Auto merge of #138165 - jdonszelmann:inline, r=oli-obk

Rewrite `inline` attribute parser to use new infrastructure and improve diagnostics for all parsed attributes

r? `@oli-obk`

This PR:
- creates a new parser for inline attributes
- creates consistent error messages and error codes between attribute parsers; inline and others
- as such changes a few error messages for other attributes to be (in my eyes) much more consistent
- tests ast-lowering lints introduced by rust-lang/rust#138164 since this is now useful for the first time
- Coalesce some useless error codes

Builds on top of rust-lang/rust#138164

Closes rust-lang/rust#137950

13 files changed, 500 insertions, 214 deletions

diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
index c9443feb021..b9b386635f6 100644
--- a/compiler/rustc_attr_parsing/messages.ftl
+++ b/compiler/rustc_attr_parsing/messages.ftl
@@ -23,8 +23,10 @@ attr_parsing_expects_feature_list =
 attr_parsing_expects_features =
     `{$name}` expects feature names
 
-attr_parsing_incorrect_meta_item = expected a quoted string literal
-attr_parsing_incorrect_meta_item_suggestion = consider surrounding this with quotes
+attr_parsing_ill_formed_attribute_input = {$num_suggestions ->
+        [1] attribute must be of the form {$suggestions}
+        *[other] valid forms for the attribute are {$suggestions}
+    }
 
 attr_parsing_incorrect_repr_format_align_one_arg =
     incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
@@ -81,9 +83,6 @@ attr_parsing_missing_note =
 attr_parsing_missing_since =
     missing 'since'
 
-attr_parsing_multiple_item =
-    multiple '{$item}' items
-
 attr_parsing_multiple_stability_levels =
     multiple stability levels
 
@@ -122,10 +121,6 @@ attr_parsing_unsupported_literal_cfg_boolean =
     literal in `cfg` predicate value must be a boolean
 attr_parsing_unsupported_literal_cfg_string =
     literal in `cfg` predicate value must be a string
-attr_parsing_unsupported_literal_deprecated_kv_pair =
-    item in `deprecated` must be a key/value pair
-attr_parsing_unsupported_literal_deprecated_string =
-    literal in `deprecated` value must be a string
 attr_parsing_unsupported_literal_generic =
     unsupported literal
 attr_parsing_unsupported_literal_suggestion =
@@ -136,6 +131,7 @@ attr_parsing_unused_duplicate =
     .suggestion = remove this attribute
     .note = attribute also specified here
     .warn = {-passes_previously_accepted}
+
 attr_parsing_unused_multiple =
     multiple `{$name}` attributes
     .suggestion = remove this attribute
diff --git a/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs b/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
index 81192f902a2..21b01a8d071 100644
--- a/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
@@ -1,6 +1,7 @@
 use std::iter;
 
 use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
 use rustc_span::{Span, Symbol, sym};
 
 use super::{CombineAttributeParser, ConvertFn};
@@ -13,6 +14,7 @@ impl<S: Stage> CombineAttributeParser<S> for AllowInternalUnstableParser {
     const PATH: &[Symbol] = &[sym::allow_internal_unstable];
     type Item = (Symbol, Span);
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::AllowInternalUnstable;
+    const TEMPLATE: AttributeTemplate = template!(Word, List: "feat1, feat2, ...");
 
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
@@ -29,6 +31,7 @@ impl<S: Stage> CombineAttributeParser<S> for AllowConstFnUnstableParser {
     const PATH: &[Symbol] = &[sym::rustc_allow_const_fn_unstable];
     type Item = Symbol;
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::AllowConstFnUnstable;
+    const TEMPLATE: AttributeTemplate = template!(Word, List: "feat1, feat2, ...");
 
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
diff --git a/compiler/rustc_attr_parsing/src/attributes/confusables.rs b/compiler/rustc_attr_parsing/src/attributes/confusables.rs
index afd3c012f05..c911908dfb3 100644
--- a/compiler/rustc_attr_parsing/src/attributes/confusables.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/confusables.rs
@@ -1,4 +1,5 @@
 use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::template;
 use rustc_span::{Span, Symbol, sym};
 use thin_vec::ThinVec;
 
@@ -13,37 +14,33 @@ pub(crate) struct ConfusablesParser {
 }
 
 impl<S: Stage> AttributeParser<S> for ConfusablesParser {
-    const ATTRIBUTES: AcceptMapping<Self, S> = &[(&[sym::rustc_confusables], |this, cx, args| {
-        let Some(list) = args.list() else {
-            // FIXME(jdonszelmann): error when not a list? Bring validation code here.
-            //       NOTE: currently subsequent attributes are silently ignored using
-            //       tcx.get_attr().
-            return;
-        };
-
-        if list.is_empty() {
-            cx.emit_err(session_diagnostics::EmptyConfusables { span: cx.attr_span });
-        }
-
-        for param in list.mixed() {
-            let span = param.span();
-
-            let Some(lit) = param.lit() else {
-                cx.emit_err(session_diagnostics::IncorrectMetaItem {
-                    span,
-                    suggestion: Some(session_diagnostics::IncorrectMetaItemSuggestion {
-                        lo: span.shrink_to_lo(),
-                        hi: span.shrink_to_hi(),
-                    }),
-                });
-                continue;
+    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
+        &[sym::rustc_confusables],
+        template!(List: r#""name1", "name2", ..."#),
+        |this, cx, args| {
+            let Some(list) = args.list() else {
+                cx.expected_list(cx.attr_span);
+                return;
             };
 
-            this.confusables.push(lit.symbol);
-        }
+            if list.is_empty() {
+                cx.emit_err(session_diagnostics::EmptyConfusables { span: cx.attr_span });
+            }
+
+            for param in list.mixed() {
+                let span = param.span();
+
+                let Some(lit) = param.lit().and_then(|i| i.value_str()) else {
+                    cx.expected_string_literal(span, param.lit());
+                    continue;
+                };
+
+                this.confusables.push(lit);
+            }
 
