--- /dev/null
+use super::method::probe::{IsSuggestion, Mode, ProbeScope};
+use super::method::MethodCallee;
+use super::{Expectation, FnCtxt, TupleArgumentsFlag};
+
+use crate::type_error_struct;
+use rustc_ast::util::parser::PREC_POSTFIX;
+use rustc_errors::{struct_span_err, Applicability, Diagnostic, StashKey};
+use rustc_hir as hir;
+use rustc_hir::def::{self, Namespace, Res};
+use rustc_hir::def_id::DefId;
+use rustc_infer::{
+ infer,
+ traits::{self, Obligation},
+};
+use rustc_infer::{
+ infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind},
+ traits::ObligationCause,
+};
+use rustc_middle::ty::adjustment::{
+ Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability,
+};
+use rustc_middle::ty::SubstsRef;
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitable};
+use rustc_span::def_id::LocalDefId;
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::Span;
+use rustc_target::spec::abi;
+use rustc_trait_selection::autoderef::Autoderef;
+use rustc_trait_selection::infer::InferCtxtExt as _;
+use rustc_trait_selection::traits::error_reporting::DefIdOrName;
+use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
+
+use std::iter;
+
+/// Checks that it is legal to call methods of the trait corresponding
+/// to `trait_id` (this only cares about the trait, not the specific
+/// method that is called).
+pub fn check_legal_trait_for_method_call(
+ tcx: TyCtxt<'_>,
+ span: Span,
+ receiver: Option<Span>,
+ expr_span: Span,
+ trait_id: DefId,
+) {
+ if tcx.lang_items().drop_trait() == Some(trait_id) {
+ let mut err = struct_span_err!(tcx.sess, span, E0040, "explicit use of destructor method");
+ err.span_label(span, "explicit destructor calls not allowed");
+
+ let (sp, suggestion) = receiver
+ .and_then(|s| tcx.sess.source_map().span_to_snippet(s).ok())
+ .filter(|snippet| !snippet.is_empty())
+ .map(|snippet| (expr_span, format!("drop({snippet})")))
+ .unwrap_or_else(|| (span, "drop".to_string()));
+
+ err.span_suggestion(
+ sp,
+ "consider using `drop` function",
+ suggestion,
+ Applicability::MaybeIncorrect,
+ );
+
+ err.emit();
+ }
+}
+
+#[derive(Debug)]
+enum CallStep<'tcx> {
+ Builtin(Ty<'tcx>),
+ DeferredClosure(LocalDefId, ty::FnSig<'tcx>),
+ /// E.g., enum variant constructors.
+ Overloaded(MethodCallee<'tcx>),
+}
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+ pub fn check_call(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let original_callee_ty = match &callee_expr.kind {
+ hir::ExprKind::Path(hir::QPath::Resolved(..) | hir::QPath::TypeRelative(..)) => self
+ .check_expr_with_expectation_and_args(
+ callee_expr,
+ Expectation::NoExpectation,
+ arg_exprs,
+ ),
+ _ => self.check_expr(callee_expr),
+ };
+
+ let expr_ty = self.structurally_resolved_type(call_expr.span, original_callee_ty);
+
+ let mut autoderef = self.autoderef(callee_expr.span, expr_ty);
+ let mut result = None;
+ while result.is_none() && autoderef.next().is_some() {
+ result = self.try_overloaded_call_step(call_expr, callee_expr, arg_exprs, &autoderef);
+ }
+ self.register_predicates(autoderef.into_obligations());
+
+ let output = match result {
+ None => {
+ // this will report an error since original_callee_ty is not a fn
+ self.confirm_builtin_call(
+ call_expr,
+ callee_expr,
+ original_callee_ty,
+ arg_exprs,
+ expected,
+ )
+ }
+
+ Some(CallStep::Builtin(callee_ty)) => {
+ self.confirm_builtin_call(call_expr, callee_expr, callee_ty, arg_exprs, expected)
+ }
+
+ Some(CallStep::DeferredClosure(def_id, fn_sig)) => {
+ self.confirm_deferred_closure_call(call_expr, arg_exprs, expected, def_id, fn_sig)
+ }
+
+ Some(CallStep::Overloaded(method_callee)) => {
+ self.confirm_overloaded_call(call_expr, arg_exprs, expected, method_callee)
+ }
+ };
+
+ // we must check that return type of called functions is WF:
+ self.register_wf_obligation(output.into(), call_expr.span, traits::WellFormed(None));
+
+ output
+ }
+
+ fn try_overloaded_call_step(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ autoderef: &Autoderef<'a, 'tcx>,
+ ) -> Option<CallStep<'tcx>> {
+ let adjusted_ty =
+ self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false));
+ debug!(
+ "try_overloaded_call_step(call_expr={:?}, adjusted_ty={:?})",
+ call_expr, adjusted_ty
+ );
+
+ // If the callee is a bare function or a closure, then we're all set.
