diff options
Diffstat (limited to 'compiler/rustc_typeck/src/check/fn_ctxt')
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs | 90 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs | 25 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/checks.rs | 752 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/mod.rs | 14 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs | 383 |
5 files changed, 915 insertions, 349 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs index 3a8093345..a40478db9 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs @@ -83,7 +83,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {}) } - #[instrument(skip(self, mutate_fulfillment_errors), level = "debug")] + #[instrument(skip(self, mutate_fulfillment_errors), level = "debug", ret)] pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment( &self, mut ty: Ty<'tcx>, @@ -107,10 +107,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // indirect dependencies that don't seem worth tracking // precisely. self.select_obligations_where_possible(false, mutate_fulfillment_errors); - ty = self.resolve_vars_if_possible(ty); - - debug!(?ty); - ty + self.resolve_vars_if_possible(ty) } pub(in super::super) fn record_deferred_call_resolution( @@ -412,7 +409,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { rhs_span: opt_input_expr.map(|expr| expr.span), is_lit: opt_input_expr .map_or(false, |expr| matches!(expr.kind, ExprKind::Lit(_))), - output_pred: None, + output_ty: None, }, ), self.param_env, @@ -498,13 +495,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { pub fn to_const(&self, ast_c: &hir::AnonConst) -> ty::Const<'tcx> { let const_def_id = self.tcx.hir().local_def_id(ast_c.hir_id); + let span = self.tcx.hir().span(ast_c.hir_id); let c = ty::Const::from_anon_const(self.tcx, const_def_id); - self.register_wf_obligation( - c.into(), - self.tcx.hir().span(ast_c.hir_id), - ObligationCauseCode::WellFormed(None), - ); - c + self.register_wf_obligation(c.into(), span, ObligationCauseCode::WellFormed(None)); + self.normalize_associated_types_in(span, c) } pub fn const_arg_to_const( @@ -618,9 +612,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { #[instrument(skip(self), level = "debug")] pub(in super::super) fn select_all_obligations_or_error(&self) { - let errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self); + let mut errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self); if !errors.is_empty() { + self.adjust_fulfillment_errors_for_expr_obligation(&mut errors); self.report_fulfillment_errors(&errors, self.inh.body_id, false); } } @@ -634,6 +629,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self); if !result.is_empty() { mutate_fulfillment_errors(&mut result); + self.adjust_fulfillment_errors_for_expr_obligation(&mut result); self.report_fulfillment_errors(&result, self.inh.body_id, fallback_has_occurred); } } @@ -831,23 +827,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let ty = item_ty.subst(self.tcx, substs); self.write_resolution(hir_id, Ok((def_kind, def_id))); - self.add_required_obligations_with_code( - span, - def_id, - &substs, - match lang_item { - hir::LangItem::IntoFutureIntoFuture => { - ObligationCauseCode::AwaitableExpr(expr_hir_id) - } - hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => { - ObligationCauseCode::ForLoopIterator - } - hir::LangItem::TryTraitFromOutput - | hir::LangItem::TryTraitFromResidual - | hir::LangItem::TryTraitBranch => ObligationCauseCode::QuestionMark, - _ => traits::ItemObligation(def_id), - }, - ); + + let code = match lang_item { + hir::LangItem::IntoFutureIntoFuture => { + Some(ObligationCauseCode::AwaitableExpr(expr_hir_id)) + } + hir::LangItem::IteratorNext | hir::LangItem::IntoIterIntoIter => { + Some(ObligationCauseCode::ForLoopIterator) + } + hir::LangItem::TryTraitFromOutput + | hir::LangItem::TryTraitFromResidual + | hir::LangItem::TryTraitBranch => Some(ObligationCauseCode::QuestionMark), + _ => None, + }; + if let Some(code) = code { + self.add_required_obligations_with_code(span, def_id, substs, move |_, _| code.clone()); + } else { + self.add_required_obligations_for_hir(span, def_id, substs, hir_id); + } + (Res::Def(def_kind, def_id), ty) } @@ -986,7 +984,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { if found != self.tcx.types.unit { return; } - if let ExprKind::MethodCall(path_segment, [rcvr, ..], _) = expr.kind { + if let ExprKind::MethodCall(path_segment, rcvr, ..) = expr.kind { if self .typeck_results .borrow() @@ -1359,7 +1357,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // First, store the "user substs" for later. self.write_user_type_annotation_from_substs(hir_id, def_id, substs, user_self_ty); - self.add_required_obligations(span, def_id, &substs); + self.add_required_obligations_for_hir(span, def_id, &substs, hir_id); // Substitute the values for the type parameters into the type of // the referenced item. @@ -1396,32 +1394,36 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } /// Add all the obligations that are required, substituting and normalized appropriately. - pub(crate) fn add_required_obligations( + pub(crate) fn add_required_obligations_for_hir( &self, span: Span, def_id: DefId, - substs: &SubstsRef<'tcx>, + substs: SubstsRef<'tcx>, + hir_id: hir::HirId, ) { - self.add_required_obligations_with_code( - span, - def_id, - substs, - traits::ItemObligation(def_id), - ) + self.add_required_obligations_with_code(span, def_id, substs, |idx, span| { + if span.is_dummy() { + ObligationCauseCode::ExprItemObligation(def_id, hir_id, idx) + } else { + ObligationCauseCode::ExprBindingObligation(def_id, span, hir_id, idx) + } + }) } - #[tracing::instrument(level = "debug", skip(self, span, def_id, substs))] + #[instrument(level = "debug", skip(self, code, span, def_id, substs))] fn add_required_obligations_with_code( &self, span: Span, def_id: DefId, - substs: &SubstsRef<'tcx>, - code: ObligationCauseCode<'tcx>, + substs: SubstsRef<'tcx>, + code: impl Fn(usize, Span) -> ObligationCauseCode<'tcx>, ) { let (bounds, _) = self.instantiate_bounds(span, def_id, &substs); for obligation in traits::predicates_for_generics( - traits::ObligationCause::new(span, self.body_id, code), + |idx, predicate_span| { + traits::ObligationCause::new(span, self.body_id, code(idx, predicate_span)) + }, self.param_env, bounds, ) { diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs b/compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs index 7602f2550..fc83994ca 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/arg_matrix.rs @@ -130,14 +130,17 @@ impl<'tcx> ArgMatrix<'tcx> { let ai = &self.expected_indices; let ii = &self.provided_indices; + // Issue: 100478, when we end the iteration, + // `next_unmatched_idx` will point to the index of the first unmatched + let mut next_unmatched_idx = 0; for i in 0..cmp::max(ai.len(), ii.len()) { - // If we eliminate the last row, any left-over inputs are considered missing + // If we eliminate the last row, any left-over arguments are considered missing if i >= mat.len() { - return Some(Issue::Missing(i)); + return Some(Issue::Missing(next_unmatched_idx)); } - // If we eliminate the last column, any left-over arguments are extra + // If we eliminate the last column, any left-over inputs are extra if mat[i].len() == 0 { - return Some(Issue::Extra(i)); + return Some(Issue::Extra(next_unmatched_idx)); } // Make sure we don't pass the bounds of our matrix @@ -145,6 +148,7 @@ impl<'tcx> ArgMatrix<'tcx> { let is_input = i < ii.len(); if is_arg && is_input && matches!