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-rw-r--r--compiler/rustc_typeck/src/check/fn_ctxt/checks.rs752
1 files changed, 537 insertions, 215 deletions
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
index 660e7e4e3..311fcaada 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
@@ -15,6 +15,7 @@ use crate::check::{
use crate::structured_errors::StructuredDiagnostic;
use rustc_ast as ast;
+use rustc_data_structures::fx::FxHashSet;
use rustc_errors::{pluralize, Applicability, Diagnostic, DiagnosticId, MultiSpan};
use rustc_hir as hir;
use rustc_hir::def::{CtorOf, DefKind, Res};
@@ -27,13 +28,14 @@ use rustc_infer::infer::InferOk;
use rustc_infer::infer::TypeTrace;
use rustc_middle::ty::adjustment::AllowTwoPhase;
use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty};
+use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty, TypeSuperVisitable, TypeVisitor};
use rustc_session::Session;
use rustc_span::symbol::Ident;
-use rustc_span::{self, Span};
+use rustc_span::{self, sym, Span};
use rustc_trait_selection::traits::{self, ObligationCauseCode, SelectionContext};
use std::iter;
+use std::ops::ControlFlow;
use std::slice;
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
@@ -58,7 +60,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
debug!("FnCtxt::check_asm: {} deferred checks", deferred_asm_checks.len());
for (asm, hir_id) in deferred_asm_checks.drain(..) {
let enclosing_id = self.tcx.hir().enclosing_body_owner(hir_id);
- InlineAsmCtxt::new_in_fn(self)
+ let get_operand_ty = |expr| {
+ let ty = self.typeck_results.borrow().expr_ty_adjusted(expr);
+ let ty = self.resolve_vars_if_possible(ty);
+ if ty.has_infer_types_or_consts() {
+ assert!(self.is_tainted_by_errors());
+ self.tcx.ty_error()
+ } else {
+ self.tcx.erase_regions(ty)
+ }
+ };
+ InlineAsmCtxt::new_in_fn(self.tcx, self.param_env, get_operand_ty)
.check_asm(asm, self.tcx.hir().local_def_id_to_hir_id(enclosing_id));
}
}
@@ -141,7 +153,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
) {
let tcx = self.tcx;
- // Conceptually, we've got some number of expected inputs, and some number of provided aguments
+ // Conceptually, we've got some number of expected inputs, and some number of provided arguments
// and we can form a grid of whether each argument could satisfy a given input:
// in1 | in2 | in3 | ...
// arg1 ? | | |
@@ -212,6 +224,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let minimum_input_count = expected_input_tys.len();
let provided_arg_count = provided_args.len();
+ let is_const_eval_select = matches!(fn_def_id, Some(def_id) if
+ self.tcx.def_kind(def_id) == hir::def::DefKind::Fn
+ && self.tcx.is_intrinsic(def_id)
+ && self.tcx.item_name(def_id) == sym::const_eval_select);
+
// We introduce a helper function to demand that a given argument satisfy a given input
// This is more complicated than just checking type equality, as arguments could be coerced
// This version writes those types back so further type checking uses the narrowed types
@@ -237,17 +254,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// Cause selection errors caused by resolving a single argument to point at the
// argument and not the call. This lets us customize the span pointed to in the
// fulfillment error to be more accurate.
- let coerced_ty =
- self.resolve_vars_with_obligations_and_mutate_fulfillment(coerced_ty, |errors| {
- self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr);
- self.point_at_arg_instead_of_call_if_possible(
- errors,
- call_expr,
- call_span,
- provided_args,
- &expected_input_tys,
- );
- });
+ let coerced_ty = self.resolve_vars_with_obligations(coerced_ty);
let coerce_error = self
.try_coerce(provided_arg, checked_ty, coerced_ty, AllowTwoPhase::Yes, None)
@@ -257,6 +264,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
return Compatibility::Incompatible(coerce_error);
}
+ // Check that second and third argument of `const_eval_select` must be `FnDef`, and additionally that
+ // the second argument must be `const fn`. The first argument must be a tuple, but this is already expressed
+ // in the function signature (`F: FnOnce<ARG>`), so I did not bother to add another check here.
+ //
+ // This check is here because there is currently no way to express a trait bound for `FnDef` types only.