-        this.first_span.get_or_insert(cx.attr_span);
-    })];
+            this.first_span.get_or_insert(cx.attr_span);
+        },
+    )];
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if self.confusables.is_empty() {
diff --git a/compiler/rustc_attr_parsing/src/attributes/deprecation.rs b/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
index 1faee41c2a9..702ad66f578 100644
--- a/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
@@ -1,4 +1,5 @@
 use rustc_attr_data_structures::{AttributeKind, DeprecatedSince, Deprecation};
+use rustc_feature::{AttributeTemplate, template};
 use rustc_span::{Span, Symbol, sym};
 
 use super::util::parse_version;
@@ -6,7 +7,6 @@ use super::{AttributeOrder, OnDuplicate, SingleAttributeParser};
 use crate::context::{AcceptContext, Stage};
 use crate::parser::ArgParser;
 use crate::session_diagnostics;
-use crate::session_diagnostics::UnsupportedLiteralReason;
 
 pub(crate) struct DeprecationParser;
 
@@ -18,25 +18,18 @@ fn get<S: Stage>(
     item: &Option<Symbol>,
 ) -> Option<Symbol> {
     if item.is_some() {
-        cx.emit_err(session_diagnostics::MultipleItem { span: param_span, item: name.to_string() });
+        cx.duplicate_key(param_span, name);
         return None;
     }
     if let Some(v) = arg.name_value() {
         if let Some(value_str) = v.value_as_str() {
             Some(value_str)
         } else {
-            let lit = v.value_as_lit();
-            cx.emit_err(session_diagnostics::UnsupportedLiteral {
-                span: v.value_span,
-                reason: UnsupportedLiteralReason::DeprecatedString,
-                is_bytestr: lit.kind.is_bytestr(),
-                start_point_span: cx.sess().source_map().start_point(lit.span),
-            });
+            cx.expected_string_literal(v.value_span, Some(&v.value_as_lit()));
             None
         }
     } else {
-        // FIXME(jdonszelmann): suggestion?
-        cx.emit_err(session_diagnostics::IncorrectMetaItem { span: param_span, suggestion: None });
+        cx.expected_name_value(param_span, Some(name));
         None
     }
 }
@@ -45,6 +38,11 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
     const PATH: &[Symbol] = &[sym::deprecated];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const TEMPLATE: AttributeTemplate = template!(
+        Word,
+        List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
+        NameValueStr: "reason"
+    );
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
         let features = cx.features();
@@ -55,57 +53,60 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
 
         let is_rustc = features.staged_api();
 
-        if let Some(value) = args.name_value()
-            && let Some(value_str) = value.value_as_str()
-        {
-            note = Some(value_str)
-        } else if let Some(list) = args.list() {
-            for param in list.mixed() {
-                let param_span = param.span();
-                let Some(param) = param.meta_item() else {
-                    cx.emit_err(session_diagnostics::UnsupportedLiteral {
-                        span: param_span,
-                        reason: UnsupportedLiteralReason::DeprecatedKvPair,
-                        is_bytestr: false,
-                        start_point_span: cx.sess().source_map().start_point(param_span),
-                    });
-                    return None;
-                };
+        match args {
+            ArgParser::NoArgs => {
+                // ok
+            }
+            ArgParser::List(list) => {
+                for param in list.mixed() {
+                    let Some(param) = param.meta_item() else {
+                        cx.unexpected_literal(param.span());
+                        return None;
+                    };
 
-                let ident_name = param.path().word_sym();
+                    let ident_name = param.path().word_sym();
 
-                match ident_name {
-                    Some(name @ sym::since) => {
-                        since = Some(get(cx, name, param_span, param.args(), &since)?);
-                    }
-                    Some(name @ sym::note) => {
-                        note = Some(get(cx, name, param_span, param.args(), &note)?);
-                    }
-                    Some(name @ sym::suggestion) => {
-                        if !features.deprecated_suggestion() {
-                            cx.emit_err(session_diagnostics::DeprecatedItemSuggestion {
-                                span: param_span,
-                                is_nightly: cx.sess().is_nightly_build(),
-                                details: (),
-                            });
+                    match ident_name {
+                        Some(name @ sym::since) => {
+                            since = Some(get(cx, name, param.span(), param.args(), &since)?);
+                        }
+                        Some(name @ sym::note) => {
+                            note = Some(get(cx, name, param.span(), param.args(), &note)?);
                         }
+                        Some(name @ sym::suggestion) => {
+                            if !features.deprecated_suggestion() {
+                                cx.emit_err(session_diagnostics::DeprecatedItemSuggestion {
+                                    span: param.span(),
+                                    is_nightly: cx.sess().is_nightly_build(),
+                                    details: (),
+                                });
+                            }
 
-                        suggestion = Some(get(cx, name, param_span, param.args(), &suggestion)?);
-                    }
-                    _ => {
-                        cx.emit_err(session_diagnostics::UnknownMetaItem {
-                            span: param_span,
-                            item: param.path().to_string(),
-                            expected: if features.deprecated_suggestion() {
-                                &["since", "note", "suggestion"]
-                            } else {
-                                &["since", "note"]
-                            },
-                        });
-                        return None;
+                            suggestion =
+                                Some(get(cx, name, param.span(), param.args(), &suggestion)?);
+                        }
+                        _ => {
+                            cx.unknown_key(
+                                param.span(),
+                                param.path().to_string(),
+                                if features.deprecated_suggestion() {
+                                    &["since", "note", "suggestion"]
+                                } else {
+                                    &["since", "note"]
+                                },
+                            );
+                            return None;
+                        }
                     }
                 }
             }
+            ArgParser::NameValue(v) => {
+                let Some(value) = v.value_as_str() else {
+                    cx.expected_string_literal(v.value_span, Some(v.value_as_lit()));
+                    return None;
+                };
+                note = Some(value);
+            }
         }
 
         let since = if let Some(since) = since {
diff --git a/compiler/rustc_attr_parsing/src/attributes/inline.rs b/compiler/rustc_attr_parsing/src/attributes/inline.rs
index c7f82082c2e..25efc3ae49b 100644
--- a/compiler/rustc_attr_parsing/src/attributes/inline.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/inline.rs
@@ -29,7 +29,7 @@ impl<S: Stage> SingleAttributeParser<S> for InlineParser {
                     return None;
                 };
 