(mat[i][i], Compatibility::Compatible) { // This is a satisfied input, so move along + next_unmatched_idx += 1; continue; } @@ -163,7 +167,7 @@ impl<'tcx> ArgMatrix<'tcx> { if is_input { for j in 0..ai.len() { // If we find at least one argument that could satisfy this input - // this argument isn't useless + // this input isn't useless if matches!(mat[i][j], Compatibility::Compatible) { useless = false; break; @@ -232,8 +236,8 @@ impl<'tcx> ArgMatrix<'tcx> { if matches!(c, Compatibility::Compatible) { Some(i) } else { None } }) .collect(); - if compat.len() != 1 { - // this could go into multiple slots, don't bother exploring both + if compat.len() < 1 { + // try to find a cycle even when this could go into multiple slots, see #101097 is_cycle = false; break; } @@ -309,7 +313,8 @@ impl<'tcx> ArgMatrix<'tcx> { } while !self.provided_indices.is_empty() || !self.expected_indices.is_empty() { - match self.find_issue() { + let res = self.find_issue(); + match res { Some(Issue::Invalid(idx)) => { let compatibility = self.compatibility_matrix[idx][idx].clone(); let input_idx = self.provided_indices[idx]; @@ -364,7 +369,9 @@ impl<'tcx> ArgMatrix<'tcx> { None => { // We didn't find any issues, so we need to push the algorithm forward // First, eliminate any arguments that currently satisfy their inputs - for (inp, arg) in self.eliminate_satisfied() { + let eliminated = self.eliminate_satisfied(); + assert!(!eliminated.is_empty(), "didn't eliminated any indice in this round"); + for (inp, arg) in eliminated { matched_inputs[arg] = Some(inp); } } diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs index 660e7e4e3..311fcaada 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs @@ -15,6 +15,7 @@ use crate::check::{ use crate::structured_errors::StructuredDiagnostic; use rustc_ast as ast; +use rustc_data_structures::fx::FxHashSet; use rustc_errors::{pluralize, Applicability, Diagnostic, DiagnosticId, MultiSpan}; use rustc_hir as hir; use rustc_hir::def::{CtorOf, DefKind, Res}; @@ -27,13 +28,14 @@ use rustc_infer::infer::InferOk; use rustc_infer::infer::TypeTrace; use rustc_middle::ty::adjustment::AllowTwoPhase; use rustc_middle::ty::visit::TypeVisitable; -use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty}; +use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty, TypeSuperVisitable, TypeVisitor}; use rustc_session::Session; use rustc_span::symbol::Ident; -use rustc_span::{self, Span}; +use rustc_span::{self, sym, Span}; use rustc_trait_selection::traits::{self, ObligationCauseCode, SelectionContext}; use std::iter; +use std::ops::ControlFlow; use std::slice; impl<'a, 'tcx> FnCtxt<'a, 'tcx> { @@ -58,7 +60,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { debug!("FnCtxt::check_asm: {} deferred checks", deferred_asm_checks.len()); for (asm, hir_id) in deferred_asm_checks.drain(..) { let enclosing_id = self.tcx.hir().enclosing_body_owner(hir_id); - InlineAsmCtxt::new_in_fn(self) + let get_operand_ty = |expr| { + let ty = self.typeck_results.borrow().expr_ty_adjusted(expr); + let ty = self.resolve_vars_if_possible(ty); + if ty.has_infer_types_or_consts() { + assert!(self.is_tainted_by_errors()); + self.tcx.ty_error() + } else { + self.tcx.erase_regions(ty) + } + }; + InlineAsmCtxt::new_in_fn(self.tcx, self.param_env, get_operand_ty) .check_asm(asm, self.tcx.hir().local_def_id_to_hir_id(enclosing_id)); } } @@ -141,7 +153,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ) { let tcx = self.tcx; - // Conceptually, we've got some number of expected inputs, and some number of provided aguments + // Conceptually, we've got some number of expected inputs, and some number of provided arguments // and we can form a grid of whether each argument could satisfy a given input: // in1 | in2 | in3 | ... // arg1 ? | | | @@ -212,6 +224,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let minimum_input_count = expected_input_tys.len(); let provided_arg_count = provided_args.len(); + let is_const_eval_select = matches!(fn_def_id, Some(def_id) if + self.tcx.def_kind(def_id) == hir::def::DefKind::Fn + && self.tcx.is_intrinsic(def_id) + && self.tcx.item_name(def_id) == sym::const_eval_select); + // We introduce a helper function to demand that a given argument satisfy a given input // This is more complicated than just checking type equality, as arguments could be coerced // This version writes those types back so further type checking uses the narrowed types @@ -237,17 +254,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // Cause selection errors caused by resolving a single argument to point at the // argument and not the call. This lets us customize the span pointed to in the // fulfillment error to be more accurate. - let coerced_ty = - self.resolve_vars_with_obligations_and_mutate_fulfillment(coerced_ty, |errors| { - self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr); - self.point_at_arg_instead_of_call_if_possible( - errors, - call_expr, - call_span, - provided_args, - &expected_input_tys, - ); - }); + let coerced_ty = self.resolve_vars_with_obligations(coerced_ty); let coerce_error = self .try_coerce(provided_arg, checked_ty, coerced_ty, AllowTwoPhase::Yes, None) @@ -257,6 +264,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { return Compatibility::Incompatible(coerce_error); } + // Check that second and third argument of `const_eval_select` must be `FnDef`, and additionally that + // the second argument must be `const fn`. The first argument must be a tuple, but this is already expressed + // in the function signature (`F: FnOnce<ARG>`), so I did not bother to add another check here. + // + // This check is here because there is currently no way to express a trait bound for `FnDef` types only. + if is_const_eval_select && (1..=2).contains(&idx) { + if let ty::FnDef(def_id, _) = checked_ty.kind() { + if idx == 1 && !self.tcx.is_const_fn_raw(*def_id) { + self.tcx + .sess + .struct_span_err(provided_arg.span, "this argument must be a `const fn`") + .help("consult the documentation on `const_eval_select` for more information") + .emit(); + } + } else { + self.tcx + .sess + .struct_span_err(provided_arg.span, "this argument must be a function item") + .note(format!("expected a function item, found {checked_ty}")) + .help( + "consult the documentation on `const_eval_select` for more information", + ) + .emit(); + } + } + // 3. Check if the formal type is a supertype of the checked one // and register any such obligations for future type checks let supertype_error = self @@ -302,16 +335,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // an "opportunistic" trait resolution of any trait bounds on // the call. This helps coercions. if check_closures { - self.select_obligations_where_possible(false, |errors| { - self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr); - self.point_at_arg_instead_of_call_if_possible( - errors, - call_expr, - call_span, - &provided_args, - &expected_input_tys, - ); - }) + self.select_obligations_where_possible(false, |_| {}) } // Check each argument, to satisfy the input it was provided for @@ -440,7 +464,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { call_expr: &hir::Expr<'tcx>, ) { // Next, let's construct the error - let (error_span, full_call_span, ctor_of) = match &call_expr.kind { + let (error_span, full_call_span, ctor_of, is_method) = match &call_expr.kind { hir::ExprKind::Call( hir::Expr { hir_id, span, kind: hir::ExprKind::Path(qpath), .. }, _, @@ -448,22 +472,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { if let Res::Def(DefKind::Ctor(of, _), _) = self.typeck_results.borrow().qpath_res(qpath, *hir_id) { - (call_span, *span, Some(of)) + (call_span, *span, Some(of), false) } else { - (call_span, *span, None) + (call_span, *span, None, false) } } - hir::ExprKind::Call(hir::Expr { span, .. }, _) => (call_span, *span, None), - hir::ExprKind::MethodCall(path_segment, _, span) => { + hir::ExprKind::Call(hir::Expr { span, .. }, _) => (call_span, *span, None, false), + hir::ExprKind::MethodCall(path_segment, _, _, span) => { let ident_span = path_segment.ident.span; let ident_span = if let Some(args) = path_segment.args { ident_span.with_hi(args.span_ext.hi()) } else { ident_span }; - ( - *span, ident_span, None, // methods are never ctors - ) + // methods are never ctors + (*span, ident_span, None, true) } k => span_bug!