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-rw-r--r--compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs912
1 files changed, 0 insertions, 912 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
deleted file mode 100644
index 57771e096..000000000
--- a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs
+++ /dev/null
@@ -1,912 +0,0 @@
-use super::FnCtxt;
-use crate::astconv::AstConv;
-use crate::errors::{AddReturnTypeSuggestion, ExpectedReturnTypeLabel};
-
-use rustc_ast::util::parser::ExprPrecedence;
-use rustc_errors::{Applicability, Diagnostic, MultiSpan};
-use rustc_hir as hir;
-use rustc_hir::def::{CtorOf, DefKind};
-use rustc_hir::lang_items::LangItem;
-use rustc_hir::{
- Expr, ExprKind, GenericBound, Node, Path, QPath, Stmt, StmtKind, TyKind, WherePredicate,
-};
-use rustc_infer::infer::{self, TyCtxtInferExt};
-use rustc_infer::traits::{self, StatementAsExpression};
-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::traits::query::evaluate_obligation::InferCtxtExt as _;
-
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
- pub(in super::super) fn suggest_semicolon_at_end(&self, span: Span, err: &mut Diagnostic) {
- err.span_suggestion_short(
- span.shrink_to_hi(),
- "consider using a semicolon here",
- ";",
- Applicability::MachineApplicable,
- );
- }
-
- /// On implicit return expressions with mismatched types, provides the following suggestions:
- ///
- /// - Points out the method's return type as the reason for the expected type.
- /// - Possible missing semicolon.
- /// - Possible missing return type if the return type is the default, and not `fn main()`.
- pub fn suggest_mismatched_types_on_tail(
- &self,
- err: &mut Diagnostic,
- expr: &'tcx hir::Expr<'tcx>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- blk_id: hir::HirId,
- ) -> bool {
- let expr = expr.peel_drop_temps();
- self.suggest_missing_semicolon(err, expr, expected, false);
- let mut pointing_at_return_type = false;
- if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) {
- let fn_id = self.tcx.hir().get_return_block(blk_id).unwrap();
- pointing_at_return_type = self.suggest_missing_return_type(
- err,
- &fn_decl,
- expected,
- found,
- can_suggest,
- fn_id,
- );
- self.suggest_missing_break_or_return_expr(
- err, expr, &fn_decl, expected, found, blk_id, fn_id,
- );
- }
- 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:
- /// ```compile_fail,E0308
- /// fn foo(x: usize) -> usize { x }
- /// let x: usize = foo; // suggest calling the `foo` function: `foo(42)`
- /// ```
- fn suggest_fn_call(
- &self,
- err: &mut Diagnostic,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) -> 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 {
- 0 => ("".to_string(), Applicability::MachineApplicable),
- 1..=4 => (
- (0..inputs).map(|_| "_").collect::<Vec<_>>().join(", "),
- Applicability::MachineApplicable,
- ),
- _ => ("...".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 sugg = match expr.kind {
- hir::ExprKind::Call(..)
- | hir::ExprKind::Path(..)
- | hir::ExprKind::Index(..)