-                match l.meta_item().and_then(|i| i.word_without_args().map(|i| i.name)) {
+                match l.meta_item().and_then(|i| i.path().word_sym()) {
                     Some(sym::always) => {
                         Some(AttributeKind::Inline(InlineAttr::Always, cx.attr_span))
                     }
@@ -63,7 +63,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcForceInlineParser {
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
     const TEMPLATE: AttributeTemplate = template!(Word, List: "reason", NameValueStr: "reason");
 
-    fn convert(cx: &AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
         let reason = match args {
             ArgParser::NoArgs => None,
             ArgParser::List(list) => {
@@ -73,7 +73,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcForceInlineParser {
                 };
 
                 let Some(reason) = l.lit().and_then(|i| i.kind.str()) else {
-                    cx.expected_string_literal(l.span());
+                    cx.expected_string_literal(l.span(), l.lit());
                     return None;
                 };
 
@@ -81,7 +81,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcForceInlineParser {
             }
             ArgParser::NameValue(v) => {
                 let Some(reason) = v.value_as_str() else {
-                    cx.expected_string_literal(v.value_span);
+                    cx.expected_string_literal(v.value_span, Some(v.value_as_lit()));
                     return None;
                 };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs b/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
index 32a20d4c5b5..d4c846de56e 100644
--- a/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
@@ -1,4 +1,5 @@
 use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
 use rustc_span::{Symbol, sym};
 
 use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
@@ -9,10 +10,9 @@ pub(crate) struct AsPtrParser;
 
 impl<S: Stage> SingleAttributeParser<S> for AsPtrParser {
     const PATH: &[Symbol] = &[sym::rustc_as_ptr];
-
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
-
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const TEMPLATE: AttributeTemplate = template!(Word);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
         // FIXME: check that there's no args (this is currently checked elsewhere)
diff --git a/compiler/rustc_attr_parsing/src/attributes/mod.rs b/compiler/rustc_attr_parsing/src/attributes/mod.rs
index df488c89a34..fa2a6087506 100644
--- a/compiler/rustc_attr_parsing/src/attributes/mod.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/mod.rs
@@ -18,6 +18,7 @@ use std::marker::PhantomData;
 
 use rustc_attr_data_structures::AttributeKind;
 use rustc_attr_data_structures::lints::AttributeLintKind;
+use rustc_feature::AttributeTemplate;
 use rustc_span::{Span, Symbol};
 use thin_vec::ThinVec;
 
@@ -29,6 +30,7 @@ pub(crate) mod allow_unstable;
 pub(crate) mod cfg;
 pub(crate) mod confusables;
 pub(crate) mod deprecation;
+pub(crate) mod inline;
 pub(crate) mod lint_helpers;
 pub(crate) mod repr;
 pub(crate) mod stability;
@@ -36,7 +38,7 @@ pub(crate) mod transparency;
 pub(crate) mod util;
 
 type AcceptFn<T, S> = for<'sess> fn(&mut T, &mut AcceptContext<'_, 'sess, S>, &ArgParser<'_>);
-type AcceptMapping<T, S> = &'static [(&'static [Symbol], AcceptFn<T, S>)];
+type AcceptMapping<T, S> = &'static [(&'static [Symbol], AttributeTemplate, AcceptFn<T, S>)];
 
 /// An [`AttributeParser`] is a type which searches for syntactic attributes.
 ///
@@ -88,6 +90,9 @@ pub(crate) trait SingleAttributeParser<S: Stage>: 'static {
     const ATTRIBUTE_ORDER: AttributeOrder;
     const ON_DUPLICATE: OnDuplicate<S>;
 
+    /// The template this attribute parser should implement. Used for diagnostics.
+    const TEMPLATE: AttributeTemplate;
+
     /// Converts a single syntactical attribute to a single semantic attribute, or [`AttributeKind`]
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind>;
 }
@@ -104,8 +109,10 @@ impl<T: SingleAttributeParser<S>, S: Stage> Default for Single<T, S> {
 }
 
 impl<T: SingleAttributeParser<S>, S: Stage> AttributeParser<S> for Single<T, S> {
-    const ATTRIBUTES: AcceptMapping<Self, S> =
-        &[(T::PATH, |group: &mut Single<T, S>, cx, args| {
+    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
+        T::PATH,
+        <T as SingleAttributeParser<S>>::TEMPLATE,
+        |group: &mut Single<T, S>, cx, args| {
             if let Some(pa) = T::convert(cx, args) {
                 match T::ATTRIBUTE_ORDER {
                     // keep the first and report immediately. ignore this attribute
@@ -126,7 +133,8 @@ impl<T: SingleAttributeParser<S>, S: Stage> AttributeParser<S> for Single<T, S>
 
                 group.1 = Some((pa, cx.attr_span));
             }
-        })];
+        },
+    )];
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         Some(self.1?.0)
@@ -223,6 +231,9 @@ pub(crate) trait CombineAttributeParser<S: Stage>: 'static {
     type Item;
     const CONVERT: ConvertFn<Self::Item>;
 
