a direction decided in a
[recent
discussion](https://docs.google.com/document/d/1Iut5f2TQBrtBNIduF4vJYOKfw7MbS8xH_J01_Q4e6Rk/edit?resourcekey=0-mc_vh5UzrzXfU4kO-3tOjA&tab=t.0#heading=h.mas1g68xx9ct)
to switch away from "template constant" when naming a constant that
doesn't depend on any generic parameters, because that creates confusion
with template-dependent constant values that depend on a template
parameter.
2025-02-12 21:24:51 +00:00
Jon Ross-Perkins 6b5eb1a101 Id::Invalid -> Id::None (#4834)
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.
2025-01-22 23:15:00 +00:00
Calvin 3f4de65ad8 Improve SemIR naming of import_refs (#4824)
Changes the name of SemIR `import_ref`s to use the format
`<package>.<entity>`.

<table>
<tr><th>Before</th><th>After</th></tr>
<tr>
<td><code>%import_ref.05a: type</code></td>
<td><code>%Main.D: type</code></td>
</tr>
<tr>
<td><code>%import_ref.8f2: &lt;witness&gt;</code></td>
<td><code>%Main.import_ref.8f2: &lt;witness&gt;</code></td>
</tr>
</table>

* [Discord discussion in
#toolchain](https://discord.com/channels/655572317891461132/655578254970716160/1330253540999827577)
* Closes #4769
2025-01-22 07:22:07 +00:00
Geoff RomerandRichard Smith 13434f0e8a Model var as a pattern operator (#4720)
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2025-01-17 17:51:34 +00:00
David BlaikieandJon Ross-Perkins e6c1f0630a Add a newline after diagnostic output when testing (#4818)
This removes some churn when adding new diagnostic cases to test files
(where previous to this change the newly added newline would cause the
previous diagnostic CHECKs to be updated including changes to the line
number because the CHECK for the blank line meant an extra line between
CHECK and source line).

A few alternatives discussed here:
https://discord.com/channels/655572317891461132/655578254970716160/1329573358475673723

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2025-01-16 23:23:57 +00:00
Richard Smith b1230218d5 Make fingerprinting stable across compatible source changes. (#4789)
Include the index rather than the name in the fingerprint of a symbolic
binding. While both the index and the name contribute to the canonical
identity, using either one of them in the fingerprint is sufficient to
ensure that distinct entities get different fingerprints. Changing the
name of a symbolic binding should ideally not result in fingerprint
changes, so exclude the name from the fingerprint when we have an index.

Use the canonical type and constraint when fingerprinting an impl, so
that uses of names in `name_ref` instructions aren't considered, only
the entity the name resolves to, and different ways of spelling the same
type have the same fingerprint. This similarly allows compatible changes
to be made to impls without changing the fingerprint.

Exclude the declaration block when determining the fingerprint of a
declaration. The declaration block contains the declarations of
parameters of the declaration, which do affect whether two declarations
are identical, but not whether they denote the same entity, because it
would be invalid to have different declaration blocks for declarations
with the same name in the same scope. Therefore changes to the
declaration block are compatible, and it's useful for such changes to
not affect the fingerprint.

This is not easy to test in isolation with our current testing
machinery. However, a follow-on PR will change the name of a parameter
in the prelude, and with this in place, will not cause any changes to
occur elsewhere in the toolchain tests.
2025-01-10 22:30:22 +00:00
Richard SmithandDana Jansens 19182f08aa Compute a fingerprint for constants and import_ref instructions. (#4763)
Use it in the instruction namer to make instruction names more stable
across unrelated changes to the toolchain or the prelude.

---------

Co-authored-by: Dana Jansens <danakj@orodu.net>
2025-01-07 20:41:44 +00:00
Dana Jansensandjonmeow 6cb660f5ad Avoid recursion in InstNamer::CollectNamesInBlock (#4706)
Use a deque to maintain the set of instructions to be walked over. so
that the loop can append more instructions (with their related scope)
during iteration without requiring recursion.

---------

Co-authored-by: jonmeow <jperkins@google.com>
2024-12-20 16:12:06 +00:00
Geoff RomerandRichard Smith a112cbde5c Model type expressions as regions (#4698)
This is a precondition for enabling the new pattern-matching subsystem
to support binding patterns that have `if` expressions in the type
position.