(call_span, "checking argument types on a non-call: `{:?}`", k), }; @@ -507,13 +530,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .collect(); let callee_expr = match &call_expr.peel_blocks().kind { hir::ExprKind::Call(callee, _) => Some(*callee), - hir::ExprKind::MethodCall(_, callee, _) => { + hir::ExprKind::MethodCall(_, receiver, ..) => { if let Some((DefKind::AssocFn, def_id)) = self.typeck_results.borrow().type_dependent_def(call_expr.hir_id) && let Some(assoc) = tcx.opt_associated_item(def_id) && assoc.fn_has_self_parameter { - Some(&callee[0]) + Some(*receiver) } else { None } @@ -545,7 +568,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let coerced_ty = expectation.only_has_type(self).unwrap_or(formal_input_ty); let can_coerce = self.can_coerce(arg_ty, coerced_ty); if !can_coerce { - return Compatibility::Incompatible(None); + return Compatibility::Incompatible(Some(ty::error::TypeError::Sorts( + ty::error::ExpectedFound::new(true, coerced_ty, arg_ty), + ))); } // Using probe here, since we don't want this subtyping to affect inference. @@ -577,7 +602,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // First, check if we just need to wrap some arguments in a tuple. if let Some((mismatch_idx, terr)) = compatibility_diagonal.iter().enumerate().find_map(|(i, c)| { - if let Compatibility::Incompatible(Some(terr)) = c { Some((i, terr)) } else { None } + if let Compatibility::Incompatible(Some(terr)) = c { + Some((i, *terr)) + } else { + None + } }) { // Is the first bad expected argument a tuple? @@ -659,7 +688,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { Applicability::MachineApplicable, ); }; - self.label_fn_like(&mut err, fn_def_id, callee_ty); + self.label_fn_like( + &mut err, + fn_def_id, + callee_ty, + Some(mismatch_idx), + is_method, + ); err.emit(); return; } @@ -701,16 +736,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } errors.drain_filter(|error| { - let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(error)) = error else { return false }; + let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(e))) = error else { return false }; let (provided_ty, provided_span) = provided_arg_tys[*provided_idx]; let (expected_ty, _) = formal_and_expected_inputs[*expected_idx]; let cause = &self.misc(provided_span); let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); - if let Some(e) = error { - if !matches!(trace.cause.as_failure_code(e), FailureCode::Error0308(_)) { - self.report_and_explain_type_error(trace, e).emit(); - return true; - } + if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308(_)) { + self.report_and_explain_type_error(trace, *e).emit(); + return true; } false }); @@ -733,7 +766,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx]; let cause = &self.misc(provided_arg_span); let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); - let mut err = self.report_and_explain_type_error(trace, err); + let mut err = self.report_and_explain_type_error(trace, *err); self.emit_coerce_suggestions( &mut err, &provided_args[*provided_idx], @@ -749,7 +782,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { format!("arguments to this {} are incorrect", call_name), ); // Call out where the function is defined - self.label_fn_like(&mut err, fn_def_id, callee_ty); + self.label_fn_like( + &mut err, + fn_def_id, + callee_ty, + Some(expected_idx.as_usize()), + is_method, + ); err.emit(); return; } @@ -797,7 +836,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { Error::Invalid(provided_idx, expected_idx, compatibility) => { let (formal_ty, expected_ty) = formal_and_expected_inputs[expected_idx]; let (provided_ty, provided_span) = provided_arg_tys[provided_idx]; - if let Compatibility::Incompatible(error) = &compatibility { + if let Compatibility::Incompatible(error) = compatibility { let cause = &self.misc(provided_span); let trace = TypeTrace::types(cause, true, expected_ty, provided_ty); if let Some(e) = error { @@ -1031,7 +1070,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } // Call out where the function is defined - self.label_fn_like(&mut err, fn_def_id, callee_ty); + self.label_fn_like(&mut err, fn_def_id, callee_ty, None, is_method); // And add a suggestion block for all of the parameters let suggestion_text = match suggestion_text { @@ -1048,11 +1087,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { }; if let Some(suggestion_text) = suggestion_text { let source_map = self.sess().source_map(); - let mut suggestion = format!( - "{}(", - source_map.span_to_snippet(full_call_span).unwrap_or_else(|_| fn_def_id - .map_or("".to_string(), |fn_def_id| tcx.item_name(fn_def_id).to_string())) - ); + let (mut suggestion, suggestion_span) = + if let Some(call_span) = full_call_span.find_ancestor_inside(error_span) { + ("(".to_string(), call_span.shrink_to_hi().to(error_span.shrink_to_hi())) + } else { + ( + format!( + "{}(", + source_map.span_to_snippet(full_call_span).unwrap_or_else(|_| { + fn_def_id.map_or("".to_string(), |fn_def_id| { + tcx.item_name(fn_def_id).to_string() + }) + }) + ), + error_span, + ) + }; let mut needs_comma = false; for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() { if needs_comma { @@ -1062,8 +1112,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } let suggestion_text = if let Some(provided_idx) = provided_idx && let (_, provided_span) = provided_arg_tys[*provided_idx] - && let Ok(arg_text) = - source_map.span_to_snippet(provided_span) + && let Ok(arg_text) = source_map.span_to_snippet(provided_span) { arg_text } else { @@ -1081,7 +1130,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } suggestion += ")"; err.span_suggestion_verbose( - error_span, + suggestion_span, &suggestion_text, suggestion, Applicability::HasPlaceholders, @@ -1129,7 +1178,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { opt_ty.unwrap_or_else(|| self.next_float_var()) } ast::LitKind::Bool(_) => tcx.types.bool, - ast::LitKind::Err(_) => tcx.ty_error(), + ast::LitKind::Err => tcx.ty_error(), } } @@ -1164,7 +1213,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.write_user_type_annotation_from_substs(hir_id, did, substs, None); // Check bounds on type arguments used in the path. - self.add_required_obligations(path_span, did, substs); + self.add_required_obligations_for_hir(path_span, did, substs, hir_id); Some((variant, ty)) } else { @@ -1601,186 +1650,420 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } - /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk - /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s - /// reference a type argument. The reason to walk also the checked type is that the coerced type - /// can be not easily comparable with predicate type (because of coercion). If the types match - /// for either checked or coerced type, and there's only *one* argument that does, we point at - /// the corresponding argument's expression span instead of the `fn` call path span. - fn point_at_arg_instead_of_call_if_possible( + /// Given a vector of fulfillment errors, try to adjust the spans of the + /// errors to more accurately point at the cause of the failure. + /// + /// This applies to calls, methods, and struct expressions. This will also + /// try to deduplicate errors that are due to the same cause but might + /// have been created with different [`ObligationCause`][traits::ObligationCause]s. + pub(super) fn adjust_fulfillment_errors_for_expr_obligation( &self, errors: &mut Vec<traits::FulfillmentError<'tcx>>, - expr: &'tcx hir::Expr<'tcx>, - call_sp: Span, - args: &'tcx [hir::Expr<'tcx>], - expected_tys: &[Ty<'tcx>], ) { - // We *do not* do this for desugared call spans to keep good diagnostics when involving - // the `?` operator. - if call_sp.desugaring_kind().is_some() { - return; - } - - 'outer: for error in errors { - // Only if the cause is somewhere inside the expression we want try to point at arg. - // Otherwise, it means that the cause is somewhere else and we should not change - // anything because we can break the correct span. - if !call_sp.contains(error.obligation.cause.span) { - continue; + // Store a mapping from `(Span, Predicate) -> ObligationCause`, so that + // other errors that have the same span and predicate can also get fixed, + // even if their `ObligationCauseCode` isn't an `Expr*Obligation` kind. + // This is important since if we adjust one span but not the other, then + // we will have "duplicated" the error on the UI side. + let mut remap_cause = FxHashSet::default(); + let mut not_adjusted = vec![]; + + for error in errors { + let before_span = error.obligation.cause.span; + if self.adjust_fulfillment_error_for_expr_obligation(error) + || before_span != error.obligation.cause.span + { + // Store both the predicate and the predicate *without constness* + // since sometimes we instantiate and check both of these in a + // method call, for example. + remap_cause.insert(( + before_span, + error.obligation.predicate, + error.obligation.cause.clone(), + )); + remap_cause.insert(( + before_span, + error.obligation.predicate.without_const(self.tcx), + error.obligation.cause.clone(), + )); + } else { + // If it failed to be adjusted once around, it may be adjusted + // via the "remap cause" mapping the second time... + not_adjusted.push(error); } + } - // Peel derived obligation, because it's the type that originally - // started this inference chain that matters, not the one we wound - // up with at the end. - fn unpeel_to_top<'a, 'tcx>( - mut code: &'a ObligationCauseCode<'tcx>, - ) -> &'a ObligationCauseCode<'tcx> { - let mut result_code = code; - loop { - let parent = match code { - ObligationCauseCode::ImplDerivedObligation(c) => &c.derived.parent_code, - ObligationCauseCode::BuiltinDerivedObligation(c) - | ObligationCauseCode::DerivedObligation(c) => &c.parent_code, - _ => break result_code, - }; - (result_code, code) = (code, parent); + for error in not_adjusted { + for (span, predicate, cause) in &remap_cause { + if *predicate == error.obligation.predicate + && span.contains(error.obligation.cause.span) + { + error.obligation.cause = cause.clone(); + continue; } } - let self_: ty::subst::GenericArg<'_> = - match unpeel_to_top(error.obligation.cause.code()) { - ObligationCauseCode::BuiltinDerivedObligation(code) - | ObligationCauseCode::DerivedObligation(code) => { - code.parent_trait_pred.self_ty().skip_binder().into() + } + } + + fn adjust_fulfillment_error_for_expr_obligation( + &self, + error: &mut traits::FulfillmentError<'tcx>, + ) -> bool { + let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx)) + = *error.obligation.cause.code().peel_derives() else { return false; }; + let hir = self.tcx.hir(); + let hir::Node::Expr(expr) = hir.get(hir_id) else { return false; }; + + // Skip over mentioning async lang item + if Some(def_id) == self.tcx.lang_items().from_generator_fn() + && error.obligation.cause.span.desugaring_kind() + == Some(rustc_span::DesugaringKind::Async) + { + return false; + } + + let Some(unsubstituted_pred) = + self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx) + else { return false; }; + + let generics = self.tcx.generics_of(def_id); + let predicate_substs = match unsubstituted_pred.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => pred.trait_ref.substs, + ty::PredicateKind::Projection(pred) => pred.projection_ty.substs, + _ => ty::List::empty(), + }; + + let find_param_matching = |matches: &dyn Fn(&ty::ParamTy) -> bool| { + predicate_substs.types().find_map(|ty| { + ty.walk().find_map(|arg| { + if let ty::GenericArgKind::Type(ty) = arg.unpack() + && let ty::Param(param_ty) = ty.kind() + && matches(param_ty) + { + Some(arg) + } else { + None } - ObligationCauseCode::ImplDerivedObligation(code) => { - code.derived.parent_trait_pred.self_ty().skip_binder().into() + }) + }) + }; + + // Prefer generics that are local to the fn item, since these are likely + // to be the cause of the unsatisfied predicate. + let mut param_to_point_at = find_param_matching(&|param_ty| { + self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) == def_id + }); + // Fall back to generic that isn't local to the fn item. This will come + // from a trait or impl, for example. + let mut fallback_param_to_point_at = find_param_matching(&|param_ty| { + self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) != def_id + && param_ty.name != rustc_span::symbol::kw::SelfUpper + }); + // Finally, the `Self` parameter is possibly the reason that the predicate + // is unsatisfied. This is less likely to be true for methods, because + // method probe means that we already kinda check that the predicates due + // to the `Self` type are true. + let mut self_param_to_point_at = + find_param_matching(&|param_ty| param_ty.name == rustc_span::symbol::kw::SelfUpper); + + // Finally, for ambiguity-related errors, we actually want to look + // for a parameter that is the source of the inference type left + // over in this predicate. + if let traits::FulfillmentErrorCode::CodeAmbiguity = error.code { + fallback_param_to_point_at = None; + self_param_to_point_at = None; + param_to_point_at = + self.find_ambiguous_parameter_in(def_id, error.root_obligation.predicate); + } + + if self.closure_span_overlaps_error(error, expr.span) { + return false; + } + + match &expr.kind { + hir::ExprKind::Path(qpath) => { + if let hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Call(callee, args), + hir_id: call_hir_id, + span: call_span, + .. + }) = hir.get(hir.get_parent_node(expr.hir_id)) + && callee.hir_id == expr.hir_id + { + if self.closure_span_overlaps_error(error, *call_span) { + return false; } - _ if let ty::PredicateKind::Trait(predicate) = - error.obligation.predicate.kind().skip_binder() => + + for param in + [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + .into_iter() + .flatten() { - predicate.self_ty().into() + if self.point_at_arg_if_possible( + error, + def_id, + param, + *call_hir_id, + callee.span, + None, + args, + ) + { + return true; + } } - _ => continue, - }; - let