+ if is_const_eval_select && (1..=2).contains(&idx) {
+ if let ty::FnDef(def_id, _) = checked_ty.kind() {
+ if idx == 1 && !self.tcx.is_const_fn_raw(*def_id) {
+ self.tcx
+ .sess
+ .struct_span_err(provided_arg.span, "this argument must be a `const fn`")
+ .help("consult the documentation on `const_eval_select` for more information")
+ .emit();
+ }
+ } else {
+ self.tcx
+ .sess
+ .struct_span_err(provided_arg.span, "this argument must be a function item")
+ .note(format!("expected a function item, found {checked_ty}"))
+ .help(
+ "consult the documentation on `const_eval_select` for more information",
+ )
+ .emit();
+ }
+ }
+
// 3. Check if the formal type is a supertype of the checked one
// and register any such obligations for future type checks
let supertype_error = self
@@ -302,16 +335,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// an "opportunistic" trait resolution of any trait bounds on
// the call. This helps coercions.
if check_closures {
- self.select_obligations_where_possible(false, |errors| {
- self.point_at_type_arg_instead_of_call_if_possible(errors, call_expr);
- self.point_at_arg_instead_of_call_if_possible(
- errors,
- call_expr,
- call_span,
- &provided_args,
- &expected_input_tys,
- );
- })
+ self.select_obligations_where_possible(false, |_| {})
}
// Check each argument, to satisfy the input it was provided for
@@ -440,7 +464,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
call_expr: &hir::Expr<'tcx>,
) {
// Next, let's construct the error
- let (error_span, full_call_span, ctor_of) = match &call_expr.kind {
+ let (error_span, full_call_span, ctor_of, is_method) = match &call_expr.kind {
hir::ExprKind::Call(
hir::Expr { hir_id, span, kind: hir::ExprKind::Path(qpath), .. },
_,
@@ -448,22 +472,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
if let Res::Def(DefKind::Ctor(of, _), _) =
self.typeck_results.borrow().qpath_res(qpath, *hir_id)
{
- (call_span, *span, Some(of))
+ (call_span, *span, Some(of), false)
} else {
- (call_span, *span, None)
+ (call_span, *span, None, false)
}
}
- hir::ExprKind::Call(hir::Expr { span, .. }, _) => (call_span, *span, None),
- hir::ExprKind::MethodCall(path_segment, _, span) => {
+ hir::ExprKind::Call(hir::Expr { span, .. }, _) => (call_span, *span, None, false),
+ hir::ExprKind::MethodCall(path_segment, _, _, span) => {
let ident_span = path_segment.ident.span;
let ident_span = if let Some(args) = path_segment.args {
ident_span.with_hi(args.span_ext.hi())
} else {
ident_span
};
- (
- *span, ident_span, None, // methods are never ctors
- )
+ // methods are never ctors
+ (*span, ident_span, None, true)
}
k => span_bug!(call_span, "checking argument types on a non-call: `{:?}`", k),
};
@@ -507,13 +530,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
.collect();
let callee_expr = match &call_expr.peel_blocks().kind {
hir::ExprKind::Call(callee, _) => Some(*callee),
- hir::ExprKind::MethodCall(_, callee, _) => {
+ hir::ExprKind::MethodCall(_, receiver, ..) => {
if let Some((DefKind::AssocFn, def_id)) =
self.typeck_results.borrow().type_dependent_def(call_expr.hir_id)
&& let Some(assoc) = tcx.opt_associated_item(def_id)
&& assoc.fn_has_self_parameter
{
- Some(&callee[0])
+ Some(*receiver)
} else {
None
}
@@ -545,7 +568,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let coerced_ty = expectation.only_has_type(self).unwrap_or(formal_input_ty);
let can_coerce = self.can_coerce(arg_ty, coerced_ty);
if !can_coerce {
- return Compatibility::Incompatible(None);
+ return Compatibility::Incompatible(Some(ty::error::TypeError::Sorts(
+ ty::error::ExpectedFound::new(true, coerced_ty, arg_ty),
+ )));
}
// Using probe here, since we don't want this subtyping to affect inference.
@@ -577,7 +602,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// First, check if we just need to wrap some arguments in a tuple.
if let Some((mismatch_idx, terr)) =
compatibility_diagonal.iter().enumerate().find_map(|(i, c)| {
- if let Compatibility::Incompatible(Some(terr)) = c { Some((i, terr)) } else { None }
+ if let Compatibility::Incompatible(Some(terr)) = c {
+ Some((i, *terr))
+ } else {
+ None
+ }
})
{
// Is the first bad expected argument a tuple?