- | hir::ExprKind::Lit(..) => {
- vec![(expr.span.shrink_to_hi(), format!("({sugg_call})"))]
- }
- hir::ExprKind::Closure { .. } => {
- // Might be `{ expr } || { bool }`
- applicability = Applicability::MaybeIncorrect;
- vec![
- (expr.span.shrink_to_lo(), "(".to_string()),
- (expr.span.shrink_to_hi(), format!(")({sugg_call})")),
- ]
- }
- _ => {
- vec![
- (expr.span.shrink_to_lo(), "(".to_string()),
- (expr.span.shrink_to_hi(), format!(")({sugg_call})")),
- ]
- }
- };
-
- err.multipart_suggestion_verbose(
- format!("use parentheses to {msg}"),
- sugg,
- applicability,
- );
-
- return true;
- }
- false
- }
-
- pub fn suggest_deref_ref_or_into(
- &self,
- err: &mut Diagnostic,
- expr: &hir::Expr<'tcx>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
- ) {
- let expr = expr.peel_blocks();
- if let Some((sp, msg, suggestion, applicability, verbose)) =
- self.check_ref(expr, found, expected)
- {
- if verbose {
- err.span_suggestion_verbose(sp, &msg, suggestion, applicability);
- } 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))
- {
- if let Some(sp) = self.tcx.hir().span_if_local(*def_id) {
- 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() {
- let mut suggestions = methods.iter()
- .filter_map(|conversion_method| {
- let receiver_method_ident = expr.method_ident();
- if let Some(method_ident) = receiver_method_ident
- && method_ident.name == conversion_method.name
- {
- return None // do not suggest code that is already there (#53348)
- }
-
- let method_call_list = [sym::to_vec, sym::to_string];
- let mut sugg = if let ExprKind::MethodCall(receiver_method, ..) = expr.kind
- && receiver_method.ident.name == sym::clone
- && method_call_list.contains(&conversion_method.name)
- // If receiver is `.clone()` and found type has one of those methods,
- // we guess that the user wants to convert from a slice type (`&[]` or `&str`)
- // to an owned type (`Vec` or `String`). These conversions clone internally,
- // so we remove the user's `clone` call.
- {
- vec![(
- receiver_method.ident.span,
- conversion_method.name.to_string()
- )]
- } else if expr.precedence().order()
- < ExprPrecedence::MethodCall.order()
- {
- vec![
- (expr.span.shrink_to_lo(), "(".to_string()),
- (expr.span.shrink_to_hi(), format!(").{}()", conversion_method.name)),
- ]
- } else {
- vec![(expr.span.shrink_to_hi(), format!(".{}()", conversion_method.name))]
- };
- let struct_pat_shorthand_field = self.maybe_get_struct_pattern_shorthand_field(expr);
- if let Some(name) = struct_pat_shorthand_field {
- sugg.insert(
- 0,
- (expr.span.shrink_to_lo(), format!("{}: ", name)),
- );
- }
- Some(sugg)
- })
- .peekable();
- if suggestions.peek().is_some() {
- err.multipart_suggestions(
- "try using a conversion method",
- suggestions,
- Applicability::MaybeIncorrect,
- );
- }
- } else if let ty::Adt(found_adt, found_substs) = found.kind()
- && self.tcx.is_diagnostic_item(sym::Option, found_adt.did())
- && let ty::Adt(expected_adt, expected_substs) = expected.kind()
- && self.tcx.is_diagnostic_item(sym::Option, expected_adt.did())
- && let ty::Ref(_, inner_ty, _) = expected_substs.type_at(0).kind()
- && inner_ty.is_str()
- {
- let ty = found_substs.type_at(0);
- let mut peeled = ty;
- let mut ref_cnt = 0;
- while let ty::Ref(_, inner, _) = peeled.kind() {
- peeled = *inner;
- ref_cnt += 1;
- }
- if let ty::Adt(adt, _) = peeled.kind()
- && self.tcx.is_diagnostic_item(sym::String, adt.did())
- {
- err.span_suggestion_verbose(
- expr.span.shrink_to_hi(),
- "try converting the passed type into a `&str`",
- format!(".map(|x| &*{}x)", "*".repeat(ref_cnt)),
- Applicability::MaybeIncorrect,
- );
- }
- }
- }
- }
-
- /// When encountering the expected boxed value allocated in the stack, suggest allocating it
- /// in the heap by calling `Box::new()`.
- pub(in super::super) fn suggest_boxing_when_appropriate(
- &self,
- err: &mut Diagnostic,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- if self.tcx.hir().is_inside_const_context(expr.hir_id) {
- // Do not suggest `Box::new` in const context.