self_ = self.resolve_vars_if_possible(self_); - let ty_matches_self = |ty: Ty<'tcx>| ty.walk().any(|arg| arg == self_); - - let typeck_results = self.typeck_results.borrow(); - - for (idx, arg) in args.iter().enumerate() { - // Don't adjust the span if we already have a more precise span - // within one of the args. - if arg.span.contains(error.obligation.cause.span) { - let references_arg = - typeck_results.expr_ty_opt(arg).map_or(false, &ty_matches_self) - || expected_tys.get(idx).copied().map_or(false, &ty_matches_self); - if references_arg && !arg.span.from_expansion() { - error.obligation.cause.map_code(|parent_code| { - ObligationCauseCode::FunctionArgumentObligation { - arg_hir_id: args[idx].hir_id, - call_hir_id: expr.hir_id, - parent_code, - } - }) + } + // Notably, we only point to params that are local to the + // item we're checking, since those are the ones we are able + // to look in the final `hir::PathSegment` for. Everything else + // would require a deeper search into the `qpath` than I think + // is worthwhile. + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath) + { + return true; + } + } + hir::ExprKind::MethodCall(segment, receiver, args, ..) => { + for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + .into_iter() + .flatten() + { + if self.point_at_arg_if_possible( + error, + def_id, + param, + hir_id, + segment.ident.span, + Some(receiver), + args, + ) { + return true; + } + } + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_generic_if_possible(error, def_id, param_to_point_at, segment) + { + return true; + } + } + hir::ExprKind::Struct(qpath, fields, ..) => { + if let Res::Def(DefKind::Struct | DefKind::Variant, variant_def_id) = + self.typeck_results.borrow().qpath_res(qpath, hir_id) + { + for param in + [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at] + { + if let Some(param) = param + && self.point_at_field_if_possible( + error, + def_id, + param, + variant_def_id, + fields, + ) + { + return true; + } } - continue 'outer; + } + if let Some(param_to_point_at) = param_to_point_at + && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath) + { + return true; } } + _ => {} + } - // Collect the argument position for all arguments that could have caused this - // `FulfillmentError`. - let mut referenced_in: Vec<_> = std::iter::zip(expected_tys, args) - .enumerate() - .flat_map(|(idx, (expected_ty, arg))| { - if let Some(arg_ty) = typeck_results.expr_ty_opt(arg) { - vec![(idx, arg_ty), (idx, *expected_ty)] - } else { - vec![] - } - }) - .filter_map(|(i, ty)| { - let ty = self.resolve_vars_if_possible(ty); - // We walk the argument type because the argument's type could have - // been `Option<T>`, but the `FulfillmentError` references `T`. - if ty_matches_self(ty) { Some(i) } else { None } - }) - .collect(); + false + } + + fn closure_span_overlaps_error( + &self, + error: &traits::FulfillmentError<'tcx>, + span: Span, + ) -> bool { + if let traits::FulfillmentErrorCode::CodeSelectionError( + traits::SelectionError::OutputTypeParameterMismatch(_, expected, _), + ) = error.code + && let ty::Closure(def_id, _) | ty::Generator(def_id, ..) = expected.skip_binder().self_ty().kind() + && span.overlaps(self.tcx.def_span(*def_id)) + { + true + } else { + false + } + } + + fn point_at_arg_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + call_hir_id: hir::HirId, + callee_span: Span, + receiver: Option<&'tcx hir::Expr<'tcx>>, + args: &'tcx [hir::Expr<'tcx>], + ) -> bool { + let sig = self.tcx.fn_sig(def_id).skip_binder(); + let args_referencing_param: Vec<_> = sig + .inputs() + .iter() + .enumerate() + .filter(|(_, ty)| find_param_in_ty(**ty, param_to_point_at)) + .collect(); + // If there's one field that references the given generic, great! + if let [(idx, _)] = args_referencing_param.as_slice() + && let Some(arg) = receiver + .map_or(args.get(*idx), |rcvr| if *idx == 0 { Some(rcvr) } else { args.get(*idx - 1) }) { + error.obligation.cause.span = arg.span.find_ancestor_in_same_ctxt(error.obligation.cause.span).unwrap_or(arg.span); + error.obligation.cause.map_code(|parent_code| { + ObligationCauseCode::FunctionArgumentObligation { + arg_hir_id: arg.hir_id, + call_hir_id, + parent_code, + } + }); + return true; + } else if args_referencing_param.len() > 0 { + // If more than one argument applies, then point to the callee span at least... + // We have chance to fix this up further in `point_at_generics_if_possible` + error.obligation.cause.span = callee_span; + } - // Both checked and coerced types could have matched, thus we need to remove - // duplicates. + false + } - // We sort primitive type usize here and can use unstable sort - referenced_in.sort_unstable(); - referenced_in.dedup(); + fn point_at_field_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + variant_def_id: DefId, + expr_fields: &[hir::ExprField<'tcx>], + ) -> bool { + let def = self.tcx.adt_def(def_id); + + let identity_substs = ty::InternalSubsts::identity_for_item(self.tcx, def_id); + let fields_referencing_param: Vec<_> = def + .variant_with_id(variant_def_id) + .fields + .iter() + .filter(|field| { + let field_ty = field.ty(self.tcx, identity_substs); + find_param_in_ty(field_ty, param_to_point_at) + }) + .collect(); - if let &[idx] = &referenced_in[..] { - // Do not point at the inside of a macro. - // That would often result in poor error messages. - if args[idx].span.from_expansion() { - continue; + if let [field] = fields_referencing_param.as_slice() { + for expr_field in expr_fields { + // Look for the ExprField that matches the field, using the + // same rules that check_expr_struct uses for macro hygiene. + if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx) + { + error.obligation.cause.span = expr_field + .expr + .span + .find_ancestor_in_same_ctxt(error.obligation.cause.span) + .unwrap_or(expr_field.span); + return true; } - // We make sure that only *one* argument matches the obligation failure - // and we assign the obligation's span to its expression's. - error.obligation.cause.span = args[idx].span; - error.obligation.cause.map_code(|parent_code| { - ObligationCauseCode::FunctionArgumentObligation { - arg_hir_id: args[idx].hir_id, - call_hir_id: expr.hir_id, - parent_code, - } - }); - } else if error.obligation.cause.span == call_sp { - // Make function calls point at the callee, not the whole thing. - if let hir::ExprKind::Call(callee, _) = expr.kind { - error.obligation.cause.span = callee.span; + } + } + + false + } + + fn point_at_path_if_possible( + &self, + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param: ty::GenericArg<'tcx>, + qpath: &QPath<'tcx>, + ) -> bool { + match qpath { + hir::QPath::Resolved(_, path) => { + if let Some(segment) = path.segments.last() + && self.point_at_generic_if_possible(error, def_id, param, segment) + { + return true; } } + hir::QPath::TypeRelative(_, segment) => { + if self.point_at_generic_if_possible(error, def_id, param, segment) { + return true; + } + } + _ => {} } + + false } - /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the - /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s - /// were caused by them. If they were, we point at the corresponding type argument's span - /// instead of the `fn` call path span. - fn point_at_type_arg_instead_of_call_if_possible( + fn point_at_generic_if_possible( &self, - errors: &mut Vec<traits::FulfillmentError<'tcx>>, - call_expr: &'tcx hir::Expr<'tcx>, - ) { - if let hir::ExprKind::Call(path, _) = &call_expr.kind { - if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = &path.kind { - for error in errors { - if let ty::PredicateKind::Trait(predicate) = - error.obligation.predicate.kind().skip_binder() - { - // If any of the type arguments in this path segment caused the - // `FulfillmentError`, point at its span (#61860). - for arg in path - .segments - .iter() - .filter_map(|seg| seg.args.as_ref()) - .flat_map(|a| a.args.iter()) - { - if let hir::GenericArg::Type(hir_ty) = &arg - && let Some(ty) = - self.typeck_results.borrow().node_type_opt(hir_ty.hir_id) - && self.resolve_vars_if_possible(ty) == predicate.self_ty() - { - error.obligation.cause.span = hir_ty.span; - break; - } - } - } + error: &mut traits::FulfillmentError<'tcx>, + def_id: DefId, + param_to_point_at: ty::GenericArg<'tcx>, + segment: &hir::PathSegment<'tcx>, + ) -> bool { + let own_substs = self + .tcx + .generics_of(def_id) + .own_substs(ty::InternalSubsts::identity_for_item(self.tcx, def_id)); + let Some((index, _)) = own_substs + .iter() + .