@@ -659,7 +688,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Applicability::MachineApplicable,
);
};
- self.label_fn_like(&mut err, fn_def_id, callee_ty);
+ self.label_fn_like(
+ &mut err,
+ fn_def_id,
+ callee_ty,
+ Some(mismatch_idx),
+ is_method,
+ );
err.emit();
return;
}
@@ -701,16 +736,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
errors.drain_filter(|error| {
- let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(error)) = error else { return false };
+ let Error::Invalid(provided_idx, expected_idx, Compatibility::Incompatible(Some(e))) = error else { return false };
let (provided_ty, provided_span) = provided_arg_tys[*provided_idx];
let (expected_ty, _) = formal_and_expected_inputs[*expected_idx];
let cause = &self.misc(provided_span);
let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
- if let Some(e) = error {
- if !matches!(trace.cause.as_failure_code(e), FailureCode::Error0308(_)) {
- self.report_and_explain_type_error(trace, e).emit();
- return true;
- }
+ if !matches!(trace.cause.as_failure_code(*e), FailureCode::Error0308(_)) {
+ self.report_and_explain_type_error(trace, *e).emit();
+ return true;
}
false
});
@@ -733,7 +766,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let (provided_ty, provided_arg_span) = provided_arg_tys[*provided_idx];
let cause = &self.misc(provided_arg_span);
let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
- let mut err = self.report_and_explain_type_error(trace, err);
+ let mut err = self.report_and_explain_type_error(trace, *err);
self.emit_coerce_suggestions(
&mut err,
&provided_args[*provided_idx],
@@ -749,7 +782,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
format!("arguments to this {} are incorrect", call_name),
);
// Call out where the function is defined
- self.label_fn_like(&mut err, fn_def_id, callee_ty);
+ self.label_fn_like(
+ &mut err,
+ fn_def_id,
+ callee_ty,
+ Some(expected_idx.as_usize()),
+ is_method,
+ );
err.emit();
return;
}
@@ -797,7 +836,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Error::Invalid(provided_idx, expected_idx, compatibility) => {
let (formal_ty, expected_ty) = formal_and_expected_inputs[expected_idx];
let (provided_ty, provided_span) = provided_arg_tys[provided_idx];
- if let Compatibility::Incompatible(error) = &compatibility {
+ if let Compatibility::Incompatible(error) = compatibility {
let cause = &self.misc(provided_span);
let trace = TypeTrace::types(cause, true, expected_ty, provided_ty);
if let Some(e) = error {
@@ -1031,7 +1070,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
// Call out where the function is defined
- self.label_fn_like(&mut err, fn_def_id, callee_ty);
+ self.label_fn_like(&mut err, fn_def_id, callee_ty, None, is_method);
// And add a suggestion block for all of the parameters
let suggestion_text = match suggestion_text {
@@ -1048,11 +1087,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
};
if let Some(suggestion_text) = suggestion_text {
let source_map = self.sess().source_map();
- let mut suggestion = format!(
- "{}(",
- source_map.span_to_snippet(full_call_span).unwrap_or_else(|_| fn_def_id
- .map_or("".to_string(), |fn_def_id| tcx.item_name(fn_def_id).to_string()))
- );
+ let (mut suggestion, suggestion_span) =
+ if let Some(call_span) = full_call_span.find_ancestor_inside(error_span) {
+ ("(".to_string(), call_span.shrink_to_hi().to(error_span.shrink_to_hi()))
+ } else {
+ (
+ format!(
+ "{}(",
+ source_map.span_to_snippet(full_call_span).unwrap_or_else(|_| {
+ fn_def_id.map_or("".to_string(), |fn_def_id| {
+ tcx.item_name(fn_def_id).to_string()
+ })
+ })
+ ),
+ error_span,
+ )
+ };
let mut needs_comma = false;
for (expected_idx, provided_idx) in matched_inputs.iter_enumerated() {
if needs_comma {
@@ -1062,8 +1112,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
let suggestion_text = if let Some(provided_idx) = provided_idx
&& let (_, provided_span) = provided_arg_tys[*provided_idx]
- && let Ok(arg_text) =
- source_map.span_to_snippet(provided_span)
+ && let Ok(arg_text) = source_map.span_to_snippet(provided_span)
{
arg_text
} else {
@@ -1081,7 +1130,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
suggestion += ")";
err.span_suggestion_verbose(
- error_span,
+ suggestion_span,
&suggestion_text,
suggestion,
Applicability::HasPlaceholders,
@@ -1129,7 +1178,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
opt_ty.unwrap_or_else(|| self.next_float_var())
}
ast::LitKind::Bool(_) => tcx.types.bool,
- ast::LitKind::Err(_) => tcx.ty_error(),
+ ast::LitKind::Err => tcx.ty_error(),
}
}
@@ -1164,7 +1213,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.write_user_type_annotation_from_substs(hir_id, did, substs, None);
// Check bounds on type arguments used in the path.
- self.add_required_obligations(path_span, did, substs);
+ self.add_required_obligations_for_hir(path_span, did, substs, hir_id);
Some((variant, ty))
} else {
@@ -1601,186 +1650,420 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
- /// Given a vec of evaluated `FulfillmentError`s and an `fn` call argument expressions, we walk
- /// the checked and coerced types for each argument to see if any of the `FulfillmentError`s
- /// reference a type argument. The reason to walk also the checked type is that the coerced type
- /// can be not easily comparable with predicate type (because of coercion). If the types match
- /// for either checked or coerced type, and there's only *one* argument that does, we point at
- /// the corresponding argument's expression span instead of the `fn` call path span.