+ match *adjusted_ty.kind() {
+ ty::FnDef(..) | ty::FnPtr(_) => {
+ let adjustments = self.adjust_steps(autoderef);
+ self.apply_adjustments(callee_expr, adjustments);
+ return Some(CallStep::Builtin(adjusted_ty));
+ }
+
+ ty::Closure(def_id, substs) => {
+ let def_id = def_id.expect_local();
+
+ // Check whether this is a call to a closure where we
+ // haven't yet decided on whether the closure is fn vs
+ // fnmut vs fnonce. If so, we have to defer further processing.
+ if self.closure_kind(substs).is_none() {
+ let closure_sig = substs.as_closure().sig();
+ let closure_sig = self.replace_bound_vars_with_fresh_vars(
+ call_expr.span,
+ infer::FnCall,
+ closure_sig,
+ );
+ let adjustments = self.adjust_steps(autoderef);
+ self.record_deferred_call_resolution(
+ def_id,
+ DeferredCallResolution {
+ call_expr,
+ callee_expr,
+ adjusted_ty,
+ adjustments,
+ fn_sig: closure_sig,
+ closure_substs: substs,
+ },
+ );
+ return Some(CallStep::DeferredClosure(def_id, closure_sig));
+ }
+ }
+
+ // Hack: we know that there are traits implementing Fn for &F
+ // where F:Fn and so forth. In the particular case of types
+ // like `x: &mut FnMut()`, if there is a call `x()`, we would
+ // normally translate to `FnMut::call_mut(&mut x, ())`, but
+ // that winds up requiring `mut x: &mut FnMut()`. A little
+ // over the top. The simplest fix by far is to just ignore
+ // this case and deref again, so we wind up with
+ // `FnMut::call_mut(&mut *x, ())`.
+ ty::Ref(..) if autoderef.step_count() == 0 => {
+ return None;
+ }
+
+ ty::Error(_) => {
+ return None;
+ }
+
+ _ => {}
+ }
+
+ // Now, we look for the implementation of a Fn trait on the object's type.
+ // We first do it with the explicit instruction to look for an impl of
+ // `Fn<Tuple>`, with the tuple `Tuple` having an arity corresponding
+ // to the number of call parameters.
+ // If that fails (or_else branch), we try again without specifying the
+ // shape of the tuple (hence the None). This allows to detect an Fn trait
+ // is implemented, and use this information for diagnostic.
+ self.try_overloaded_call_traits(call_expr, adjusted_ty, Some(arg_exprs))
+ .or_else(|| self.try_overloaded_call_traits(call_expr, adjusted_ty, None))
+ .map(|(autoref, method)| {
+ let mut adjustments = self.adjust_steps(autoderef);
+ adjustments.extend(autoref);
+ self.apply_adjustments(callee_expr, adjustments);
+ CallStep::Overloaded(method)
+ })
+ }
+
+ fn try_overloaded_call_traits(
+ &self,
+ call_expr: &hir::Expr<'_>,
+ adjusted_ty: Ty<'tcx>,
+ opt_arg_exprs: Option<&'tcx [hir::Expr<'tcx>]>,
+ ) -> Option<(Option<Adjustment<'tcx>>, MethodCallee<'tcx>)> {
+ // Try the options that are least restrictive on the caller first.
