| use crate::check::FnCtxt; |
| use rustc_infer::infer::InferOk; |
| use rustc_trait_selection::infer::InferCtxtExt as _; |
| use rustc_trait_selection::traits::ObligationCause; |
| |
| use rustc_ast::util::parser::PREC_POSTFIX; |
| use rustc_errors::{Applicability, DiagnosticBuilder}; |
| use rustc_hir as hir; |
| use rustc_hir::lang_items::CloneTraitLangItem; |
| use rustc_hir::{is_range_literal, Node}; |
| use rustc_middle::ty::adjustment::AllowTwoPhase; |
| use rustc_middle::ty::{self, AssocItem, Ty, TypeAndMut}; |
| use rustc_span::symbol::sym; |
| use rustc_span::Span; |
| |
| use super::method::probe; |
| |
| use std::fmt; |
| |
| impl<'a, 'tcx> FnCtxt<'a, 'tcx> { |
| pub fn emit_coerce_suggestions( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr<'_>, |
| expr_ty: Ty<'tcx>, |
| expected: Ty<'tcx>, |
| expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, |
| ) { |
| self.annotate_expected_due_to_let_ty(err, expr); |
| self.suggest_compatible_variants(err, expr, expected, expr_ty); |
| self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr); |
| if self.suggest_calling_boxed_future_when_appropriate(err, expr, expected, expr_ty) { |
| return; |
| } |
| self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty); |
| self.suggest_missing_await(err, expr, expected, expr_ty); |
| self.note_need_for_fn_pointer(err, expected, expr_ty); |
| } |
| |
| // Requires that the two types unify, and prints an error message if |
| // they don't. |
| pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) { |
| if let Some(mut e) = self.demand_suptype_diag(sp, expected, actual) { |
| e.emit(); |
| } |
| } |
| |
| pub fn demand_suptype_diag( |
| &self, |
| sp: Span, |
| expected: Ty<'tcx>, |
| actual: Ty<'tcx>, |
| ) -> Option<DiagnosticBuilder<'tcx>> { |
| self.demand_suptype_with_origin(&self.misc(sp), expected, actual) |
| } |
| |
| pub fn demand_suptype_with_origin( |
| &self, |
| cause: &ObligationCause<'tcx>, |
| expected: Ty<'tcx>, |
| actual: Ty<'tcx>, |
| ) -> Option<DiagnosticBuilder<'tcx>> { |
| match self.at(cause, self.param_env).sup(expected, actual) { |
| Ok(InferOk { obligations, value: () }) => { |
| self.register_predicates(obligations); |
| None |
| } |
| Err(e) => Some(self.report_mismatched_types(&cause, expected, actual, e)), |
| } |
| } |
| |
| pub fn demand_eqtype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) { |
| if let Some(mut err) = self.demand_eqtype_diag(sp, expected, actual) { |
| err.emit(); |
| } |
| } |
| |
| pub fn demand_eqtype_diag( |
| &self, |
| sp: Span, |
| expected: Ty<'tcx>, |
| actual: Ty<'tcx>, |
| ) -> Option<DiagnosticBuilder<'tcx>> { |
| self.demand_eqtype_with_origin(&self.misc(sp), expected, actual) |
| } |
| |
| pub fn demand_eqtype_with_origin( |
| &self, |
| cause: &ObligationCause<'tcx>, |
| expected: Ty<'tcx>, |
| actual: Ty<'tcx>, |
| ) -> Option<DiagnosticBuilder<'tcx>> { |
| match self.at(cause, self.param_env).eq(expected, actual) { |
| Ok(InferOk { obligations, value: () }) => { |
| self.register_predicates(obligations); |
| None |
| } |
| Err(e) => Some(self.report_mismatched_types(cause, expected, actual, e)), |
| } |
| } |
| |
| pub fn demand_coerce( |
| &self, |
| expr: &hir::Expr<'_>, |
| checked_ty: Ty<'tcx>, |
| expected: Ty<'tcx>, |
| expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, |
| allow_two_phase: AllowTwoPhase, |
| ) -> Ty<'tcx> { |
| let (ty, err) = |
| self.demand_coerce_diag(expr, checked_ty, expected, expected_ty_expr, allow_two_phase); |
| if let Some(mut err) = err { |
| err.emit(); |
| } |
| ty |
| } |
| |
| // Checks that the type of `expr` can be coerced to `expected`. |
| // |
| // N.B., this code relies on `self.diverges` to be accurate. In |
| // particular, assignments to `!` will be permitted if the |
| // diverges flag is currently "always". |
| pub fn demand_coerce_diag( |
| &self, |
| expr: &hir::Expr<'_>, |
| checked_ty: Ty<'tcx>, |
