diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_borrowck/src/diagnostics/move_errors.rs | 20 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/method/suggest.rs | 88 |
2 files changed, 107 insertions, 1 deletions
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs index 695ac6980cd..41d6b98d7cf 100644 --- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs @@ -2,7 +2,7 @@ use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed use rustc_middle::mir::*; use rustc_middle::ty::{self, Ty}; use rustc_mir_dataflow::move_paths::{LookupResult, MovePathIndex}; -use rustc_span::{BytePos, Span}; +use rustc_span::{BytePos, ExpnKind, MacroKind, Span}; use crate::diagnostics::CapturedMessageOpt; use crate::diagnostics::{DescribePlaceOpt, UseSpans}; @@ -488,6 +488,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { args_span, } }); + + self.add_note_for_packed_struct_derive(err, original_path.local); } } } @@ -594,4 +596,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { ); } } + + /// Adds an explanatory note if the move error occurs in a derive macro + /// expansion of a packed struct. + /// Such errors happen because derive macro expansions shy away from taking + /// references to the struct's fields since doing so would be undefined behaviour + fn add_note_for_packed_struct_derive(&self, err: &mut Diagnostic, local: Local) { + let local_place: PlaceRef<'tcx> = local.into(); + let local_ty = local_place.ty(self.body.local_decls(), self.infcx.tcx).ty.peel_refs(); + + if let Some(adt) = local_ty.ty_adt_def() + && adt.repr().packed() + && let ExpnKind::Macro(MacroKind::Derive, name) = self.body.span.ctxt().outer_expn_data().kind + { + err.note(format!("`#[derive({name})]` triggers a move because taking references to the fields of a packed struct is undefined behaviour")); + } + } } diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs index 12cc5ed2f1a..87dfcf09cdd 100644 --- a/compiler/rustc_hir_typeck/src/method/suggest.rs +++ b/compiler/rustc_hir_typeck/src/method/suggest.rs @@ -409,6 +409,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { err.downgrade_to_delayed_bug(); } + self.find_builder_fn(&mut err, rcvr_ty, source); if tcx.ty_is_opaque_future(rcvr_ty) && item_name.name == sym::poll { err.help(format!( "method `poll` found on `Pin<&mut {ty_str}>`, \ @@ -1407,6 +1408,93 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } + /// Look at all the associated functions without receivers in the type's inherent impls + /// to look for builders that return `Self`, `Option<Self>` or `Result<Self, _>`. + fn find_builder_fn(&self, err: &mut Diagnostic, rcvr_ty: Ty<'tcx>, source: SelfSource<'tcx>) { + let ty::Adt(adt_def, _) = rcvr_ty.kind() else { + return; + }; + let SelfSource::QPath(ty) = source else { + return; + }; + let hir = self.tcx.hir(); + if let Some(Node::Pat(_)) = hir.find(hir.parent_id(ty.hir_id)) { + // Do not suggest a fn call when a pattern is expected. + return; + } + let mut items = self + .tcx + .inherent_impls(adt_def.did()) + .iter() + .flat_map(|i| self.tcx.associated_items(i).in_definition_order()) + // Only assoc fn with no receivers. + .filter(|item| matches!(item.kind, ty::AssocKind::Fn) && !item.fn_has_self_parameter) + .filter_map(|item| { + // Only assoc fns that return `Self`, `Option<Self>` or `Result<Self, _>`. + let ret_ty = self.tcx.fn_sig(item.def_id).skip_binder().output(); + let ret_ty = self.tcx.erase_late_bound_regions(ret_ty); + let ty::Adt(def, args) = ret_ty.kind() else { + return None; + }; + // Check for `-> Self` + if self.can_eq(self.param_env, ret_ty, rcvr_ty) { + return Some((item.def_id, ret_ty)); + } + // Check for `-> Option<Self>` or `-> Result<Self, _>` + if ![self.tcx.lang_items().option_type(), self.tcx.get_diagnostic_item(sym::Result)] + .contains(&Some(def.did())) + { + return None; + } + let arg = args.get(0)?.expect_ty(); + if self.can_eq(self.param_env, rcvr_ty, arg) { + Some((item.def_id, ret_ty)) + } else { + None + } + }) + .collect::<Vec<_>>(); + let post = if items.len() > 5 { + let items_len = items.len(); + items.truncate(4); + format!("\nand {} others", items_len - 4) + } else { + String::new() + }; + match &items[..] { + [] => {} + [(def_id, ret_ty)] => { + err.span_note( + self.tcx.def_span(def_id), + format!( + "if you're trying to build a new `{rcvr_ty}`, consider using `{}` which \ + returns `{ret_ty}`", + self.tcx.def_path_str(def_id), + ), + ); + } + _ => { + let span: MultiSpan = items + .iter() + .map(|(def_id, _)| self.tcx.def_span(def_id)) + .collect::<Vec<Span>>() + .into(); + err.span_note( + span, + format!( + "if you're trying to build a new `{rcvr_ty}` consider using one of the \ + following associated functions:\n{}{post}", + items + .iter() + .map(|(def_id, _ret_ty)| self.tcx.def_path_str(def_id)) + .collect::<Vec<String>>() + .join("\n") + ), + ); + } + } + } + /// Suggest calling `Ty::method` if `.method()` isn't found because the method /// doesn't take a `self` receiver. fn suggest_associated_call_syntax( |