- return;
- }
- if !expected.is_box() || found.is_box() {
- return;
- }
- let boxed_found = self.tcx.mk_box(found);
- if self.can_coerce(boxed_found, expected) {
- err.multipart_suggestion(
- "store this in the heap by calling `Box::new`",
- vec![
- (expr.span.shrink_to_lo(), "Box::new(".to_string()),
- (expr.span.shrink_to_hi(), ")".to_string()),
- ],
- Applicability::MachineApplicable,
- );
- err.note(
- "for more on the distinction between the stack and the heap, read \
- https://doc.rust-lang.org/book/ch15-01-box.html, \
- https://doc.rust-lang.org/rust-by-example/std/box.html, and \
- https://doc.rust-lang.org/std/boxed/index.html",
- );
- }
- }
-
- /// When encountering a closure that captures variables, where a FnPtr is expected,
- /// suggest a non-capturing closure
- pub(in super::super) fn suggest_no_capture_closure(
- &self,
- err: &mut Diagnostic,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) {
- if let (ty::FnPtr(_), ty::Closure(def_id, _)) = (expected.kind(), found.kind()) {
- if let Some(upvars) = self.tcx.upvars_mentioned(*def_id) {
- // Report upto four upvars being captured to reduce the amount error messages
- // reported back to the user.
- let spans_and_labels = upvars
- .iter()
- .take(4)
- .map(|(var_hir_id, upvar)| {
- let var_name = self.tcx.hir().name(*var_hir_id).to_string();
- let msg = format!("`{}` captured here", var_name);
- (upvar.span, msg)
- })
- .collect::<Vec<_>>();
-
- let mut multi_span: MultiSpan =
- spans_and_labels.iter().map(|(sp, _)| *sp).collect::<Vec<_>>().into();
- for (sp, label) in spans_and_labels {
- multi_span.push_span_label(sp, label);
- }
- err.span_note(
- multi_span,
- "closures can only be coerced to `fn` types if they do not capture any variables"
- );
- }
- }
- }
-
- /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`.
- #[instrument(skip(self, err))]
- pub(in super::super) fn suggest_calling_boxed_future_when_appropriate(
- &self,
- err: &mut Diagnostic,
- expr: &hir::Expr<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- ) -> bool {
- // Handle #68197.
-
- if self.tcx.hir().is_inside_const_context(expr.hir_id) {
- // Do not suggest `Box::new` in const context.
- return false;
- }
- let pin_did = self.tcx.lang_items().pin_type();
- // This guards the `unwrap` and `mk_box` below.
- if pin_did.is_none() || self.tcx.lang_items().owned_box().is_none() {
- return false;
- }
- let box_found = self.tcx.mk_box(found);
- let pin_box_found = self.tcx.mk_lang_item(box_found, LangItem::Pin).unwrap();
- let pin_found = self.tcx.mk_lang_item(found, LangItem::Pin).unwrap();
- match expected.kind() {
- ty::Adt(def, _) if Some(def.did()) == pin_did => {
- if self.can_coerce(pin_box_found, expected) {
- debug!("can coerce {:?} to {:?}, suggesting Box::pin", pin_box_found, expected);
- match found.kind() {
- ty::Adt(def, _) if def.is_box() => {
- err.help("use `Box::pin`");
- }
- _ => {
- err.multipart_suggestion(
- "you need to pin and box this expression",
- vec![
- (expr.span.shrink_to_lo(), "Box::pin(".to_string()),
- (expr.span.shrink_to_hi(), ")".to_string()),
- ],
- Applicability::MaybeIncorrect,
- );
- }
- }
- true
- } else if self.can_coerce(pin_found, expected) {
- match found.kind() {
- ty::Adt(def, _) if def.is_box() => {
- err.help("use `Box::pin`");
- true
- }
- _ => false,
- }
- } else {
- false
- }
- }
- ty::Adt(def, _) if def.is_box() && self.can_coerce(box_found, expected) => {
- // Check if the parent expression is a call to Pin::new. If it
- // is and we were expecting a Box, ergo Pin<Box<expected>>, we
- // can suggest Box::pin.
- let parent = self.tcx.hir().get_parent_node(expr.hir_id);
- let Some(Node::Expr(Expr { kind: ExprKind::Call(fn_name, _), .. })) = self.tcx.hir().find(parent) else {
- return false;
- };
- match fn_name.kind {
- ExprKind::Path(QPath::TypeRelative(
- hir::Ty {
- kind: TyKind::Path(QPath::Resolved(_, Path { res: recv_ty, .. })),
- ..