+    /// The template this attribute parser should implement. Used for diagnostics.
+    const TEMPLATE: AttributeTemplate;
+
     /// Converts a single syntactical attribute to a number of elements of the semantic attribute, or [`AttributeKind`]
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
@@ -242,8 +253,11 @@ impl<T: CombineAttributeParser<S>, S: Stage> Default for Combine<T, S> {
 }
 
 impl<T: CombineAttributeParser<S>, S: Stage> AttributeParser<S> for Combine<T, S> {
-    const ATTRIBUTES: AcceptMapping<Self, S> =
-        &[(T::PATH, |group: &mut Combine<T, S>, cx, args| group.1.extend(T::extend(cx, args)))];
+    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
+        T::PATH,
+        <T as CombineAttributeParser<S>>::TEMPLATE,
+        |group: &mut Combine<T, S>, cx, args| group.1.extend(T::extend(cx, args)),
+    )];
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if self.1.is_empty() { None } else { Some(T::CONVERT(self.1)) }
diff --git a/compiler/rustc_attr_parsing/src/attributes/repr.rs b/compiler/rustc_attr_parsing/src/attributes/repr.rs
index 753b2366b41..ae9e7871874 100644
--- a/compiler/rustc_attr_parsing/src/attributes/repr.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/repr.rs
@@ -1,6 +1,7 @@
 use rustc_abi::Align;
 use rustc_ast::{IntTy, LitIntType, LitKind, UintTy};
 use rustc_attr_data_structures::{AttributeKind, IntType, ReprAttr};
+use rustc_feature::{AttributeTemplate, template};
 use rustc_span::{DUMMY_SP, Span, Symbol, sym};
 
 use super::{CombineAttributeParser, ConvertFn};
@@ -23,6 +24,8 @@ impl<S: Stage> CombineAttributeParser<S> for ReprParser {
     type Item = (ReprAttr, Span);
     const PATH: &[Symbol] = &[sym::repr];
     const CONVERT: ConvertFn<Self::Item> = AttributeKind::Repr;
+    // FIXME(jdonszelmann): never used
+    const TEMPLATE: AttributeTemplate = template!(List: "C");
 
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
@@ -31,6 +34,7 @@ impl<S: Stage> CombineAttributeParser<S> for ReprParser {
         let mut reprs = Vec::new();
 
         let Some(list) = args.list() else {
+            cx.expected_list(cx.attr_span);
             return reprs;
         };
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/stability.rs b/compiler/rustc_attr_parsing/src/attributes/stability.rs
index 6589a51db2b..6871ff4ec9f 100644
--- a/compiler/rustc_attr_parsing/src/attributes/stability.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/stability.rs
@@ -5,7 +5,8 @@ use rustc_attr_data_structures::{
     StableSince, UnstableReason, VERSION_PLACEHOLDER,
 };
 use rustc_errors::ErrorGuaranteed;
-use rustc_span::{Span, Symbol, sym};
+use rustc_feature::{AttributeTemplate, template};
+use rustc_span::{Ident, Span, Symbol, sym};
 
 use super::util::parse_version;
 use super::{AcceptMapping, AttributeOrder, AttributeParser, OnDuplicate, SingleAttributeParser};
@@ -43,26 +44,39 @@ impl StabilityParser {
 
 impl<S: Stage> AttributeParser<S> for StabilityParser {
     const ATTRIBUTES: AcceptMapping<Self, S> = &[
-        (&[sym::stable], |this, cx, args| {
-            reject_outside_std!(cx);
-            if !this.check_duplicate(cx)
-                && let Some((feature, level)) = parse_stability(cx, args)
-            {
-                this.stability = Some((Stability { level, feature }, cx.attr_span));
-            }
-        }),
-        (&[sym::unstable], |this, cx, args| {
-            reject_outside_std!(cx);
-            if !this.check_duplicate(cx)
-                && let Some((feature, level)) = parse_unstability(cx, args)
-            {
-                this.stability = Some((Stability { level, feature }, cx.attr_span));
-            }
-        }),
-        (&[sym::rustc_allowed_through_unstable_modules], |this, cx, args| {
-            reject_outside_std!(cx);
-            this.allowed_through_unstable_modules = args.name_value().and_then(|i| i.value_as_str())
-        }),
+        (
+            &[sym::stable],
+            template!(List: r#"feature = "name", since = "version""#),
+            |this, cx, args| {
+                reject_outside_std!(cx);
+                if !this.check_duplicate(cx)
+                    && let Some((feature, level)) = parse_stability(cx, args)
+                {
+                    this.stability = Some((Stability { level, feature }, cx.attr_span));
+                }
+            },
+        ),
+        (
+            &[sym::unstable],
+            template!(List: r#"feature = "name", reason = "...", issue = "N""#),
+            |this, cx, args| {
+                reject_outside_std!(cx);
+                if !this.check_duplicate(cx)
+                    && let Some((feature, level)) = parse_unstability(cx, args)
+                {
+                    this.stability = Some((Stability { level, feature }, cx.attr_span));
+                }
+            },
+        ),
+        (
+            &[sym::rustc_allowed_through_unstable_modules],
+            template!(NameValueStr: "deprecation message"),
+            |this, cx, args| {
+                reject_outside_std!(cx);
+                this.allowed_through_unstable_modules =
+                    args.name_value().and_then(|i| i.value_as_str())
+            },
+        ),
     ];
 
     fn finalize(mut self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
@@ -96,8 +110,10 @@ pub(crate) struct BodyStabilityParser {
 }
 
 impl<S: Stage> AttributeParser<S> for BodyStabilityParser {
-    const ATTRIBUTES: AcceptMapping<Self, S> =
-        &[(&[sym::rustc_default_body_unstable], |this, cx, args| {
+    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
+        &[sym::rustc_default_body_unstable],
+        template!(List: r#"feature = "name", reason = "...", issue = "N""#),
+        |this, cx, args| {
             reject_outside_std!(cx);
             if this.stability.is_some() {
                 cx.dcx()
@@ -105,7 +121,8 @@ impl<S: Stage> AttributeParser<S> for BodyStabilityParser {
             } else if let Some((feature, level)) = parse_unstability(cx, args) {
                 this.stability = Some((DefaultBodyStability { level, feature }, cx.attr_span));
             }
-        })];
+        },
+    )];
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         let (stability, span) = self.stability?;
@@ -120,6 +137,7 @@ impl<S: Stage> SingleAttributeParser<S> for ConstStabilityIndirectParser {
     const PATH: &[Symbol] = &[sym::rustc_const_stable_indirect];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepFirst;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
+    const TEMPLATE: AttributeTemplate = template!(Word);
 