- fn point_at_arg_instead_of_call_if_possible(
+ /// Given a vector of fulfillment errors, try to adjust the spans of the
+ /// errors to more accurately point at the cause of the failure.
+ ///
+ /// This applies to calls, methods, and struct expressions. This will also
+ /// try to deduplicate errors that are due to the same cause but might
+ /// have been created with different [`ObligationCause`][traits::ObligationCause]s.
+ pub(super) fn adjust_fulfillment_errors_for_expr_obligation(
&self,
errors: &mut Vec<traits::FulfillmentError<'tcx>>,
- expr: &'tcx hir::Expr<'tcx>,
- call_sp: Span,
- args: &'tcx [hir::Expr<'tcx>],
- expected_tys: &[Ty<'tcx>],
) {
- // We *do not* do this for desugared call spans to keep good diagnostics when involving
- // the `?` operator.
- if call_sp.desugaring_kind().is_some() {
- return;
- }
-
- 'outer: for error in errors {
- // Only if the cause is somewhere inside the expression we want try to point at arg.
- // Otherwise, it means that the cause is somewhere else and we should not change
- // anything because we can break the correct span.
- if !call_sp.contains(error.obligation.cause.span) {
- continue;
+ // Store a mapping from `(Span, Predicate) -> ObligationCause`, so that
+ // other errors that have the same span and predicate can also get fixed,
+ // even if their `ObligationCauseCode` isn't an `Expr*Obligation` kind.
+ // This is important since if we adjust one span but not the other, then
+ // we will have "duplicated" the error on the UI side.
+ let mut remap_cause = FxHashSet::default();
+ let mut not_adjusted = vec![];
+
+ for error in errors {
+ let before_span = error.obligation.cause.span;
+ if self.adjust_fulfillment_error_for_expr_obligation(error)
+ || before_span != error.obligation.cause.span
+ {
+ // Store both the predicate and the predicate *without constness*
+ // since sometimes we instantiate and check both of these in a
+ // method call, for example.
+ remap_cause.insert((
+ before_span,
+ error.obligation.predicate,
+ error.obligation.cause.clone(),
+ ));
+ remap_cause.insert((
+ before_span,
+ error.obligation.predicate.without_const(self.tcx),
+ error.obligation.cause.clone(),
+ ));
+ } else {
+ // If it failed to be adjusted once around, it may be adjusted
+ // via the "remap cause" mapping the second time...
+ not_adjusted.push(error);
}
+ }
- // Peel derived obligation, because it's the type that originally
- // started this inference chain that matters, not the one we wound
- // up with at the end.
- fn unpeel_to_top<'a, 'tcx>(
- mut code: &'a ObligationCauseCode<'tcx>,
- ) -> &'a ObligationCauseCode<'tcx> {
- let mut result_code = code;
- loop {
- let parent = match code {
- ObligationCauseCode::ImplDerivedObligation(c) => &c.derived.parent_code,
- ObligationCauseCode::BuiltinDerivedObligation(c)
- | ObligationCauseCode::DerivedObligation(c) => &c.parent_code,
- _ => break result_code,
- };
- (result_code, code) = (code, parent);
+ for error in not_adjusted {
+ for (span, predicate, cause) in &remap_cause {
+ if *predicate == error.obligation.predicate
+ && span.contains(error.obligation.cause.span)
+ {
+ error.obligation.cause = cause.clone();
+ continue;
}
}
- let self_: ty::subst::GenericArg<'_> =
- match unpeel_to_top(error.obligation.cause.code()) {
- ObligationCauseCode::BuiltinDerivedObligation(code)
- | ObligationCauseCode::DerivedObligation(code) => {
- code.parent_trait_pred.self_ty().skip_binder().into()
+ }
+ }
+
+ fn adjust_fulfillment_error_for_expr_obligation(
+ &self,
+ error: &mut traits::FulfillmentError<'tcx>,
+ ) -> bool {
+ let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx))
+ = *error.obligation.cause.code().peel_derives() else { return false; };
+ let hir = self.tcx.hir();
+ let hir::Node::Expr(expr) = hir.get(hir_id) else { return false; };
+
+ // Skip over mentioning async lang item
+ if Some(def_id) == self.tcx.lang_items().from_generator_fn()
+ && error.obligation.cause.span.desugaring_kind()
+ == Some(rustc_span::DesugaringKind::Async)
+ {
+ return false;
+ }
+
+ let Some(unsubstituted_pred) =
+ self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx)
+ else { return false; };
+
+ let generics = self.tcx.generics_of(def_id);
+ let predicate_substs = match unsubstituted_pred.kind().skip_binder() {
+ ty::PredicateKind::Trait(pred) => pred.trait_ref.substs,
+ ty::PredicateKind::Projection(pred) => pred.projection_ty.substs,
+ _ => ty::List::empty(),
+ };
+
+ let find_param_matching = |matches: &dyn Fn(&ty::ParamTy) -> bool| {
+ predicate_substs.types().find_map(|ty| {
+ ty.walk().find_map(|arg| {
+ if let ty::GenericArgKind::Type(ty) = arg.unpack()
+ && let ty::Param(param_ty) = ty.kind()
+ && matches(param_ty)
+ {
+ Some(arg)
+ } else {
+ None
}
- ObligationCauseCode::ImplDerivedObligation(code) => {
- code.derived.parent_trait_pred.self_ty().skip_binder().into()
+ })
+ })
+ };
+
+ // Prefer generics that are local to the fn item, since these are likely
+ // to be the cause of the unsatisfied predicate.