- },
- method,
- )) if recv_ty.opt_def_id() == pin_did && method.ident.name == sym::new => {
- err.span_suggestion(
- fn_name.span,
- "use `Box::pin` to pin and box this expression",
- "Box::pin",
- Applicability::MachineApplicable,
- );
- true
- }
- _ => false,
- }
- }
- _ => false,
- }
- }
-
- /// A common error is to forget to add a semicolon at the end of a block, e.g.,
- ///
- /// ```compile_fail,E0308
- /// # fn bar_that_returns_u32() -> u32 { 4 }
- /// fn foo() {
- /// bar_that_returns_u32()
- /// }
- /// ```
- ///
- /// This routine checks if the return expression in a block would make sense on its own as a
- /// statement and the return type has been left as default or has been specified as `()`. If so,
- /// it suggests adding a semicolon.
- ///
- /// If the expression is the expression of a closure without block (`|| expr`), a
- /// block is needed to be added too (`|| { expr; }`). This is denoted by `needs_block`.
- pub fn suggest_missing_semicolon(
- &self,
- err: &mut Diagnostic,
- expression: &'tcx hir::Expr<'tcx>,
- expected: Ty<'tcx>,
- needs_block: bool,
- ) {
- if expected.is_unit() {
- // `BlockTailExpression` only relevant if the tail expr would be
- // useful on its own.
- match expression.kind {
- ExprKind::Call(..)
- | ExprKind::MethodCall(..)
- | ExprKind::Loop(..)
- | ExprKind::If(..)
- | ExprKind::Match(..)
- | ExprKind::Block(..)
- if expression.can_have_side_effects()
- // If the expression is from an external macro, then do not suggest
- // adding a semicolon, because there's nowhere to put it.
- // See issue #81943.
- && !in_external_macro(self.tcx.sess, expression.span) =>
- {
- if needs_block {
- err.multipart_suggestion(
- "consider using a semicolon here",
- vec![
- (expression.span.shrink_to_lo(), "{ ".to_owned()),
- (expression.span.shrink_to_hi(), "; }".to_owned()),
- ],
- Applicability::MachineApplicable,
- );
- } else {
- err.span_suggestion(
- expression.span.shrink_to_hi(),
- "consider using a semicolon here",
- ";",
- Applicability::MachineApplicable,
- );
- }
- }
- _ => (),
- }
- }
- }
-
- /// A possible error is to forget to add a return type that is needed:
- ///
- /// ```compile_fail,E0308
- /// # fn bar_that_returns_u32() -> u32 { 4 }
- /// fn foo() {
- /// bar_that_returns_u32()
- /// }
- /// ```
- ///
- /// This routine checks if the return type is left as default, the method is not part of an
- /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return
- /// type.