     fn convert(_cx: &mut AcceptContext<'_, '_, S>, _args: &ArgParser<'_>) -> Option<AttributeKind> {
         Some(AttributeKind::ConstStabilityIndirect)
@@ -146,7 +164,7 @@ impl ConstStabilityParser {
 
 impl<S: Stage> AttributeParser<S> for ConstStabilityParser {
     const ATTRIBUTES: AcceptMapping<Self, S> = &[
-        (&[sym::rustc_const_stable], |this, cx, args| {
+        (&[sym::rustc_const_stable], template!(List: r#"feature = "name""#), |this, cx, args| {
             reject_outside_std!(cx);
 
             if !this.check_duplicate(cx)
@@ -158,7 +176,7 @@ impl<S: Stage> AttributeParser<S> for ConstStabilityParser {
                 ));
             }
         }),
-        (&[sym::rustc_const_unstable], |this, cx, args| {
+        (&[sym::rustc_const_unstable], template!(List: r#"feature = "name""#), |this, cx, args| {
             reject_outside_std!(cx);
             if !this.check_duplicate(cx)
                 && let Some((feature, level)) = parse_unstability(cx, args)
@@ -169,7 +187,7 @@ impl<S: Stage> AttributeParser<S> for ConstStabilityParser {
                 ));
             }
         }),
-        (&[sym::rustc_promotable], |this, cx, _| {
+        (&[sym::rustc_promotable], template!(Word), |this, cx, _| {
             reject_outside_std!(cx);
             this.promotable = true;
         }),
@@ -199,12 +217,10 @@ fn insert_value_into_option_or_error<S: Stage>(
     cx: &AcceptContext<'_, '_, S>,
     param: &MetaItemParser<'_>,
     item: &mut Option<Symbol>,
+    name: Ident,
 ) -> Option<()> {
     if item.is_some() {
-        cx.emit_err(session_diagnostics::MultipleItem {
-            span: param.span(),
-            item: param.path().to_string(),
-        });
+        cx.duplicate_key(name.span, name.name);
         None
     } else if let Some(v) = param.args().name_value()
         && let Some(s) = v.value_as_str()
@@ -212,10 +228,7 @@ fn insert_value_into_option_or_error<S: Stage>(
         *item = Some(s);
         Some(())
     } else {
-        cx.emit_err(session_diagnostics::IncorrectMetaItem {
-            span: param.span(),
-            suggestion: None,
-        });
+        cx.expected_name_value(param.span(), Some(name.name));
         None
     }
 }
@@ -241,9 +254,14 @@ pub(crate) fn parse_stability<S: Stage>(
             return None;
         };
 
-        match param.path().word_sym() {
-            Some(sym::feature) => insert_value_into_option_or_error(cx, &param, &mut feature)?,
-            Some(sym::since) => insert_value_into_option_or_error(cx, &param, &mut since)?,
+        let word = param.path().word();
+        match word.map(|i| i.name) {
+            Some(sym::feature) => {
+                insert_value_into_option_or_error(cx, &param, &mut feature, word.unwrap())?
+            }
+            Some(sym::since) => {
+                insert_value_into_option_or_error(cx, &param, &mut since, word.unwrap())?
+            }
             _ => {
                 cx.emit_err(session_diagnostics::UnknownMetaItem {
                     span: param_span,
@@ -310,11 +328,16 @@ pub(crate) fn parse_unstability<S: Stage>(
             return None;
         };
 
-        match param.path().word_sym() {
-            Some(sym::feature) => insert_value_into_option_or_error(cx, &param, &mut feature)?,
-            Some(sym::reason) => insert_value_into_option_or_error(cx, &param, &mut reason)?,
+        let word = param.path().word();
+        match word.map(|i| i.name) {
+            Some(sym::feature) => {
+                insert_value_into_option_or_error(cx, &param, &mut feature, word.unwrap())?
+            }
+            Some(sym::reason) => {
+                insert_value_into_option_or_error(cx, &param, &mut reason, word.unwrap())?
+            }
             Some(sym::issue) => {
-                insert_value_into_option_or_error(cx, &param, &mut issue)?;
+                insert_value_into_option_or_error(cx, &param, &mut issue, word.unwrap())?;
 
                 // These unwraps are safe because `insert_value_into_option_or_error` ensures the meta item
                 // is a name/value pair string literal.
@@ -344,9 +367,11 @@ pub(crate) fn parse_unstability<S: Stage>(
                 is_soft = true;
             }
             Some(sym::implied_by) => {
-                insert_value_into_option_or_error(cx, &param, &mut implied_by)?
+                insert_value_into_option_or_error(cx, &param, &mut implied_by, word.unwrap())?
+            }
+            Some(sym::old_name) => {
+                insert_value_into_option_or_error(cx, &param, &mut old_name, word.unwrap())?
             }
-            Some(sym::old_name) => insert_value_into_option_or_error(cx, &param, &mut old_name)?,
             _ => {
                 cx.emit_err(session_diagnostics::UnknownMetaItem {
                     span: param.span(),
diff --git a/compiler/rustc_attr_parsing/src/attributes/transparency.rs b/compiler/rustc_attr_parsing/src/attributes/transparency.rs
index 16ad9d03e50..ce5ceb9139a 100644
--- a/compiler/rustc_attr_parsing/src/attributes/transparency.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/transparency.rs
@@ -1,4 +1,5 @@
 use rustc_attr_data_structures::AttributeKind;
+use rustc_feature::{AttributeTemplate, template};
 use rustc_span::hygiene::Transparency;
 use rustc_span::{Symbol, sym};
 
