use crate::FnCtxt;
use rustc_ast::util::parser::PREC_POSTFIX;
+use rustc_data_structures::fx::FxHashMap;
use rustc_errors::MultiSpan;
use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
use rustc_hir as hir;
use rustc_hir::def::CtorKind;
+use rustc_hir::intravisit::Visitor;
use rustc_hir::lang_items::LangItem;
use rustc_hir::{is_range_literal, Node};
use rustc_infer::infer::InferOk;
use rustc_middle::middle::stability::EvalResult;
use rustc_middle::ty::adjustment::AllowTwoPhase;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::print::with_no_trimmed_paths;
-use rustc_middle::ty::{self, Article, AssocItem, Ty, TypeAndMut};
+use rustc_middle::ty::fold::{BottomUpFolder, TypeFolder};
+use rustc_middle::ty::print::{with_forced_trimmed_paths, with_no_trimmed_paths};
+use rustc_middle::ty::relate::TypeRelation;
+use rustc_middle::ty::{self, Article, AssocItem, Ty, TypeAndMut, TypeVisitable};
use rustc_span::symbol::{sym, Symbol};
use rustc_span::{BytePos, Span};
use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::traits::error_reporting::method_chain::CollectAllMismatches;
use rustc_trait_selection::traits::ObligationCause;
use super::method::probe;
self.annotate_alternative_method_deref(err, expr, error);
// Use `||` to give these suggestions a precedence
- let _ = self.suggest_missing_parentheses(err, expr)
+ let suggested = self.suggest_missing_parentheses(err, expr)
|| self.suggest_remove_last_method_call(err, expr, expected)
|| self.suggest_associated_const(err, expr, expected)
|| self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr)
|| self.suggest_copied_or_cloned(err, expr, expr_ty, expected)
|| self.suggest_into(err, expr, expr_ty, expected)
|| self.suggest_floating_point_literal(err, expr, expected);
+ if !suggested {
+ self.point_at_expr_source_of_inferred_type(err, expr, expr_ty, expected);
+ }
}
pub fn emit_coerce_suggestions(
(expected, Some(err))
}
+ pub fn point_at_expr_source_of_inferred_type(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ found: Ty<'tcx>,
+ expected: Ty<'tcx>,
+ ) -> bool {
+ let map = self.tcx.hir();
+
+ let hir::ExprKind::Path(hir::QPath::Resolved(None, p)) = expr.kind else { return false; };
+ let [hir::PathSegment { ident, args: None, .. }] = p.segments else { return false; };
+ let hir::def::Res::Local(hir_id) = p.res else { return false; };
+ let Some(hir::Node::Pat(pat)) = map.find(hir_id) else { return false; };
+ let Some(hir::Node::Local(hir::Local {
+ ty: None,
+ init: Some(init),
+ ..
+ })) = map.find_parent(pat.hir_id) else { return false; };
+ let Some(ty) = self.node_ty_opt(init.hir_id) else { return false; };
+ if ty.is_closure() || init.span.overlaps(expr.span) || pat.span.from_expansion() {
+ return false;
+ }
+
+ // Locate all the usages of the relevant binding.
+ struct FindExprs<'hir> {
+ hir_id: hir::HirId,
+ uses: Vec<&'hir hir::Expr<'hir>>,
+ }
+ impl<'v> Visitor<'v> for FindExprs<'v> {
+ fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {
+ if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = ex.kind
+ && let hir::def::Res::Local(hir_id) = path.res
+ && hir_id == self.hir_id
+ {
+ self.uses.push(ex);
+ }
+ hir::intravisit::walk_expr(self, ex);
+ }
+ }
+
+ let mut expr_finder = FindExprs { hir_id, uses: vec![] };
+ let id = map.get_parent_item(hir_id);
+ let hir_id: hir::HirId = id.into();
+
+ let Some(node) = map.find(hir_id) else { return false; };
+ let Some(body_id) = node.body_id() else { return false; };
+ let body = map.body(body_id);
+ expr_finder.visit_expr(body.value);
+ // Hack to make equality checks on types with inference variables and regions useful.
+ let mut eraser = BottomUpFolder {
+ tcx: self.tcx,
+ lt_op: |_| self.tcx.lifetimes.re_erased,
+ ct_op: |c| c,
+ ty_op: |t| match *t.kind() {
+ ty::Infer(ty::TyVar(vid)) => self.tcx.mk_ty_infer(ty::TyVar(self.root_var(vid))),
+ ty::Infer(ty::IntVar(_)) => {
+ self.tcx.mk_ty_infer(ty::IntVar(ty::IntVid { index: 0 }))
+ }
+ ty::Infer(ty::FloatVar(_)) => {
+ self.tcx.mk_ty_infer(ty::FloatVar(ty::FloatVid { index: 0 }))
+ }
+ _ => t,
+ },
+ };
+ let mut prev = eraser.fold_ty(ty);
+ let mut prev_span = None;
+
+ for binding in expr_finder.uses {
+ // In every expression where the binding is referenced, we will look at that
+ // expression's type and see if it is where the incorrect found type was fully
+ // "materialized" and point at it. We will also try to provide a suggestion there.
+ if let Some(hir::Node::Expr(expr)
+ | hir::Node::Stmt(hir::Stmt {
+ kind: hir::StmtKind::Expr(expr) | hir::StmtKind::Semi(expr),
+ ..