- pub(in super::super) fn suggest_missing_return_type(
- &self,
- err: &mut Diagnostic,
- fn_decl: &hir::FnDecl<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- can_suggest: bool,
- fn_id: hir::HirId,
- ) -> bool {
- let found =
- 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) => {
- // `fn main()` must return `()`, do not suggest changing return type
- err.subdiagnostic(ExpectedReturnTypeLabel::Unit { span });
- true
- }
- // expectation was caused by something else, not the default return
- (&hir::FnRetTy::DefaultReturn(_), _, _, false) => false,
- (&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);
- let span = ty.span;
- let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, ty);
- debug!("suggest_missing_return_type: return type {:?}", ty);
- debug!("suggest_missing_return_type: expected type {:?}", ty);
- let bound_vars = self.tcx.late_bound_vars(fn_id);
- let ty = Binder::bind_with_vars(ty, bound_vars);
- let ty = self.normalize_associated_types_in(span, ty);
- let ty = self.tcx.erase_late_bound_regions(ty);
- if self.can_coerce(expected, ty) {
- err.subdiagnostic(ExpectedReturnTypeLabel::Other { span, expected });
- self.try_suggest_return_impl_trait(err, expected, ty, fn_id);
- return true;
- }
- false
- }
- }
- }
-
- /// check whether the return type is a generic type with a trait bound
- /// only suggest this if the generic param is not present in the arguments
- /// if this is true, hint them towards changing the return type to `impl Trait`
- /// ```compile_fail,E0308
- /// fn cant_name_it<T: Fn() -> u32>() -> T {
- /// || 3
- /// }
- /// ```
- fn try_suggest_return_impl_trait(
- &self,
- err: &mut Diagnostic,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- fn_id: hir::HirId,
- ) {
- // Only apply the suggestion if:
- // - the return type is a generic parameter
- // - the generic param is not used as a fn param
- // - the generic param has at least one bound
- // - the generic param doesn't appear in any other bounds where it's not the Self type
- // Suggest:
- // - Changing the return type to be `impl <all bounds>`
-
- debug!("try_suggest_return_impl_trait, expected = {:?}, found = {:?}", expected, found);
-
- let ty::Param(expected_ty_as_param) = expected.kind() else { return };
-
- let fn_node = self.tcx.hir().find(fn_id);
-
- let Some(hir::Node::Item(hir::Item {
- kind:
- hir::ItemKind::Fn(
- hir::FnSig { decl: hir::FnDecl { inputs: fn_parameters, output: fn_return, .. }, .. },
- hir::Generics { params, predicates, .. },
- _body_id,
- ),
- ..
- })) = fn_node else { return };
-
- if params.get(expected_ty_as_param.index as usize).is_none() {
- return;
- };
-
- // get all where BoundPredicates here, because they are used in to cases below
- let where_predicates = predicates
- .iter()
- .filter_map(|p| match p {
- WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
- bounds,
- bounded_ty,
- ..
- }) => {
- // FIXME: Maybe these calls to `ast_ty_to_ty` can be removed (and the ones below)
- let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, bounded_ty);
- Some((ty, bounds))
- }
- _ => None,
- })
- .map(|(ty, bounds)| match ty.kind() {
- ty::Param(param_ty) if param_ty == expected_ty_as_param => Ok(Some(bounds)),
- // check whether there is any predicate that contains our `T`, like `Option<T>: Send`
- _ => match ty.contains(expected) {
- true => Err(()),
- false => Ok(None),
- },
- })
- .collect::<Result<Vec<_>, _>>();
-
- let Ok(where_predicates) = where_predicates else { return };
-
- // now get all predicates in the same types as the where bounds, so we can chain them
- let predicates_from_where =
- where_predicates.iter().flatten().flat_map(|bounds| bounds.iter());
-
- // extract all bounds from the source code using their spans
- let all_matching_bounds_strs = predicates_from_where
- .filter_map(|bound| match bound {
- GenericBound::Trait(_, _) => {
- self.tcx.sess.source_map().span_to_snippet(bound.span()).ok()
- }
- _ => None,
- })
- .collect::<Vec<String>>();
-
- if all_matching_bounds_strs.len() == 0 {
- return;
- }
-
- let all_bounds_str = all_matching_bounds_strs.join(" + ");
-
- let ty_param_used_in_fn_params = fn_parameters.iter().any(|param| {
- let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, param);
- matches!(ty.kind(), ty::Param(fn_param_ty_param) if expected_ty_as_param == fn_param_ty_param)
- });
-
- if ty_param_used_in_fn_params {
- return;
- }
-
- err.span_suggestion(
- fn_return.span(),
- "consider using an impl return type",