| expected: Ty<'tcx>, |
| expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, |
| allow_two_phase: AllowTwoPhase, |
| ) -> (Ty<'tcx>, Option<DiagnosticBuilder<'tcx>>) { |
| let expected = self.resolve_vars_with_obligations(expected); |
| |
| let e = match self.try_coerce(expr, checked_ty, expected, allow_two_phase) { |
| Ok(ty) => return (ty, None), |
| Err(e) => e, |
| }; |
| |
| let expr = expr.peel_drop_temps(); |
| let cause = self.misc(expr.span); |
| let expr_ty = self.resolve_vars_with_obligations(checked_ty); |
| let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e); |
| |
| if self.is_assign_to_bool(expr, expected) { |
| // Error reported in `check_assign` so avoid emitting error again. |
| err.delay_as_bug(); |
| return (expected, None); |
| } |
| |
| self.emit_coerce_suggestions(&mut err, expr, expr_ty, expected, expected_ty_expr); |
| |
| (expected, Some(err)) |
| } |
| |
| fn annotate_expected_due_to_let_ty( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr<'_>, |
| ) { |
| let parent = self.tcx.hir().get_parent_node(expr.hir_id); |
| if let Some(hir::Node::Local(hir::Local { ty: Some(ty), init: Some(init), .. })) = |
| self.tcx.hir().find(parent) |
| { |
| if init.hir_id == expr.hir_id { |
| // Point at `let` assignment type. |
| err.span_label(ty.span, "expected due to this"); |
| } |
| } |
| } |
| |
| /// Returns whether the expected type is `bool` and the expression is `x = y`. |
| pub fn is_assign_to_bool(&self, expr: &hir::Expr<'_>, expected: Ty<'tcx>) -> bool { |
| if let hir::ExprKind::Assign(..) = expr.kind { |
| return expected == self.tcx.types.bool; |
| } |
| false |
| } |
| |
| /// If the expected type is an enum (Issue #55250) with any variants whose |
| /// sole field is of the found type, suggest such variants. (Issue #42764) |
| fn suggest_compatible_variants( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr<'_>, |
| expected: Ty<'tcx>, |
| expr_ty: Ty<'tcx>, |
| ) { |
| if let ty::Adt(expected_adt, substs) = expected.kind { |
| if !expected_adt.is_enum() { |
| return; |
| } |
| |
| let mut compatible_variants = expected_adt |
| .variants |
| .iter() |
| .filter(|variant| variant.fields.len() == 1) |
| .filter_map(|variant| { |
| let sole_field = &variant.fields[0]; |
| let sole_field_ty = sole_field.ty(self.tcx, substs); |
| if self.can_coerce(expr_ty, sole_field_ty) { |
| let variant_path = self.tcx.def_path_str(variant.def_id); |
| // FIXME #56861: DRYer prelude filtering |
| Some(variant_path.trim_start_matches("std::prelude::v1::").to_string()) |
| } else { |
| None |
| } |
| }) |
| .peekable(); |
| |
| if compatible_variants.peek().is_some() { |
| if let Ok(expr_text) = self.tcx.sess.source_map().span_to_snippet(expr.span) { |
| let suggestions = compatible_variants.map(|v| format!("{}({})", v, expr_text)); |
| let msg = "try using a variant of the expected enum"; |
| err.span_suggestions( |
| expr.span, |
| msg, |
| suggestions, |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| } |
| } |
| |
| pub fn get_conversion_methods( |
| &self, |
| span: Span, |
| expected: Ty<'tcx>, |
| checked_ty: Ty<'tcx>, |
| hir_id: hir::HirId, |
| ) -> Vec<AssocItem> { |
| let mut methods = |
| self.probe_for_return_type(span, probe::Mode::MethodCall, expected, checked_ty, hir_id); |
| methods.retain(|m| { |
| self.has_only_self_parameter(m) |
| && self |
| .tcx |
| .get_attrs(m.def_id) |
| .iter() |
| // This special internal attribute is used to permit |
| // "identity-like" conversion methods to be suggested here. |
| // |
| // FIXME (#46459 and #46460): ideally |
| // `std::convert::Into::into` and `std::borrow:ToOwned` would |
| // also be `#[rustc_conversion_suggestion]`, if not for |
| // method-probing false-positives and -negatives (respectively). |
| // |
| // FIXME? Other potential candidate methods: `as_ref` and |
| // `as_mut`? |
| .any(|a| a.check_name(sym::rustc_conversion_suggestion)) |
| }); |