@@ -17,14 +18,23 @@ impl<S: Stage> SingleAttributeParser<S> for TransparencyParser {
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Custom(|cx, used, unused| {
         cx.dcx().span_err(vec![used, unused], "multiple macro transparency attributes");
     });
+    const TEMPLATE: AttributeTemplate =
+        template!(NameValueStr: "transparent|semitransparent|opaque");
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
-        match args.name_value().and_then(|nv| nv.value_as_str()) {
+        let Some(nv) = args.name_value() else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+        match nv.value_as_str() {
             Some(sym::transparent) => Some(Transparency::Transparent),
             Some(sym::semiopaque | sym::semitransparent) => Some(Transparency::SemiOpaque),
             Some(sym::opaque) => Some(Transparency::Opaque),
-            Some(other) => {
-                cx.dcx().span_err(cx.attr_span, format!("unknown macro transparency: `{other}`"));
+            Some(_) => {
+                cx.expected_specific_argument_strings(
+                    nv.value_span,
+                    vec!["transparent", "semitransparent", "opaque"],
+                );
                 None
             }
             None => None,
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index 3193d8975e9..51c1760da30 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -5,12 +5,11 @@ use std::ops::{Deref, DerefMut};
 use std::sync::LazyLock;
 
 use private::Sealed;
-use rustc_ast as ast;
-use rustc_ast::NodeId;
+use rustc_ast::{self as ast, MetaItemLit, NodeId};
 use rustc_attr_data_structures::AttributeKind;
 use rustc_attr_data_structures::lints::{AttributeLint, AttributeLintKind};
 use rustc_errors::{DiagCtxtHandle, Diagnostic};
-use rustc_feature::Features;
+use rustc_feature::{AttributeTemplate, Features};
 use rustc_hir::{AttrArgs, AttrItem, AttrPath, Attribute, HashIgnoredAttrId, HirId};
 use rustc_session::Session;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
@@ -18,6 +17,7 @@ use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
 use crate::attributes::allow_unstable::{AllowConstFnUnstableParser, AllowInternalUnstableParser};
 use crate::attributes::confusables::ConfusablesParser;
 use crate::attributes::deprecation::DeprecationParser;
+use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
 use crate::attributes::lint_helpers::AsPtrParser;
 use crate::attributes::repr::ReprParser;
 use crate::attributes::stability::{
@@ -26,11 +26,12 @@ use crate::attributes::stability::{
 use crate::attributes::transparency::TransparencyParser;
 use crate::attributes::{AttributeParser as _, Combine, Single};
 use crate::parser::{ArgParser, MetaItemParser};
+use crate::session_diagnostics::{AttributeParseError, AttributeParseErrorReason, UnknownMetaItem};
 
 macro_rules! group_type {
     ($stage: ty) => {
          LazyLock<(
-            BTreeMap<&'static [Symbol], Box<dyn for<'sess, 'a> Fn(&mut AcceptContext<'_, 'sess, $stage>, &ArgParser<'a>) + Send + Sync>>,
+            BTreeMap<&'static [Symbol], Vec<(AttributeTemplate, Box<dyn for<'sess, 'a> Fn(&mut AcceptContext<'_, 'sess, $stage>, &ArgParser<'a>) + Send + Sync>)>>,
             Vec<Box<dyn Send + Sync + Fn(&mut FinalizeContext<'_, '_, $stage>) -> Option<AttributeKind>>>
         )>
     };
@@ -59,7 +60,7 @@ macro_rules! attribute_parsers {
         @[$ty: ty] pub(crate) static $name: ident = [$($names: ty),* $(,)?];
     ) => {
         pub(crate) static $name: group_type!($ty) = LazyLock::new(|| {
-            let mut accepts = BTreeMap::<_, Box<dyn for<'sess, 'a> Fn(&mut AcceptContext<'_, 'sess, $ty>, &ArgParser<'a>) + Send + Sync>>::new();
+            let mut accepts = BTreeMap::<_, Vec<(AttributeTemplate, Box<dyn for<'sess, 'a> Fn(&mut AcceptContext<'_, 'sess, $ty>, &ArgParser<'a>) + Send + Sync>)>>::new();
             let mut finalizes = Vec::<Box<dyn Send + Sync + Fn(&mut FinalizeContext<'_, '_, $ty>) -> Option<AttributeKind>>>::new();
             $(
                 {
@@ -67,13 +68,12 @@ macro_rules! attribute_parsers {
                         static STATE_OBJECT: RefCell<$names> = RefCell::new(<$names>::default());
                     };
 
-                    for (k, v) in <$names>::ATTRIBUTES {
-                        let old = accepts.insert(*k, Box::new(|cx, args| {
+                    for (path, template, accept_fn) in <$names>::ATTRIBUTES {
+                        accepts.entry(*path).or_default().push((*template, Box::new(|cx, args| {
                             STATE_OBJECT.with_borrow_mut(|s| {
-                                v(s, cx, args)
+                                accept_fn(s, cx, args)
                             })
-                        }));
-                        assert!(old.is_none());
+                        })));
                     }
 
                     finalizes.push(Box::new(|cx| {
@@ -106,6 +106,8 @@ attribute_parsers!(
         Single<AsPtrParser>,
         Single<ConstStabilityIndirectParser>,
         Single<DeprecationParser>,
+        Single<InlineParser>,
+        Single<RustcForceInlineParser>,
         Single<TransparencyParser>,
         // tidy-alphabetical-end
     ];
@@ -165,6 +167,14 @@ pub(crate) struct AcceptContext<'f, 'sess, S: Stage> {
     pub(crate) finalize_cx: FinalizeContext<'f, 'sess, S>,
     /// The span of the attribute currently being parsed
     pub(crate) attr_span: Span,
+
+    /// The expected structure of the attribute.
+    ///
+    /// Used in reporting errors to give a hint to users what the attribute *should* look like.
+    pub(crate) template: &'f AttributeTemplate,
+
+    /// The name of the attribute we're currently accepting.
+    pub(crate) attr_path: AttrPath,
 }
 
 impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
@@ -172,10 +182,133 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
         S::emit_err(&self.sess, diag)
     }
 