- format!("impl {}", all_bounds_str),
- Applicability::MaybeIncorrect,
- );
- }
-
- pub(in super::super) fn suggest_missing_break_or_return_expr(
- &self,
- err: &mut Diagnostic,
- expr: &'tcx hir::Expr<'tcx>,
- fn_decl: &hir::FnDecl<'_>,
- expected: Ty<'tcx>,
- found: Ty<'tcx>,
- id: hir::HirId,
- fn_id: hir::HirId,
- ) {
- if !expected.is_unit() {
- return;
- }
- let found = self.resolve_vars_with_obligations(found);
-
- let in_loop = self.is_loop(id)
- || self.tcx.hir().parent_iter(id).any(|(parent_id, _)| self.is_loop(parent_id));
-
- let in_local_statement = self.is_local_statement(id)
- || self
- .tcx
- .hir()
- .parent_iter(id)
- .any(|(parent_id, _)| self.is_local_statement(parent_id));
-
- if in_loop && in_local_statement {
- err.multipart_suggestion(
- "you might have meant to break the loop with this value",
- vec![
- (expr.span.shrink_to_lo(), "break ".to_string()),
- (expr.span.shrink_to_hi(), ";".to_string()),
- ],
- Applicability::MaybeIncorrect,
- );
- return;
- }
-
- if let hir::FnRetTy::Return(ty) = fn_decl.output {
- let ty = <dyn AstConv<'_>>::ast_ty_to_ty(self, ty);
- let bound_vars = self.tcx.late_bound_vars(fn_id);
- let ty = self.tcx.erase_late_bound_regions(Binder::bind_with_vars(ty, bound_vars));
- let ty = self.normalize_associated_types_in(expr.span, ty);
- let ty = match self.tcx.asyncness(fn_id.owner) {
- hir::IsAsync::Async => self
- .tcx
- .infer_ctxt()
- .enter(|infcx| {
- infcx.get_impl_future_output_ty(ty).unwrap_or_else(|| {
- span_bug!(
- fn_decl.output.span(),
- "failed to get output type of async function"
- )
- })
- })
- .skip_binder(),
- hir::IsAsync::NotAsync => ty,
- };
- if self.can_coerce(found, ty) {
- err.multipart_suggestion(
- "you might have meant to return this value",
- vec![
- (expr.span.shrink_to_lo(), "return ".to_string()),
- (expr.span.shrink_to_hi(), ";".to_string()),
- ],
- Applicability::MaybeIncorrect,
- );
- }
- }
- }
-
- pub(in super::super) fn suggest_missing_parentheses(
- &self,
- err: &mut Diagnostic,
- expr: &hir::Expr<'_>,
- ) {
- let sp = self.tcx.sess.source_map().start_point(expr.span);
- if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) {
- // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }`
- self.tcx.sess.parse_sess.expr_parentheses_needed(err, *sp);
- }
- }
-
- /// Given an expression type mismatch, peel any `&` expressions until we get to
- /// a block expression, and then suggest replacing the braces with square braces
- /// if it was possibly mistaken array syntax.
- pub(crate) fn suggest_block_to_brackets_peeling_refs(
- &self,
- diag: &mut Diagnostic,
- mut expr: &hir::Expr<'_>,
- mut expr_ty: Ty<'tcx>,
- mut expected_ty: Ty<'tcx>,
- ) {
- loop {
- match (&expr.kind, expr_ty.kind(), expected_ty.kind()) {
- (
- hir::ExprKind::AddrOf(_, _, inner_expr),
- ty::Ref(_, inner_expr_ty, _),
- ty::Ref(_, inner_expected_ty, _),
- ) => {
- expr = *inner_expr;
- expr_ty = *inner_expr_ty;
- expected_ty = *inner_expected_ty;
- }
- (hir::ExprKind::Block(blk, _), _, _) => {
- self.suggest_block_to_brackets(diag, *blk, expr_ty, expected_ty);
- break;
- }
- _ => break,
- }
- }
- }
-
- /// 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(
- &self,
- diag: &mut Diagnostic,
- blk: &hir::Block<'_>,
- blk_ty: Ty<'tcx>,
- expected_ty: Ty<'tcx>,
- ) {
- if let ty::Slice(elem_ty) | ty::Array(elem_ty, _) = expected_ty.kind() {
- if self.can_coerce(blk_ty, *elem_ty)
- && blk.stmts.is_empty()
- && blk.rules == hir::BlockCheckMode::DefaultBlock
- {
- let source_map = self.tcx.sess.source_map();
- if let Ok(snippet) = source_map.span_to_snippet(blk.span) {
- if snippet.starts_with('{') && snippet.ends_with('}') {
- diag.multipart_suggestion_verbose(
- "to create an array, use square brackets instead of curly braces",
- vec![
- (
- blk.span
- .shrink_to_lo()
- .with_hi(rustc_span::BytePos(blk.span.lo().0 + 1)),
- "[".to_string(),
- ),
- (
- blk.span
- .shrink_to_hi()
- .with_lo(rustc_span::BytePos(blk.span.hi().0 - 1)),
- "]".to_string(),
- ),
- ],
- Applicability::MachineApplicable,
- );
- }
- }
- }
- }
- }
-
- fn is_loop(&self, id: hir::HirId) -> bool {
- let node = self.tcx.hir().get(id);
- matches!(node, Node::Expr(Expr { kind: ExprKind::Loop(..), .. }))
- }
-
- fn is_local_statement(&self, id: hir::HirId) -> bool {
- let node = self.tcx.hir().get(id);
- matches!(node, Node::Stmt(Stmt { kind: StmtKind::Local(..), .. }))
- }
-
- /// Suggest that `&T` was cloned instead of `T` because `T` does not implement `Clone`,
- /// which is a side-effect of autoref.
