diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src/check/mod.rs')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/mod.rs | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs index c9e74896ac0..d8e9e5a0152 100644 --- a/compiler/rustc_hir_analysis/src/check/mod.rs +++ b/compiler/rustc_hir_analysis/src/check/mod.rs @@ -403,7 +403,32 @@ fn fn_sig_suggestion<'tcx>( .flatten() .collect::<Vec<String>>() .join(", "); - let output = sig.output(); + let mut output = sig.output(); + + let asyncness = if tcx.asyncness(assoc.def_id).is_async() { + output = if let ty::Alias(_, alias_ty) = *output.kind() { + tcx.explicit_item_bounds(alias_ty.def_id) + .subst_iter_copied(tcx, alias_ty.substs) + .find_map(|(bound, _)| { + bound.to_opt_poly_projection_pred()?.no_bound_vars()?.term.ty() + }) + .unwrap_or_else(|| { + span_bug!( + ident.span, + "expected async fn to have `impl Future` output, but it returns {output}" + ) + }) + } else { + span_bug!( + ident.span, + "expected async fn to have `impl Future` output, but it returns {output}" + ) + }; + "async " + } else { + "" + }; + let output = if !output.is_unit() { format!(" -> {output}") } else { String::new() }; let unsafety = sig.unsafety.prefix_str(); @@ -414,7 +439,9 @@ fn fn_sig_suggestion<'tcx>( // lifetimes between the `impl` and the `trait`, but this should be good enough to // fill in a significant portion of the missing code, and other subsequent // suggestions can help the user fix the code. - format!("{unsafety}fn {ident}{generics}({args}){output}{where_clauses} {{ todo!() }}") + format!( + "{unsafety}{asyncness}fn {ident}{generics}({args}){output}{where_clauses} {{ todo!() }}" + ) } pub fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> { |