diff options
| -rw-r--r-- | compiler/rustc_infer/src/infer/error_reporting/mod.rs | 662 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/error_reporting/note_region.rs | 427 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/error_reporting/suggest.rs | 672 | ||||
| -rw-r--r-- | compiler/rustc_infer/src/infer/note.rs | 203 | ||||
| -rw-r--r-- | compiler/rustc_traits/src/lib.rs | 2 |
5 files changed, 1305 insertions, 661 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs index 3256ca1fb20..afcdfef79fc 100644 --- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs +++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs @@ -56,22 +56,17 @@ use crate::infer::ExpectedFound; use crate::traits::error_reporting::report_object_safety_error; use crate::traits::{ IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, - StatementAsExpression, }; -use crate::errors::SuggAddLetForLetChains; -use hir::intravisit::{walk_expr, walk_stmt}; use rustc_data_structures::fx::{FxIndexMap, FxIndexSet}; use rustc_errors::{pluralize, struct_span_err, Diagnostic, ErrorGuaranteed, IntoDiagnosticArg}; use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString, MultiSpan}; use rustc_hir as hir; -use rustc_hir::def::{CtorKind, DefKind}; +use rustc_hir::def::DefKind; use rustc_hir::def_id::{DefId, LocalDefId}; -use rustc_hir::intravisit::Visitor; use rustc_hir::lang_items::LangItem; use rustc_hir::Node; use rustc_middle::dep_graph::DepContext; -use rustc_middle::ty::print::with_no_trimmed_paths; use rustc_middle::ty::relate::{self, RelateResult, TypeRelation}; use rustc_middle::ty::{ self, error::TypeError, List, Region, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable, @@ -83,6 +78,7 @@ use std::ops::{ControlFlow, Deref}; use std::{cmp, fmt, iter}; mod note; +mod suggest; pub(crate) mod need_type_info; pub use need_type_info::TypeAnnotationNeeded; @@ -806,87 +802,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { } } - fn suggest_remove_semi_or_return_binding( - &self, - err: &mut Diagnostic, - first_id: Option<hir::HirId>, - first_ty: Ty<'tcx>, - first_span: Span, - second_id: Option<hir::HirId>, - second_ty: Ty<'tcx>, - second_span: Span, - ) { - let remove_semicolon = [ - (first_id, self.resolve_vars_if_possible(second_ty)), - (second_id, self.resolve_vars_if_possible(first_ty)), - ] - .into_iter() - .find_map(|(id, ty)| { - let hir::Node::Block(blk) = self.tcx.hir().get(id?) else { return None }; - self.could_remove_semicolon(blk, ty) - }); - match remove_semicolon { - Some((sp, StatementAsExpression::NeedsBoxing)) => { - err.multipart_suggestion( - "consider removing this semicolon and boxing the expressions", - vec![ - (first_span.shrink_to_lo(), "Box::new(".to_string()), - (first_span.shrink_to_hi(), ")".to_string()), - (second_span.shrink_to_lo(), "Box::new(".to_string()), - (second_span.shrink_to_hi(), ")".to_string()), - (sp, String::new()), - ], - Applicability::MachineApplicable, - ); - } - Some((sp, StatementAsExpression::CorrectType)) => { - err.span_suggestion_short( - sp, - "consider removing this semicolon", - "", - Applicability::MachineApplicable, - ); - } - None => { - for (id, ty) in [(first_id, second_ty), (second_id, first_ty)] { - if let Some(id) = id - && let hir::Node::Block(blk) = self.tcx.hir().get(id) - && self.consider_returning_binding(blk, ty, err) - { - break; - } - } - } - } - } - - fn suggest_boxing_for_return_impl_trait( - &self, - err: &mut Diagnostic, - return_sp: Span, - arm_spans: impl Iterator<Item = Span>, - ) { - err.multipart_suggestion( - "you could change the return type to be a boxed trait object", - vec![ - (return_sp.with_hi(return_sp.lo() + BytePos(4)), "Box<dyn".to_string()), - (return_sp.shrink_to_hi(), ">".to_string()), - ], - Applicability::MaybeIncorrect, - ); - let sugg = arm_spans - .flat_map(|sp| { - [(sp.shrink_to_lo(), "Box::new(".to_string()), (sp.shrink_to_hi(), ")".to_string())] - .into_iter() - }) - .collect::<Vec<_>>(); - err.multipart_suggestion( - "if you change the return type to expect trait objects, box the returned expressions", - sugg, - Applicability::MaybeIncorrect, - ); - } - /// Given that `other_ty` is the same as a type argument for `name` in `sub`, populate `value` /// highlighting `name` and every type argument that isn't at `pos` (which is `other_ty`), and /// populate `other_value` with `other_ty`. @@ -1940,310 +1855,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { debug!(?diag); } - fn suggest_tuple_pattern( - &self, - cause: &ObligationCause<'tcx>, - exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, - diag: &mut Diagnostic, - ) { - // Heavily inspired by `FnCtxt::suggest_compatible_variants`, with - // some modifications due to that being in typeck and this being in infer. - if let ObligationCauseCode::Pattern { .. } = cause.code() { - if let ty::Adt(expected_adt, substs) = exp_found.expected.kind() { - let compatible_variants: Vec<_> = expected_adt - .variants() - .iter() - .filter(|variant| { - variant.fields.len() == 1 && variant.ctor_kind() == Some(CtorKind::Fn) - }) - .filter_map(|variant| { - let sole_field = &variant.fields[0]; - let sole_field_ty = sole_field.ty(self.tcx, substs); - if self.same_type_modulo_infer(sole_field_ty, exp_found.found) { - let variant_path = - with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id)); - // FIXME #56861: DRYer prelude filtering - if let Some(path) = variant_path.strip_prefix("std::prelude::") { - if let Some((_, path)) = path.split_once("::") { - return Some(path.to_string()); - } - } - Some(variant_path) - } else { - None - } - }) - .collect(); - match &compatible_variants[..] { - [] => {} - [variant] => { - diag.multipart_suggestion_verbose( - &format!("try wrapping the pattern in `{}`", variant), - vec![ - (cause.span.shrink_to_lo(), format!("{}(", variant)), - (cause.span.shrink_to_hi(), ")".to_string()), - ], - Applicability::MaybeIncorrect, - ); - } - _ => { - // More than one matching variant. - diag.multipart_suggestions( - &format!( - "try wrapping the pattern in a variant of `{}`", - self.tcx.def_path_str(expected_adt.did()) - ), - compatible_variants.into_iter().map(|variant| { - vec![ - (cause.span.shrink_to_lo(), format!("{}(", variant)), - (cause.span.shrink_to_hi(), ")".to_string()), - ] - }), - Applicability::MaybeIncorrect, - ); - } - } - } - } - } - - /// A possible error is to forget to add `.await` when using futures: - /// - /// ```compile_fail,E0308 - /// async fn make_u32() -> u32 { - /// 22 - /// } - /// - /// fn take_u32(x: u32) {} - /// - /// async fn foo() { - /// let x = make_u32(); - /// take_u32(x); - /// } - /// ``` - /// - /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the - /// expected type. If this is the case, and we are inside of an async body, it suggests adding - /// `.await` to the tail of the expression. - fn suggest_await_on_expect_found( - &self, - cause: &ObligationCause<'tcx>, - exp_span: Span, - exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, - diag: &mut Diagnostic, - ) { - debug!