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Inline expected_inputs_for_expected_output into check_argument_types/check_expr_struct_fields

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This commit is contained in:
Michael Goulet 2024-08-25 12:45:58 -04:00
parent c3f9c4f4d4
commit 95b9ecd6d6
5 changed files with 71 additions and 77 deletions
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21
compiler/rustc_hir_typeck/src/callee.rs
View File

@ -503,18 +503,12 @@ fn confirm_builtin_call(
let fn_sig = self.instantiate_binder_with_fresh_vars(call_expr.span, infer::FnCall, fn_sig);
let fn_sig = self.normalize(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,
fn_sig.output(),
expected,
arg_exprs,
fn_sig.c_variadic,
TupleArgumentsFlag::DontTupleArguments,
@ -866,19 +860,12 @@ fn confirm_deferred_closure_call(
// 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,
fn_sig.output(),
expected,
arg_exprs,
fn_sig.c_variadic,
TupleArgumentsFlag::TupleArguments,

25
compiler/rustc_hir_typeck/src/expr.rs
View File

@ -1673,15 +1673,22 @@ fn check_expr_struct_fields(
) {
let tcx = self.tcx;
let expected_inputs =
self.expected_inputs_for_expected_output(span, expected, adt_ty, &[adt_ty]);
let adt_ty_hint = if let Some(expected_inputs) = expected_inputs {
expected_inputs.get(0).cloned().unwrap_or(adt_ty)
} else {
adt_ty
};
// re-link the regions that EIfEO can erase.
self.demand_eqtype(span, adt_ty_hint, adt_ty);
let adt_ty = self.resolve_vars_with_obligations(adt_ty);
let adt_ty_hint = expected.only_has_type(self).and_then(|expected| {
self.fudge_inference_if_ok(|| {
let ocx = ObligationCtxt::new(self);
ocx.sup(&self.misc(span), self.param_env, expected, adt_ty)?;
if !ocx.select_where_possible().is_empty() {
return Err(TypeError::Mismatch);
}
Ok(self.resolve_vars_if_possible(adt_ty))
})
.ok()
});
if let Some(adt_ty_hint) = adt_ty_hint {
// re-link the variables that the fudging above can create.
self.demand_eqtype(span, adt_ty_hint, adt_ty);
}
let ty::Adt(adt, args) = adt_ty.kind() else {
span_bug!(span, "non-ADT passed to check_expr_struct_fields");

39
compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
View File

@ -20,7 +20,6 @@
use rustc_infer::infer::{DefineOpaqueTypes, InferResult};
use rustc_lint::builtin::SELF_CONSTRUCTOR_FROM_OUTER_ITEM;
use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::fold::TypeFoldable;
use rustc_middle::ty::visit::{TypeVisitable, TypeVisitableExt};
use rustc_middle::ty::{
@ -36,7 +35,7 @@
use rustc_target::abi::FieldIdx;
use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded;
use rustc_trait_selection::traits::{
self, NormalizeExt, ObligationCauseCode, ObligationCtxt, StructurallyNormalizeExt,
self, NormalizeExt, ObligationCauseCode, StructurallyNormalizeExt,
};
use tracing::{debug, instrument};
@ -689,42 +688,6 @@ pub(crate) fn err_args(&self, len: usize, guar: ErrorGuaranteed) -> Vec<Ty<'tcx>
vec![ty_error; len]
}
/// Unifies the output type with the expected type early, for more coercions
/// and forward type information on the input expressions.
#[instrument(skip(self, call_span), level = "debug")]
pub(crate) fn expected_inputs_for_expected_output(
&self,
call_span: Span,
expected_ret: Expectation<'tcx>,
formal_ret: Ty<'tcx>,
formal_args: &[Ty<'tcx>],
) -> Option<Vec<Ty<'tcx>>> {
let formal_ret = self.resolve_vars_with_obligations(formal_ret);
let ret_ty = expected_ret.only_has_type(self)?;
let expect_args = self
.fudge_inference_if_ok(|| {
let ocx = ObligationCtxt::new(self);
// Attempt to apply a subtyping relationship between the formal
// return type (likely containing type variables if the function
// is polymorphic) and the expected return type.
// No argument expectations are produced if unification fails.
let origin = self.misc(call_span);
ocx.sup(&origin, self.param_env, ret_ty, formal_ret)?;
if !ocx.select_where_possible().is_empty() {
return Err(TypeError::Mismatch);
}
// Record all the argument types, with the args
// produced from the above subtyping unification.
Ok(Some(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect()))
})
.unwrap_or_default();
debug!(?formal_args, ?formal_ret, ?expect_args, ?expected_ret);
expect_args
}
pub(crate) fn resolve_lang_item_path(
&self,
lang_item: hir::LangItem,