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_))) + .enumerate() + .find(|(_, arg)| **arg == param_to_point_at) else { return false }; + let Some(arg) = segment + .args() + .args + .iter() + .filter(|arg| matches!(arg, hir::GenericArg::Type(_))) + .nth(index) else { return false; }; + error.obligation.cause.span = arg + .span() + .find_ancestor_in_same_ctxt(error.obligation.cause.span) + .unwrap_or(arg.span()); + true + } + + fn find_ambiguous_parameter_in<T: TypeVisitable<'tcx>>( + &self, + item_def_id: DefId, + t: T, + ) -> Option<ty::GenericArg<'tcx>> { + struct FindAmbiguousParameter<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, DefId); + impl<'tcx> TypeVisitor<'tcx> for FindAmbiguousParameter<'_, 'tcx> { + type BreakTy = ty::GenericArg<'tcx>; + fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> { + if let Some(origin) = self.0.type_var_origin(ty) + && let TypeVariableOriginKind::TypeParameterDefinition(_, Some(def_id)) = + origin.kind + && let generics = self.0.tcx.generics_of(self.1) + && let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id) + && let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1) + .get(index as usize) + { + ControlFlow::Break(*subst) + } else { + ty.super_visit_with(self) } } } + t.visit_with(&mut FindAmbiguousParameter(self, item_def_id)).break_value() } fn label_fn_like( &self, - err: &mut rustc_errors::DiagnosticBuilder<'tcx, rustc_errors::ErrorGuaranteed>, + err: &mut Diagnostic, callable_def_id: Option<DefId>, callee_ty: Option<Ty<'tcx>>, + // A specific argument should be labeled, instead of all of them + expected_idx: Option<usize>, + is_method: bool, ) { let Some(mut def_id) = callable_def_id else { return; @@ -1838,14 +2121,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let new_def_id = self.probe(|_| { let trait_ref = ty::TraitRef::new( call_kind.to_def_id(self.tcx), - self.tcx.mk_substs([ - ty::GenericArg::from(callee_ty), - self.next_ty_var(TypeVariableOrigin { - kind: TypeVariableOriginKind::MiscVariable, - span: rustc_span::DUMMY_SP, - }) - .into(), - ].into_iter()), + self.tcx.mk_substs( + [ + ty::GenericArg::from(callee_ty), + self.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span: rustc_span::DUMMY_SP, + }) + .into(), + ] + .into_iter(), + ), ); let obligation = traits::Obligation::new( traits::ObligationCause::dummy(), @@ -1860,7 +2146,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { Ok(Some(traits::ImplSource::UserDefined(impl_source))) => { Some(impl_source.impl_def_id) } - _ => None + _ => None, } }); if let Some(new_def_id) = new_def_id { @@ -1881,14 +2167,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .get_if_local(def_id) .and_then(|node| node.body_id()) .into_iter() - .flat_map(|id| self.tcx.hir().body(id).params); + .flat_map(|id| self.tcx.hir().body(id).params) + .skip(if is_method { 1 } else { 0 }); - for param in params { + for (_, param) in params + .into_iter() + .enumerate() + .filter(|(idx, _)| expected_idx.map_or(true, |expected_idx| expected_idx == *idx)) + { spans.push_span_label(param.span, ""); } let def_kind = self.tcx.def_kind(def_id); err.span_note(spans, &format!("{} defined here", def_kind.descr(def_id))); + } else if let Some(hir::Node::Expr(e)) = self.tcx.hir().get_if_local(def_id) + && let hir::ExprKind::Closure(hir::Closure { body, .. }) = &e.kind + { + let param = expected_idx + .and_then(|expected_idx| self.tcx.hir().body(*body).params.get(expected_idx)); + let (kind, span) = if let Some(param) = param { + ("closure parameter", param.span) + } else { + ("closure", self.tcx.def_span(def_id)) + }; + err.span_note(span, &format!("{} defined here", kind)); } else { let def_kind = self.tcx.def_kind(def_id); err.span_note( @@ -1898,3 +2200,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } } + +fn find_param_in_ty<'tcx>(ty: Ty<'tcx>, param_to_point_at: ty::GenericArg<'tcx>) -> bool { + let mut walk = ty.walk(); + while let Some(arg) = walk.next() { + if arg == param_to_point_at { + return true; + } else if let ty::GenericArgKind::Type(ty) = arg.unpack() + && let ty::Projection(..) = ty.kind() + { + // This logic may seem a bit strange, but typically when + // we have a projection type in a function signature, the + // argument that's being passed into that signature is + // not actually constraining that projection's substs in + // a meaningful way. So we skip it, and see improvements + // in some UI tests. + walk.skip_current_subtree(); + } + } + false +} diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs index 05bcc710e..0e22971d3 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs @@ -26,6 +26,17 @@ use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode}; use std::cell::{Cell, RefCell}; use std::ops::Deref; +/// The `FnCtxt` stores type-checking context needed to type-check bodies of +/// functions, closures, and `const`s, including performing type inference +/// with [`InferCtxt`]. +/// +/// This is in contrast to [`ItemCtxt`], which is used to type-check item *signatures* +/// and thus does not perform type inference. +/// +/// See [`ItemCtxt`]'s docs for more. +/// +/// [`ItemCtxt`]: crate::collect::ItemCtxt +/// [`InferCtxt`]: infer::InferCtxt pub struct FnCtxt<'a, 'tcx> { pub(super) body_id: hir::HirId, @@ -57,8 +68,6 @@ pub struct FnCtxt<'a, 'tcx> { /// any). pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>, - pub(super) ret_type_span: Option<Span>, - /// Used exclusively to reduce cost of advanced evaluation used for /// more helpful diagnostics. pub(super) in_tail_expr: bool, @@ -131,7 +140,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { param_env, err_count_on_creation: inh.tcx.sess.err_count(), ret_coercion: None, - ret_type_span: None, in_tail_expr: false, ret_coercion_span: Cell::new(None), resume_yield_tys: None, diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs index 57771e096..ee0ad7b5d 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs @@ -2,6 +2,7 @@ use super::FnCtxt; use crate::astconv::AstConv; use crate::errors::{AddReturnTypeSuggestion, ExpectedReturnTypeLabel}; +use hir::def_id::DefId; use rustc_ast::util::parser::ExprPrecedence; use rustc_errors::{Applicability, Diagnostic, MultiSpan}; use rustc_hir as hir; @@ -16,6 +17,7 @@ use rustc_middle::lint::in_external_macro; use rustc_middle::ty::{self, Binder, IsSuggestable, Subst, ToPredicate, Ty}; use rustc_span::symbol::sym; use rustc_span::Span; +use