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Rollup merge of #48123 - nikomatsakis:issue-47244-expected-num-args, r=estebank
detect wrong number of args when type-checking a closure Instead of creating inference variables for those argument types, use the trait error-reporting code to give a nicer error. This also improves some other spans for existing tests. Fixes #47244 r? @estebank
This commit is contained in:
Manish Goregaokar
GitHub
commit
1e67c1315b
@ -747,7 +747,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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ty::TyTuple(ref tys, _) => tys.iter()
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.map(|t| match t.sty {
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ty::TypeVariants::TyTuple(ref tys, _) => ArgKind::Tuple(
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span,
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Some(span),
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tys.iter()
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.map(|ty| ("_".to_owned(), format!("{}", ty.sty)))
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.collect::<Vec<_>>()
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@ -815,7 +815,11 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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}
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}
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fn get_fn_like_arguments(&self, node: hir::map::Node) -> (Span, Vec<ArgKind>) {
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/// Given some node representing a fn-like thing in the HIR map,
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/// returns a span and `ArgKind` information that describes the
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/// arguments it expects. This can be supplied to
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/// `report_arg_count_mismatch`.
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pub fn get_fn_like_arguments(&self, node: hir::map::Node) -> (Span, Vec<ArgKind>) {
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match node {
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hir::map::NodeExpr(&hir::Expr {
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node: hir::ExprClosure(_, ref _decl, id, span, _),
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@ -829,7 +833,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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..
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} = arg.pat.clone().into_inner() {
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ArgKind::Tuple(
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span,
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Some(span),
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args.iter().map(|pat| {
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let snippet = self.tcx.sess.codemap()
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.span_to_snippet(pat.span).unwrap();
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@ -862,7 +866,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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(self.tcx.sess.codemap().def_span(span), decl.inputs.iter()
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.map(|arg| match arg.clone().into_inner().node {
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hir::TyTup(ref tys) => ArgKind::Tuple(
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arg.span,
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Some(arg.span),
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tys.iter()
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.map(|_| ("_".to_owned(), "_".to_owned()))
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.collect::<Vec<_>>(),
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@ -874,7 +878,10 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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}
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}
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fn report_arg_count_mismatch(
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/// Reports an error when the number of arguments needed by a
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/// trait match doesn't match the number that the expression
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/// provides.
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pub fn report_arg_count_mismatch(
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&self,
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span: Span,
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found_span: Option<Span>,
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@ -1385,13 +1392,34 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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}
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}
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enum ArgKind {
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/// Summarizes information
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pub enum ArgKind {
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/// An argument of non-tuple type. Parameters are (name, ty)
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Arg(String, String),
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Tuple(Span, Vec<(String, String)>),
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/// An argument of tuple type. For a "found" argument, the span is
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/// the locationo in the source of the pattern. For a "expected"
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/// argument, it will be None. The vector is a list of (name, ty)
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/// strings for the components of the tuple.
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Tuple(Option<Span>, Vec<(String, String)>),
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}
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impl ArgKind {
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fn empty() -> ArgKind {
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ArgKind::Arg("_".to_owned(), "_".to_owned())
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}
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/// Creates an `ArgKind` from the expected type of an
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/// argument. This has no name (`_`) and no source spans..
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pub fn from_expected_ty(t: Ty<'_>) -> ArgKind {
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match t.sty {
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ty::TyTuple(ref tys, _) => ArgKind::Tuple(
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None,
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tys.iter()
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.map(|ty| ("_".to_owned(), format!("{}", ty.sty)))
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.collect::<Vec<_>>()
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),
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_ => ArgKind::Arg("_".to_owned(), format!("{}", t.sty)),
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}
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}
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}
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@ -49,7 +49,7 @@ pub use self::util::SupertraitDefIds;
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pub use self::util::transitive_bounds;
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mod coherence;
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mod error_reporting;
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pub mod error_reporting;
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mod fulfill;
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mod project;
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mod object_safety;
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@ -17,14 +17,24 @@ use rustc::hir::def_id::DefId;
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use rustc::infer::{InferOk, InferResult};
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use rustc::infer::LateBoundRegionConversionTime;
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use rustc::infer::type_variable::TypeVariableOrigin;
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use rustc::traits::error_reporting::ArgKind;
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use rustc::ty::{self, ToPolyTraitRef, Ty};
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use rustc::ty::subst::Substs;
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use rustc::ty::TypeFoldable;
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use std::cmp;
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use std::iter;
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use syntax::abi::Abi;
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use syntax::codemap::Span;
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use rustc::hir;
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/// What signature do we *expect* the closure to have from context?
