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Commit b1b9278

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nnethercotennethercote
committedJan 8, 2024
Make DiagnosticBuilder::emit consuming.
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`.
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‎compiler/rustc_ast_passes/src/feature_gate.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@ macro_rules! gate {
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($visitor:expr, $feature:ident, $span:expr, $explain:expr, $help:expr) => {{
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if !$visitor.features.$feature && !$span.allows_unstable(sym::$feature) {
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feature_err(&$visitor.sess.parse_sess, sym::$feature, $span, $explain)
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.help($help)
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.help_mv($help)
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.emit();
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}
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}};

‎compiler/rustc_borrowck/src/diagnostics/region_errors.rs

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Original file line numberDiff line numberDiff line change
@@ -348,7 +348,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
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let named_ty = self.regioncx.name_regions(self.infcx.tcx, hidden_ty);
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let named_key = self.regioncx.name_regions(self.infcx.tcx, key);
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let named_region = self.regioncx.name_regions(self.infcx.tcx, member_region);
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let mut diag = unexpected_hidden_region_diagnostic(
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let diag = unexpected_hidden_region_diagnostic(
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self.infcx.tcx,
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span,
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named_ty,

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