+ for (opt_trait_def_id, method_name, borrow) in [
+ (self.tcx.lang_items().fn_trait(), Ident::with_dummy_span(sym::call), true),
+ (self.tcx.lang_items().fn_mut_trait(), Ident::with_dummy_span(sym::call_mut), true),
+ (self.tcx.lang_items().fn_once_trait(), Ident::with_dummy_span(sym::call_once), false),
+ ] {
+ let Some(trait_def_id) = opt_trait_def_id else { continue };
+
+ let opt_input_types = opt_arg_exprs.map(|arg_exprs| {
+ [self.tcx.mk_tup(arg_exprs.iter().map(|e| {
+ self.next_ty_var(TypeVariableOrigin {
+ kind: TypeVariableOriginKind::TypeInference,
+ span: e.span,
+ })
+ }))]
+ });
+ let opt_input_types = opt_input_types.as_ref().map(AsRef::as_ref);
+
+ if let Some(ok) = self.lookup_method_in_trait(
+ call_expr.span,
+ method_name,
+ trait_def_id,
+ adjusted_ty,
+ opt_input_types,
+ ) {
+ let method = self.register_infer_ok_obligations(ok);
+ let mut autoref = None;
+ if borrow {
+ // Check for &self vs &mut self in the method signature. Since this is either
+ // the Fn or FnMut trait, it should be one of those.
+ let ty::Ref(region, _, mutbl) = method.sig.inputs()[0].kind() else {
+ // The `fn`/`fn_mut` lang item is ill-formed, which should have
+ // caused an error elsewhere.
+ self.tcx
+ .sess
+ .delay_span_bug(call_expr.span, "input to call/call_mut is not a ref?");
+ return None;
+ };
+
+ let mutbl = match mutbl {
+ hir::Mutability::Not => AutoBorrowMutability::Not,
+ hir::Mutability::Mut => AutoBorrowMutability::Mut {
+ // For initial two-phase borrow
+ // deployment, conservatively omit
+ // overloaded function call ops.
+ allow_two_phase_borrow: AllowTwoPhase::No,
+ },
+ };
+ autoref = Some(Adjustment {
+ kind: Adjust::Borrow(AutoBorrow::Ref(*region, mutbl)),
+ target: method.sig.inputs()[0],
+ });
+ }
+ return Some((autoref, method));
+ }
+ }
+
+ None
+ }
+
+ /// Give appropriate suggestion when encountering `||{/* not callable */}()`, where the
+ /// likely intention is to call the closure, suggest `(||{})()`. (#55851)
+ fn identify_bad_closure_def_and_call(
+ &self,
+ err: &mut Diagnostic,
+ hir_id: hir::HirId,
+ callee_node: &hir::ExprKind<'_>,
+ callee_span: Span,
+ ) {
+ let hir = self.tcx.hir();
+ let parent_hir_id = hir.get_parent_node(hir_id);
+ let parent_node = hir.get(parent_hir_id);
+ if let (
+ hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Closure(&hir::Closure { fn_decl_span, body, .. }),
+ ..
+ }),
+ hir::ExprKind::Block(..),
+ ) = (parent_node, callee_node)
+ {
+ let fn_decl_span = if hir.body(body).generator_kind
+ == Some(hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Closure))
+ {
+ // Actually need to unwrap a few more layers of HIR to get to
+ // the _real_ closure...
+ let async_closure = hir.get_parent_node(hir.get_parent_node(parent_hir_id));
+ if let hir::Node::Expr(hir::Expr {
+ kind: hir::ExprKind::Closure(&hir::Closure { fn_decl_span, .. }),
+ ..
+ }) = hir.get(async_closure)
+ {
+ fn_decl_span
+ } else {
+ return;
+ }
+ } else {
+ fn_decl_span
+ };
+
+ let start = fn_decl_span.shrink_to_lo();
+ let end = callee_span.shrink_to_hi();
+ err.multipart_suggestion(
+ "if you meant to create this closure and immediately call it, surround the \
+ closure with parentheses",
+ vec![(start, "(".to_string()), (end, ")".to_string())],
+ Applicability::MaybeIncorrect,
+ );
+ }
+ }
+
+ /// Give appropriate suggestion when encountering `[("a", 0) ("b", 1)]`, where the
+ /// likely intention is to create an array containing tuples.