( - "suggest_await_on_expect_found: exp_span={:?}, expected_ty={:?}, found_ty={:?}", - exp_span, exp_found.expected, exp_found.found, - ); - - if let ObligationCauseCode::CompareImplItemObligation { .. } = cause.code() { - return; - } - - match ( - self.get_impl_future_output_ty(exp_found.expected), - self.get_impl_future_output_ty(exp_found.found), - ) { - (Some(exp), Some(found)) if self.same_type_modulo_infer(exp, found) => match cause - .code() - { - ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => { - let then_span = self.find_block_span_from_hir_id(*then_id); - diag.multipart_suggestion( - "consider `await`ing on both `Future`s", - vec![ - (then_span.shrink_to_hi(), ".await".to_string()), - (exp_span.shrink_to_hi(), ".await".to_string()), - ], - Applicability::MaybeIncorrect, - ); - } - ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { - prior_arms, - .. - }) => { - if let [.., arm_span] = &prior_arms[..] { - diag.multipart_suggestion( - "consider `await`ing on both `Future`s", - vec![ - (arm_span.shrink_to_hi(), ".await".to_string()), - (exp_span.shrink_to_hi(), ".await".to_string()), - ], - Applicability::MaybeIncorrect, - ); - } else { - diag.help("consider `await`ing on both `Future`s"); - } - } - _ => { - diag.help("consider `await`ing on both `Future`s"); - } - }, - (_, Some(ty)) if self.same_type_modulo_infer(exp_found.expected, ty) => { - diag.span_suggestion_verbose( - exp_span.shrink_to_hi(), - "consider `await`ing on the `Future`", - ".await", - Applicability::MaybeIncorrect, - ); - } - (Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code() - { - ObligationCauseCode::Pattern { span: Some(then_span), .. } => { - diag.span_suggestion_verbose( - then_span.shrink_to_hi(), - "consider `await`ing on the `Future`", - ".await", - Applicability::MaybeIncorrect, - ); - } - ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => { - let then_span = self.find_block_span_from_hir_id(*then_id); - diag.span_suggestion_verbose( - then_span.shrink_to_hi(), - "consider `await`ing on the `Future`", - ".await", - Applicability::MaybeIncorrect, - ); - } - ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { - ref prior_arms, - .. - }) => { - diag.multipart_suggestion_verbose( - "consider `await`ing on the `Future`", - prior_arms - .iter() - .map(|arm| (arm.shrink_to_hi(), ".await".to_string())) - .collect(), - Applicability::MaybeIncorrect, - ); - } - _ => {} - }, - _ => {} - } - } - - fn suggest_accessing_field_where_appropriate( - &self, - cause: &ObligationCause<'tcx>, - exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, - diag: &mut Diagnostic, - ) { - debug!( - "suggest_accessing_field_where_appropriate(cause={:?}, exp_found={:?})", - cause, exp_found - ); - if let ty::Adt(expected_def, expected_substs) = exp_found.expected.kind() { - if expected_def.is_enum() { - return; - } - - if let Some((name, ty)) = expected_def - .non_enum_variant() - .fields - .iter() - .filter(|field| field.vis.is_accessible_from(field.did, self.tcx)) - .map(|field| (field.name, field.ty(self.tcx, expected_substs))) - .find(|(_, ty)| self.same_type_modulo_infer(*ty, exp_found.found)) - { - if let ObligationCauseCode::Pattern { span: Some(span), .. } = *cause.code() { - if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) { - let suggestion = if expected_def.is_struct() { - format!("{}.{}", snippet, name) - } else if expected_def.is_union() { - format!("unsafe {{ {}.{} }}", snippet, name) - } else { - return; - }; - diag.span_suggestion( - span, - &format!( - "you might have meant to use field `{}` whose type is `{}`", - name, ty - ), - suggestion, - Applicability::MaybeIncorrect, - ); - } - } - } - } - } - - /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate, - /// suggests it. - fn suggest_as_ref_where_appropriate( - &self, - span: Span, - exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, - diag: &mut Diagnostic, - ) { - if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) - && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found) - { - diag.span_suggestion( - span, - msg, - // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&` - format!("{}.as_ref()", snippet.trim_start_matches('&')), - Applicability::MachineApplicable, - ); - } - } - - pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> { - if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) = - (expected.kind(), found.kind()) - { - if let ty::Adt(found_def, found_substs) = *found_ty.kind() { - if exp_def == &found_def { - let have_as_ref = &[ - ( - sym::Option, - "you can convert from `&Option<T>` to `Option<&T>` using \ - `.as_ref()`", - ), - ( - sym::Result, - "you can convert from `&Result<T, E>` to \ - `Result<&T, &E>` using `.as_ref()`", - ), - ]; - if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| { - self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg) - }) { - let mut show_suggestion = true; - for (exp_ty, found_ty) in - iter::zip(exp_substs.types(), found_substs.types()) - { - match *exp_ty.kind() { - ty::Ref(_, exp_ty, _) => { - match (exp_ty.kind(), found_ty.kind()) { - (_, ty::Param(_)) - | (_, ty::Infer(_)) - | (ty::Param(_), _) - | (ty::Infer(_), _) => {} - _ if self.same_type_modulo_infer(exp_ty, found_ty) => {} - _ => show_suggestion = false, - }; - } - ty::Param(_) | ty::Infer(_) => {} - _ => show_suggestion = false, - } - } - if show_suggestion { - return Some(*msg); - } - } - } - } - } - None - } - pub fn report_and_explain_type_error( &self, trace: TypeTrace<'tcx>, @@ -2357,67 +1968,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { diag } - /// Try to find code with pattern `if Some(..) = expr` - /// use a `visitor` to mark the `if` which its span contains given error span, - /// and then try to find a assignment in the `cond` part, which span is equal with error span - fn suggest_let_for_letchains( - &self, - err: &mut Diagnostic, - cause: &ObligationCause<'_>, - span: Span, - ) { - let hir = self.tcx.hir(); - let fn_hir_id = hir.get_parent_node(cause.body_id); - if let Some(node) = self.tcx.hir().find(fn_hir_id) && - let hir::Node::Item(hir::Item { - kind: hir::ItemKind::Fn(_sig, _, body_id), .. - }) = node { - let body = hir.body(*body_id); - - /// Find the if expression with given span - struct IfVisitor { - pub result: bool, - pub found_if: bool, - pub err_span: Span, - } - - impl<'v> Visitor<'v> for IfVisitor { - fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) { - if self.result { return; } - match ex.kind { - hir::ExprKind::If(cond, _, _) => { - self.found_if = true; - walk_expr(self, cond); - self.found_if = false; - } - _ => walk_expr(self, ex), - } - } - - fn visit_stmt(&mut self, ex: &'v hir::Stmt<'v>) { - if let hir::StmtKind::Local(hir::Local { - span, pat: hir::Pat{..