+ let mut param_to_point_at = find_param_matching(&|param_ty| {
+ self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) == def_id
+ });
+ // Fall back to generic that isn't local to the fn item. This will come
+ // from a trait or impl, for example.
+ let mut fallback_param_to_point_at = find_param_matching(&|param_ty| {
+ self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) != def_id
+ && param_ty.name != rustc_span::symbol::kw::SelfUpper
+ });
+ // Finally, the `Self` parameter is possibly the reason that the predicate
+ // is unsatisfied. This is less likely to be true for methods, because
+ // method probe means that we already kinda check that the predicates due
+ // to the `Self` type are true.
+ let mut self_param_to_point_at =
+ find_param_matching(&|param_ty| param_ty.name == rustc_span::symbol::kw::SelfUpper);
+
+ // Finally, for ambiguity-related errors, we actually want to look
+ // for a parameter that is the source of the inference type left
+ // over in this predicate.
+ if let traits::FulfillmentErrorCode::CodeAmbiguity = error.code {
+ fallback_param_to_point_at = None;
+ self_param_to_point_at = None;
+ param_to_point_at =
+ self.find_ambiguous_parameter_in(def_id, error.root_obligation.predicate);
+ }
+
+ if self.closure_span_overlaps_error(error, expr.span) {
+ return false;
+ }
+
+ match &expr.kind {
+ hir::ExprKind::Path(qpath) => {
+ if let hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Call(callee, args),
+ hir_id: call_hir_id,
+ span: call_span,
+ ..
+ }) = hir.get(hir.get_parent_node(expr.hir_id))
+ && callee.hir_id == expr.hir_id
+ {
+ if self.closure_span_overlaps_error(error, *call_span) {
+ return false;
}
- _ if let ty::PredicateKind::Trait(predicate) =
- error.obligation.predicate.kind().skip_binder() =>
+
+ for param in
+ [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+ .into_iter()
+ .flatten()
{
- predicate.self_ty().into()
+ if self.point_at_arg_if_possible(
+ error,
+ def_id,
+ param,
+ *call_hir_id,
+ callee.span,
+ None,
+ args,
+ )
+ {
+ return true;
+ }
}
- _ => continue,
- };
- let self_ = self.resolve_vars_if_possible(self_);
- let ty_matches_self = |ty: Ty<'tcx>| ty.walk().any(|arg| arg == self_);
-
- let typeck_results = self.typeck_results.borrow();
-
- for (idx, arg) in args.iter().enumerate() {
- // Don't adjust the span if we already have a more precise span
- // within one of the args.
- if arg.span.contains(error.obligation.cause.span) {
- let references_arg =
- typeck_results.expr_ty_opt(arg).map_or(false, &ty_matches_self)
- || expected_tys.get(idx).copied().map_or(false, &ty_matches_self);
- if references_arg && !arg.span.from_expansion() {
- error.obligation.cause.map_code(|parent_code| {
- ObligationCauseCode::FunctionArgumentObligation {
- arg_hir_id: args[idx].hir_id,
- call_hir_id: expr.hir_id,
- parent_code,
- }
- })
+ }
+ // Notably, we only point to params that are local to the
+ // item we're checking, since those are the ones we are able
+ // to look in the final `hir::PathSegment` for. Everything else
+ // would require a deeper search into the `qpath` than I think
+ // is worthwhile.