+ })) = &map.find_parent(binding.hir_id)
+ && let hir::ExprKind::MethodCall(segment, rcvr, args, _span) = expr.kind
+ && rcvr.hir_id == binding.hir_id
+ && let Some(def_id) = self.typeck_results.borrow().type_dependent_def_id(expr.hir_id)
+ {
+ // We special case methods, because they can influence inference through the
+ // call's arguments and we can provide a more explicit span.
+ let sig = self.tcx.fn_sig(def_id);
+ let def_self_ty = sig.input(0).skip_binder();
+ let rcvr_ty = self.node_ty(rcvr.hir_id);
+ // Get the evaluated type *after* calling the method call, so that the influence
+ // of the arguments can be reflected in the receiver type. The receiver
+ // expression has the type *before* theis analysis is done.
+ let ty = match self.lookup_probe(
+ segment.ident,
+ rcvr_ty,
+ expr,
+ probe::ProbeScope::TraitsInScope,
+ ) {
+ Ok(pick) => pick.self_ty,
+ Err(_) => rcvr_ty,
+ };
+ // Remove one layer of references to account for `&mut self` and
+ // `&self`, so that we can compare it against the binding.
+ let (ty, def_self_ty) = match (ty.kind(), def_self_ty.kind()) {
+ (ty::Ref(_, ty, a), ty::Ref(_, self_ty, b)) if a == b => (*ty, *self_ty),
+ _ => (ty, def_self_ty),
+ };
+ let mut param_args = FxHashMap::default();
+ let mut param_expected = FxHashMap::default();
+ let mut param_found = FxHashMap::default();
+ if self.can_eq(self.param_env, ty, found).is_ok() {
+ // We only point at the first place where the found type was inferred.
+ for (i, param_ty) in sig.inputs().skip_binder().iter().skip(1).enumerate() {
+ if def_self_ty.contains(*param_ty) && let ty::Param(_) = param_ty.kind() {
+ // We found an argument that references a type parameter in `Self`,
+ // so we assume that this is the argument that caused the found
+ // type, which we know already because of `can_eq` above was first
+ // inferred in this method call.
+ let arg = &args[i];
+ let arg_ty = self.node_ty(arg.hir_id);
+ err.span_label(
+ arg.span,
+ &format!(
+ "this is of type `{arg_ty}`, which causes `{ident}` to be \
+ inferred as `{ty}`",
+ ),
+ );
+ param_args.insert(param_ty, (arg, arg_ty));
+ }
+ }
+ }
+
+ // Here we find, for a type param `T`, the type that `T` is in the current
+ // method call *and* in the original expected type. That way, we can see if we
+ // can give any structured suggestion for the function argument.
+ let mut c = CollectAllMismatches {
+ infcx: &self.infcx,
+ param_env: self.param_env,
+ errors: vec![],
+ };
+ let _ = c.relate(def_self_ty, ty);
+ for error in c.errors {
+ if let TypeError::Sorts(error) = error {
+ param_found.insert(error.expected, error.found);
+ }
+ }
+ c.errors = vec![];
+ let _ = c.relate(def_self_ty, expected);
+ for error in c.errors {
+ if let TypeError::Sorts(error) = error {
+ param_expected.insert(error.expected, error.found);
+ }
+ }
+ for (param, (arg, arg_ty)) in param_args.iter() {
+ let Some(expected) = param_expected.get(param) else { continue; };
+ let Some(found) = param_found.get(param) else { continue; };
+ if self.can_eq(self.param_env, *arg_ty, *found).is_err() { continue; }
+ self.emit_coerce_suggestions(err, arg, *found, *expected, None, None);
+ }
+
+ let ty = eraser.fold_ty(ty);
+ if ty.references_error() {
+ break;
+ }
+ if ty != prev
+ && param_args.is_empty()
+ && self.can_eq(self.param_env, ty, found).is_ok()
+ {
+ // We only point at the first place where the found type was inferred.
+ err.span_label(
+ segment.ident.span,
+ with_forced_trimmed_paths!(format!(
+ "here the type of `{ident}` is inferred to be `{ty}`",
+ )),
+ );
+ break;
+ } else if !param_args.is_empty() {
+ break;
+ }
+ prev = ty;
+ } else {
+ let ty = eraser.fold_ty(self.node_ty(binding.hir_id));
+ if ty.references_error() {
+ break;
+ }
+ if ty != prev
+ && let Some(span) = prev_span
+ && self.can_eq(self.param_env, ty, found).is_ok()
+ {
+ // We only point at the first place where the found type was inferred.
+ // We use the *previous* span because if the type is known *here* it means
+ // it was *evaluated earlier*. We don't do this for method calls because we
+ // evaluate the method's self type eagerly, but not in any other case.
+ err.span_label(
+ span,
+ with_forced_trimmed_paths!(format!(
+ "here the type of `{ident}` is inferred to be `{ty}`",
+ )),
+ );
+ break;
+ }
+ prev = ty;
+ }
+ if binding.hir_id == expr.hir_id {
+ // Do not look at expressions that come after the expression we were originally
+ // evaluating and had a type error.
+ break;
+ }
+ prev_span = Some(binding.span);
+ }
+ true
+ }
+
fn annotate_expected_due_to_let_ty(
&self,
err: &mut Diagnostic,
projects / rust.git / blobdiff