+ fn maybe_suggest_bad_array_definition(
+ &self,
+ err: &mut Diagnostic,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ ) -> bool {
+ let hir_id = self.tcx.hir().get_parent_node(call_expr.hir_id);
+ let parent_node = self.tcx.hir().get(hir_id);
+ if let (
+ hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Array(_), .. }),
+ hir::ExprKind::Tup(exp),
+ hir::ExprKind::Call(_, args),
+ ) = (parent_node, &callee_expr.kind, &call_expr.kind)
+ && args.len() == exp.len()
+ {
+ let start = callee_expr.span.shrink_to_hi();
+ err.span_suggestion(
+ start,
+ "consider separating array elements with a comma",
+ ",",
+ Applicability::MaybeIncorrect,
+ );
+ return true;
+ }
+ false
+ }
+
+ fn confirm_builtin_call(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ callee_ty: Ty<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ ) -> Ty<'tcx> {
+ let (fn_sig, def_id) = match *callee_ty.kind() {
+ ty::FnDef(def_id, subst) => {
+ let fn_sig = self.tcx.bound_fn_sig(def_id).subst(self.tcx, subst);
+
+ // Unit testing: function items annotated with
+ // `#[rustc_evaluate_where_clauses]` trigger special output
+ // to let us test the trait evaluation system.
+ if self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses) {
+ let predicates = self.tcx.predicates_of(def_id);
+ let predicates = predicates.instantiate(self.tcx, subst);
+ for (predicate, predicate_span) in
+ predicates.predicates.iter().zip(&predicates.spans)
+ {
+ let obligation = Obligation::new(
+ ObligationCause::dummy_with_span(callee_expr.span),
+ self.param_env,
+ *predicate,
+ );
+ let result = self.evaluate_obligation(&obligation);
+ self.tcx
+ .sess
+ .struct_span_err(
+ callee_expr.span,
+ &format!("evaluate({:?}) = {:?}", predicate, result),
+ )
+ .span_label(*predicate_span, "predicate")
+ .emit();
+ }
+ }
+ (fn_sig, Some(def_id))
+ }
+ ty::FnPtr(sig) => (sig, None),
+ _ => {
+ if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = &callee_expr.kind
+ && let [segment] = path.segments
+ && let Some(mut diag) = self
+ .tcx
+ .sess
+ .diagnostic()
+ .steal_diagnostic(segment.ident.span, StashKey::CallIntoMethod)
+ {
+ // Try suggesting `foo(a)` -> `a.foo()` if possible.
+ if let Some(ty) =
+ self.suggest_call_as_method(
+ &mut diag,
+ segment,
+ arg_exprs,
+ call_expr,
+ expected
+ )
+ {
+ diag.emit();
+ return ty;
+ } else {
+ diag.emit();
+ }
+ }
+
+ self.report_invalid_callee(call_expr, callee_expr, callee_ty, arg_exprs);
+
+ // This is the "default" function signature, used in case of error.
+ // In that case, we check each argument against "error" in order to
+ // set up all the node type bindings.
+ (
+ ty::Binder::dummy(self.tcx.mk_fn_sig(
+ self.err_args(arg_exprs.len()).into_iter(),
+ self.tcx.ty_error(),
+ false,
+ hir::Unsafety::Normal,
+ abi::Abi::Rust,
+ )),
+ None,
+ )
+ }
+ };
+
+ // Replace any late-bound regions that appear in the function
+ // signature with region variables. We also have to
+ // renormalize the associated types at this point, since they
+ // previously appeared within a `Binder<>` and hence would not
+ // have been normalized before.
+ let fn_sig = self.replace_bound_vars_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);
+ let fn_sig = self.normalize_associated_types_in(call_expr.span, fn_sig);
+
+ // Call the generic checker.
+ let expected_arg_tys = self.expected_inputs_for_expected_output(
+ call_expr.span,
+ expected,
+ fn_sig.output(),
+ fn_sig.inputs(),
+ );
+ self.check_argument_types(
+ call_expr.span,
+ call_expr,
+ fn_sig.inputs(),
+ expected_arg_tys,
+ arg_exprs,
+ fn_sig.c_variadic,
+ TupleArgumentsFlag::DontTupleArguments,
+ def_id,
+ );
+
+ fn_sig.output()
+ }
+
+ /// Attempts to reinterpret `method(rcvr, args...)` as `rcvr.method(args...)`
+ /// and suggesting the fix if the method probe is successful.