+ if let Some(param_to_point_at) = param_to_point_at
+ && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
+ {
+ return true;
+ }
+ }
+ hir::ExprKind::MethodCall(segment, receiver, args, ..) => {
+ for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+ .into_iter()
+ .flatten()
+ {
+ if self.point_at_arg_if_possible(
+ error,
+ def_id,
+ param,
+ hir_id,
+ segment.ident.span,
+ Some(receiver),
+ args,
+ ) {
+ return true;
+ }
+ }
+ if let Some(param_to_point_at) = param_to_point_at
+ && self.point_at_generic_if_possible(error, def_id, param_to_point_at, segment)
+ {
+ return true;
+ }
+ }
+ hir::ExprKind::Struct(qpath, fields, ..) => {
+ if let Res::Def(DefKind::Struct | DefKind::Variant, variant_def_id) =
+ self.typeck_results.borrow().qpath_res(qpath, hir_id)
+ {
+ for param in
+ [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
+ {
+ if let Some(param) = param
+ && self.point_at_field_if_possible(
+ error,
+ def_id,
+ param,
+ variant_def_id,
+ fields,
+ )
+ {
+ return true;
+ }
}
- continue 'outer;
+ }
+ if let Some(param_to_point_at) = param_to_point_at
+ && self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
+ {
+ return true;
}
}
+ _ => {}
+ }
- // Collect the argument position for all arguments that could have caused this
- // `FulfillmentError`.
- let mut referenced_in: Vec<_> = std::iter::zip(expected_tys, args)
- .enumerate()
- .flat_map(|(idx, (expected_ty, arg))| {
- if let Some(arg_ty) = typeck_results.expr_ty_opt(arg) {
- vec![(idx, arg_ty), (idx, *expected_ty)]
- } else {
- vec![]
- }
- })
- .filter_map(|(i, ty)| {
- let ty = self.resolve_vars_if_possible(ty);
- // We walk the argument type because the argument's type could have
- // been `Option<T>`, but the `FulfillmentError` references `T`.
- if ty_matches_self(ty) { Some(i) } else { None }
- })
- .collect();
+ false
+ }
+
+ fn closure_span_overlaps_error(
+ &self,
+ error: &traits::FulfillmentError<'tcx>,
+ span: Span,
+ ) -> bool {
+ if let traits::FulfillmentErrorCode::CodeSelectionError(
+ traits::SelectionError::OutputTypeParameterMismatch(_, expected, _),
+ ) = error.code
+ && let ty::Closure(def_id, _) | ty::Generator(def_id, ..) = expected.skip_binder().self_ty().kind()
+ && span.overlaps(self.tcx.def_span(*def_id))
+ {
+ true
+ } else {
+ false
+ }
+ }
+
+ fn point_at_arg_if_possible(
+ &self,
+ error: &mut traits::FulfillmentError<'tcx>,
+ def_id: DefId,
+ param_to_point_at: ty::GenericArg<'tcx>,
+ call_hir_id: hir::HirId,
+ callee_span: Span,
+ receiver: Option<&'tcx hir::Expr<'tcx>>,
+ args: &'tcx [hir::Expr<'tcx>],
+ ) -> bool {
+ let sig = self.tcx.fn_sig(def_id).skip_binder();
+ let args_referencing_param: Vec<_> = sig
+ .inputs()
+ .iter()
+ .enumerate()
+ .filter(|(_, ty)| find_param_in_ty(**ty, param_to_point_at))
+ .collect();
+ // If there's one field that references the given generic, great!
+ if let [(idx, _)] = args_referencing_param.as_slice()
+ && let Some(arg) = receiver
+ .map_or(args.get(*idx), |rcvr| if *idx == 0 { Some(rcvr) } else { args.get(*idx - 1) }) {
+ error.obligation.cause.span = arg.span.find_ancestor_in_same_ctxt(error.obligation.cause.span).unwrap_or(arg.span);
+ error.obligation.cause.map_code(|parent_code| {
+ ObligationCauseCode::FunctionArgumentObligation {
+ arg_hir_id: arg.hir_id,
+ call_hir_id,
+ parent_code,
+ }
+ });
+ return true;
+ } else if args_referencing_param.len() > 0 {
+ // If more than one argument applies, then point to the callee span at least...
+ // We have chance to fix this up further in `point_at_generics_if_possible`
+ error.obligation.cause.span = callee_span;
+ }
- // Both checked and coerced types could have matched, thus we need to remove
- // duplicates.
+ false
+ }
- // We sort primitive type usize here and can use unstable sort
- referenced_in.sort_unstable();
- referenced_in.dedup();
+ fn point_at_field_if_possible(
+ &self,
+ error: &mut traits::FulfillmentError<'tcx>,
+ def_id: DefId,
+ param_to_point_at: ty::GenericArg<'tcx>,
+ variant_def_id: DefId,
+ expr_fields: &[hir::ExprField<'tcx>],
+ ) -> bool {
+ let def = self.tcx.adt_def(def_id);
+
+ let identity_substs = ty::InternalSubsts::identity_for_item(self.tcx, def_id);
+ let fields_referencing_param: Vec<_> = def
+ .variant_with_id(variant_def_id)
+ .fields
+ .iter()
+ .filter(|field| {
+ let field_ty = field.ty(self.tcx, identity_substs);
+ find_param_in_ty(field_ty, param_to_point_at)
+ })
+ .collect();
- if let &[idx] = &referenced_in[..] {
- // Do not point at the inside of a macro.