| |
| methods |
| } |
| |
| /// This function checks whether the method is not static and does not accept other parameters than `self`. |
| fn has_only_self_parameter(&self, method: &AssocItem) -> bool { |
| match method.kind { |
| ty::AssocKind::Fn => { |
| method.fn_has_self_parameter |
| && self.tcx.fn_sig(method.def_id).inputs().skip_binder().len() == 1 |
| } |
| _ => false, |
| } |
| } |
| |
| /// Identify some cases where `as_ref()` would be appropriate and suggest it. |
| /// |
| /// Given the following code: |
| /// ``` |
| /// struct Foo; |
| /// fn takes_ref(_: &Foo) {} |
| /// let ref opt = Some(Foo); |
| /// |
| /// opt.map(|param| takes_ref(param)); |
| /// ``` |
| /// Suggest using `opt.as_ref().map(|param| takes_ref(param));` instead. |
| /// |
| /// It only checks for `Option` and `Result` and won't work with |
| /// ``` |
| /// opt.map(|param| { takes_ref(param) }); |
| /// ``` |
| fn can_use_as_ref(&self, expr: &hir::Expr<'_>) -> Option<(Span, &'static str, String)> { |
| let path = match expr.kind { |
| hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) => path, |
| _ => return None, |
| }; |
| |
| let local_id = match path.res { |
| hir::def::Res::Local(id) => id, |
| _ => return None, |
| }; |
| |
| let local_parent = self.tcx.hir().get_parent_node(local_id); |
| let param_hir_id = match self.tcx.hir().find(local_parent) { |
| Some(Node::Param(hir::Param { hir_id, .. })) => hir_id, |
| _ => return None, |
| }; |
| |
| let param_parent = self.tcx.hir().get_parent_node(*param_hir_id); |
| let (expr_hir_id, closure_fn_decl) = match self.tcx.hir().find(param_parent) { |
| Some(Node::Expr(hir::Expr { |
| hir_id, |
| kind: hir::ExprKind::Closure(_, decl, ..), |
| .. |
| })) => (hir_id, decl), |
| _ => return None, |
| }; |
| |
| let expr_parent = self.tcx.hir().get_parent_node(*expr_hir_id); |
| let hir = self.tcx.hir().find(expr_parent); |
| let closure_params_len = closure_fn_decl.inputs.len(); |
| let (method_path, method_span, method_expr) = match (hir, closure_params_len) { |
| ( |
| Some(Node::Expr(hir::Expr { |
| kind: hir::ExprKind::MethodCall(path, span, expr, _), |
| .. |
| })), |
| 1, |
| ) => (path, span, expr), |
| _ => return None, |
| }; |
| |
| let self_ty = self.tables.borrow().node_type(method_expr[0].hir_id); |
| let self_ty = format!("{:?}", self_ty); |
| let name = method_path.ident.as_str(); |
| let is_as_ref_able = (self_ty.starts_with("&std::option::Option") |
| || self_ty.starts_with("&std::result::Result") |
| || self_ty.starts_with("std::option::Option") |
| || self_ty.starts_with("std::result::Result")) |
| && (name == "map" || name == "and_then"); |
| match (is_as_ref_able, self.sess().source_map().span_to_snippet(*method_span)) { |
| (true, Ok(src)) => { |
| let suggestion = format!("as_ref().{}", src); |
| Some((*method_span, "consider using `as_ref` instead", suggestion)) |
| } |
| _ => None, |
| } |
| } |
| |
| crate fn is_hir_id_from_struct_pattern_shorthand_field( |
| &self, |
| hir_id: hir::HirId, |
| sp: Span, |
| ) -> bool { |
| let sm = self.sess().source_map(); |
| let parent_id = self.tcx.hir().get_parent_node(hir_id); |
| if let Some(parent) = self.tcx.hir().find(parent_id) { |
| // Account for fields |
| if let Node::Expr(hir::Expr { kind: hir::ExprKind::Struct(_, fields, ..), .. }) = parent |
| { |
| if let Ok(src) = sm.span_to_snippet(sp) { |
| for field in *fields { |
| if field.ident.as_str() == src && field.is_shorthand { |
| return true; |
| } |
| } |
| } |
| } |
| } |
| false |
| } |
| |
| fn replace_prefix<A, B, C>(&self, s: A, old: B, new: C) -> Option<String> |
| where |
| A: AsRef<str>, |
| B: AsRef<str>, |
| C: AsRef<str>, |
| { |
| let s = s.as_ref(); |
| let old = old.as_ref(); |
| if s.starts_with(old) { Some(new.as_ref().to_owned() + &s[old.len()..]) } else { None } |
| } |
| |
| /// This function is used to determine potential "simple" improvements or users' errors and |