+    /// Emit a lint. This method is somewhat special, since lints emitted during attribute parsing
+    /// must be delayed until after HIR is built. This method will take care of the details of
+    /// that.
     pub(crate) fn emit_lint(&mut self, lint: AttributeLintKind, span: Span) {
         let id = self.target_id;
         (self.emit_lint)(AttributeLint { id, span, kind: lint });
     }
+
+    pub(crate) fn unknown_key(
+        &self,
+        span: Span,
+        found: String,
+        options: &'static [&'static str],
+    ) -> ErrorGuaranteed {
+        self.emit_err(UnknownMetaItem { span, item: found, expected: options })
+    }
+
+    /// error that a string literal was expected.
+    /// You can optionally give the literal you did find (which you found not to be a string literal)
+    /// which can make better errors. For example, if the literal was a byte string it will suggest
+    /// removing the `b` prefix.
+    pub(crate) fn expected_string_literal(
+        &self,
+        span: Span,
+        actual_literal: Option<&MetaItemLit>,
+    ) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedStringLiteral {
+                byte_string: actual_literal.and_then(|i| {
+                    i.kind.is_bytestr().then(|| self.sess().source_map().start_point(i.span))
+                }),
+            },
+        })
+    }
+
+    pub(crate) fn expected_list(&self, span: Span) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedList,
+        })
+    }
+
+    /// emit an error that a `name = value` pair was expected at this span. The symbol can be given for
+    /// a nicer error message talking about the specific name that was found lacking a value.
+    pub(crate) fn expected_name_value(&self, span: Span, name: Option<Symbol>) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedNameValue(name),
+        })
+    }
+
+    /// emit an error that a `name = value` pair was found where that name was already seen.
+    pub(crate) fn duplicate_key(&self, span: Span, key: Symbol) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::DuplicateKey(key),
+        })
+    }
+
+    /// an error that should be emitted when a [`MetaItemOrLitParser`](crate::parser::MetaItemOrLitParser)
+    /// was expected *not* to be a literal, but instead a meta item.
+    pub(crate) fn unexpected_literal(&self, span: Span) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::UnexpectedLiteral,
+        })
+    }
+
+    pub(crate) fn expected_single_argument(&self, span: Span) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedSingleArgument,
+        })
+    }
+
+    pub(crate) fn expected_specific_argument(
+        &self,
+        span: Span,
+        possibilities: Vec<&'static str>,
+    ) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedSpecificArgument {
+                possibilities,
+                strings: false,
+            },
+        })
+    }
+
+    pub(crate) fn expected_specific_argument_strings(
+        &self,
+        span: Span,
+        possibilities: Vec<&'static str>,
+    ) -> ErrorGuaranteed {
+        self.emit_err(AttributeParseError {
+            span,
+            attr_span: self.attr_span,
+            template: self.template.clone(),
+            attribute: self.attr_path.clone(),
+            reason: AttributeParseErrorReason::ExpectedSpecificArgument {
+                possibilities,
+                strings: true,
+            },
+        })
+    }
 }
 
 impl<'f, 'sess, S: Stage> Deref for AcceptContext<'f, 'sess, S> {
@@ -374,18 +507,22 @@ impl<'sess, S: Stage> AttributeParser<'sess, S> {
                     let args = parser.args();
                     let parts = path.segments().map(|i| i.name).collect::<Vec<_>>();
 
-                    if let Some(accept) = S::parsers().0.get(parts.as_slice()) {
-                        let mut cx: AcceptContext<'_, 'sess, S> = AcceptContext {
-                            finalize_cx: FinalizeContext {
-                                cx: self,
-                                target_span,
-                                target_id,
-                                emit_lint: &mut emit_lint,
-                            },
-                            attr_span: lower_span(attr.span),
-                        };
-
-                        accept(&mut cx, args)
+                    if let Some(accepts) = S::parsers().0.get(parts.as_slice()) {
+                        for (template, accept) in accepts {
+                            let mut cx: AcceptContext<'_, 'sess, S> = AcceptContext {
+                                finalize_cx: FinalizeContext {
+                                    cx: self,
+                                    target_span,
+                                    target_id,
+                                    emit_lint: &mut emit_lint,
+                                },
+                                attr_span: lower_span(attr.span),
+                                template,
+                                attr_path: path.get_attribute_path(),
+                            };
+
+                            accept(&mut cx, args)
+                        }
                     } else {
                         // If we're here, we must be compiling a tool attribute... Or someone
                         // forgot to parse their fancy new attribute. Let's warn them in any case.
diff --git a/compiler/rustc_attr_parsing/src/lints.rs b/compiler/rustc_attr_parsing/src/lints.rs
index d0d112446b4..fee22293b47 100644
--- a/compiler/rustc_attr_parsing/src/lints.rs
+++ b/compiler/rustc_attr_parsing/src/lints.rs
@@ -1,5 +1,5 @@
 use rustc_attr_data_structures::lints::{AttributeLint, AttributeLintKind};
-use rustc_errors::LintEmitter;
+use rustc_errors::{DiagArgValue, LintEmitter};
 use rustc_hir::HirId;
 
 use crate::session_diagnostics;
@@ -15,5 +15,18 @@ pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emi
                 *span,
                 session_diagnostics::UnusedDuplicate { this, other, warning },
             ),
+        AttributeLintKind::IllFormedAttributeInput { suggestions } => {
+            lint_emitter.emit_node_span_lint(
+                rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT,
+                *id,
+                *span,
+                session_diagnostics::IllFormedAttributeInput {
+                    num_suggestions: suggestions.len(),
+                    suggestions: DiagArgValue::StrListSepByAnd(
+                        suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
+                    ),
+                },
+            );
+        }
     }
 }
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
index 7f847d3dd4c..57ac92a0ca1 100644
--- a/compiler/rustc_attr_parsing/src/session_diagnostics.rs
+++ b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -2,7 +2,11 @@ use std::num::IntErrorKind;
 
 use rustc_ast as ast;
 use rustc_errors::codes::*;
-use rustc_errors::{Applicability, Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level};
+use rustc_errors::{
+    Applicability, Diag, DiagArgValue, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level,
+};
+use rustc_feature::AttributeTemplate;
+use rustc_hir::AttrPath;
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
 