- // That would often result in poor error messages.
- if args[idx].span.from_expansion() {
- continue;
+ if let [field] = fields_referencing_param.as_slice() {
+ for expr_field in expr_fields {
+ // Look for the ExprField that matches the field, using the
+ // same rules that check_expr_struct uses for macro hygiene.
+ if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx)
+ {
+ error.obligation.cause.span = expr_field
+ .expr
+ .span
+ .find_ancestor_in_same_ctxt(error.obligation.cause.span)
+ .unwrap_or(expr_field.span);
+ return true;
}
- // We make sure that only *one* argument matches the obligation failure
- // and we assign the obligation's span to its expression's.
- error.obligation.cause.span = args[idx].span;
- error.obligation.cause.map_code(|parent_code| {
- ObligationCauseCode::FunctionArgumentObligation {
- arg_hir_id: args[idx].hir_id,
- call_hir_id: expr.hir_id,
- parent_code,
- }
- });
- } else if error.obligation.cause.span == call_sp {
- // Make function calls point at the callee, not the whole thing.
- if let hir::ExprKind::Call(callee, _) = expr.kind {
- error.obligation.cause.span = callee.span;
+ }
+ }
+
+ false
+ }
+
+ fn point_at_path_if_possible(
+ &self,
+ error: &mut traits::FulfillmentError<'tcx>,
+ def_id: DefId,
+ param: ty::GenericArg<'tcx>,
+ qpath: &QPath<'tcx>,
+ ) -> bool {
+ match qpath {
+ hir::QPath::Resolved(_, path) => {
+ if let Some(segment) = path.segments.last()
+ && self.point_at_generic_if_possible(error, def_id, param, segment)
+ {
+ return true;
}
}
+ hir::QPath::TypeRelative(_, segment) => {
+ if self.point_at_generic_if_possible(error, def_id, param, segment) {
+ return true;
+ }
+ }
+ _ => {}
}
+
+ false
}
- /// Given a vec of evaluated `FulfillmentError`s and an `fn` call expression, we walk the
- /// `PathSegment`s and resolve their type parameters to see if any of the `FulfillmentError`s
- /// were caused by them. If they were, we point at the corresponding type argument's span
- /// instead of the `fn` call path span.
- fn point_at_type_arg_instead_of_call_if_possible(
+ fn point_at_generic_if_possible(
&self,
- errors: &mut Vec<traits::FulfillmentError<'tcx>>,
- call_expr: &'tcx hir::Expr<'tcx>,
- ) {
- if let hir::ExprKind::Call(path, _) = &call_expr.kind {
- if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = &path.kind {
- for error in errors {
- if let ty::PredicateKind::Trait(predicate) =
- error.obligation.predicate.kind().skip_binder()
- {
- // If any of the type arguments in this path segment caused the
- // `FulfillmentError`, point at its span (#61860).
- for arg in path
- .segments
- .iter()
- .filter_map(|seg| seg.args.as_ref())
- .flat_map(|a| a.args.iter())
- {
- if let hir::GenericArg::Type(hir_ty) = &arg
- && let Some(ty) =
- self.typeck_results.borrow().node_type_opt(hir_ty.hir_id)
- && self.resolve_vars_if_possible(ty) == predicate.self_ty()
- {
- error.obligation.cause.span = hir_ty.span;
- break;
- }
- }
- }
+ error: &mut traits::FulfillmentError<'tcx>,
+ def_id: DefId,
+ param_to_point_at: ty::GenericArg<'tcx>,
+ segment: &hir::PathSegment<'tcx>,
+ ) -> bool {
+ let own_substs = self
+ .tcx
+ .generics_of(def_id)
+ .own_substs(ty::InternalSubsts::identity_for_item(self.tcx, def_id));
+ let Some((index, _)) = own_substs
+ .iter()
+ .filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
+ .enumerate()
+ .find(|(_, arg)| **arg == param_to_point_at) else { return false };
+ let Some(arg) = segment
+ .args()
+ .args
+ .iter()
+ .filter(|arg| matches!(arg, hir::GenericArg::Type(_)))
+ .nth(index) else { return false; };
+ error.obligation.cause.span = arg
+ .span()
+ .find_ancestor_in_same_ctxt(error.obligation.cause.span)
+ .unwrap_or(arg.span());
+ true
+ }
+
+ fn find_ambiguous_parameter_in<T: TypeVisitable<'tcx>>(
+ &self,
+ item_def_id: DefId,
+ t: T,
+ ) -> Option<ty::GenericArg<'tcx>> {
+ struct FindAmbiguousParameter<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, DefId);