| /// provide them useful help. For example: |
| /// |
| /// ``` |
| /// fn some_fn(s: &str) {} |
| /// |
| /// let x = "hey!".to_owned(); |
| /// some_fn(x); // error |
| /// ``` |
| /// |
| /// No need to find every potential function which could make a coercion to transform a |
| /// `String` into a `&str` since a `&` would do the trick! |
| /// |
| /// In addition of this check, it also checks between references mutability state. If the |
| /// expected is mutable but the provided isn't, maybe we could just say "Hey, try with |
| /// `&mut`!". |
| pub fn check_ref( |
| &self, |
| expr: &hir::Expr<'_>, |
| checked_ty: Ty<'tcx>, |
| expected: Ty<'tcx>, |
| ) -> Option<(Span, &'static str, String, Applicability)> { |
| let sm = self.sess().source_map(); |
| let sp = expr.span; |
| if sm.is_imported(sp) { |
| // Ignore if span is from within a macro #41858, #58298. We previously used the macro |
| // call span, but that breaks down when the type error comes from multiple calls down. |
| return None; |
| } |
| |
| let is_struct_pat_shorthand_field = |
| self.is_hir_id_from_struct_pattern_shorthand_field(expr.hir_id, sp); |
| |
| // If the span is from a macro, then it's hard to extract the text |
| // and make a good suggestion, so don't bother. |
| let is_macro = sp.from_expansion() && sp.desugaring_kind().is_none(); |
| |
| // `ExprKind::DropTemps` is semantically irrelevant for these suggestions. |
| let expr = expr.peel_drop_temps(); |
| |
| match (&expr.kind, &expected.kind, &checked_ty.kind) { |
| (_, &ty::Ref(_, exp, _), &ty::Ref(_, check, _)) => match (&exp.kind, &check.kind) { |
| (&ty::Str, &ty::Array(arr, _) | &ty::Slice(arr)) if arr == self.tcx.types.u8 => { |
| if let hir::ExprKind::Lit(_) = expr.kind { |
| if let Ok(src) = sm.span_to_snippet(sp) { |
| if let Some(src) = self.replace_prefix(src, "b\"", "\"") { |
| return Some(( |
| sp, |
| "consider removing the leading `b`", |
| src, |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| } |
| } |
| (&ty::Array(arr, _) | &ty::Slice(arr), &ty::Str) if arr == self.tcx.types.u8 => { |
| if let hir::ExprKind::Lit(_) = expr.kind { |
| if let Ok(src) = sm.span_to_snippet(sp) { |
| if let Some(src) = self.replace_prefix(src, "\"", "b\"") { |
| return Some(( |
| sp, |
| "consider adding a leading `b`", |
| src, |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| } |
| } |
| _ => {} |
| }, |
| (_, &ty::Ref(_, _, mutability), _) => { |
| // Check if it can work when put into a ref. For example: |
| // |
| // ``` |
| // fn bar(x: &mut i32) {} |
| // |
| // let x = 0u32; |
| // bar(&x); // error, expected &mut |
| // ``` |
| let ref_ty = match mutability { |
| hir::Mutability::Mut => { |
| self.tcx.mk_mut_ref(self.tcx.mk_region(ty::ReStatic), checked_ty) |
| } |
| hir::Mutability::Not => { |
| self.tcx.mk_imm_ref(self.tcx.mk_region(ty::ReStatic), checked_ty) |
| } |
| }; |
| if self.can_coerce(ref_ty, expected) { |
| let mut sugg_sp = sp; |
| if let hir::ExprKind::MethodCall(ref segment, sp, ref args, _) = expr.kind { |
| let clone_trait = self.tcx.require_lang_item(CloneTraitLangItem, Some(sp)); |
| if let ([arg], Some(true), sym::clone) = ( |
| &args[..], |
| self.tables.borrow().type_dependent_def_id(expr.hir_id).map(|did| { |
| let ai = self.tcx.associated_item(did); |
| ai.container == ty::TraitContainer(clone_trait) |
| }), |
| segment.ident.name, |
| ) { |
| // If this expression had a clone call when suggesting borrowing |
| // we want to suggest removing it because it'd now be unnecessary. |
| sugg_sp = arg.span; |
| } |
| } |
| if let Ok(src) = sm.span_to_snippet(sugg_sp) { |
| let needs_parens = match expr.kind { |
| // parenthesize if needed (Issue #46756) |
| hir::ExprKind::Cast(_, _) | hir::ExprKind::Binary(_, _, _) => true, |
| // parenthesize borrows of range literals (Issue #54505) |
| _ if is_range_literal(self.tcx.sess.source_map(), expr) => true, |
| _ => false, |
| }; |