rustc_trait_selection::infer::InferCtxtExt; use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; impl<'a, 'tcx> FnCtxt<'a, 'tcx> { @@ -61,70 +63,51 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { pointing_at_return_type } - /// When encountering an fn-like ctor that needs to unify with a value, check whether calling - /// the ctor would successfully solve the type mismatch and if so, suggest it: + /// When encountering an fn-like type, try accessing the output of the type + /// // and suggesting calling it if it satisfies a predicate (i.e. if the + /// output has a method or a field): /// ```compile_fail,E0308 /// fn foo(x: usize) -> usize { x } /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)` /// ``` - fn suggest_fn_call( + pub(crate) fn suggest_fn_call( &self, err: &mut Diagnostic, expr: &hir::Expr<'_>, - expected: Ty<'tcx>, found: Ty<'tcx>, + can_satisfy: impl FnOnce(Ty<'tcx>) -> bool, ) -> bool { - let (def_id, output, inputs) = match *found.kind() { - ty::FnDef(def_id, _) => { - let fn_sig = found.fn_sig(self.tcx); - (def_id, fn_sig.output(), fn_sig.inputs().skip_binder().len()) - } - ty::Closure(def_id, substs) => { - let fn_sig = substs.as_closure().sig(); - (def_id, fn_sig.output(), fn_sig.inputs().skip_binder().len() - 1) - } - ty::Opaque(def_id, substs) => { - let sig = self.tcx.bound_item_bounds(def_id).subst(self.tcx, substs).iter().find_map(|pred| { - if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder() - && Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output() - // args tuple will always be substs[1] - && let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind() - { - Some(( - pred.kind().rebind(proj.term.ty().unwrap()), - args.len(), - )) - } else { - None - } - }); - if let Some((output, inputs)) = sig { - (def_id, output, inputs) - } else { - return false; - } - } - _ => return false, - }; - - let output = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, output); - let output = self.normalize_associated_types_in(expr.span, output); - if !output.is_ty_var() && self.can_coerce(output, expected) { - let (sugg_call, mut applicability) = match inputs { + let Some((def_id_or_name, output, inputs)) = self.extract_callable_info(expr, found) + else { return false; }; + if can_satisfy(output) { + let (sugg_call, mut applicability) = match inputs.len() { 0 => ("".to_string(), Applicability::MachineApplicable), 1..=4 => ( - (0..inputs).map(|_| "_").collect::<Vec<_>>().join(", "), - Applicability::MachineApplicable, + inputs + .iter() + .map(|ty| { + if ty.is_suggestable(self.tcx, false) { + format!("/* {ty} */") + } else { + "".to_string() + } + }) + .collect::<Vec<_>>() + .join(", "), + Applicability::HasPlaceholders, ), - _ => ("...".to_string(), Applicability::HasPlaceholders), + _ => ("/* ... */".to_string(), Applicability::HasPlaceholders), }; - let msg = match self.tcx.def_kind(def_id) { - DefKind::Fn => "call this function", - DefKind::Closure | DefKind::OpaqueTy => "call this closure", - DefKind::Ctor(CtorOf::Struct, _) => "instantiate this tuple struct", - DefKind::Ctor(CtorOf::Variant, _) => "instantiate this tuple variant", - _ => "call this function", + let msg = match def_id_or_name { + DefIdOrName::DefId(def_id) => match self.tcx.def_kind(def_id) { + DefKind::Ctor(CtorOf::Struct, _) => "instantiate this tuple struct".to_string(), + DefKind::Ctor(CtorOf::Variant, _) => { + "instantiate this tuple variant".to_string() + } + kind => format!("call this {}", kind.descr(def_id)), + }, + DefIdOrName::Name(name) => format!("call this {name}"), }; let sugg = match expr.kind { @@ -161,6 +144,182 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { false } + /// Extracts information about a callable type for diagnostics. This is a + /// heuristic -- it doesn't necessarily mean that a type is always callable, + /// because the callable type must also be well-formed to be called. + pub(in super::super) fn extract_callable_info( + &self, + expr: &Expr<'_>, + found: Ty<'tcx>, + ) -> Option<(DefIdOrName, Ty<'tcx>, Vec<Ty<'tcx>>)> { + // Autoderef is useful here because sometimes we box callables, etc. + let Some((def_id_or_name, output, inputs)) = self.autoderef(expr.span, found).silence_errors().find_map(|(found, _)| { + match *found.kind() { + ty::FnPtr(fn_sig) => + Some((DefIdOrName::Name("function pointer"), fn_sig.output(), fn_sig.inputs())), + ty::FnDef(def_id, _) => { + let fn_sig = found.fn_sig(self.tcx); + Some((DefIdOrName::DefId(def_id), fn_sig.output(), fn_sig.inputs())) + } + ty::Closure(def_id, substs) => { + let fn_sig = substs.as_closure().sig(); + Some((DefIdOrName::DefId(def_id), fn_sig.output(), fn_sig.inputs().map_bound(|inputs| &inputs[1..]))) + } + ty::Opaque(def_id, substs) => { + self.tcx.bound_item_bounds(def_id).subst(self.tcx, substs).iter().find_map(|pred| { + if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder() + && Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output() + // args tuple will always be substs[1] + && let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind() + { + Some(( + DefIdOrName::DefId(def_id), + pred.kind().rebind(proj.term.ty().unwrap()), + pred.kind().rebind(args.as_slice()), + )) + } else { + None + } + }) + } + ty::Dynamic(data, _, ty::Dyn) => { + data.iter().find_map(|pred| { + if let ty::ExistentialPredicate::Projection(proj) = pred.skip_binder() + && Some(proj.item_def_id) == self.tcx.lang_items().fn_once_output() + // for existential projection, substs are shifted over by 1 + && let ty::Tuple(args) = proj.substs.type_at(0).kind() + { + Some(( + DefIdOrName::Name("trait object"), + pred.rebind(proj.term.ty().unwrap()), + pred.rebind(args.as_slice()), + )) + } else { + None + } + }) + } + ty::Param(param) => { + let def_id = self.tcx.generics_of(self.body_id.owner).type_param(¶m, self.tcx).def_id; + self.tcx.predicates_of(self.body_id.owner).predicates.iter().find_map(|(pred, _)| { + if let ty::PredicateKind::Projection(proj) = pred.kind().skip_binder() + && Some(proj.projection_ty.item_def_id) == self.tcx.lang_items().fn_once_output() + && proj.projection_ty.self_ty() == found + // args tuple will always be substs[1] + && let ty::Tuple(args) = proj.projection_ty.substs.type_at(1).kind() + { + Some(( + DefIdOrName::DefId(def_id), + pred.kind().rebind(proj.term.ty().unwrap()), + pred.kind().rebind(args.as_slice()), + )) + } else { + None + } + }) + } + _ => None, + } + }) else { return None; }; + + let output = self.replace_bound_vars_with_fresh_vars(expr.span, infer::FnCall, output); + let inputs = inputs + .skip_binder() + .iter() + .map(|ty| { + self.replace_bound_vars_with_fresh_vars( + expr.span, + infer::FnCall, + inputs.rebind(*ty), + ) + }) + .collect(); + + // We don't want to register any extra obligations, which should be + // implied by wf, but also because that would possibly result in + // erroneous errors later on. + let infer::InferOk { value: output, obligations: _ } = + self.normalize_associated_types_in_as_infer_ok(expr.span, output); + + if output.is_ty_var() { None } else { Some((def_id_or_name, output, inputs)) } + } + + pub fn suggest_two_fn_call( + &self, + err: &mut Diagnostic, + lhs_expr: &'tcx hir::Expr<'tcx>, + lhs_ty: Ty<'tcx>, + rhs_expr: &'tcx hir::Expr<'tcx>, + rhs_ty: Ty<'tcx>, + can_satisfy: impl FnOnce(Ty<'tcx>, Ty<'tcx>) -> bool, + ) -> bool { + let Some((_, lhs_output_ty, lhs_inputs)) = self.extract_callable_info(lhs_expr, lhs_ty) + else { return false; }; + let Some((_, rhs_output_ty, rhs_inputs)) = self.extract_callable_info(rhs_expr, rhs_ty) + else { return false; }; + + if can_satisfy(lhs_output_ty, rhs_output_ty) { + let mut sugg = vec![]; + let mut applicability = Applicability::MachineApplicable; + + for (expr, inputs) in [(lhs_expr, lhs_inputs), (rhs_expr, rhs_inputs)] { + let (sugg_call, this_applicability) = match inputs.len() { + 0 => ("".to_string(), Applicability::MachineApplicable), + 1..