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#[derive(Debug)]
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struct ExpectedSig<'tcx> {
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/// Span that gave us this expectation, if we know that.
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cause_span: Option<Span>,
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sig: ty::FnSig<'tcx>,
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}
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struct ClosureSignatures<'tcx> {
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bound_sig: ty::PolyFnSig<'tcx>,
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liberated_sig: ty::FnSig<'tcx>,
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@ -42,8 +52,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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) -> Ty<'tcx> {
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debug!(
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"check_expr_closure(expr={:?},expected={:?})",
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expr,
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expected
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expr, expected
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);
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// It's always helpful for inference if we know the kind of
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@ -64,12 +73,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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decl: &'gcx hir::FnDecl,
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body: &'gcx hir::Body,
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gen: Option<hir::GeneratorMovability>,
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expected_sig: Option<ty::FnSig<'tcx>>,
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expected_sig: Option<ExpectedSig<'tcx>>,
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) -> Ty<'tcx> {
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debug!(
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"check_closure(opt_kind={:?}, expected_sig={:?})",
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opt_kind,
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expected_sig
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opt_kind, expected_sig
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);
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let expr_def_id = self.tcx.hir.local_def_id(expr.id);
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@ -109,19 +117,22 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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let closure_type = self.tcx.mk_closure(expr_def_id, substs);
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if let Some(GeneratorTypes { yield_ty, interior }) = generator_types {
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self.demand_eqtype(expr.span,
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yield_ty,
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substs.generator_yield_ty(expr_def_id, self.tcx));
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self.demand_eqtype(expr.span,
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liberated_sig.output(),
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substs.generator_return_ty(expr_def_id, self.tcx));
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self.demand_eqtype(
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expr.span,
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yield_ty,
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substs.generator_yield_ty(expr_def_id, self.tcx),
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);
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self.demand_eqtype(
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expr.span,
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liberated_sig.output(),
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substs.generator_return_ty(expr_def_id, self.tcx),
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);
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return self.tcx.mk_generator(expr_def_id, substs, interior);
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}
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debug!(
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"check_closure: expr.id={:?} closure_type={:?}",
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expr.id,
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closure_type
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expr.id, closure_type
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);
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// Tuple up the arguments and insert the resulting function type into
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@ -138,29 +149,33 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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debug!(
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"check_closure: expr_def_id={:?}, sig={:?}, opt_kind={:?}",
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expr_def_id,
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sig,
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opt_kind
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expr_def_id, sig, opt_kind
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);
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let sig_fn_ptr_ty = self.tcx.mk_fn_ptr(sig);
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self.demand_eqtype(expr.span,
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sig_fn_ptr_ty,
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substs.closure_sig_ty(expr_def_id, self.tcx));
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self.demand_eqtype(
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expr.span,
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sig_fn_ptr_ty,
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substs.closure_sig_ty(expr_def_id, self.tcx),
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);
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if let Some(kind) = opt_kind {
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self.demand_eqtype(expr.span,
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kind.to_ty(self.tcx),
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substs.closure_kind_ty(expr_def_id, self.tcx));
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self.demand_eqtype(
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expr.span,
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kind.to_ty(self.tcx),
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substs.closure_kind_ty(expr_def_id, self.tcx),
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);
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}
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closure_type
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}
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/// Given the expected type, figures out what it can about this closure we
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/// are about to type check:
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fn deduce_expectations_from_expected_type(
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&self,
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expected_ty: Ty<'tcx>,
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) -> (Option<ty::FnSig<'tcx>>, Option<ty::ClosureKind>) {
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) -> (Option<ExpectedSig<'tcx>>, Option<ty::ClosureKind>) {
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debug!(
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"deduce_expectations_from_expected_type(expected_ty={:?})",
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expected_ty
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@ -172,7 +187,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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.projection_bounds()
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.filter_map(|pb| {
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let pb = pb.with_self_ty(self.tcx, self.tcx.types.err);
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self.deduce_sig_from_projection(&pb)
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self.deduce_sig_from_projection(None, &pb)
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})
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.next();