+ impl<'tcx> TypeVisitor<'tcx> for FindAmbiguousParameter<'_, 'tcx> {
+ type BreakTy = ty::GenericArg<'tcx>;
+ fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> {
+ if let Some(origin) = self.0.type_var_origin(ty)
+ && let TypeVariableOriginKind::TypeParameterDefinition(_, Some(def_id)) =
+ origin.kind
+ && let generics = self.0.tcx.generics_of(self.1)
+ && let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id)
+ && let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1)
+ .get(index as usize)
+ {
+ ControlFlow::Break(*subst)
+ } else {
+ ty.super_visit_with(self)
}
}
}
+ t.visit_with(&mut FindAmbiguousParameter(self, item_def_id)).break_value()
}
fn label_fn_like(
&self,
- err: &mut rustc_errors::DiagnosticBuilder<'tcx, rustc_errors::ErrorGuaranteed>,
+ err: &mut Diagnostic,
callable_def_id: Option<DefId>,
callee_ty: Option<Ty<'tcx>>,
+ // A specific argument should be labeled, instead of all of them
+ expected_idx: Option<usize>,
+ is_method: bool,
) {
let Some(mut def_id) = callable_def_id else {
return;
@@ -1838,14 +2121,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let new_def_id = self.probe(|_| {
let trait_ref = ty::TraitRef::new(
call_kind.to_def_id(self.tcx),
- self.tcx.mk_substs([
- ty::GenericArg::from(callee_ty),
- self.next_ty_var(TypeVariableOrigin {
- kind: TypeVariableOriginKind::MiscVariable,
- span: rustc_span::DUMMY_SP,
- })
- .into(),
- ].into_iter()),
+ self.tcx.mk_substs(
+ [
+ ty::GenericArg::from(callee_ty),
+ self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::MiscVariable,
+ span: rustc_span::DUMMY_SP,
+ })
+ .into(),
+ ]
+ .into_iter(),
+ ),
);
let obligation = traits::Obligation::new(
traits::ObligationCause::dummy(),
@@ -1860,7 +2146,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
Ok(Some(traits::ImplSource::UserDefined(impl_source))) => {
Some(impl_source.impl_def_id)
}
- _ => None
+ _ => None,
}
});
if let Some(new_def_id) = new_def_id {
@@ -1881,14 +2167,30 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
.get_if_local(def_id)
.and_then(|node| node.body_id())
.into_iter()
- .flat_map(|id| self.tcx.hir().body(id).params);
+ .flat_map(|id| self.tcx.hir().body(id).params)
+ .skip(if is_method { 1 } else { 0 });
- for param in params {
+ for (_, param) in params
+ .into_iter()
+ .enumerate()
+ .filter(|(idx, _)| expected_idx.map_or(true, |expected_idx| expected_idx == *idx))
+ {
spans.push_span_label(param.span, "");
}
let def_kind = self.tcx.def_kind(def_id);
err.span_note(spans, &format!("{} defined here", def_kind.descr(def_id)));
+ } else if let Some(hir::Node::Expr(e)) = self.tcx.hir().get_if_local(def_id)
+ && let hir::ExprKind::Closure(hir::Closure { body, .. }) = &e.kind
+ {
+ let param = expected_idx
+ .and_then(|expected_idx| self.tcx.hir().body(*body).params.get(expected_idx));
+ let (kind, span) = if let Some(param) = param {
+ ("closure parameter", param.span)
+ } else {
+ ("closure", self.tcx.def_span(def_id))
+ };
+ err.span_note(span, &format!("{} defined here", kind));
} else {
let def_kind = self.tcx.def_kind(def_id);
err.span_note(
@@ -1898,3 +2200,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
}
+
+fn find_param_in_ty<'tcx>(ty: Ty<'tcx>, param_to_point_at: ty::GenericArg<'tcx>) -> bool {
+ let mut walk = ty.walk();
+ while let Some(arg) = walk.next() {
+ if arg == param_to_point_at {
+ return true;
+ } else if let ty::GenericArgKind::Type(ty) = arg.unpack()
+ && let ty::Projection(..) = ty.kind()
+ {
+ // This logic may seem a bit strange, but typically when
+ // we have a projection type in a function signature, the
+ // argument that's being passed into that signature is
+ // not actually constraining that projection's substs in
+ // a meaningful way. So we skip it, and see improvements
+ // in some UI tests.
+ walk.skip_current_subtree();
+ }
+ }
+ false
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-09 12:19:35 +0000