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Rollup merge of #91516 - rukai:improve_mut_addition_help, r=estebank

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Improve suggestion to change struct field to &mut

r? ``@estebank``

Now displays a proper underline style suggestion instead of including the code change inline with the message.
This commit is contained in:
Matthias Krüger 2021-12-18 10:26:36 +01:00 • committed by GitHub
commit 57d49f15c9
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4 changed files with 41 additions and 36 deletions
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39
compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
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@ -229,15 +229,15 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
} => {
err.span_label(span, format!("cannot {ACT}", ACT = act));
if let Some((span, message)) = annotate_struct_field(
if let Some(span) = get_mut_span_in_struct_field(
self.infcx.tcx,
Place::ty_from(local, proj_base, self.body, self.infcx.tcx).ty,
field,
) {
err.span_suggestion(
err.span_suggestion_verbose(
span,
"consider changing this to be mutable",
message,
" mut ".into(),
Applicability::MaybeIncorrect,
);
}
@ -1059,18 +1059,18 @@ fn is_closure_or_generator(ty: Ty<'_>) -> bool {
ty.is_closure() || ty.is_generator()
}
/// Adds a suggestion to a struct definition given a field access to a local.
/// This function expects the local to be a reference to a struct in order to produce a suggestion.
/// Given a field that needs to be mutable, returns a span where the " mut " could go.
/// This function expects the local to be a reference to a struct in order to produce a span.
///
/// ```text
/// LL | s: &'a String
/// | ---------- use `&'a mut String` here to make mutable
/// LL | s: &'a String
/// | ^^^ returns a span taking up the space here
/// ```
fn annotate_struct_field<'tcx>(
fn get_mut_span_in_struct_field<'tcx>(
tcx: TyCtxt<'tcx>,
ty: Ty<'tcx>,
field: &mir::Field,
) -> Option<(Span, String)> {
) -> Option<Span> {
// Expect our local to be a reference to a struct of some kind.
if let ty::Ref(_, ty, _) = ty.kind() {
if let ty::Adt(def, _) = ty.kind() {
@ -1081,25 +1081,10 @@ fn annotate_struct_field<'tcx>(
// Now we're dealing with the actual struct that we're going to suggest a change to,
// we can expect a field that is an immutable reference to a type.
if let hir::Node::Field(field) = node {
if let hir::TyKind::Rptr(
lifetime,
hir::MutTy { mutbl: hir::Mutability::Not, ref ty },
) = field.ty.kind
if let hir::TyKind::Rptr(lifetime, hir::MutTy { mutbl: hir::Mutability::Not, ty }) =
field.ty.kind
{
// Get the snippets in two parts - the named lifetime (if there is one) and
// type being referenced, that way we can reconstruct the snippet without loss
// of detail.
let type_snippet = tcx.sess.source_map().span_to_snippet(ty.span).ok()?;
let lifetime_snippet = if !lifetime.is_elided() {
format!("{} ", tcx.sess.source_map().span_to_snippet(lifetime.span).ok()?)
} else {
String::new()
};
return Some((
field.ty.span,
format!("&{}mut {}", lifetime_snippet, &*type_snippet,),
));
return Some(lifetime.span.between(ty.span));
}
}
}