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let kind = object_type
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@ -181,7 +196,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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(sig, kind)
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}
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ty::TyInfer(ty::TyVar(vid)) => self.deduce_expectations_from_obligations(vid),
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ty::TyFnPtr(sig) => (Some(sig.skip_binder().clone()), Some(ty::ClosureKind::Fn)),
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ty::TyFnPtr(sig) => {
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let expected_sig = ExpectedSig {
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cause_span: None,
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sig: sig.skip_binder().clone(),
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};
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(Some(expected_sig), Some(ty::ClosureKind::Fn))
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}
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_ => (None, None),
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}
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}
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@ -189,7 +210,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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fn deduce_expectations_from_obligations(
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&self,
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expected_vid: ty::TyVid,
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) -> (Option<ty::FnSig<'tcx>>, Option<ty::ClosureKind>) {
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) -> (Option<ExpectedSig<'tcx>>, Option<ty::ClosureKind>) {
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let fulfillment_cx = self.fulfillment_cx.borrow();
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// Here `expected_ty` is known to be a type inference variable.
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@ -209,7 +230,12 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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ty::Predicate::Projection(ref proj_predicate) => {
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let trait_ref = proj_predicate.to_poly_trait_ref(self.tcx);
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self.self_type_matches_expected_vid(trait_ref, expected_vid)
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.and_then(|_| self.deduce_sig_from_projection(proj_predicate))
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.and_then(|_| {
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self.deduce_sig_from_projection(
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Some(obligation.cause.span),
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proj_predicate,
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)
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})
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}
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_ => None,
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}
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@ -259,10 +285,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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/// Given a projection like "<F as Fn(X)>::Result == Y", we can deduce
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/// everything we need to know about a closure.
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///
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/// The `cause_span` should be the span that caused us to
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/// have this expected signature, or `None` if we can't readily
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/// know that.
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fn deduce_sig_from_projection(
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&self,
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cause_span: Option<Span>,
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projection: &ty::PolyProjectionPredicate<'tcx>,
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) -> Option<ty::FnSig<'tcx>> {
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) -> Option<ExpectedSig<'tcx>> {
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let tcx = self.tcx;
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debug!("deduce_sig_from_projection({:?})", projection);
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@ -294,16 +325,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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ret_param_ty
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);
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let fn_sig = self.tcx.mk_fn_sig(
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let sig = self.tcx.mk_fn_sig(
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input_tys.cloned(),
|
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ret_param_ty,
|
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false,
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hir::Unsafety::Normal,
|
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Abi::Rust,
|
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);
|
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debug!("deduce_sig_from_projection: fn_sig {:?}", fn_sig);
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debug!("deduce_sig_from_projection: sig {:?}", sig);
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|
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Some(fn_sig)
|
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Some(ExpectedSig { cause_span, sig })
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}
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|
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fn self_type_matches_expected_vid(
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@ -314,8 +345,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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let self_ty = self.shallow_resolve(trait_ref.self_ty());
|
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debug!(
|
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"self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?})",
|
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trait_ref,
|
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self_ty
|
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trait_ref, self_ty
|
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);
|
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match self_ty.sty {
|
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ty::TyInfer(ty::TyVar(v)) if expected_vid == v => Some(trait_ref),
|
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@ -328,7 +358,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
|
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expr_def_id: DefId,
|
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decl: &hir::FnDecl,
|
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body: &hir::Body,
|
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expected_sig: Option<ty::FnSig<'tcx>>,
|
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expected_sig: Option<ExpectedSig<'tcx>>,
|
||||
) -> ClosureSignatures<'tcx> {
|
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if let Some(e) = expected_sig {
|
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self.sig_of_closure_with_expectation(expr_def_id, decl, body, e)
|
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@ -404,7 +434,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
|
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expr_def_id: DefId,
|
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decl: &hir::FnDecl,
|
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body: &hir::Body,
|
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expected_sig: ty::FnSig<'tcx>,
|
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expected_sig: ExpectedSig<'tcx>,
|
||||
) -> ClosureSignatures<'tcx> {
|
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debug!(
|
||||
"sig_of_closure_with_expectation(expected_sig={:?})",
|
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@ -414,20 +444,24 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
|
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// Watch out for some surprises and just ignore the
|
||||
// expectation if things don't see to match up with what we
|
||||
// expect.