}, ty: None, init: Some(_), .. - }) = &ex.kind - && self.found_if - && span.eq(&self.err_span) { - self.result = true; - } - walk_stmt(self, ex); - } - - fn visit_body(&mut self, body: &'v hir::Body<'v>) { - hir::intravisit::walk_body(self, body); - } - } - - let mut visitor = IfVisitor { err_span: span, found_if: false, result: false }; - visitor.visit_body(&body); - if visitor.result { - err.subdiagnostic(SuggAddLetForLetChains{span: span.shrink_to_lo()}); - } - } - } - fn emit_tuple_wrap_err( &self, err: &mut Diagnostic, @@ -3228,211 +2778,3 @@ impl<'tcx> InferCtxt<'tcx> { } } } - -impl<'tcx> TypeErrCtxt<'_, 'tcx> { - /// Be helpful when the user wrote `{... expr; }` and taking the `;` off - /// is enough to fix the error. - pub fn could_remove_semicolon( - &self, - blk: &'tcx hir::Block<'tcx>, - expected_ty: Ty<'tcx>, - ) -> Option<(Span, StatementAsExpression)> { - let blk = blk.innermost_block(); - // Do not suggest if we have a tail expr. - if blk.expr.is_some() { - return None; - } - let last_stmt = blk.stmts.last()?; - let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else { - return None; - }; - let last_expr_ty = self.typeck_results.as_ref()?.expr_ty_opt(*last_expr)?; - let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) { - _ if last_expr_ty.references_error() => return None, - _ if self.same_type_modulo_infer(last_expr_ty, expected_ty) => { - StatementAsExpression::CorrectType - } - (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _)) - if last_def_id == exp_def_id => - { - StatementAsExpression::CorrectType - } - (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => { - debug!( - "both opaque, likely future {:?} {:?} {:?} {:?}", - last_def_id, last_bounds, exp_def_id, exp_bounds - ); - - let last_local_id = last_def_id.as_local()?; - let exp_local_id = exp_def_id.as_local()?; - - match ( - &self.tcx.hir().expect_item(last_local_id).kind, - &self.tcx.hir().expect_item(exp_local_id).kind, - ) { - ( - hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }), - hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }), - ) if iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| { - match (left, right) { - ( - hir::GenericBound::Trait(tl, ml), - hir::GenericBound::Trait(tr, mr), - ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id() - && ml == mr => - { - true - } - ( - hir::GenericBound::LangItemTrait(langl, _, _, argsl), - hir::GenericBound::LangItemTrait(langr, _, _, argsr), - ) if langl == langr => { - // FIXME: consider the bounds! - debug!("{:?} {:?}", argsl, argsr); - true - } - _ => false, - } - }) => - { - StatementAsExpression::NeedsBoxing - } - _ => StatementAsExpression::CorrectType, - } - } - _ => return None, - }; - let span = if last_stmt.span.from_expansion() { - let mac_call = rustc_span::source_map::original_sp(last_stmt.span, blk.span); - self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)? - } else { - last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1)) - }; - Some((span, needs_box)) - } - - /// Suggest returning a local binding with a compatible type if the block - /// has no return expression. - pub fn consider_returning_binding( - &self, - blk: &'tcx hir::Block<'tcx>, - expected_ty: Ty<'tcx>, - err: &mut Diagnostic, - ) -> bool { - let blk = blk.innermost_block(); - // Do not suggest if we have a tail expr. - if blk.expr.is_some() { - return false; - } - let mut shadowed = FxIndexSet::default(); - let mut candidate_idents = vec![]; - let mut find_compatible_candidates = |pat: &hir::Pat<'_>| { - if let hir::PatKind::Binding(_, hir_id, ident, _) = &pat.kind - && let Some(pat_ty) = self - .typeck_results - .as_ref() - .and_then(|typeck_results| typeck_results.node_type_opt(*hir_id)) - { - let pat_ty = self.resolve_vars_if_possible(pat_ty); - if self.same_type_modulo_infer(pat_ty, expected_ty) - && !(pat_ty, expected_ty).references_error() - && shadowed.insert(ident.name) - { - candidate_idents.push((*ident, pat_ty)); - } - } - true - }; - - let hir = self.tcx.hir(); - for stmt in blk.stmts.iter().rev() { - let hir::StmtKind::Local(local) = &stmt.kind else { continue; }; - local.pat.walk(&mut find_compatible_candidates); - } - match hir.find(hir.get_parent_node(blk.hir_id)) { - Some(hir::Node::Expr(hir::Expr { hir_id, .. })) => { - match hir.find(hir.get_parent_node(*hir_id)) { - Some(hir::Node::Arm(hir::Arm { pat, .. })) => { - pat.walk(&mut find_compatible_candidates); - } - Some( - hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body), .. }) - | hir::Node::ImplItem(hir::ImplItem { - kind: hir::ImplItemKind::Fn(_, body), - .. - }) - | hir::Node::TraitItem(hir::TraitItem { - kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body)), - .. - }) - | hir::Node::Expr(hir::Expr { - kind: hir::ExprKind::Closure(hir::Closure { body, .. }), - .. - }), - ) => { - for param in hir.body(*body).params { - param.pat.walk(&mut find_compatible_candidates); - } - } - Some(hir::Node::Expr(hir::Expr { - kind: - hir::ExprKind::If( - hir::Expr { kind: hir::ExprKind::Let(let_), .. }, - then_block, - _, - ), - .. - })) if then_block.hir_id == *hir_id => { - let_.pat.walk(&mut find_compatible_candidates); - } - _ => {} - } - } - _ => {} - } - - match &candidate_idents[..] { - [(ident, _ty)] => { - let sm = self.tcx.sess.source_map(); - if let Some(stmt) = blk.stmts.last() { - let stmt_span = sm.stmt_span(stmt.span, blk.span); - let sugg = if sm.is_multiline(blk.span) - && let Some(spacing) = sm.indentation_before(stmt_span) - { - format!("\n{spacing}{ident}") - } else { - format!(" {ident}") - }; - err.span_suggestion_verbose( - stmt_span.shrink_to_hi(), - format!("consider returning the local binding `{ident}`"), - sugg, - Applicability::MaybeIncorrect, - ); - } else { - let sugg = if sm.is_multiline(blk.span) - && let Some(spacing) = sm.indentation_before(blk.span.shrink_to_lo()) - { - format!("\n{spacing} {ident}\n{spacing}") - } else { - format!(" {ident} ") - }; - let left_span = sm.span_through_char(blk.span, '{').shrink_to_hi(); - err.span_suggestion_verbose( - sm.span_extend_while(left_span, |c| c.is_whitespace()).unwrap_or(left_span), - format!