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Make DiagnosticBuilder::emit consuming.

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This works for most of its call sites. This is nice, because `emit` very
much makes sense as a consuming operation -- indeed,
`DiagnosticBuilderState` exists to ensure no diagnostic is emitted
twice, but it uses runtime checks.

For the small number of call sites where a consuming emit doesn't work,
the commit adds `DiagnosticBuilder::emit_without_consuming`. (This will
be removed in subsequent commits.)

Likewise, `emit_unless` becomes consuming. And `delay_as_bug` becomes
consuming, while `delay_as_bug_without_consuming` is added (which will
also be removed in subsequent commits.)

All this requires significant changes to `DiagnosticBuilder`'s chaining
methods. Currently `DiagnosticBuilder` method chaining uses a
non-consuming `&mut self -> &mut Self` style, which allows chaining to
be used when the chain ends in `emit()`, like so:
```
    struct_err(msg).span(span).emit();
```
But it doesn't work when producing a `DiagnosticBuilder` value,
requiring this:
```
    let mut err = self.struct_err(msg);
    err.span(span);
    err
```
This style of chaining won't work with consuming `emit` though. For
that, we need to use to a `self -> Self` style. That also would allow
`DiagnosticBuilder` production to be chained, e.g.:
```
    self.struct_err(msg).span(span)
```
However, removing the `&mut self -> &mut Self` style would require that
individual modifications of a `DiagnosticBuilder` go from this:
```
    err.span(span);
```
to this:
```
    err = err.span(span);
```
There are *many* such places. I have a high tolerance for tedious
refactorings, but even I gave up after a long time trying to convert
them all.

Instead, this commit has it both ways: the existing `&mut self -> Self`
chaining methods are kept, and new `self -> Self` chaining methods are
added, all of which have a `_mv` suffix (short for "move"). Changes to
the existing `forward!` macro lets this happen with very little
additional boilerplate code. I chose to add the suffix to the new
chaining methods rather than the existing ones, because the number of
changes required is much smaller that way.

This doubled chainging is a bit clumsy, but I think it is worthwhile
because it allows a *lot* of good things to subsequently happen. In this
commit, there are many `mut` qualifiers removed in places where
diagnostics are emitted without being modified. In subsequent commits:
- chaining can be used more, making the code more concise;
- more use of chaining also permits the removal of redundant diagnostic
  APIs like `struct_err_with_code`, which can be replaced easily with
  `struct_err` + `code_mv`;
- `emit_without_diagnostic` can be removed, which simplifies a lot of
  machinery, removing the need for `DiagnosticBuilderState`.
This commit is contained in:
Nicholas Nethercote
2024-01-03 12:17:35 +11:00
parent ca2fc426a9
commit b1b9278851
86 changed files with 329 additions and 312 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
compiler/rustc_hir_analysis/src/check/check.rs
View File

@@ -550,8 +550,8 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
E0044,
"foreign items may not have {kinds} parameters",
)
.span_label(item.span, format!("can't have {kinds} parameters"))
.help(
.span_label_mv(item.span, format!("can't have {kinds} parameters"))
.help_mv(
// FIXME: once we start storing spans for type arguments, turn this
// into a suggestion.
format!(
@@ -788,7 +788,7 @@ fn check_impl_items_against_trait<'tcx>(
};
tcx.dcx()
.struct_span_err(tcx.def_span(def_id), msg)
.note(format!(
.note_mv(format!(
"specialization behaves in inconsistent and \
surprising ways with {feature}, \
and for now is disallowed"
@@ -830,7 +830,7 @@ pub fn check_simd(tcx: TyCtxt<'_>, sp: Span, def_id: LocalDefId) {
let e = fields[FieldIdx::from_u32(0)].ty(tcx, args);
if !fields.iter().all(|f| f.ty(tcx, args) == e) {
struct_span_err!(tcx.dcx(), sp, E0076, "SIMD vector should be homogeneous")
.span_label(sp, "SIMD elements must have the same type")
.span_label_mv(sp, "SIMD elements must have the same type")
.emit();
return;
}
@@ -1107,7 +1107,7 @@ fn check_enum(tcx: TyCtxt<'_>, def_id: LocalDefId) {
E0084,
"unsupported representation for zero-variant enum"
)
.span_label(tcx.def_span(def_id), "zero-variant enum")
.span_label_mv(tcx.def_span(def_id), "zero-variant enum")
.emit();
}
}
@@ -1140,7 +1140,7 @@ fn check_enum(tcx: TyCtxt<'_>, def_id: LocalDefId) {
let disr_non_unit = def.variants().iter().any(|var| !is_unit(var) && has_disr(var));
if disr_non_unit || (disr_units && has_non_units) {
let mut err = struct_span_err!(
let err = struct_span_err!(
tcx.dcx(),
tcx.def_span(def_id),
E0732,
@@ -1249,7 +1249,7 @@ fn detect_discriminant_duplicate<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>)
}
}
if let Some(mut e) = error {
if let Some(e) = error {
e.emit();
}
@@ -1294,7 +1294,7 @@ pub(super) fn check_type_params_are_used<'tcx>(
{
let span = tcx.def_span(param.def_id);
struct_span_err!(tcx.dcx(), span, E0091, "type parameter `{}` is unused", param.name,)
.span_label(span, "unused type parameter")
.span_label_mv(span, "unused type parameter")
.emit();
}
}
@@ -1302,9 +1302,9 @@ pub(super) fn check_type_params_are_used<'tcx>(
fn async_opaque_type_cycle_error(tcx: TyCtxt<'_>, span: Span) -> ErrorGuaranteed {
struct_span_err!(tcx.dcx(), span, E0733, "recursion in an `async fn` requires boxing")
.span_label(span, "recursive `async fn`")
.note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`")
.note(
.span_label_mv(span, "recursive `async fn`")
.note_mv("a recursive `async fn` must be rewritten to return a boxed `dyn Future`")
.note_mv(
"consider using the `async_recursion` crate: https://crates.io/crates/async_recursion",
)
.emit()