---------

Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-12-19 21:41:06 +00:00
Richard Smith a10c79569e Model Core.Int as a class type (#4644)
Instead of treating `Core.Int` as the toolchain's builtin `IntType`,
model it as a class that adapts the builtin type. This aligns us better
with the intended language model, gives an associated library for
`impl`s involving `Core.Int` to live within, and opens the door adding
member functions to `Core.Int` if we decide that is desirable.
Remarkably it also seems to make the formatted SemIR a little smaller,
because a call to a generic class generates less IR than a call to a
function.
2024-12-16 22:19:23 +00:00
33110d096c Facet types support rewrite (where .A =...) constraints (#4613)
* Rewrite constraints are stored in a facet type, substituted, imported,
and formatted.
* We now distinguish `.Self` from other symbolic bindings in two ways:
* `.Self` itself now has an invalid compile time binding index (since it
doesn't bind to any of the generic parameters). As a result, we no
longer need to create a generic region in `handle_where.cpp`.
* There is a new phase tracking values that are only symbolic because
they transitively depend on `.Self`. This allows us to give the result
of a `where` expression template phase as long as it doesn't use any
symbolic constants other than `.Self` or other designators.
* `AddConstant` has been removed from `check/context` since it was only
used from `eval`. This meant less plumbing of the phase change.
* Evaluation of `BindSymbolicName` now also performs substitution into
its type.
* Include a bit more information in some diagnostics.
* `StringifyTypeExpr` outputs rewrites, which required adding support
for associated entities as well.
  * Associated entities now have an entity name set when importing.
* Adds tests for some interesting cases with rewrites and uses of
`.Self` mixed with other symbolic constants.

Still to do:
* There is no validation that any particular type satisfies rewrite
constraints.
  * Access to members of a facet type do not see the rewritten values.
* Impls don't recognize whether associated constants have rewrites
setting their values.
  * No support for resolving facet types.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
2024-12-03 22:44:39 +00:00
josh11bandJosh L 5d1b39e1f2 More instructions get named (#4615)
Goal is to reduce churn in names in test updates (by churning a lot of
them in this PR).

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
2024-12-03 20:47:53 +00:00
Richard SmithandJon Ross-Perkins e2ae5f212c Remove the special case for i32. (#4543)
For the few remaining uses of the builtin `i32` type, manually build an
`IntType(Signed, 32)` value instead. These are:

- The return type of `Run`.
- The type that int literals in an `if` expression are converted into.
- The type of an array index expression.

We should consider converting those three cases away from `i32` over
time.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-11-18 23:19:36 +00:00
Richard Smith 145f878ce8 Allow extend adapt of non-class types. (#4544)
Stop rejecting `extend adapt` of non-class types such as struct and
tuple. These don't actually work just yet because name lookup into
struct and tuple types is a special case that doesn't handle adapters,
but this gets us a bit closer.

This also slightly improves error recovery for name lookup into an
invalid scope.
2024-11-18 16:01:44 +00:00
Richard Smith bc395eb889 Represent integer literals as IntLiteral not as i32. (#4532)
When an `IntLiteral` appears as an operand of an `if` expression,
convert it to `i32` for now, so that we don't reject things like `if
cond then 1 else 2` due to having a non-constant value of type
`IntLiteral`.

For tuple indexing expressions such as `(a, b).0`, convert the index to
type `IntLiteral`, not to type `i32`. This isn't strictly necessary to
do in this PR, but avoids the need to provide an `IntLiteral` -> `i32`
implicit conversion for `no_prelude` tests using this syntax.
2024-11-15 23:24:15 +00:00
4ee65ef58a Reduce the size of formatted SemIR. (#4534)
- Do not include entities imported from files that we are not dumping.
- Do not include constants and import_refs that are not referenced by
something that we are including in the formatted output.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com>
2024-11-15 21:00:26 +00:00
a69c2630f9 Replace InterfaceType with FacetType (#4499)
This does a few things:
* Replaces the single `TypeId` in the `FacetTypeInfo` struct with a
vector of `InterfaceId`, `SpecificId` pairs (sorted in id order)
representing the set of interface requirements of the facet type. This
will later be used to support facet types with multiple interface
requirements (as in `I & J` or `I where .Self impls J`).
* Replace `InterfaceType` instructions (used as the type of an
`InterfaceDecl` instruction) with `FacetType` instructions (introduced
in #4460) with a (newly introduced) `FacetTypeFromInterface()` function.
* Replace code that consumed `InterfaceType` values with code that
consumed `FaceType` values. I've generally left the assumption in the
code that it is dealing with a single interface, using the (newly
introduced) `FacetTypeInfo::TryAsSingleInterface`, and producing an
error otherwise. There isn't yet support for the `&` operator or `where
.Self impls`, so this is generally a good assumption for now, except you
can get a facet type with no associated interfaces from a `type
where`... expression. In some cases, the facet type value is pulled from
the evaluation of an `InterfaceDecl` instruction, where the single
interface assumption will hold permanently.
* Some related cleans up: nicer stringification and formatting of facet
types, suppression of some errors when there already was an error.