("consider returning the local binding `{ident}`"), - sugg, - Applicability::MaybeIncorrect, - ); - } - true - } - values if (1..3).contains(&values.len()) => { - let spans = values.iter().map(|(ident, _)| ident.span).collect::<Vec<_>>(); - err.span_note(spans, "consider returning one of these bindings"); - true - } - _ => false, - } - } -} diff --git a/compiler/rustc_infer/src/infer/error_reporting/note_region.rs b/compiler/rustc_infer/src/infer/error_reporting/note_region.rs new file mode 100644 index 00000000000..41b115f3377 --- /dev/null +++ b/compiler/rustc_infer/src/infer/error_reporting/note_region.rs @@ -0,0 +1,427 @@ +use crate::errors::RegionOriginNote; +use crate::infer::error_reporting::{note_and_explain_region, TypeErrCtxt}; +use crate::infer::{self, SubregionOrigin}; +use rustc_errors::{ + fluent, struct_span_err, AddToDiagnostic, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, +}; +use rustc_middle::traits::ObligationCauseCode; +use rustc_middle::ty::error::TypeError; +use rustc_middle::ty::{self, Region}; + +use super::ObligationCauseAsDiagArg; + +impl<'tcx> TypeErrCtxt<'_, 'tcx> { + pub(super) fn note_region_origin(&self, err: &mut Diagnostic, origin: &SubregionOrigin<'tcx>) { + match *origin { + infer::Subtype(ref trace) => RegionOriginNote::WithRequirement { + span: trace.cause.span, + requirement: ObligationCauseAsDiagArg(trace.cause.clone()), + expected_found: self.values_str(trace.values), + } + .add_to_diagnostic(err), + infer::Reborrow(span) => { + RegionOriginNote::Plain { span, msg: fluent::infer_reborrow }.add_to_diagnostic(err) + } + infer::ReborrowUpvar(span, ref upvar_id) => { + let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id); + RegionOriginNote::WithName { + span, + msg: fluent::infer_reborrow, + name: &var_name.to_string(), + continues: false, + } + .add_to_diagnostic(err); + } + infer::RelateObjectBound(span) => { + RegionOriginNote::Plain { span, msg: fluent::infer_relate_object_bound } + .add_to_diagnostic(err); + } + infer::DataBorrowed(ty, span) => { + RegionOriginNote::WithName { + span, + msg: fluent::infer_data_borrowed, + name: &self.ty_to_string(ty), + continues: false, + } + .add_to_diagnostic(err); + } + infer::ReferenceOutlivesReferent(ty, span) => { + RegionOriginNote::WithName { + span, + msg: fluent::infer_reference_outlives_referent, + name: &self.ty_to_string(ty), + continues: false, + } + .add_to_diagnostic(err); + } + infer::RelateParamBound(span, ty, opt_span) => { + RegionOriginNote::WithName { + span, + msg: fluent::infer_relate_param_bound, + name: &self.ty_to_string(ty), + continues: opt_span.is_some(), + } + .add_to_diagnostic(err); + if let Some(span) = opt_span { + RegionOriginNote::Plain { span, msg: fluent::infer_relate_param_bound_2 } + .add_to_diagnostic(err); + } + } + infer::RelateRegionParamBound(span) => { + RegionOriginNote::Plain { span, msg: fluent::infer_relate_region_param_bound } + .add_to_diagnostic(err); + } + infer::CompareImplItemObligation { span, .. } => { + RegionOriginNote::Plain { span, msg: fluent::infer_compare_impl_item_obligation } + .add_to_diagnostic(err); + } + infer::CheckAssociatedTypeBounds { ref parent, .. } => { + self.note_region_origin(err, &parent); + } + infer::AscribeUserTypeProvePredicate(span) => { + RegionOriginNote::Plain { + span, + msg: fluent::infer_ascribe_user_type_prove_predicate, + } + .add_to_diagnostic(err); + } + } + } + + pub(super) fn report_concrete_failure( + &self, + origin: SubregionOrigin<'tcx>, + sub: Region<'tcx>, + sup: Region<'tcx>, + ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + match origin { + infer::Subtype(box trace) => { + let terr = TypeError::RegionsDoesNotOutlive(sup, sub); + let mut err = self.report_and_explain_type_error(trace, terr); + match (*sub, *sup) { + (ty::RePlaceholder(_), ty::RePlaceholder(_)) => {} + (ty::RePlaceholder(_), _) => { + note_and_explain_region( + self.tcx, + &mut err, + "", + sup, + " doesn't meet the lifetime requirements", + None, + ); + } + (_, ty::RePlaceholder(_)) => { + note_and_explain_region( + self.tcx, + &mut err, + "the required lifetime does not necessarily outlive ", + sub, + "", + None, + ); + } + _ => { + note_and_explain_region(self.tcx, &mut err, "", sup, "...", None); + note_and_explain_region( + self.tcx, + &mut err, + "...does not necessarily outlive ", + sub, + "", + None, + ); + } + } + err + } + infer::Reborrow(span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0312, + "lifetime of reference outlives lifetime of borrowed content..." + ); + note_and_explain_region( + self.tcx, + &mut err, + "...the reference is valid for ", + sub, + "...", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "...but the borrowed content is only valid for ", + sup, + "", + None, + ); + err + } + infer::ReborrowUpvar(span, ref upvar_id) => { + let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id); + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0313, + "lifetime of borrowed pointer outlives lifetime of captured variable `{}`...", + var_name + ); + note_and_explain_region( + self.tcx, + &mut err, + "...the borrowed pointer is valid for ", + sub, + "...", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + &format!("...but `{}` is only valid for ", var_name), + sup, + "", + None, + ); + err + } + infer::RelateObjectBound(span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0476, + "lifetime of the source pointer does not outlive lifetime bound of the \ + object type" + ); + note_and_explain_region( + self.tcx, + &mut err, + "object type is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "source pointer is only valid for ", + sup, + "", + None, + ); + err + } + infer::RelateParamBound(span, ty, opt_span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0477, + "the type `{}` does not fulfill the required lifetime", + self.ty_to_string(ty) + ); + match *sub { + ty::ReStatic => note_and_explain_region( + self.tcx, + &mut err, + "type must satisfy ", + sub, + if opt_span.is_some() { " as required by this binding" } else { "" }, + opt_span, + ), + _ => note_and_explain_region( + self.tcx, + &mut err, + "type must outlive ", + sub, + if opt_span.is_some() { " as required by this binding" } else { "" }, + opt_span, + ), + } + err + } + infer::RelateRegionParamBound(span) => { + let mut err = + struct_span_err!(self.tcx.sess, span, E0478, "lifetime bound not satisfied"); + note_and_explain_region( + self.tcx, + &mut err, + "lifetime parameter instantiated with ", + sup, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but lifetime parameter must outlive ", + sub, + "", + None, + ); + err + } + infer::DataBorrowed(ty, span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0490, + "a value of type `{}` is borrowed for too long", + self.ty_to_string(ty) + ); + note_and_explain_region( + self.tcx, + &mut err, + "the type is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but the borrow lasts for ", + sup, + "", + None, + ); + err + } + infer::ReferenceOutlivesReferent(ty, span) => { + let mut err = struct_span_err!( + self.tcx.sess, + span, + E0491, + "in type `{}`, reference has a longer lifetime than the data it references", + self.ty_to_string(ty) + ); + note_and_explain_region( + self.tcx, + &mut err, + "the pointer is valid for ", + sub, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but the referenced data is only valid for ", + sup, + "", + None, + ); + err + } + infer::CompareImplItemObligation { span, impl_item_def_id, trait_item_def_id } => self + .report_extra_impl_obligation( + span, + impl_item_def_id, + trait_item_def_id, + &format!("`{}: {}`", sup, sub), + ), + infer::CheckAssociatedTypeBounds { impl_item_def_id, trait_item_def_id, parent } => { + let mut err = self.report_concrete_failure(*parent, sub, sup); + + let trait_item_span = self.tcx.def_span(trait_item_def_id); + let item_name = self.tcx.item_name(impl_item_def_id.to_def_id()); + err.span_label( + trait_item_span, + format!