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Prevent spurious unreachable pattern lints

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Means you'll get more `non-exhaustive` patterns
This commit is contained in:
Oli Scherer 2023-09-18 15:54:23 +00:00
parent 71704c4f84
commit d1fd11f3f9
14 changed files with 164 additions and 198 deletions
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61
compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
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@ -180,23 +180,26 @@ impl<'tcx> ConstToPat<'tcx> {
if let Some(non_sm_ty) = structural {
if !self.type_has_partial_eq_impl(cv.ty()) {
if let ty::Adt(def, ..) = non_sm_ty.kind() {
let e = if let ty::Adt(def, ..) = non_sm_ty.kind() {
if def.is_union() {
let err = UnionPattern { span: self.span };
self.tcx().sess.emit_err(err);
self.tcx().sess.emit_err(err)
} else {
// fatal avoids ICE from resolution of nonexistent method (rare case).
self.tcx()
.sess
.emit_fatal(TypeNotStructural { span: self.span, non_sm_ty });
.emit_fatal(TypeNotStructural { span: self.span, non_sm_ty })
}
} else {
let err = InvalidPattern { span: self.span, non_sm_ty };
self.tcx().sess.emit_err(err);
}
self.tcx().sess.emit_err(err)
};
// All branches above emitted an error. Don't print any more lints.
// The pattern we return is irrelevant since we errored.
return Box::new(Pat { span: self.span, ty: cv.ty(), kind: PatKind::Wild });
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
let kind = PatKind::Constant {
value: mir::Const::Ty(ty::Const::new_error(self.tcx(), e, cv.ty())),
};
return Box::new(Pat { span: self.span, ty: cv.ty(), kind });
} else if !self.saw_const_match_lint.get() {
if let Some(mir_structural_match_violation) = mir_structural_match_violation {
match non_sm_ty.kind() {
@ -346,17 +349,17 @@ impl<'tcx> ConstToPat<'tcx> {
}
ty::FnDef(..) => {
self.saw_const_match_error.set(true);
tcx.sess.emit_err(InvalidPattern { span, non_sm_ty: ty });
// We errored, so the pattern we generate is irrelevant.
PatKind::Wild
let e = tcx.sess.emit_err(InvalidPattern { span, non_sm_ty: ty });
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant { value: mir::Const::Ty(ty::Const::new_error(tcx, e, ty)) }
}
ty::Adt(adt_def, _) if !self.type_marked_structural(ty) => {
debug!("adt_def {:?} has !type_marked_structural for cv.ty: {:?}", adt_def, ty,);
self.saw_const_match_error.set(true);
let err = TypeNotStructural { span, non_sm_ty: ty };
tcx.sess.emit_err(err);
// We errored, so the pattern we generate is irrelevant.
PatKind::Wild
let e = tcx.sess.emit_err(err);
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant { value: mir::Const::Ty(ty::Const::new_error(tcx, e, ty)) }
}
ty::Adt(adt_def, args) if adt_def.is_enum() => {
let (&variant_index, fields) = cv.unwrap_branch().split_first().unwrap();
@ -427,14 +430,20 @@ impl<'tcx> ConstToPat<'tcx> {
}
return Err(FallbackToOpaqueConst);
} else {
if !self.saw_const_match_error.get() {
if self.saw_const_match_error.get() {
// We already errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant {
value: mir::Const::Ty(ty::Const::new_misc_error(tcx, ty)),
}
} else {
self.saw_const_match_error.set(true);
let err = TypeNotStructural { span, non_sm_ty: *pointee_ty };
tcx.sess.emit_err(err);
let e = tcx.sess.emit_err(err);
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant {
value: mir::Const::Ty(ty::Const::new_error(tcx, e, ty)),
}
}
tcx.sess.delay_span_bug(span, "`saw_const_match_error` set but no error?");
// We errored, so the pattern we generate is irrelevant.
PatKind::Wild
}
}
// All other references are converted into deref patterns and then recursively
@ -443,11 +452,11 @@ impl<'tcx> ConstToPat<'tcx> {
_ => {
if !pointee_ty.is_sized(tcx, param_env) && !pointee_ty.is_slice() {
let err = UnsizedPattern { span, non_sm_ty: *pointee_ty };
tcx.sess.emit_err(err);
// FIXME: introduce PatKind::Error to silence follow up diagnostics due to unreachable patterns.
// We errored, so the pattern we generate is irrelevant.
PatKind::Wild
let e = tcx.sess.emit_err(err);
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant {
value: mir::Const::Ty(ty::Const::new_error(tcx, e, ty)),
}
} else {
let old = self.behind_reference.replace(true);
// `b"foo"` produces a `&[u8; 3]`, but you can't use constants of array type when
@ -476,9 +485,9 @@ impl<'tcx> ConstToPat<'tcx> {
_ => {
self.saw_const_match_error.set(true);
let err = InvalidPattern { span, non_sm_ty: ty };
tcx.sess.emit_err(err);
// We errored, so the pattern we generate is irrelevant.
PatKind::Wild
let e = tcx.sess.emit_err(err);
// We errored. Signal that in the pattern, so that follow up errors can be silenced.
PatKind::Constant { value: mir::Const::Ty(ty::Const::new_error(tcx, e, ty)) }
}
};