58
compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
View File

@ -17,6 +17,7 @@
use rustc_index::IndexVec;
use rustc_infer::infer::{DefineOpaqueTypes, InferOk, TypeTrace};
use rustc_middle::ty::adjustment::AllowTwoPhase;
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::visit::TypeVisitableExt;
use rustc_middle::ty::{self, IsSuggestable, Ty, TyCtxt};
use rustc_middle::{bug, span_bug};
@ -25,7 +26,7 @@
use rustc_span::{sym, Span, DUMMY_SP};
use rustc_trait_selection::error_reporting::infer::{FailureCode, ObligationCauseExt};
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_trait_selection::traits::{self, ObligationCauseCode, SelectionContext};
use rustc_trait_selection::traits::{self, ObligationCauseCode, ObligationCtxt, SelectionContext};
use tracing::debug;
use {rustc_ast as ast, rustc_hir as hir};
@ -124,6 +125,7 @@ pub(in super::super) fn check_method_argument_types(
};
if let Err(guar) = has_error {
let err_inputs = self.err_args(args_no_rcvr.len(), guar);
let err_output = Ty::new_error(self.tcx, guar);
let err_inputs = match tuple_arguments {
DontTupleArguments => err_inputs,
@ -134,28 +136,23 @@ pub(in super::super) fn check_method_argument_types(
sp,
expr,
&err_inputs,
None,
err_output,
NoExpectation,
args_no_rcvr,
false,
tuple_arguments,
method.ok().map(|method| method.def_id),
);
return Ty::new_error(self.tcx, guar);
return err_output;
}
let method = method.unwrap();
// HACK(eddyb) ignore self in the definition (see above).
let expected_input_tys = self.expected_inputs_for_expected_output(
sp,
expected,
method.sig.output(),
&method.sig.inputs()[1..],
);
self.check_argument_types(
sp,
expr,
&method.sig.inputs()[1..],
expected_input_tys,
method.sig.output(),
expected,
args_no_rcvr,
method.sig.c_variadic,
tuple_arguments,
@ -175,8 +172,9 @@ pub(in super::super) fn check_argument_types(
call_expr: &'tcx hir::Expr<'tcx>,
// Types (as defined in the *signature* of the target function)
formal_input_tys: &[Ty<'tcx>],
// More specific expected types, after unifying with caller output types
expected_input_tys: Option<Vec<Ty<'tcx>>>,
formal_output: Ty<'tcx>,
// Expected output from the parent expression or statement
expectation: Expectation<'tcx>,
// The expressions for each provided argument
provided_args: &'tcx [hir::Expr<'tcx>],
// Whether the function is variadic, for example when imported from C
@ -210,6 +208,40 @@ pub(in super::super) fn check_argument_types(
);
}
// First, let's unify the formal method signature with the expectation eagerly.
// We use this to guide coercion inference; it's output is "fudged" which means
// any remaining type variables are assigned to new, unrelated variables. This
// is because the inference guidance here is only speculative.
let formal_output = self.resolve_vars_with_obligations(formal_output);
let expected_input_tys: Option<Vec<_>> = expectation
.only_has_type(self)
.and_then(|expected_output| {
self.fudge_inference_if_ok(|| {
let ocx = ObligationCtxt::new(self);
// Attempt to apply a subtyping relationship between the formal
// return type (likely containing type variables if the function
// is polymorphic) and the expected return type.
// No argument expectations are produced if unification fails.
let origin = self.misc(call_span);
ocx.sup(&origin, self.param_env, expected_output, formal_output)?;
if !ocx.select_where_possible().is_empty() {
return Err(TypeError::Mismatch);
}
// Record all the argument types, with the args
// produced from the above subtyping unification.
Ok(Some(
formal_input_tys
.iter()
.map(|&ty| self.resolve_vars_if_possible(ty))
.collect(),
))
})
.ok()
})
.unwrap_or_default();
let mut err_code = E0061;
// If the arguments should be wrapped in a tuple (ex: closures), unwrap them here

5
tests/ui/coercion/constrain-expectation-in-arg.rs
View File

@ -1,5 +1,10 @@
//@ check-pass
// Regression test for for #129286.
// Makes sure that we don't have unconstrained type variables that come from
// bivariant type parameters due to the way that we construct expectation types
// when checking call expressions in HIR typeck.
trait Trait {
type Item;
}