bjoernager/rust
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introduce a unit testing feature rustc_evaluate_where_clauses

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This attribute will cause us to invoke evaluate on every where clause of an
invoked function and to generate an error with the result.

Without this, it is very difficult to observe the effects of invoking the trait
evaluator.
This commit is contained in:
Niko Matsakis 2021-05-12 11:46:14 -04:00
parent 506e75cbf8
commit c7cb72828d
6 changed files with 174 additions and 3 deletions
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40
compiler/rustc_typeck/src/check/callee.rs
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@ -6,8 +6,14 @@ use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir as hir;
use rustc_hir::def::{Namespace, Res};
use rustc_hir::def_id::{DefId, LOCAL_CRATE};
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_infer::{infer, traits};
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,
};
@ -17,6 +23,7 @@ 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::traits::query::evaluate_obligation::InferCtxtExt;
use std::iter;
/// Checks that it is legal to call methods of the trait corresponding
@ -294,7 +301,34 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
expected: Expectation<'tcx>,
) -> Ty<'tcx> {
let (fn_sig, def_id) = match *callee_ty.kind() {
ty::FnDef(def_id, _) => (callee_ty.fn_sig(self.tcx), Some(def_id)),
ty::FnDef(def_id, 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.clone(),
);
let result = self.infcx.evaluate_obligation(&obligation);
self.tcx
.sess
.struct_span_err(
callee_expr.span,
&format!("evaluate({:?}) = {:?}", predicate, result),
)
.span_label(*predicate_span, "predicate")
.emit();
}
}
(callee_ty.fn_sig(self.tcx), Some(def_id))
}
ty::FnPtr(sig) => (sig, None),
ref t => {
let mut unit_variant = None;