+ fn suggest_call_as_method(
+ &self,
+ diag: &mut Diagnostic,
+ segment: &'tcx hir::PathSegment<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ call_expr: &'tcx hir::Expr<'tcx>,
+ expected: Expectation<'tcx>,
+ ) -> Option<Ty<'tcx>> {
+ if let [callee_expr, rest @ ..] = arg_exprs {
+ let callee_ty = self.check_expr(callee_expr);
+ // First, do a probe with `IsSuggestion(true)` to avoid emitting
+ // any strange errors. If it's successful, then we'll do a true
+ // method lookup.
+ let Ok(pick) = self
+ .probe_for_name(
+ call_expr.span,
+ Mode::MethodCall,
+ segment.ident,
+ IsSuggestion(true),
+ callee_ty,
+ call_expr.hir_id,
+ // We didn't record the in scope traits during late resolution
+ // so we need to probe AllTraits unfortunately
+ ProbeScope::AllTraits,
+ ) else {
+ return None;
+ };
+
+ let pick = self.confirm_method(
+ call_expr.span,
+ callee_expr,
+ call_expr,
+ callee_ty,
+ pick,
+ segment,
+ );
+ if pick.illegal_sized_bound.is_some() {
+ return None;
+ }
+
+ let up_to_rcvr_span = segment.ident.span.until(callee_expr.span);
+ let rest_span = callee_expr.span.shrink_to_hi().to(call_expr.span.shrink_to_hi());
+ let rest_snippet = if let Some(first) = rest.first() {
+ self.tcx
+ .sess
+ .source_map()
+ .span_to_snippet(first.span.to(call_expr.span.shrink_to_hi()))
+ } else {
+ Ok(")".to_string())
+ };
+
+ if let Ok(rest_snippet) = rest_snippet {
+ let sugg = if callee_expr.precedence().order() >= PREC_POSTFIX {
+ vec![
+ (up_to_rcvr_span, "".to_string()),
+ (rest_span, format!(".{}({rest_snippet}", segment.ident)),
+ ]
+ } else {
+ vec![
+ (up_to_rcvr_span, "(".to_string()),
+ (rest_span, format!(").{}({rest_snippet}", segment.ident)),
+ ]
+ };
+ let self_ty = self.resolve_vars_if_possible(pick.callee.sig.inputs()[0]);
+ diag.multipart_suggestion(
+ format!(
+ "use the `.` operator to call the method `{}{}` on `{self_ty}`",
+ self.tcx
+ .associated_item(pick.callee.def_id)
+ .trait_container(self.tcx)
+ .map_or_else(
+ || String::new(),
+ |trait_def_id| self.tcx.def_path_str(trait_def_id) + "::"
+ ),
+ segment.ident
+ ),
+ sugg,
+ Applicability::MaybeIncorrect,
+ );
+
+ // Let's check the method fully now
+ let return_ty = self.check_method_argument_types(
+ segment.ident.span,
+ call_expr,
+ Ok(pick.callee),
+ rest,
+ TupleArgumentsFlag::DontTupleArguments,
+ expected,
+ );
+
+ return Some(return_ty);
+ }
+ }
+
+ None
+ }
+
+ fn report_invalid_callee(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ callee_ty: Ty<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ ) {
+ let mut unit_variant = None;
+ if let hir::ExprKind::Path(qpath) = &callee_expr.kind
+ && let Res::Def(def::DefKind::Ctor(kind, def::CtorKind::Const), _)
+ = self.typeck_results.borrow().qpath_res(qpath, callee_expr.hir_id)
+ // Only suggest removing parens if there are no arguments
+ && arg_exprs.is_empty()
+ {
+ let descr = match kind {
+ def::CtorOf::Struct => "struct",
+ def::CtorOf::Variant => "enum variant",
+ };
+ let removal_span = callee_expr.span.shrink_to_hi().to(call_expr.span.shrink_to_hi());
+ unit_variant = Some((removal_span, descr, rustc_hir_pretty::qpath_to_string(qpath)));
+ }
+
+ let callee_ty = self.resolve_vars_if_possible(callee_ty);
+ let mut err = type_error_struct!(
+ self.tcx.sess,
+ callee_expr.span,
+ callee_ty,
+ E0618,
+ "expected function, found {}",
+ match &unit_variant {
+ Some((_, kind, path)) => format!("{kind} `{path}`"),
+ None => format!("`{callee_ty}`"),
+ }
+ );