=4 => ( + inputs + .iter() + .map(|ty| { + if ty.is_suggestable(self.tcx, false) { + format!("/* {ty} */") + } else { + "/* value */".to_string() + } + }) + .collect::<Vec<_>>() + .join(", "), + Applicability::HasPlaceholders, + ), + _ => ("/* ... */".to_string(), Applicability::HasPlaceholders), + }; + + applicability = applicability.max(this_applicability); + + match expr.kind { + hir::ExprKind::Call(..) + | hir::ExprKind::Path(..) + | hir::ExprKind::Index(..) + | hir::ExprKind::Lit(..) => { + sugg.extend([(expr.span.shrink_to_hi(), format!("({sugg_call})"))]); + } + hir::ExprKind::Closure { .. } => { + // Might be `{ expr } || { bool }` + applicability = Applicability::MaybeIncorrect; + sugg.extend([ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ]); + } + _ => { + sugg.extend([ + (expr.span.shrink_to_lo(), "(".to_string()), + (expr.span.shrink_to_hi(), format!(")({sugg_call})")), + ]); + } + } + } + + err.multipart_suggestion_verbose( + format!("use parentheses to call these"), + sugg, + applicability, + ); + + true + } else { + false + } + } + pub fn suggest_deref_ref_or_into( &self, err: &mut Diagnostic, @@ -178,12 +337,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } else { err.span_suggestion(sp, &msg, suggestion, applicability); } - } else if let (ty::FnDef(def_id, ..), true) = - (&found.kind(), self.suggest_fn_call(err, expr, expected, found)) + } else if self.suggest_fn_call(err, expr, found, |output| self.can_coerce(output, expected)) + && let ty::FnDef(def_id, ..) = &found.kind() + && let Some(sp) = self.tcx.hir().span_if_local(*def_id) { - if let Some(sp) = self.tcx.hir().span_if_local(*def_id) { - err.span_label(sp, format!("{found} defined here")); - } + err.span_label(sp, format!("{found} defined here")); } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) { let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id); if !methods.is_empty() { @@ -506,30 +664,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.resolve_numeric_literals_with_default(self.resolve_vars_if_possible(found)); // Only suggest changing the return type for methods that // haven't set a return type at all (and aren't `fn main()` or an impl). - match ( - &fn_decl.output, - found.is_suggestable(self.tcx, false), - can_suggest, - expected.is_unit(), - ) { - (&hir::FnRetTy::DefaultReturn(span), true, true, true) => { - err.subdiagnostic(AddReturnTypeSuggestion::Add { span, found }); - true - } - (&hir::FnRetTy::DefaultReturn(span), false, true, true) => { - // FIXME: if `found` could be `impl Iterator` or `impl Fn*`, we should suggest - // that. - err.subdiagnostic(AddReturnTypeSuggestion::MissingHere { span }); - true - } - (&hir::FnRetTy::DefaultReturn(span), _, false, true) => { + match &fn_decl.output { + &hir::FnRetTy::DefaultReturn(span) if expected.is_unit() && !can_suggest => { // `fn main()` must return `()`, do not suggest changing return type err.subdiagnostic(ExpectedReturnTypeLabel::Unit { span }); - true + return true; + } + &hir::FnRetTy::DefaultReturn(span) if expected.is_unit() => { + if found.is_suggestable(self.tcx, false) { + err.subdiagnostic(AddReturnTypeSuggestion::Add { span, found: found.to_string() }); + return true; + } else if let ty::Closure(_, substs) = found.kind() + // FIXME(compiler-errors): Get better at printing binders... + && let closure = substs.as_closure() + && closure.sig().is_suggestable(self.tcx, false) + { + err.subdiagnostic(AddReturnTypeSuggestion::Add { span, found: closure.print_as_impl_trait().to_string() }); + return true; + } else { + // FIXME: if `found` could be `impl Iterator` we should suggest that. + err.subdiagnostic(AddReturnTypeSuggestion::MissingHere { span }); + return true + } } - // expectation was caused by something else, not the default return - (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false, - (&hir::FnRetTy::Return(ref ty), _, _, _) => { + &hir::FnRetTy::Return(ref ty) => { // Only point to return type if the expected type is the return type, as if they // are not, the expectation must have been caused by something else. debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind); @@ -546,9 +704,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.try_suggest_return_impl_trait(err, expected, ty, fn_id); return true; } - false } + _ => {} } + false } /// check whether the return type is a generic type with a trait bound @@ -770,6 +929,69 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } + pub(crate) fn suggest_copied_or_cloned( + &self, + diag: &mut Diagnostic, + expr: &hir::Expr<'_>, + expr_ty: Ty<'tcx>, + expected_ty: Ty<'tcx>, + ) { + let ty::Adt(adt_def, substs) = expr_ty.kind() else { return; }; + let ty::Adt(expected_adt_def, expected_substs) = expected_ty.kind() else { return; }; + if adt_def != expected_adt_def { + return; + } + + let mut suggest_copied_or_cloned = || { + let expr_inner_ty = substs.type_at(0); + let expected_inner_ty = expected_substs.type_at(0); + if let ty::Ref(_, ty, hir::Mutability::Not) = expr_inner_ty.kind() + && self.can_eq(self.param_env, *ty, expected_inner_ty).is_ok() + { + let def_path = self.tcx.def_path_str(adt_def.did()); + if self.type_is_copy_modulo_regions(self.param_env, *ty, expr.span) { + diag.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "use `{def_path}::copied` to copy the value inside the `{def_path}`" + ), + ".copied()", + Applicability::MachineApplicable, + ); + } else if let Some(clone_did) = self.tcx.lang_items().clone_trait() + && rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions( + self, + self.param_env, + *ty, + clone_did, + expr.span + ) + { + diag.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "use `{def_path}::cloned` to clone the value inside the `{def_path}`" + ), + ".cloned()", + Applicability::MachineApplicable, + ); + } + } + }; + + if let Some(result_did) = self.tcx.get_diagnostic_item(sym::Result) + && adt_def.did() == result_did + // Check that the error types are equal + && self.can_eq(self.param_env, substs.type_at(1), expected_substs.type_at(1)).is_ok() + { + suggest_copied_or_cloned(); + } else if let Some(option_did) = self.tcx.get_diagnostic_item(sym::Option) + && adt_def.did() == option_did + { + suggest_copied_or_cloned(); + } + } + /// Suggest wrapping the block in square brackets instead of curly braces /// in case the block was mistaken array syntax, e.g. `{ 1 }` -> `[ 1 ]`. pub(crate) fn suggest_block_to_brackets( @@ -830,7 +1052,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { found_ty: Ty<'tcx>, expr: &hir::Expr<'_>, ) { - let hir::ExprKind::MethodCall(segment, &[ref callee_expr], _) = expr.kind else { return; }; + let hir::ExprKind::MethodCall(segment, callee_expr, &[], _) = expr.kind else { return; }; let Some(clone_trait_did) = self.tcx.lang_items().clone_trait() else { return; }; let ty::Ref(_, pointee_ty, _) = found_ty.kind() else { return }; let results = self.typeck_results.borrow(); @@ -910,3 +1132,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } } + +pub enum DefIdOrName { + DefId(DefId), + Name(&'static str), +} |