bjoernager/rust
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better suggestion based on hir

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Signed-off-by: Alex Chi <iskyzh@gmail.com>
This commit is contained in:
Alex Chi 2023-03-17 22:22:49 -04:00
parent 6e17349b12
commit 54c11a688f
6 changed files with 200 additions and 45 deletions
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2
compiler/rustc_infer/src/infer/error_reporting/mod.rs
View file

@ -1927,7 +1927,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
{
let span = self.tcx.def_span(def_id);
diag.span_note(span, "this closure does not fulfill the lifetime requirements");
self.suggest_for_all_lifetime_closure(span, &exp_found, diag);
self.suggest_for_all_lifetime_closure(span, self.tcx.hir().get_by_def_id(def_id), &exp_found, diag);
}
// It reads better to have the error origin as the final

88
compiler/rustc_infer/src/infer/error_reporting/suggest.rs
View file

@ -542,54 +542,62 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
pub(super) fn suggest_for_all_lifetime_closure(
&self,
span: Span,
hir: hir::Node<'_>,
exp_found: &ty::error::ExpectedFound<ty::PolyTraitRef<'tcx>>,
diag: &mut Diagnostic,
) {
// 0. Extract fn_decl from hir
let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(hir::Closure { fn_decl, .. }), .. }) = hir else { return; };
// 1. Get the substs of the closure.
// 2. Assume exp_found is FnOnce / FnMut / Fn, we can extract function parameters from [1].
let expected = exp_found.expected.map_bound(|x| x.substs.get(1).cloned()).transpose();
let found = exp_found.found.map_bound(|x| x.substs.get(1).cloned()).transpose();
let Some(expected) = exp_found.expected.skip_binder().substs.get(1) else { return; };
let Some(found) = exp_found.found.skip_binder().substs.get(1) else { return; };
let expected = expected.unpack();
let found = found.unpack();
// 3. Extract the tuple type from Fn trait and suggest the change.
if let (Some(expected), Some(found)) = (expected, found) {
let expected = expected.skip_binder().unpack();
let found = found.skip_binder().unpack();
if let (GenericArgKind::Type(expected), GenericArgKind::Type(found)) = (expected, found)
&& let (ty::Tuple(expected), ty::Tuple(found)) = (expected.kind(), found.kind())
&& expected.len() == found.len() {
let mut suggestion = "|".to_string();
let mut is_first = true;
let mut has_suggestion = false;
if let GenericArgKind::Type(expected) = expected &&
let GenericArgKind::Type(found) = found &&
let ty::Tuple(expected) = expected.kind() &&
let ty::Tuple(found)= found.kind() &&
expected.len() == found.len() {
let mut suggestion = "|".to_string();
let mut is_first = true;
let mut has_suggestion = false;
for (expected, found) in expected.iter().zip(found.iter()) {
if is_first {
is_first = true;
} else {
suggestion += ", ";
}
if let (ty::Ref(expected_region, _, _), ty::Ref(found_region, _, _)) = (expected.kind(), found.kind())
&& expected_region.is_late_bound() && !found_region.is_late_bound() {
// If the expected region is late bound, and the found region is not, we can suggest adding `: &_`.
// FIXME: use the actual type + variable name provided by user instead of `_`.
suggestion += "_: &_";
has_suggestion = true;
} else {
// Otherwise, keep it as-is.
suggestion += "_";
}
}
suggestion += "|";
if has_suggestion {
diag.span_suggestion_verbose(
span,
"consider changing the type of the closure parameters",
suggestion,
Applicability::MaybeIncorrect,
);
}
for ((expected, found), arg_hir) in expected.iter().zip(found.iter()).zip(fn_decl.inputs.iter()) {
if is_first {
is_first = false;
} else {
suggestion += ", ";
}
if let ty::Ref(expected_region, _, _) = expected.kind() &&
let ty::Ref(found_region, _, _) = found.kind() &&
expected_region.is_late_bound() &&
!found_region.is_late_bound() &&
let hir::TyKind::Infer = arg_hir.kind {
// If the expected region is late bound, the found region is not, and users are asking compiler
// to infer the type, we can suggest adding `: &_`.
let Ok(arg) = self.tcx.sess.source_map().span_to_snippet(arg_hir.span) else { return; };
suggestion += &format!("{}: &_", arg);
has_suggestion = true;
} else {
let Ok(arg) = self.tcx.sess.source_map().span_to_snippet(arg_hir.span) else { return; };
// Otherwise, keep it as-is.
suggestion += &arg;
}
}
suggestion += "|";
if has_suggestion {
diag.span_suggestion_verbose(
span,
"consider specifying the type of the closure parameters",
suggestion,
Applicability::MaybeIncorrect,
);
}
}
}
}