("definition of `{}` from trait", item_name), + ); + + let trait_predicates = self.tcx.explicit_predicates_of(trait_item_def_id); + let impl_predicates = self.tcx.explicit_predicates_of(impl_item_def_id); + + let impl_predicates: rustc_data_structures::fx::FxHashSet<_> = + impl_predicates.predicates.into_iter().map(|(pred, _)| pred).collect(); + let clauses: Vec<_> = trait_predicates + .predicates + .into_iter() + .filter(|&(pred, _)| !impl_predicates.contains(pred)) + .map(|(pred, _)| format!("{}", pred)) + .collect(); + + if !clauses.is_empty() { + let generics = self.tcx.hir().get_generics(impl_item_def_id).unwrap(); + let where_clause_span = generics.tail_span_for_predicate_suggestion(); + + let suggestion = format!( + "{} {}", + generics.add_where_or_trailing_comma(), + clauses.join(", "), + ); + err.span_suggestion( + where_clause_span, + &format!( + "try copying {} from the trait", + if clauses.len() > 1 { "these clauses" } else { "this clause" } + ), + suggestion, + rustc_errors::Applicability::MaybeIncorrect, + ); + } + + err + } + infer::AscribeUserTypeProvePredicate(span) => { + let mut err = + struct_span_err!(self.tcx.sess, span, E0478, "lifetime bound not satisfied"); + note_and_explain_region( + self.tcx, + &mut err, + "lifetime instantiated with ", + sup, + "", + None, + ); + note_and_explain_region( + self.tcx, + &mut err, + "but lifetime must outlive ", + sub, + "", + None, + ); + err + } + } + } + + pub(super) fn report_placeholder_failure( + &self, + placeholder_origin: SubregionOrigin<'tcx>, + sub: Region<'tcx>, + sup: Region<'tcx>, + ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { + // I can't think how to do better than this right now. -nikomatsakis + debug!(?placeholder_origin, ?sub, ?sup, "report_placeholder_failure"); + match placeholder_origin { + infer::Subtype(box ref trace) + if matches!( + &trace.cause.code().peel_derives(), + ObligationCauseCode::BindingObligation(..) + | ObligationCauseCode::ExprBindingObligation(..) + ) => + { + // Hack to get around the borrow checker because trace.cause has an `Rc`. + if let ObligationCauseCode::BindingObligation(_, span) + | ObligationCauseCode::ExprBindingObligation(_, span, ..) = + &trace.cause.code().peel_derives() + { + let span = *span; + let mut err = self.report_concrete_failure(placeholder_origin, sub, sup); + err.span_note(span, "the lifetime requirement is introduced here"); + err + } else { + unreachable!() + } + } + infer::Subtype(box trace) => { + let terr = TypeError::RegionsPlaceholderMismatch; + return self.report_and_explain_type_error(trace, terr); + } + _ => return self.report_concrete_failure(placeholder_origin, sub, sup), + } + } +} diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs new file mode 100644 index 00000000000..73b5a2cc4ad --- /dev/null +++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs @@ -0,0 +1,672 @@ +use hir::def::CtorKind; +use hir::intravisit::{walk_expr, walk_stmt, Visitor}; +use rustc_data_structures::fx::FxIndexSet; +use rustc_errors::{Applicability, Diagnostic}; +use rustc_hir as hir; +use rustc_middle::traits::{ + IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, + StatementAsExpression, +}; +use rustc_middle::ty::print::with_no_trimmed_paths; +use rustc_middle::ty::{self as ty, Ty, TypeVisitable}; +use rustc_span::{sym, BytePos, Span}; + +use crate::errors::SuggAddLetForLetChains; + +use super::TypeErrCtxt; + +impl<'tcx> TypeErrCtxt<'_, 'tcx> { + pub(super) fn suggest_remove_semi_or_return_binding( + &self, + err: &mut Diagnostic, + first_id: Option<hir::HirId>, + first_ty: Ty<'tcx>, + first_span: Span, + second_id: Option<hir::HirId>, + second_ty: Ty<'tcx>, + second_span: Span, + ) { + let remove_semicolon = [ + (first_id, self.resolve_vars_if_possible(second_ty)), + (second_id, self.resolve_vars_if_possible(first_ty)), + ] + .into_iter() + .find_map(|(id, ty)| { + let hir::Node::Block(blk) = self.tcx.hir().get(id?) else { return None }; + self.could_remove_semicolon(blk, ty) + }); + match remove_semicolon { + Some((sp, StatementAsExpression::NeedsBoxing)) => { + err.multipart_suggestion( + "consider removing this semicolon and boxing the expressions", + vec![ + (first_span.shrink_to_lo(), "Box::new(".to_string()), + (first_span.shrink_to_hi(), ")".to_string()), + (second_span.shrink_to_lo(), "Box::new(".to_string()), + (second_span.shrink_to_hi(), ")".to_string()), + (sp, String::new()), + ], + Applicability::MachineApplicable, + ); + } + Some((sp, StatementAsExpression::CorrectType)) => { + err.span_suggestion_short( + sp, + "consider removing this semicolon", + "", + Applicability::MachineApplicable, + ); + } + None => { + for (id, ty) in [(first_id, second_ty), (second_id, first_ty)] { + if let Some(id) = id + && let hir::Node::Block(blk) = self.tcx.hir().get(id) + && self.consider_returning_binding(blk, ty, err) + { + break; + } + } + } + } + } + + pub(super) fn suggest_boxing_for_return_impl_trait( + &self, + err: &mut Diagnostic, + return_sp: Span, + arm_spans: impl Iterator<Item = Span>, + ) { + err.multipart_suggestion( + "you could change the return type to be a boxed trait object", + vec![ + (return_sp.with_hi(return_sp.lo() + BytePos(4)), "Box<dyn".to_string()), + (return_sp.shrink_to_hi(), ">".to_string()), + ], + Applicability::MaybeIncorrect, + ); + let sugg = arm_spans + .flat_map(|sp| { + [(sp.shrink_to_lo(), "Box::new(".to_string()), (sp.shrink_to_hi(), ")".to_string())] + .into_iter() + }) + .collect::<Vec<_>>(); + err.multipart_suggestion( + "if you change the return type to expect trait objects, box the returned expressions", + sugg, + Applicability::MaybeIncorrect, + ); + } + + pub(super) fn suggest_tuple_pattern( + &self, + cause: &ObligationCause<'tcx>, + exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, + diag: &mut Diagnostic, + ) { + // Heavily inspired by `FnCtxt::suggest_compatible_variants`, with + // some modifications due to that being in typeck and this being in infer. + if let ObligationCauseCode::Pattern { .. } = cause.code() { + if let ty::Adt(expected_adt, substs) = exp_found.expected.kind() { + let compatible_variants: Vec<_> = expected_adt + .variants() + .iter() + .filter(|variant| { + variant.fields.len() == 1 && variant.ctor_kind() == Some(CtorKind::Fn) + }) + .filter_map(|variant| { + let sole_field = &variant.fields[0]; + let sole_field_ty = sole_field.ty(self.tcx, substs); + if self.same_type_modulo_infer(sole_field_ty, exp_found.found) { + let variant_path = + with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id)); + // FIXME #56861: DRYer prelude filtering + if let Some(path) = variant_path.strip_prefix("std::prelude::") { + if let Some((_, path)) = path.split_once("::") { + return Some(path.to_string()); + } + } + Some(variant_path) + } else { + None + } + }) + .collect(); + match &compatible_variants[..] { + [] => {} + [variant] => { + diag.multipart_suggestion_verbose( + &format!