There is still a lot left to do, including:
* Type `type` should be a facet type with a reserved id, replacing the
built-in instruction.
* Code using `TryAsSingleInterface` should generally be upgraded to
handle more than (or less than) one interface. Name lookup should be
particularly exciting.
* Operator `&` should be defined on facet types, unioning their
interface and other requirements.
* Requirements from a `where` clause don't do anything yet.
* Impls and impl lookup need to resolve facet types, and do things like
determine if all the associated constants are given values.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
Co-authored-by: Geoff Romer <gromer@google.com>
2024-11-11 18:01:50 +00:00
Jon Ross-Perkins 10e256a241 Name empty tuples distinctly in SemIR. (#4503)
Building on #4502, give empty tuple values a distinct name, and also
explicitly name tuple types (previously values but not types were
named).
2024-11-08 17:14:52 +00:00
Richard Smith db76e81630 Rename IntLiteral to IntValue. (#4475)
This instruction represents integer values, whether they come from
literals or calculations, so it the old name is inaccurate. I also plan
to rename `BigInt` to `IntLiteral` based on recent discussion and this
change aims to avoid confusion stemming from the same name being used
for two different things.

I'm not renaming `FloatLiteral` because recent discussion suggests we
may want distinct `FloatLiteral` versus `FloatValue` representations in
SemIR.
2024-11-02 01:19:39 +00:00
Jon Ross-Perkins d944347e7b Elide prelude components in the IR formatter. (#4453)
This is in particular to avoid churn from changes such as #4370. I think
the import list can be helpful (particularly to understand what the
library is aware of), but it's a different trade-off for the prelude
package due to the implicit imports.
2024-10-30 22:45:26 +00:00
Brymer MenesesandJon Ross-Perkins 89eed4220f Expose indexing as a language interface (#4370)
This PR makes it so that types can implement the `IndexWith` interface
so that they can provide their custom indexing behavior.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-10-29 21:25:02 +00:00
josh11bandJosh L c30b1d1124 Fix where crash when empty decl_name_stack (#4451)
Bug found by fuzzer.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
2024-10-29 19:38:02 +00:00
Geoff Romer b67d03126e Separate inst kind for out params (#4442) 2024-10-24 15:22:32 +00:00
Richard Smith 2e63da1a40 Move diagnostic kind name to the end of the diagnostic. (#4437)
Also surround it in square brackets rather than parentheses. This
matches the format used by Clang and GCC, and means diagnostics will
still match the `file:line:col: error: ` pattern used by some IDE tools.

Before:
```console
fail_builtins.carbon:11:11: error(AliasRequiresNameRef): alias initializer must be a name reference
```

After:
```console
fail_builtins.carbon:11:11: error: alias initializer must be a name reference [AliasRequiresNameRef]
```

Also tighten up test regex to only match on `STDERR` lines that list a
file name.
2024-10-23 16:56:23 +00:00
Geoff Romer 9266f867f9 Model the return slot as an output parameter (#4432)
Also fix `Param` insts to have meaningful names in pretty-printing, to
help clarify relationship with return slot.
2024-10-23 16:53:34 +00:00
Jon Ross-Perkins 62c36eceda Support printing the diagnostic kind for verification. (#4425)
This is to help identify which diagnostics we're actually using.

Note that driver/testdata still has tests which don't pass this flag,
and so continue to test the kind-less (default) behavior.
2024-10-18 22:33:56 +00:00
Richard Smith a02dfe0226 Superficial support for Core.BigInt type (#4414)
Add a `Core.BigInt` type and a corresponding builtin type in the
toolchain. See [corresponding section of the
design](https://docs.carbon-lang.dev/docs/design/expressions/literals.html#defined-types).

So far this type is not used for anything, and there is no way to create
an instance of it.
2024-10-16 23:27:01 +00:00
Geoff RomerandJon Ross-Perkins 9d942f4633 Generate parameter pattern-match IR from pattern IR (#4388)
Also propagate the pattern IR along with the pattern-match IR, and use
it where appropriate.

Strictly speaking, some parts of the pattern-match IR are allocated
eagerly, while traversing the pattern's parse tree, but they still
aren't actually emitted until we traverse the associated pattern insts.

---------

Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
2024-10-16 19:15:29 +00:00
Richard Smith efb5d6d25a Assign locations to instructions in a generic eval block. (#4393)
The locations point to the first instruction in the generic that needed
the relevant constant value or type.

For now, this must makes the formatted SemIR a bit more useful, but in
the future it will also provide locations for diagnostics caused by
monomorphization failure.
2024-10-09 19:03:15 +00:00
josh11bandJosh L 6dbeda612a where check stage, step 3: some type checking (#4364)
With this, we now check:

* The left argument to `where` is a facet type
* The right argument of a rewrite (`=`) requirement converts to the type
of the left argument.
* The left argument of an `impls` requirement is a type and the right
argument is a facet type.

No checking is done for `==` constraints yet.

In addition, make the "is facet type" query into its own function and
fix some comments noticed as part of this change.

This change reveals that accessing the members of a facet, like `.Self`,
isn't doing the right thing, and will have to be fixed in a follow-on
PR. Some tests have been adjusted or disabled as a result.

---------

Co-authored-by: Josh L <josh11b@users.noreply.github.com>
2024-10-05 01:03:43 +00:00