| let sugg_expr = if needs_parens { format!("({})", src) } else { src }; |
| |
| if let Some(sugg) = self.can_use_as_ref(expr) { |
| return Some(( |
| sugg.0, |
| sugg.1, |
| sugg.2, |
| Applicability::MachineApplicable, |
| )); |
| } |
| let field_name = if is_struct_pat_shorthand_field { |
| format!("{}: ", sugg_expr) |
| } else { |
| String::new() |
| }; |
| if let Some(hir::Node::Expr(hir::Expr { |
| kind: hir::ExprKind::Assign(left_expr, ..), |
| .. |
| })) = self.tcx.hir().find(self.tcx.hir().get_parent_node(expr.hir_id)) |
| { |
| if mutability == hir::Mutability::Mut { |
| // Found the following case: |
| // fn foo(opt: &mut Option<String>){ opt = None } |
| // --- ^^^^ |
| // | | |
| // consider dereferencing here: `*opt` | |
| // expected mutable reference, found enum `Option` |
| if let Ok(src) = sm.span_to_snippet(left_expr.span) { |
| return Some(( |
| left_expr.span, |
| "consider dereferencing here to assign to the mutable \ |
| borrowed piece of memory", |
| format!("*{}", src), |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| } |
| |
| return Some(match mutability { |
| hir::Mutability::Mut => ( |
| sp, |
| "consider mutably borrowing here", |
| format!("{}&mut {}", field_name, sugg_expr), |
| Applicability::MachineApplicable, |
| ), |
| hir::Mutability::Not => ( |
| sp, |
| "consider borrowing here", |
| format!("{}&{}", field_name, sugg_expr), |
| Applicability::MachineApplicable, |
| ), |
| }); |
| } |
| } |
| } |
| ( |
| hir::ExprKind::AddrOf(hir::BorrowKind::Ref, _, ref expr), |
| _, |
| &ty::Ref(_, checked, _), |
| ) if { |
| self.infcx.can_sub(self.param_env, checked, &expected).is_ok() && !is_macro |
| } => |
| { |
| // We have `&T`, check if what was expected was `T`. If so, |
| // we may want to suggest removing a `&`. |
| if sm.is_imported(expr.span) { |
| if let Ok(src) = sm.span_to_snippet(sp) { |
| if let Some(src) = self.replace_prefix(src, "&", "") { |
| return Some(( |
| sp, |
| "consider removing the borrow", |
| src, |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| return None; |
| } |
| if let Ok(code) = sm.span_to_snippet(expr.span) { |
| return Some(( |
| sp, |
| "consider removing the borrow", |
| code, |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| ( |
| _, |
| &ty::RawPtr(TypeAndMut { ty: ty_b, mutbl: mutbl_b }), |
| &ty::Ref(_, ty_a, mutbl_a), |
| ) => { |
| if let Some(steps) = self.deref_steps(ty_a, ty_b) { |
| // Only suggest valid if dereferencing needed. |
| if steps > 0 { |
| // The pointer type implements `Copy` trait so the suggestion is always valid. |
| if let Ok(src) = sm.span_to_snippet(sp) { |
| let derefs = &"*".repeat(steps); |
| if let Some((src, applicability)) = match mutbl_b { |
| hir::Mutability::Mut => { |
| let new_prefix = "&mut ".to_owned() + derefs; |
| match mutbl_a { |
| hir::Mutability::Mut => { |
| if let Some(s) = |
| self.replace_prefix(src, "&mut ", new_prefix) |
| { |
| Some((s, Applicability::MachineApplicable)) |
| } else { |
| None |
| } |
| } |
| hir::Mutability::Not => { |
| if let Some(s) = |
| self.replace_prefix(src, "&", new_prefix) |
| { |
| Some((s, Applicability::Unspecified)) |
| } else { |
| None |
| } |
| } |
| } |
| } |
| hir::Mutability::Not => { |
| let new_prefix = "&".to_owned() + derefs; |
| match mutbl_a { |
| hir::Mutability::Mut => { |
| if let Some(s) = |
| self.replace_prefix(src, "&mut ", new_prefix) |
| { |
| Some((s, Applicability::MachineApplicable)) |
| } else { |
| None |
| } |
| } |
| hir::Mutability::Not => { |
| if let Some(s) = |
| self.replace_prefix(src, "&", new_prefix) |
| { |
| Some((s, Applicability::MachineApplicable)) |
| } else { |
| None |
| } |
| } |
| } |
| } |
| } { |
| return Some((sp, "consider dereferencing", src, applicability)); |
| } |
| } |
| } |
| } |
| } |
| _ if sp == expr.span && !is_macro => { |
| if let Some(steps) = self.deref_steps(checked_ty, expected) { |
| if steps == 1 { |