("try wrapping the pattern in `{}`", variant), + vec![ + (cause.span.shrink_to_lo(), format!("{}(", variant)), + (cause.span.shrink_to_hi(), ")".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } + _ => { + // More than one matching variant. + diag.multipart_suggestions( + &format!( + "try wrapping the pattern in a variant of `{}`", + self.tcx.def_path_str(expected_adt.did()) + ), + compatible_variants.into_iter().map(|variant| { + vec![ + (cause.span.shrink_to_lo(), format!("{}(", variant)), + (cause.span.shrink_to_hi(), ")".to_string()), + ] + }), + Applicability::MaybeIncorrect, + ); + } + } + } + } + } + + /// A possible error is to forget to add `.await` when using futures: + /// + /// ```compile_fail,E0308 + /// async fn make_u32() -> u32 { + /// 22 + /// } + /// + /// fn take_u32(x: u32) {} + /// + /// async fn foo() { + /// let x = make_u32(); + /// take_u32(x); + /// } + /// ``` + /// + /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the + /// expected type. If this is the case, and we are inside of an async body, it suggests adding + /// `.await` to the tail of the expression. + pub(super) fn suggest_await_on_expect_found( + &self, + cause: &ObligationCause<'tcx>, + exp_span: Span, + exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, + diag: &mut Diagnostic, + ) { + debug!( + "suggest_await_on_expect_found: exp_span={:?}, expected_ty={:?}, found_ty={:?}", + exp_span, exp_found.expected, exp_found.found, + ); + + if let ObligationCauseCode::CompareImplItemObligation { .. } = cause.code() { + return; + } + + match ( + self.get_impl_future_output_ty(exp_found.expected), + self.get_impl_future_output_ty(exp_found.found), + ) { + (Some(exp), Some(found)) if self.same_type_modulo_infer(exp, found) => match cause + .code() + { + ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => { + let then_span = self.find_block_span_from_hir_id(*then_id); + diag.multipart_suggestion( + "consider `await`ing on both `Future`s", + vec![ + (then_span.shrink_to_hi(), ".await".to_string()), + (exp_span.shrink_to_hi(), ".await".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } + ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { + prior_arms, + .. + }) => { + if let [.., arm_span] = &prior_arms[..] { + diag.multipart_suggestion( + "consider `await`ing on both `Future`s", + vec![ + (arm_span.shrink_to_hi(), ".await".to_string()), + (exp_span.shrink_to_hi(), ".await".to_string()), + ], + Applicability::MaybeIncorrect, + ); + } else { + diag.help("consider `await`ing on both `Future`s"); + } + } + _ => { + diag.help("consider `await`ing on both `Future`s"); + } + }, + (_, Some(ty)) if self.same_type_modulo_infer(exp_found.expected, ty) => { + diag.span_suggestion_verbose( + exp_span.shrink_to_hi(), + "consider `await`ing on the `Future`", + ".await", + Applicability::MaybeIncorrect, + ); + } + (Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code() + { + ObligationCauseCode::Pattern { span: Some(then_span), .. } => { + diag.span_suggestion_verbose( + then_span.shrink_to_hi(), + "consider `await`ing on the `Future`", + ".await", + Applicability::MaybeIncorrect, + ); + } + ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => { + let then_span = self.find_block_span_from_hir_id(*then_id); + diag.span_suggestion_verbose( + then_span.shrink_to_hi(), + "consider `await`ing on the `Future`", + ".await", + Applicability::MaybeIncorrect, + ); + } + ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { + ref prior_arms, + .. + }) => { + diag.multipart_suggestion_verbose( + "consider `await`ing on the `Future`", + prior_arms + .iter() + .map(|arm| (arm.shrink_to_hi(), ".await".to_string())) + .collect(), + Applicability::MaybeIncorrect, + ); + } + _ => {} + }, + _ => {} + } + } + + pub(super) fn suggest_accessing_field_where_appropriate( + &self, + cause: &ObligationCause<'tcx>, + exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, + diag: &mut Diagnostic, + ) { + debug!( + "suggest_accessing_field_where_appropriate(cause={:?}, exp_found={:?})", + cause, exp_found + ); + if let ty::Adt(expected_def, expected_substs) = exp_found.expected.kind() { + if expected_def.is_enum() { + return; + } + + if let Some((name, ty)) = expected_def + .non_enum_variant() + .fields + .iter() + .filter(|field| field.vis.is_accessible_from(field.did, self.tcx)) + .map(|field| (field.name, field.ty(self.tcx, expected_substs))) + .find(|(_, ty)| self.same_type_modulo_infer(*ty, exp_found.found)) + { + if let ObligationCauseCode::Pattern { span: Some(span), .. } = *cause.code() { + if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) { + let suggestion = if expected_def.is_struct() { + format!("{}.{}", snippet, name) + } else if expected_def.is_union() { + format!("unsafe {{ {}.{} }}", snippet, name) + } else { + return; + }; + diag.span_suggestion( + span, + &format!( + "you might have meant to use field `{}` whose type is `{}`", + name, ty + ), + suggestion, + Applicability::MaybeIncorrect, + ); + } + } + } + } + } + + /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate, + /// suggests it. + pub(super) fn suggest_as_ref_where_appropriate( + &self, + span: Span, + exp_found: &ty::error::ExpectedFound<Ty<'tcx>>, + diag: &mut Diagnostic, + ) { + if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) + && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found) + { + diag.span_suggestion( + span, + msg, + // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&` + format!("{}.as_ref()", snippet.trim_start_matches('&')), + Applicability::MachineApplicable, + ); + } + } + + pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> { + if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) = + (expected.kind(), found.kind()) + { + if let ty::Adt(found_def, found_substs) = *found_ty.kind() { + if exp_def == &found_def { + let have_as_ref = &[ + ( + sym::Option, + "you can convert from `&Option<T>` to `Option<&T>` using \ + `.as_ref()`", + ), + ( + sym::Result, + "you can convert from `&Result<T, E>` to \ + `Result<&T, &E>` using `.as_ref()`", + ), + ]; + if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| { + self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg) + }) { + let mut show_suggestion = true; + for (exp_ty, found_ty) in + std::iter::zip(exp_substs.types(), found_substs.types()) + { + match *exp_ty.kind() { + ty::Ref(_, exp_ty, _) => { + match (exp_ty.kind(), found_ty.kind()) { + (_, ty::Param(_)) + | (_, ty::Infer(_)) + | (ty::Param(_), _) + | (ty::Infer(_), _) => {} + _ if self.same_type_modulo_infer(exp_ty, found_ty) => {} + _ => show_suggestion = false, + }; + } + ty::Param(_) | ty::Infer(_) => {} + _ => show_suggestion = false, + } + } + if show_suggestion { + return Some(*msg); + } + } + } + } + } + None + } + + /// Try to find code with pattern `if Some(..) = expr` + /// use a `visitor` to mark the `if` which its span contains given error span, + /// and then try to find a assignment in the `cond` part, which span is equal with error span + pub(super) fn suggest_let_for_letchains( + &self, + err: &mut Diagnostic, + cause: &ObligationCause<'_>, + span: Span, + ) { + let hir = self.tcx.hir(); + let fn_hir_id = hir.get_parent_node(cause.body_id); + if let Some(node) = self.tcx.hir().find(fn_hir_id) && + let hir::Node::Item(hir::Item { + kind: hir::ItemKind::Fn(_sig, _, body_id), .. + }) = node { + let body = hir.body(*body_id); + + /// Find the if expression with given span + struct IfVisitor { + pub result: bool, + pub found_if: bool, + pub err_span: Span, + } + + impl<'v> Visitor<'v> for IfVisitor { + fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) { + if self.result { return; } + match ex.kind { + hir::ExprKind::If(cond, _, _) => { + self.found_if = true; + walk_expr(self, cond); + self.found_if = false; + } + _ => walk_expr(self, ex), + } + } + + fn visit_stmt(&mut self, ex: &'v hir::Stmt<'v>) { + if let hir::StmtKind::Local(hir::Local { + span, pat: hir::Pat{..