-// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-
-use check::FnCtxt;
-use rustc::infer::InferOk;
-use rustc::traits::ObligationCause;
-
-use syntax::ast;
-use syntax_pos::{self, Span};
-use rustc::hir;
-use rustc::hir::def::Def;
-use rustc::ty::{self, Ty, AssociatedItem};
-use errors::DiagnosticBuilder;
+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;
-impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
+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>) {
- let cause = self.misc(sp);
- match self.sub_types(false, &cause, actual, expected) {
+ 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);
- },
- Err(e) => {
- self.report_mismatched_types(&cause, expected, actual, e).emit();
+ None
}
+ Err(e) => Some(self.report_mismatched_types(&cause, expected, actual, e)),
}
}
}
}
- pub fn demand_eqtype_diag(&self,
- sp: Span,
- expected: Ty<'tcx>,
- actual: Ty<'tcx>) -> Option<DiagnosticBuilder<'tcx>> {
+ 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.eq_types(false, cause, actual, expected) {
+ 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))
}
+ 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`.
//
- // NB: This code relies on `self.diverges` to be accurate. In
+ // 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(&self,
- expr: &hir::Expr,
- checked_ty: Ty<'tcx>,
- expected: Ty<'tcx>) {
- let expected = self.resolve_type_vars_with_obligations(expected);
-
- if let Err(e) = self.try_coerce(expr, checked_ty, self.diverges.get(), expected) {
- let cause = self.misc(expr.span);
- let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
- let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
- if let Some(suggestion) = self.check_ref(expr,
- checked_ty,
- expected) {
- err.help(&suggestion);
- } else {
- let mode = probe::Mode::MethodCall;
- let suggestions = self.probe_for_return_type(syntax_pos::DUMMY_SP,
- mode,
- expected,
- checked_ty,
- ast::DUMMY_NODE_ID);
- if suggestions.len() > 0 {
- err.help(&format!("here are some functions which \
- might fulfill your needs:\n{}",
- self.get_best_match(&suggestions).join("\n")));
- }
+ 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");
}
- err.emit();
}
}
- fn format_method_suggestion(&self, method: &AssociatedItem) -> String {
- format!("- .{}({})",
- method.name,
- if self.has_no_input_arg(method) {
- ""
- } else {
- "..."
+ /// 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,
+ );
+ }
+ }
+ }
}
- fn display_suggested_methods(&self, methods: &[AssociatedItem]) -> Vec<String> {
- methods.iter()
- .take(5)
- .map(|method| self.format_method_suggestion(&*method))
- .collect::<Vec<String>>()
+ 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
}
- fn get_best_match(&self, methods: &[AssociatedItem]) -> Vec<String> {
- let no_argument_methods: Vec<_> =
- methods.iter()
- .filter(|ref x| self.has_no_input_arg(&*x))
- .map(|x| x.clone())
- .collect();
- if no_argument_methods.len() > 0 {
- self.display_suggested_methods(&no_argument_methods)
- } else {
- self.display_suggested_methods(&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,
}
}
- // This function checks if the method isn't static and takes other arguments than `self`.
- fn has_no_input_arg(&self, method: &AssociatedItem) -> bool {
- match method.def() {
- Def::Method(def_id) => {
- match self.tcx.item_type(def_id).sty {
- ty::TypeVariants::TyFnDef(_, _, sig) => {
- sig.inputs().skip_binder().len() == 1
+ /// 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,
}
}
- _ => false,
}
+ 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
/// 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`!".
- fn check_ref(&self,
- expr: &hir::Expr,
- checked_ty: Ty<'tcx>,
- expected: Ty<'tcx>)
- -> Option<String> {
- match (&expected.sty, &checked_ty.sty) {
- (&ty::TyRef(_, _), &ty::TyRef(_, _)) => None,
- (&ty::TyRef(_, mutability), _) => {
+ 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:
//
// ```
// let x = 0u32;
// bar(&x); // error, expected &mut
// ```
- let ref_ty = match mutability.mutbl {
- hir::Mutability::MutMutable => self.tcx.mk_mut_ref(
- self.tcx.mk_region(ty::ReStatic),
- checked_ty),
- hir::Mutability::MutImmutable => self.tcx.mk_imm_ref(
- self.tcx.mk_region(ty::ReStatic),
- checked_ty),
+ 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) {
- if let Ok(src) = self.tcx.sess.codemap().span_to_snippet(expr.span) {
- return Some(format!("try with `{}{}`",
- match mutability.mutbl {
- hir::Mutability::MutMutable => "&mut ",
- hir::Mutability::MutImmutable => "&",
- },
- &src));
+ 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,
+ ),
+ });
}
}
- None
}
- _ => None,
+ (
+ 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,
}
}
}
projects / rustc.git / blobdiff