| // For a suggestion to make sense, the type would need to be `Copy`. |
| if self.infcx.type_is_copy_modulo_regions(self.param_env, expected, sp) { |
| if let Ok(code) = sm.span_to_snippet(sp) { |
| let message = if checked_ty.is_region_ptr() { |
| "consider dereferencing the borrow" |
| } else { |
| "consider dereferencing the type" |
| }; |
| let suggestion = if is_struct_pat_shorthand_field { |
| format!("{}: *{}", code, code) |
| } else { |
| format!("*{}", code) |
| }; |
| return Some(( |
| sp, |
| message, |
| suggestion, |
| Applicability::MachineApplicable, |
| )); |
| } |
| } |
| } |
| } |
| } |
| _ => {} |
| } |
| None |
| } |
| |
| pub fn check_for_cast( |
| &self, |
| err: &mut DiagnosticBuilder<'_>, |
| expr: &hir::Expr<'_>, |
| checked_ty: Ty<'tcx>, |
| expected_ty: Ty<'tcx>, |
| expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>, |
| ) -> bool { |
| if self.tcx.sess.source_map().is_imported(expr.span) { |
| // Ignore if span is from within a macro. |
| return false; |
| } |
| |
| let src = if let Ok(src) = self.tcx.sess.source_map().span_to_snippet(expr.span) { |
| src |
| } else { |
| return false; |
| }; |
| |
| // If casting this expression to a given numeric type would be appropriate in case of a type |
| // mismatch. |
| // |
| // We want to minimize the amount of casting operations that are suggested, as it can be a |
| // lossy operation with potentially bad side effects, so we only suggest when encountering |
| // an expression that indicates that the original type couldn't be directly changed. |
| // |
| // For now, don't suggest casting with `as`. |
| let can_cast = false; |
| |
| let prefix = if let Some(hir::Node::Expr(hir::Expr { |
| kind: hir::ExprKind::Struct(_, fields, _), |
| .. |
| })) = self.tcx.hir().find(self.tcx.hir().get_parent_node(expr.hir_id)) |
| { |
| // `expr` is a literal field for a struct, only suggest if appropriate |
| match (*fields) |
| .iter() |
| .find(|field| field.expr.hir_id == expr.hir_id && field.is_shorthand) |
| { |
| // This is a field literal |
| Some(field) => format!("{}: ", field.ident), |
| // Likely a field was meant, but this field wasn't found. Do not suggest anything. |
| None => return false, |
| } |
| } else { |
| String::new() |
| }; |
| |
| if let hir::ExprKind::Call(path, args) = &expr.kind { |
| if let (hir::ExprKind::Path(hir::QPath::TypeRelative(base_ty, path_segment)), 1) = |
| (&path.kind, args.len()) |
| { |
| // `expr` is a conversion like `u32::from(val)`, do not suggest anything (#63697). |
| if let (hir::TyKind::Path(hir::QPath::Resolved(None, base_ty_path)), sym::from) = |
| (&base_ty.kind, path_segment.ident.name) |
| { |
| if let Some(ident) = &base_ty_path.segments.iter().map(|s| s.ident).next() { |
| match ident.name { |
| sym::i128 |
| | sym::i64 |
| | sym::i32 |
| | sym::i16 |
| | sym::i8 |
| | sym::u128 |
| | sym::u64 |
| | sym::u32 |
| | sym::u16 |
| | sym::u8 |
| | sym::isize |
| | sym::usize |
| if base_ty_path.segments.len() == 1 => |
| { |
| return false; |
| } |
| _ => {} |
| } |
| } |
| } |
| } |
| } |
| |
| let msg = format!("you can convert an `{}` to `{}`", checked_ty, expected_ty); |
| let cast_msg = format!("you can cast an `{} to `{}`", checked_ty, expected_ty); |
| let lit_msg = format!( |
| "change the type of the numeric literal from `{}` to `{}`", |
| checked_ty, expected_ty, |
| ); |
| |
| let with_opt_paren: fn(&dyn fmt::Display) -> String = |
| if expr.precedence().order() < PREC_POSTFIX { |
| |s| format!("({})", s) |
| } else { |
| |s| s.to_string() |
| }; |
| |
| let cast_suggestion = format!("{}{} as {}", prefix, with_opt_paren(&src), expected_ty); |
| let into_suggestion = format!("{}{}.into()", prefix, with_opt_paren(&src)); |
| let suffix_suggestion = with_opt_paren(&format_args!( |
| "{}{}", |
| if matches!( |
| (&expected_ty.kind, &checked_ty.kind), |
| (ty::Int(_) | ty::Uint(_), ty::Float(_)) |
| ) { |