}, ty: None, init: Some(_), .. + }) = &ex.kind + && self.found_if + && span.eq(&self.err_span) { + self.result = true; + } + walk_stmt(self, ex); + } + + fn visit_body(&mut self, body: &'v hir::Body<'v>) { + hir::intravisit::walk_body(self, body); + } + } + + let mut visitor = IfVisitor { err_span: span, found_if: false, result: false }; + visitor.visit_body(&body); + if visitor.result { + err.subdiagnostic(SuggAddLetForLetChains{span: span.shrink_to_lo()}); + } + } + } +} + +impl<'tcx> TypeErrCtxt<'_, 'tcx> { + /// Be helpful when the user wrote `{... expr; }` and taking the `;` off + /// is enough to fix the error. + pub fn could_remove_semicolon( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + ) -> Option<(Span, StatementAsExpression)> { + let blk = blk.innermost_block(); + // Do not suggest if we have a tail expr. + if blk.expr.is_some() { + return None; + } + let last_stmt = blk.stmts.last()?; + let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else { + return None; + }; + let last_expr_ty = self.typeck_results.as_ref()?.expr_ty_opt(*last_expr)?; + let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) { + _ if last_expr_ty.references_error() => return None, + _ if self.same_type_modulo_infer(last_expr_ty, expected_ty) => { + StatementAsExpression::CorrectType + } + (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _)) + if last_def_id == exp_def_id => + { + StatementAsExpression::CorrectType + } + (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => { + debug!( + "both opaque, likely future {:?} {:?} {:?} {:?}", + last_def_id, last_bounds, exp_def_id, exp_bounds + ); + + let last_local_id = last_def_id.as_local()?; + let exp_local_id = exp_def_id.as_local()?; + + match ( + &self.tcx.hir().expect_item(last_local_id).kind, + &self.tcx.hir().expect_item(exp_local_id).kind, + ) { + ( + hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }), + hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }), + ) if std::iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| { + match (left, right) { + ( + hir::GenericBound::Trait(tl, ml), + hir::GenericBound::Trait(tr, mr), + ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id() + && ml == mr => + { + true + } + ( + hir::GenericBound::LangItemTrait(langl, _, _, argsl), + hir::GenericBound::LangItemTrait(langr, _, _, argsr), + ) if langl == langr => { + // FIXME: consider the bounds! + debug!("{:?} {:?}", argsl, argsr); + true + } + _ => false, + } + }) => + { + StatementAsExpression::NeedsBoxing + } + _ => StatementAsExpression::CorrectType, + } + } + _ => return None, + }; + let span = if last_stmt.span.from_expansion() { + let mac_call = rustc_span::source_map::original_sp(last_stmt.span, blk.span); + self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)? + } else { + last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1)) + }; + Some((span, needs_box)) + } + + /// Suggest returning a local binding with a compatible type if the block + /// has no return expression. + pub fn consider_returning_binding( + &self, + blk: &'tcx hir::Block<'tcx>, + expected_ty: Ty<'tcx>, + err: &mut Diagnostic, + ) -> bool { + let blk = blk.innermost_block(); + // Do not suggest if we have a tail expr. + if blk.expr.is_some() { + return false; + } + let mut shadowed = FxIndexSet::default(); + let mut candidate_idents = vec![]; + let mut find_compatible_candidates = |pat: &hir::Pat<'_>| { + if let hir::PatKind::Binding(_, hir_id, ident, _) = &pat.kind + && let Some(pat_ty) = self + .typeck_results + .as_ref() + .and_then(|typeck_results| typeck_results.node_type_opt(*hir_id)) + { + let pat_ty = self.resolve_vars_if_possible(pat_ty); + if self.same_type_modulo_infer(pat_ty, expected_ty) + && !(pat_ty, expected_ty).references_error() + && shadowed.insert(ident.name) + { + candidate_idents.push((*ident, pat_ty)); + } + } + true + }; + + let hir = self.tcx.hir(); + for stmt in blk.stmts.iter().rev() { + let hir::StmtKind::Local(local) = &stmt.kind else { continue; }; + local.pat.walk(&mut find_compatible_candidates); + } + match hir.find(hir.get_parent_node(blk.hir_id)) { + Some(hir::Node::Expr(hir::Expr { hir_id, .. })) => { + match hir.find(hir.get_parent_node(*hir_id)) { + Some(hir::Node::Arm(hir::Arm { pat, .. })) => { + pat.walk(&mut find_compatible_candidates); + } + Some( + hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body), .. }) + | hir::Node::ImplItem(hir::ImplItem { + kind: hir::ImplItemKind::Fn(_, body), + .. + }) + | hir::Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body)), + .. + }) + | hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Closure(hir::Closure { body, .. }), + .. + }), + ) => { + for param in hir.body(*body).params { + param.pat.walk(&mut find_compatible_candidates); + } + } + Some(hir::Node::Expr(hir::Expr { + kind: + hir::ExprKind::If( + hir::Expr { kind: hir::ExprKind::Let(let_), .. }, + then_block, + _, + ), + .. + })) if then_block.hir_id == *hir_id => { + let_.pat.walk(&mut find_compatible_candidates); + } + _ => {} + } + } + _ => {} + } + + match &candidate_idents[..] { + [(ident, _ty)] => { + let sm = self.tcx.sess.source_map(); + if let Some(stmt) = blk.stmts.last() { + let stmt_span = sm.stmt_span(stmt.span, blk.span); + let sugg = if sm.is_multiline(blk.span) + && let Some(spacing) = sm.indentation_before(stmt_span) + { + format!("\n{spacing}{ident}") + } else { + format!(" {ident}") + }; + err.span_suggestion_verbose( + stmt_span.shrink_to_hi(), + format!("consider returning the local binding `{ident}`"), + sugg, + Applicability::MaybeIncorrect, + ); + } else { + let sugg = if sm.is_multiline(blk.span) + && let Some(spacing) = sm.indentation_before(blk.span.shrink_to_lo()) + { + format!("\n{spacing} {ident}\n{spacing}") + } else { + format!(" {ident} ") + }; + let left_span = sm.span_through_char(blk.span, '{').shrink_to_hi(); + err.span_suggestion_verbose( + sm.span_extend_while(left_span, |c| c.is_whitespace()).unwrap_or(left_span), + format!