|
||||
if expected_sig.variadic != decl.variadic {
|
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return self.sig_of_closure_no_expectation(expr_def_id, decl, body);
|
||||
} else if expected_sig.inputs_and_output.len() != decl.inputs.len() + 1 {
|
||||
// we could probably handle this case more gracefully
|
||||
if expected_sig.sig.variadic != decl.variadic {
|
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return self.sig_of_closure_no_expectation(expr_def_id, decl, body);
|
||||
} else if expected_sig.sig.inputs_and_output.len() != decl.inputs.len() + 1 {
|
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return self.sig_of_closure_with_mismatched_number_of_arguments(
|
||||
expr_def_id,
|
||||
decl,
|
||||
body,
|
||||
expected_sig,
|
||||
);
|
||||
}
|
||||
|
||||
// Create a `PolyFnSig`. Note the oddity that late bound
|
||||
// regions appearing free in `expected_sig` are now bound up
|
||||
// in this binder we are creating.
|
||||
assert!(!expected_sig.has_regions_escaping_depth(1));
|
||||
assert!(!expected_sig.sig.has_regions_escaping_depth(1));
|
||||
let bound_sig = ty::Binder(self.tcx.mk_fn_sig(
|
||||
expected_sig.inputs().iter().cloned(),
|
||||
expected_sig.output(),
|
||||
expected_sig.sig.inputs().iter().cloned(),
|
||||
expected_sig.sig.output(),
|
||||
decl.variadic,
|
||||
hir::Unsafety::Normal,
|
||||
Abi::RustCall,
|
||||
@ -453,6 +487,35 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
|
||||
closure_sigs
|
||||
}
|
||||
|
||||
fn sig_of_closure_with_mismatched_number_of_arguments(
|
||||
&self,
|
||||
expr_def_id: DefId,
|
||||
decl: &hir::FnDecl,
|
||||
body: &hir::Body,
|
||||
expected_sig: ExpectedSig<'tcx>,
|
||||
) -> ClosureSignatures<'tcx> {
|
||||
let expr_map_node = self.tcx.hir.get_if_local(expr_def_id).unwrap();
|
||||
let expected_args: Vec<_> = expected_sig
|
||||
.sig
|
||||
.inputs()
|
||||
.iter()
|
||||
.map(|ty| ArgKind::from_expected_ty(ty))
|
||||
.collect();
|
||||
let (closure_span, found_args) = self.get_fn_like_arguments(expr_map_node);
|
||||
let expected_span = expected_sig.cause_span.unwrap_or(closure_span);
|
||||
self.report_arg_count_mismatch(
|
||||
expected_span,
|
||||
Some(closure_span),
|
||||
expected_args,
|
||||
found_args,
|
||||
true,
|
||||
).emit();
|
||||
|
||||
let error_sig = self.error_sig_of_closure(decl);
|
||||
|
||||
self.closure_sigs(expr_def_id, body, error_sig)
|
||||
}
|
||||
|
||||
/// Enforce the user's types against the expectation. See
|
||||
/// `sig_of_closure_with_expectation` for details on the overall
|
||||
/// strategy.
