From 232aaeba7c6779233659b0a57ed75a5d7a48cfb0 Mon Sep 17 00:00:00 2001
From: Georg Semmler <github@weiznich.de>
Date: Wed, 11 Oct 2023 21:57:53 +0200
Subject: [PATCH] Handle several `#[diagnostic::on_unimplemented]` attributes
correctly
This PR fixes an issues where rustc would ignore subsequent
`#[diagnostic::on_unimplemented]` attributes. The [corresponding
RFC](https://rust-lang.github.io/rfcs/3368-diagnostic-attribute-namespace.html)
specifies that the first matching instance of each option is used.
Invalid attributes are linted and otherwise ignored.
---
.../error_reporting/on_unimplemented.rs | 46 +++++++++++-----
...ed_options_and_continue_to_use_fallback.rs | 22 ++++++++
...ptions_and_continue_to_use_fallback.stderr | 52 +++++++++++++++++++
3 files changed, 108 insertions(+), 12 deletions(-)
create mode 100644 tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
create mode 100644 tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
index d9059e46a8c..cc1f13a2f0f 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs
@@ -1,6 +1,6 @@
use super::{ObligationCauseCode, PredicateObligation};
use crate::infer::error_reporting::TypeErrCtxt;
-use rustc_ast::{MetaItem, NestedMetaItem};
+use rustc_ast::{Attribute, MetaItem, NestedMetaItem};
use rustc_attr as attr;
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{struct_span_err, ErrorGuaranteed};
@@ -474,18 +474,40 @@ impl<'tcx> OnUnimplementedDirective {
}
pub fn of_item(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> Result<Option<Self>, ErrorGuaranteed> {
- let mut is_diagnostic_namespace_variant = false;
- let Some(attr) = tcx.get_attr(item_def_id, sym::rustc_on_unimplemented).or_else(|| {
- if tcx.features().diagnostic_namespace {
- is_diagnostic_namespace_variant = true;
- tcx.get_attrs_by_path(item_def_id, &[sym::diagnostic, sym::on_unimplemented]).next()
- } else {
- None
- }
- }) else {
- return Ok(None);
- };
+ if let Some(attr) = tcx.get_attr(item_def_id, sym::rustc_on_unimplemented) {
+ return Self::parse_attribute(attr, false, tcx, item_def_id);
+ } else if tcx.features().diagnostic_namespace {
+ tcx.get_attrs_by_path(item_def_id, &[sym::diagnostic, sym::on_unimplemented])
+ .filter_map(|attr| Self::parse_attribute(attr, true, tcx, item_def_id).transpose())
+ .try_fold(None, |aggr: Option<Self>, directive| {
+ let directive = directive?;
+ if let Some(aggr) = aggr {
+ let mut subcommands = aggr.subcommands;
+ subcommands.extend(directive.subcommands);
+ Ok(Some(Self {
+ condition: aggr.condition.or(directive.condition),
+ subcommands,
+ message: aggr.message.or(directive.message),
+ label: aggr.label.or(directive.label),
+ note: aggr.note.or(directive.note),
+ parent_label: aggr.parent_label.or(directive.parent_label),
+ append_const_msg: aggr.append_const_msg.or(directive.append_const_msg),
+ }))
+ } else {
+ Ok(Some(directive))
+ }
+ })
+ } else {
+ Ok(None)
+ }
+ }
+ fn parse_attribute(
+ attr: &Attribute,
+ is_diagnostic_namespace_variant: bool,
+ tcx: TyCtxt<'tcx>,
+ item_def_id: DefId,
+ ) -> Result<Option<Self>, ErrorGuaranteed> {
let result = if let Some(items) = attr.meta_item_list() {
Self::parse(tcx, item_def_id, &items, attr.span, true, is_diagnostic_namespace_variant)
} else if let Some(value) = attr.value_str() {
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
new file mode 100644
index 00000000000..35307586391
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
@@ -0,0 +1,22 @@
+#![feature(diagnostic_namespace)]
+
+#[diagnostic::on_unimplemented(
+ //~^WARN malformed `on_unimplemented` attribute
+ //~|WARN malformed `on_unimplemented` attribute
+ if(Self = ()),
+ message = "not used yet",
+ label = "not used yet",
+ note = "not used yet"
+)]
+#[diagnostic::on_unimplemented(message = "fallback!!")]
+#[diagnostic::on_unimplemented(label = "fallback label")]
+#[diagnostic::on_unimplemented(note = "fallback note")]
+#[diagnostic::on_unimplemented(message = "fallback2!!")]
+trait Foo {}
+
+fn takes_foo(_: impl Foo) {}
+
+fn main() {
+ takes_foo(());
+ //~^ERROR fallback!!
+}
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
new file mode 100644
index 00000000000..6a83d8e39c6
--- /dev/null
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
@@ -0,0 +1,52 @@
+warning: malformed `on_unimplemented` attribute
+ --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:3:1
+ |
+LL | / #[diagnostic::on_unimplemented(
+LL | |
+LL | |
+LL | | if(Self = ()),
+... |
+LL | | note = "not used yet"
+LL | | )]
+ | |__^
+ |
+ = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
+
+warning: malformed `on_unimplemented` attribute
+ --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:3:1
+ |
+LL | / #[diagnostic::on_unimplemented(
+LL | |
+LL | |
+LL | | if(Self = ()),
+... |
+LL | | note = "not used yet"
+LL | | )]
+ | |__^
+ |
+ = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0277]: fallback!!
+ --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:20:15
+ |
+LL | takes_foo(());
+ | --------- ^^ fallback label
+ | |
+ | required by a bound introduced by this call
+ |
+ = help: the trait `Foo` is not implemented for `()`
+ = note: fallback note
+help: this trait has no implementations, consider adding one
+ --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:15:1
+ |
+LL | trait Foo {}
+ | ^^^^^^^^^
+note: required by a bound in `takes_foo`
+ --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:17:22
+ |
+LL | fn takes_foo(_: impl Foo) {}
+ | ^^^ required by this bound in `takes_foo`
+
+error: aborting due to previous error; 2 warnings emitted
+
+For more information about this error, try `rustc --explain E0277`.