+
+ self.identify_bad_closure_def_and_call(
+ &mut err,
+ call_expr.hir_id,
+ &callee_expr.kind,
+ callee_expr.span,
+ );
+
+ if let Some((removal_span, kind, path)) = &unit_variant {
+ err.span_suggestion_verbose(
+ *removal_span,
+ &format!(
+ "`{path}` is a unit {kind}, and does not take parentheses to be constructed",
+ ),
+ "",
+ Applicability::MachineApplicable,
+ );
+ }
+
+ let mut inner_callee_path = None;
+ let def = match callee_expr.kind {
+ hir::ExprKind::Path(ref qpath) => {
+ self.typeck_results.borrow().qpath_res(qpath, callee_expr.hir_id)
+ }
+ hir::ExprKind::Call(ref inner_callee, _) => {
+ // If the call spans more than one line and the callee kind is
+ // itself another `ExprCall`, that's a clue that we might just be
+ // missing a semicolon (Issue #51055)
+ let call_is_multiline = self.tcx.sess.source_map().is_multiline(call_expr.span);
+ if call_is_multiline {
+ err.span_suggestion(
+ callee_expr.span.shrink_to_hi(),
+ "consider using a semicolon here",
+ ";",
+ Applicability::MaybeIncorrect,
+ );
+ }
+ if let hir::ExprKind::Path(ref inner_qpath) = inner_callee.kind {
+ inner_callee_path = Some(inner_qpath);
+ self.typeck_results.borrow().qpath_res(inner_qpath, inner_callee.hir_id)
+ } else {
+ Res::Err
+ }
+ }
+ _ => Res::Err,
+ };
+
+ if !self.maybe_suggest_bad_array_definition(&mut err, call_expr, callee_expr) {
+ if let Some((maybe_def, output_ty, _)) =
+ self.extract_callable_info(callee_expr, callee_ty)
+ && !self.type_is_sized_modulo_regions(self.param_env, output_ty, callee_expr.span)
+ {
+ let descr = match maybe_def {
+ DefIdOrName::DefId(def_id) => self.tcx.def_kind(def_id).descr(def_id),
+ DefIdOrName::Name(name) => name,
+ };
+ err.span_label(
+ callee_expr.span,
+ format!("this {descr} returns an unsized value `{output_ty}`, so it cannot be called")
+ );
+ if let DefIdOrName::DefId(def_id) = maybe_def
+ && let Some(def_span) = self.tcx.hir().span_if_local(def_id)
+ {
+ err.span_label(def_span, "the callable type is defined here");
+ }
+ } else {
+ err.span_label(call_expr.span, "call expression requires function");
+ }
+ }
+
+ if let Some(span) = self.tcx.hir().res_span(def) {
+ let callee_ty = callee_ty.to_string();
+ let label = match (unit_variant, inner_callee_path) {
+ (Some((_, kind, path)), _) => Some(format!("{kind} `{path}` defined here")),
+ (_, Some(hir::QPath::Resolved(_, path))) => self
+ .tcx
+ .sess
+ .source_map()
+ .span_to_snippet(path.span)
+ .ok()
+ .map(|p| format!("`{p}` defined here returns `{callee_ty}`")),
+ _ => {
+ match def {
+ // Emit a different diagnostic for local variables, as they are not
+ // type definitions themselves, but rather variables *of* that type.
+ Res::Local(hir_id) => Some(format!(
+ "`{}` has type `{}`",
+ self.tcx.hir().name(hir_id),
+ callee_ty
+ )),
+ Res::Def(kind, def_id) if kind.ns() == Some(Namespace::ValueNS) => {
+ Some(format!("`{}` defined here", self.tcx.def_path_str(def_id),))
+ }
+ _ => Some(format!("`{callee_ty}` defined here")),
+ }
+ }
+ };
+ if let Some(label) = label {
+ err.span_label(span, label);
+ }
+ }
+ err.emit();
+ }
+
+ fn confirm_deferred_closure_call(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ closure_def_id: LocalDefId,
+ fn_sig: ty::FnSig<'tcx>,
+ ) -> Ty<'tcx> {
+ // `fn_sig` is the *signature* of the closure being called. We
+ // don't know the full details yet (`Fn` vs `FnMut` etc), but we
+ // do know the types expected for each argument and the return
+ // type.