|
||||
@ -558,13 +621,46 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
|
||||
result
|
||||
}
|
||||
|
||||
/// Converts the types that the user supplied, in case that doing
|
||||
/// so should yield an error, but returns back a signature where
|
||||
/// all parameters are of type `TyErr`.
|
||||
fn error_sig_of_closure(&self, decl: &hir::FnDecl) -> ty::PolyFnSig<'tcx> {
|
||||
let astconv: &AstConv = self;
|
||||
|
||||
let supplied_arguments = decl.inputs.iter().map(|a| {
|
||||
// Convert the types that the user supplied (if any), but ignore them.
|
||||
astconv.ast_ty_to_ty(a);
|
||||
self.tcx.types.err
|
||||
});
|
||||
|
||||
match decl.output {
|
||||
hir::Return(ref output) => {
|
||||
astconv.ast_ty_to_ty(&output);
|
||||
}
|
||||
hir::DefaultReturn(_) => {}
|
||||
}
|
||||
|
||||
let result = ty::Binder(self.tcx.mk_fn_sig(
|
||||
supplied_arguments,
|
||||
self.tcx.types.err,
|
||||
decl.variadic,
|
||||
hir::Unsafety::Normal,
|
||||
Abi::RustCall,
|
||||
));
|
||||
|
||||
debug!("supplied_sig_of_closure: result={:?}", result);
|
||||
|
||||
result
|
||||
}
|
||||
|
||||
fn closure_sigs(
|
||||
&self,
|
||||
expr_def_id: DefId,
|
||||
body: &hir::Body,
|
||||
bound_sig: ty::PolyFnSig<'tcx>,
|
||||
) -> ClosureSignatures<'tcx> {
|
||||
let liberated_sig = self.tcx().liberate_late_bound_regions(expr_def_id, &bound_sig);
|
||||
let liberated_sig = self.tcx()
|
||||
.liberate_late_bound_regions(expr_def_id, &bound_sig);
|
||||
let liberated_sig = self.inh.normalize_associated_types_in(
|
||||
body.value.span,
|
||||
body.value.id,
|
||||
|
||||
@ -0,0 +1,29 @@
|
||||
// Copyright 2016 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.
|
||||
|
||||
// Regression test for #47244: in this specific scenario, when the
|
||||
// expected type indicated 1 argument but the closure takes two, we
|
||||
// would (early on) create type variables for the type of `b`. If the
|
||||
// user then attempts to invoke a method on `b`, we would get an error
|
||||
// saying that the type of `b` must be known, which was not very
|
||||
// helpful.
|
||||
|
||||
use std::collections::HashMap;
|
||||
fn main() {
|
||||
|
||||
let m = HashMap::new();
|
||||
m.insert( "foo", "bar" );
|
||||
|
||||
m.iter().map( |_, b| {
|
||||
//~^ ERROR closure is expected to take a single 2-tuple
|
||||
|
||||
b.to_string()
|
||||
});
|
||||
}
|
||||
@ -0,0 +1,14 @@
|
||||
error[E0593]: closure is expected to take a single 2-tuple as argument, but it takes 2 distinct arguments
|
||||
--> $DIR/closure-arg-count-expected-type-issue-47244.rs:24:14
|
||||
|
|
||||
24 | m.iter().map( |_, b| {
|
||||
| ^^^ ------ takes 2 distinct arguments
|
||||
| |
|
||||
| expected closure that takes a single 2-tuple as argument
|
||||
help: change the closure to accept a tuple instead of individual arguments
|
||||
|
|
||||
24 | m.iter().map( |(_, b)| {
|
||||
| ^^^^^^^^
|
||||
|
||||
error: aborting due to previous error
|
||||
|
||||
Loading…
Reference in New Issue
Block a user