- pub(crate) fn note_type_is_not_clone(
- &self,
- diag: &mut Diagnostic,
- expected_ty: Ty<'tcx>,
- found_ty: Ty<'tcx>,
- expr: &hir::Expr<'_>,
- ) {
- let hir::ExprKind::MethodCall(segment, &[ref 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();
- // First, look for a `Clone::clone` call
- if segment.ident.name == sym::clone
- && results.type_dependent_def_id(expr.hir_id).map_or(
- false,
- |did| {
- let assoc_item = self.tcx.associated_item(did);
- assoc_item.container == ty::AssocItemContainer::TraitContainer
- && assoc_item.container_id(self.tcx) == clone_trait_did
- },
- )
- // If that clone call hasn't already dereferenced the self type (i.e. don't give this
- // diagnostic in cases where we have `(&&T).clone()` and we expect `T`).
- && !results.expr_adjustments(callee_expr).iter().any(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(..)))
- // Check that we're in fact trying to clone into the expected type
- && self.can_coerce(*pointee_ty, expected_ty)
- // And the expected type doesn't implement `Clone`
- && !self.predicate_must_hold_considering_regions(&traits::Obligation {
- cause: traits::ObligationCause::dummy(),
- param_env: self.param_env,
- recursion_depth: 0,
- predicate: ty::Binder::dummy(ty::TraitRef {
- def_id: clone_trait_did,
- substs: self.tcx.mk_substs([expected_ty.into()].iter()),
- })
- .without_const()
- .to_predicate(self.tcx),
- })
- {
- diag.span_note(
- callee_expr.span,
- &format!(
- "`{expected_ty}` does not implement `Clone`, so `{found_ty}` was cloned instead"
- ),
- );
- }
- }
-
- /// A common error is to add an extra semicolon:
- ///
- /// ```compile_fail,E0308
- /// fn foo() -> usize {
- /// 22;
- /// }
- /// ```
- ///
- /// This routine checks if the final statement in a block is an
- /// expression with an explicit semicolon whose type is compatible
- /// with `expected_ty`. If so, it suggests removing the semicolon.
- pub(crate) fn consider_removing_semicolon(
- &self,
- blk: &'tcx hir::Block<'tcx>,
- expected_ty: Ty<'tcx>,
- err: &mut Diagnostic,
- ) -> bool {
- if let Some((span_semi, boxed)) = self.could_remove_semicolon(blk, expected_ty) {
- if let StatementAsExpression::NeedsBoxing = boxed {
- err.span_suggestion_verbose(
- span_semi,
- "consider removing this semicolon and boxing the expression",
- "",
- Applicability::HasPlaceholders,
- );
- } else {
- err.span_suggestion_short(
- span_semi,
- "remove this semicolon",
- "",
- Applicability::MachineApplicable,
- );
- }
- true
- } else {
- false
- }
- }
-}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-09 15:38:19 +0000