("consider returning the local binding `{ident}`"), + sugg, + Applicability::MaybeIncorrect, + ); + } + true + } + values if (1..3).contains(&values.len()) => { + let spans = values.iter().map(|(ident, _)| ident.span).collect::<Vec<_>>(); + err.span_note(spans, "consider returning one of these bindings"); + true + } + _ => false, + } + } +} diff --git a/compiler/rustc_infer/src/infer/note.rs b/compiler/rustc_infer/src/infer/note.rs new file mode 100644 index 00000000000..2ccbd164faa --- /dev/null +++ b/compiler/rustc_infer/src/infer/note.rs @@ -0,0 +1,203 @@ +impl<'tcx> TypeErrCtxt<'_, 'tcx> { + fn note_error_origin( + &self, + err: &mut Diagnostic, + cause: &ObligationCause<'tcx>, + exp_found: Option<ty::error::ExpectedFound<Ty<'tcx>>>, + terr: TypeError<'tcx>, + ) { + match *cause.code() { + ObligationCauseCode::Pattern { origin_expr: true, span: Some(span), root_ty } => { + let ty = self.resolve_vars_if_possible(root_ty); + if !matches!(ty.kind(), ty::Infer(ty::InferTy::TyVar(_) | ty::InferTy::FreshTy(_))) + { + // don't show type `_` + if span.desugaring_kind() == Some(DesugaringKind::ForLoop) + && let ty::Adt(def, substs) = ty.kind() + && Some(def.did()) == self.tcx.get_diagnostic_item(sym::Option) + { + err.span_label(span, format!("this is an iterator with items of type `{}`", substs.type_at(0))); + } else { + err.span_label(span, format!("this expression has type `{}`", ty)); + } + } + if let Some(ty::error::ExpectedFound { found, .. }) = exp_found + && ty.is_box() && ty.boxed_ty() == found + && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) + { + err.span_suggestion( + span, + "consider dereferencing the boxed value", + format!("*{}", snippet), + Applicability::MachineApplicable, + ); + } + } + ObligationCauseCode::Pattern { origin_expr: false, span: Some(span), .. } => { + err.span_label(span, "expected due to this"); + } + ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause { + arm_block_id, + arm_span, + arm_ty, + prior_arm_block_id, + prior_arm_span, + prior_arm_ty, + source, + ref prior_arms, + scrut_hir_id, + opt_suggest_box_span, + scrut_span, + .. + }) => match source { + hir::MatchSource::TryDesugar => { + if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found { + let scrut_expr = self.tcx.hir().expect_expr(scrut_hir_id); + let scrut_ty = if let hir::ExprKind::Call(_, args) = &scrut_expr.kind { + let arg_expr = args.first().expect("try desugaring call w/out arg"); + self.typeck_results.as_ref().and_then(|typeck_results| { + typeck_results.expr_ty_opt(arg_expr) + }) + } else { + bug!("try desugaring w/out call expr as scrutinee"); + }; + + match scrut_ty { + Some(ty) if expected == ty => { + let source_map = self.tcx.sess.source_map(); + err.span_suggestion( + source_map.end_point(cause.span), + "try removing this `?`", + "", + Applicability::MachineApplicable, + ); + } + _ => {} + } + } + } + _ => { + // `prior_arm_ty` can be `!`, `expected` will have better info when present. + let t = self.resolve_vars_if_possible(match exp_found { + Some(ty::error::ExpectedFound { expected, .. }) => expected, + _ => prior_arm_ty, + }); + let source_map = self.tcx.sess.source_map(); + let mut any_multiline_arm = source_map.is_multiline(arm_span); + if prior_arms.len() <= 4 { + for sp in prior_arms { + any_multiline_arm |= source_map.is_multiline(*sp); + err.span_label(*sp, format!("this is found to be of type `{}`", t)); + } + } else if let Some(sp) = prior_arms.last() { + any_multiline_arm |= source_map.is_multiline(*sp); + err.span_label( + *sp, + format!("this and all prior arms are found to be of type `{}`", t), + ); + } + let outer_error_span = if any_multiline_arm { + // Cover just `match` and the scrutinee expression, not + // the entire match body, to reduce diagram noise. + cause.span.shrink_to_lo().to(scrut_span) + } else { + cause.span + }; + let msg = "`match` arms have incompatible types"; + err.span_label(outer_error_span, msg); + self.suggest_remove_semi_or_return_binding( + err, + prior_arm_block_id, + prior_arm_ty, + prior_arm_span, + arm_block_id, + arm_ty, + arm_span, + ); + if let Some(ret_sp) = opt_suggest_box_span { + // Get return type span and point to it. + self.suggest_boxing_for_return_impl_trait( + err, + ret_sp, + prior_arms.iter().chain(std::iter::once(&arm_span)).map(|s| *s), + ); + } + } + }, + ObligationCauseCode::IfExpression(box IfExpressionCause { + then_id, + else_id, + then_ty, + else_ty, + outer_span, + opt_suggest_box_span, + }) => { + let then_span = self.find_block_span_from_hir_id(then_id); + let else_span = self.find_block_span_from_hir_id(else_id); + err.span_label(then_span, "expected because of this"); + if let Some(sp) = outer_span { + err.span_label(sp, "`if` and `else` have incompatible types"); + } + self.suggest_remove_semi_or_return_binding( + err, + Some(then_id), + then_ty, + then_span, + Some(else_id), + else_ty, + else_span, + ); + if let Some(ret_sp) = opt_suggest_box_span { + self.suggest_boxing_for_return_impl_trait( + err, + ret_sp, + [then_span, else_span].into_iter(), + ); + } + } + ObligationCauseCode::LetElse => { + err.help("try adding a diverging expression, such as `return` or `panic!(..)`"); + err.help("...or use `match` instead of `let...else`"); + } + _ => { + if let ObligationCauseCode::BindingObligation(_, span) + | ObligationCauseCode::ExprBindingObligation(_, span, ..) + = cause.code().peel_derives() + && let TypeError::RegionsPlaceholderMismatch = terr + { + err.span_note( * span, + "the lifetime requirement is introduced here"); + } + } + } + } +} + +impl<'tcx> InferCtxt<'tcx> { + /// Given a [`hir::Block`], get the span of its last expression or + /// statement, peeling off any inner blocks. + pub fn find_block_span(&self, block: &'tcx hir::Block<'tcx>) -> Span { + let block = block.innermost_block(); + if let Some(expr) = &block.expr { + expr.span + } else if let Some(stmt) = block.stmts.last() { + // possibly incorrect trailing `;` in the else arm + stmt.span + } else { + // empty block; point at its entirety + block.span + } + } + + /// Given a [`hir::HirId`] for a block, get the span of its last expression + /// or statement, peeling off any inner blocks. + pub fn find_block_span_from_hir_id(&self, hir_id: hir::HirId) -> Span { + match self.tcx.hir().get(hir_id) { + hir::Node::Block(blk) => self.find_block_span(blk), + // The parser was in a weird state if either of these happen, but + // it's better not to panic. + hir::Node::Expr(e) => e.span, + _ => rustc_span::DUMMY_SP, + } + } +} diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs index 4041fbc2ffa..9aa26667e7b 100644 --- a/compiler/rustc_traits/src/lib.rs +++ b/compiler/rustc_traits/src/lib.rs @@ -12,13 +12,13 @@ extern crate tracing; extern crate rustc_middle; mod chalk; +mod codegen; mod dropck_outlives; mod evaluate_obligation; mod implied_outlives_bounds; mod normalize_erasing_regions; mod normalize_projection_ty; mod type_op; -mod codegen; pub use type_op::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_cause}; |