+
+ let expected_arg_tys = self.expected_inputs_for_expected_output(
+ call_expr.span,
+ expected,
+ fn_sig.output(),
+ fn_sig.inputs(),
+ );
+
+ self.check_argument_types(
+ call_expr.span,
+ call_expr,
+ fn_sig.inputs(),
+ expected_arg_tys,
+ arg_exprs,
+ fn_sig.c_variadic,
+ TupleArgumentsFlag::TupleArguments,
+ Some(closure_def_id.to_def_id()),
+ );
+
+ fn_sig.output()
+ }
+
+ fn confirm_overloaded_call(
+ &self,
+ call_expr: &'tcx hir::Expr<'tcx>,
+ arg_exprs: &'tcx [hir::Expr<'tcx>],
+ expected: Expectation<'tcx>,
+ method_callee: MethodCallee<'tcx>,
+ ) -> Ty<'tcx> {
+ let output_type = self.check_method_argument_types(
+ call_expr.span,
+ call_expr,
+ Ok(method_callee),
+ arg_exprs,
+ TupleArgumentsFlag::TupleArguments,
+ expected,
+ );
+
+ self.write_method_call(call_expr.hir_id, method_callee);
+ output_type
+ }
+}
+
+#[derive(Debug)]
+pub struct DeferredCallResolution<'tcx> {
+ call_expr: &'tcx hir::Expr<'tcx>,
+ callee_expr: &'tcx hir::Expr<'tcx>,
+ adjusted_ty: Ty<'tcx>,
+ adjustments: Vec<Adjustment<'tcx>>,
+ fn_sig: ty::FnSig<'tcx>,
+ closure_substs: SubstsRef<'tcx>,
+}
+
+impl<'a, 'tcx> DeferredCallResolution<'tcx> {
+ pub fn resolve(self, fcx: &FnCtxt<'a, 'tcx>) {
+ debug!("DeferredCallResolution::resolve() {:?}", self);
+
+ // we should not be invoked until the closure kind has been
+ // determined by upvar inference
+ assert!(fcx.closure_kind(self.closure_substs).is_some());
+
+ // We may now know enough to figure out fn vs fnmut etc.
+ match fcx.try_overloaded_call_traits(self.call_expr, self.adjusted_ty, None) {
+ Some((autoref, method_callee)) => {
+ // One problem is that when we get here, we are going
+ // to have a newly instantiated function signature
+ // from the call trait. This has to be reconciled with
+ // the older function signature we had before. In
+ // principle we *should* be able to fn_sigs(), but we
+ // can't because of the annoying need for a TypeTrace.
+ // (This always bites me, should find a way to
+ // refactor it.)
+ let method_sig = method_callee.sig;
+
+ debug!("attempt_resolution: method_callee={:?}", method_callee);
+
+ for (method_arg_ty, self_arg_ty) in
+ iter::zip(method_sig.inputs().iter().skip(1), self.fn_sig.inputs())
+ {
+ fcx.demand_eqtype(self.call_expr.span, *self_arg_ty, *method_arg_ty);
+ }
+
+ fcx.demand_eqtype(self.call_expr.span, method_sig.output(), self.fn_sig.output());
+
+ let mut adjustments = self.adjustments;
+ adjustments.extend(autoref);
+ fcx.apply_adjustments(self.callee_expr, adjustments);
+
+ fcx.write_method_call(self.call_expr.hir_id, method_callee);
+ }
+ None => {
+ // This can happen if `#![no_core]` is used and the `fn/fn_mut/fn_once`
+ // lang items are not defined (issue #86238).
+ let mut err = fcx.inh.tcx.sess.struct_span_err(
+ self.call_expr.span,
+ "failed to find an overloaded call trait for closure call",
+ );
+ err.help(
+ "make sure the `fn`/`fn_mut`/`fn_once` lang items are defined \
+ and have associated `call`/`call_mut`/`call_once` functions",
+ );
+ err.emit();
+ }
+ }
+ }
+}
projects / rustc.git / blobdiff