Another incremental change to diagnostic formatting. I simply recurse
over all the tokens in the subtree of a parse node and construct a
`DiagnosticLocation` that covers all of the tokens.
I believe it's nicer for the user to be directed at the entire chunk of
source where the error is occurring rather then just pointing at the
bracketing/terminator tokens, but let me know if you all agree.
This creates a namespace for `package` scope.
It looks like names of class_decls in namespaces lead to an unexpected
instref. This is already true, as best as I can tell. I'm not sure if
there's a preferred approach to address that, so I've left a TODO for
now.
This removes the filename from the file-scoped block, and places it
above to make it clear where the full SemIR begins (with multifile,
providing a barrier between).
Add a `NameId` that is effectively just a wrapper around a `StringId`,
with
some additional predefined values for names that don't correspond to
strings, such as the name of `self` or the function's return slot.
This replaces the use of `VarStorage` in this case.
Add an `UnboundFieldType` type as the type of a field, in cases where
it's referenced without an accompanying object.
Add a `BindName` node to describe the name binding performed for both
variables and fields so that we can handle them more uniformly.
This makes the difference between errors and lower-level diagnostics
visible to users, and aligns the toolchain's behavior with the
expectations in `driver_fuzzer.cpp`.
Building on #3214 and #3215, updates sem_ir yaml to be:
```
- filename: name
sem_ir: [ ... ]
```
Also, changes the textual format from `package { ... }` to `file
<filename> { ... }`. My thought on packages there is:
```
file "foo.carbon" {
package MyPackage
...
}
```
The reason for putting the file first is that it's easier if we put what
we're grouping on first, whereas the package is an "annotation" on the
file.