| // Remove fractional part from literal, for example `42.0f32` into `42` |
| let src = src.trim_end_matches(&checked_ty.to_string()); |
| src.split('.').next().unwrap() |
| } else { |
| src.trim_end_matches(&checked_ty.to_string()) |
| }, |
| expected_ty, |
| )); |
| let literal_is_ty_suffixed = |expr: &hir::Expr<'_>| { |
| if let hir::ExprKind::Lit(lit) = &expr.kind { lit.node.is_suffixed() } else { false } |
| }; |
| let is_negative_int = |
| |expr: &hir::Expr<'_>| matches!(expr.kind, hir::ExprKind::Unary(hir::UnOp::UnNeg, ..)); |
| let is_uint = |ty: Ty<'_>| matches!(ty.kind, ty::Uint(..)); |
| |
| let in_const_context = self.tcx.hir().is_inside_const_context(expr.hir_id); |
| |
| let suggest_fallible_into_or_lhs_from = |
| |err: &mut DiagnosticBuilder<'_>, exp_to_found_is_fallible: bool| { |
| // If we know the expression the expected type is derived from, we might be able |
| // to suggest a widening conversion rather than a narrowing one (which may |
| // panic). For example, given x: u8 and y: u32, if we know the span of "x", |
| // x > y |
| // can be given the suggestion "u32::from(x) > y" rather than |
| // "x > y.try_into().unwrap()". |
| let lhs_expr_and_src = expected_ty_expr.and_then(|expr| { |
| match self.tcx.sess.source_map().span_to_snippet(expr.span).ok() { |
| Some(src) => Some((expr, src)), |
| None => None, |
| } |
| }); |
| let (span, msg, suggestion) = if let (Some((lhs_expr, lhs_src)), false) = |
| (lhs_expr_and_src, exp_to_found_is_fallible) |
| { |
| let msg = format!( |
| "you can convert `{}` from `{}` to `{}`, matching the type of `{}`", |
| lhs_src, expected_ty, checked_ty, src |
| ); |
| let suggestion = format!("{}::from({})", checked_ty, lhs_src); |
| (lhs_expr.span, msg, suggestion) |
| } else { |
| let msg = format!("{} and panic if the converted value wouldn't fit", msg); |
| let suggestion = |
| format!("{}{}.try_into().unwrap()", prefix, with_opt_paren(&src)); |
| (expr.span, msg, suggestion) |
| }; |
| err.span_suggestion(span, &msg, suggestion, Applicability::MachineApplicable); |
| }; |
| |
| let suggest_to_change_suffix_or_into = |
| |err: &mut DiagnosticBuilder<'_>, |
| found_to_exp_is_fallible: bool, |
| exp_to_found_is_fallible: bool| { |
| let always_fallible = found_to_exp_is_fallible |
| && (exp_to_found_is_fallible || expected_ty_expr.is_none()); |
| let msg = if literal_is_ty_suffixed(expr) { |
| &lit_msg |
| } else if always_fallible && (is_negative_int(expr) && is_uint(expected_ty)) { |
| // We now know that converting either the lhs or rhs is fallible. Before we |
| // suggest a fallible conversion, check if the value can never fit in the |
| // expected type. |
| let msg = format!("`{}` cannot fit into type `{}`", src, expected_ty); |
| err.note(&msg); |
| return; |
| } else if in_const_context { |
| // Do not recommend `into` or `try_into` in const contexts. |
| return; |
| } else if found_to_exp_is_fallible { |
| return suggest_fallible_into_or_lhs_from(err, exp_to_found_is_fallible); |
| } else { |
| &msg |
| }; |
| let suggestion = if literal_is_ty_suffixed(expr) { |
| suffix_suggestion.clone() |
| } else { |
| into_suggestion.clone() |
| }; |
| err.span_suggestion(expr.span, msg, suggestion, Applicability::MachineApplicable); |
| }; |
| |
| match (&expected_ty.kind, &checked_ty.kind) { |
| (&ty::Int(ref exp), &ty::Int(ref found)) => { |
| let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width()) |
| { |
| (Some(exp), Some(found)) if exp < found => (true, false), |
| (Some(exp), Some(found)) if exp > found => (false, true), |
| (None, Some(8 | 16)) => (false, true), |
| (Some(8 | 16), None) => (true, false), |
| (None, _) | (_, None) => (true, true), |
| _ => (false, false), |
| }; |
| suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible); |
| true |
| } |
| (&ty::Uint(ref exp), &ty::Uint(ref found)) => { |
| let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width()) |
| { |
| (Some(exp), Some(found)) if exp < found => (true, false), |
| (Some(exp), Some(found)) if exp > found => (false, true), |
| (None, Some(8 | 16)) => (false, true), |
| (Some(8 | 16), None) => (true, false), |
| (None, _) | (_, None) => (true, true), |
| _ => (false, false), |
| }; |
| suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible); |
| true |
| } |
| (&ty::Int(exp), &ty::Uint(found)) => { |
| let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width()) |
| { |
| (Some(exp), Some(found)) if found < exp => (false, true), |
| (None, Some(8)) => (false, true), |
| _ => (true, true), |
| }; |
| suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible); |
| true |
| } |
| (&ty::Uint(exp), &ty::Int(found)) => { |
| let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width()) |
| { |
| (Some(exp), Some(found)) if found > exp => (true, false), |
| (Some(8), None) => (true, false), |
| _ => (true, true), |
| }; |
| suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible); |
| true |
| } |
| (&ty::Float(ref exp), &ty::Float(ref found)) => { |
| if found.bit_width() < exp.bit_width() { |
| suggest_to_change_suffix_or_into(err, false, true); |
| } else if literal_is_ty_suffixed(expr) { |
| err.span_suggestion( |
| expr.span, |
| &lit_msg, |
| suffix_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else if can_cast { |
| // Missing try_into implementation for `f64` to `f32` |
| err.span_suggestion( |
| expr.span, |
| &format!("{}, producing the closest possible value", cast_msg), |
| cast_suggestion, |
| Applicability::MaybeIncorrect, // lossy conversion |
| ); |
| } |
| true |
| } |
| (&ty::Uint(_) | &ty::Int(_), &ty::Float(_)) => { |
| if literal_is_ty_suffixed(expr) { |
| err.span_suggestion( |
| expr.span, |
| &lit_msg, |
| suffix_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else if can_cast { |
| // Missing try_into implementation for `{float}` to `{integer}` |
| err.span_suggestion( |
| expr.span, |
| &format!("{}, rounding the float towards zero", msg), |
| cast_suggestion, |
| Applicability::MaybeIncorrect, // lossy conversion |
| ); |
| } |
| true |
| } |
| (&ty::Float(ref exp), &ty::Uint(ref found)) => { |
| // if `found` is `None` (meaning found is `usize`), don't suggest `.into()` |
| if exp.bit_width() > found.bit_width().unwrap_or(256) { |
| err.span_suggestion( |
| expr.span, |
| &format!( |
| "{}, producing the floating point representation of the integer", |
| msg, |
| ), |
| into_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else if literal_is_ty_suffixed(expr) { |
| err.span_suggestion( |
| expr.span, |
| &lit_msg, |
| suffix_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| // Missing try_into implementation for `{integer}` to `{float}` |
| err.span_suggestion( |
| expr.span, |
| &format!( |
| "{}, producing the floating point representation of the integer, |
| rounded if necessary", |
| cast_msg, |
| ), |
| cast_suggestion, |
| Applicability::MaybeIncorrect, // lossy conversion |
| ); |
| } |
| true |
| } |
| (&ty::Float(ref exp), &ty::Int(ref found)) => { |
| // if `found` is `None` (meaning found is `isize`), don't suggest `.into()` |
| if exp.bit_width() > found.bit_width().unwrap_or(256) { |
| err.span_suggestion( |
| expr.span, |
| &format!( |
| "{}, producing the floating point representation of the integer", |
| &msg, |
| ), |
| into_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else if literal_is_ty_suffixed(expr) { |
| err.span_suggestion( |
| expr.span, |
| &lit_msg, |
| suffix_suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| // Missing try_into implementation for `{integer}` to `{float}` |
| err.span_suggestion( |
| expr.span, |
| &format!( |
| "{}, producing the floating point representation of the integer, \ |
| rounded if necessary", |
| &msg, |
| ), |
| cast_suggestion, |
| Applicability::MaybeIncorrect, // lossy conversion |
| ); |
| } |
| true |
| } |
| _ => false, |
| } |
| } |
| } |