@@ -12,8 +16,6 @@ pub(crate) enum UnsupportedLiteralReason {
     Generic,
     CfgString,
     CfgBoolean,
-    DeprecatedString,
-    DeprecatedKvPair,
 }
 
 #[derive(Diagnostic)]
@@ -32,37 +34,6 @@ pub(crate) struct InvalidPredicate {
     pub predicate: String,
 }
 
-#[derive(Diagnostic)]
-#[diag(attr_parsing_multiple_item, code = E0538)]
-pub(crate) struct MultipleItem {
-    #[primary_span]
-    pub span: Span,
-
-    pub item: String,
-}
-
-#[derive(Diagnostic)]
-#[diag(attr_parsing_incorrect_meta_item, code = E0539)]
-pub(crate) struct IncorrectMetaItem {
-    #[primary_span]
-    pub span: Span,
-
-    #[subdiagnostic]
-    pub suggestion: Option<IncorrectMetaItemSuggestion>,
-}
-
-#[derive(Subdiagnostic)]
-#[multipart_suggestion(
-    attr_parsing_incorrect_meta_item_suggestion,
-    applicability = "maybe-incorrect"
-)]
-pub(crate) struct IncorrectMetaItemSuggestion {
-    #[suggestion_part(code = "\"")]
-    pub lo: Span,
-    #[suggestion_part(code = "\"")]
-    pub hi: Span,
-}
-
 /// Error code: E0541
 pub(crate) struct UnknownMetaItem<'a> {
     pub span: Span,
@@ -217,6 +188,7 @@ pub(crate) struct InvalidReprHintNoValue {
 }
 
 /// Error code: E0565
+// FIXME(jdonszelmann): slowly phased out
 pub(crate) struct UnsupportedLiteral {
     pub span: Span,
     pub reason: UnsupportedLiteralReason,
@@ -239,12 +211,6 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for UnsupportedLiteral {
                 UnsupportedLiteralReason::CfgBoolean => {
                     fluent::attr_parsing_unsupported_literal_cfg_boolean
                 }
-                UnsupportedLiteralReason::DeprecatedString => {
-                    fluent::attr_parsing_unsupported_literal_deprecated_string
-                }
-                UnsupportedLiteralReason::DeprecatedKvPair => {
-                    fluent::attr_parsing_unsupported_literal_deprecated_kv_pair
-                }
             },
         );
         diag.span(self.span);
@@ -462,6 +428,14 @@ pub(crate) struct UnusedDuplicate {
     pub warning: bool,
 }
 
+// FIXME(jdonszelmann): duplicated in rustc_lints, should be moved here completely.
+#[derive(LintDiagnostic)]
+#[diag(attr_parsing_ill_formed_attribute_input)]
+pub(crate) struct IllFormedAttributeInput {
+    pub num_suggestions: usize,
+    pub suggestions: DiagArgValue,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_parsing_stability_outside_std, code = E0734)]
 pub(crate) struct StabilityOutsideStd {
@@ -490,3 +464,115 @@ pub(crate) struct UnrecognizedReprHint {
     #[primary_span]
     pub span: Span,
 }
+
+pub(crate) enum AttributeParseErrorReason {
+    ExpectedStringLiteral { byte_string: Option<Span> },
+    ExpectedSingleArgument,
+    ExpectedList,
+    UnexpectedLiteral,
+    ExpectedNameValue(Option<Symbol>),
+    DuplicateKey(Symbol),
+    ExpectedSpecificArgument { possibilities: Vec<&'static str>, strings: bool },
+}
+
+pub(crate) struct AttributeParseError {
+    pub(crate) span: Span,
+    pub(crate) attr_span: Span,
+    pub(crate) template: AttributeTemplate,
+    pub(crate) attribute: AttrPath,
+    pub(crate) reason: AttributeParseErrorReason,
+}
+
+impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
+        let name = self.attribute.to_string();
+
+        let mut diag = Diag::new(dcx, level, format!("malformed `{name}` attribute input"));
+        diag.span(self.attr_span);
+        diag.code(E0539);
+        match self.reason {
+            AttributeParseErrorReason::ExpectedStringLiteral { byte_string } => {
+                if let Some(start_point_span) = byte_string {
+                    diag.span_suggestion(
+                        start_point_span,
+                        fluent::attr_parsing_unsupported_literal_suggestion,
+                        "",
+                        Applicability::MaybeIncorrect,
+                    );
+                    diag.note("expected a normal string literal, not a byte string literal");
+
+                    return diag;
+                } else {
+                    diag.span_label(self.span, "expected a string literal here");
+                }
+            }
+            AttributeParseErrorReason::ExpectedSingleArgument => {
+                diag.span_label(self.span, "expected a single argument here");
+                diag.code(E0805);
+            }
+            AttributeParseErrorReason::ExpectedList => {
+                diag.span_label(self.span, "expected this to be a list");
+            }
+            AttributeParseErrorReason::DuplicateKey(key) => {
+                diag.span_label(self.span, format!("found `{key}` used as a key more than once"));
+                diag.code(E0538);
+            }
+            AttributeParseErrorReason::UnexpectedLiteral => {
+                diag.span_label(self.span, format!("didn't expect a literal here"));
+                diag.code(E0565);
+            }
+            AttributeParseErrorReason::ExpectedNameValue(None) => {
+                diag.span_label(
+                    self.span,
+                    format!("expected this to be of the form `{name} = \"...\"`"),
+                );
+            }
+            AttributeParseErrorReason::ExpectedNameValue(Some(name)) => {
+                diag.span_label(
+                    self.span,
+                    format!("expected this to be of the form `{name} = \"...\"`"),
+                );
+            }
+            AttributeParseErrorReason::ExpectedSpecificArgument { possibilities, strings } => {
+                let quote = if strings { '"' } else { '`' };
+                match possibilities.as_slice() {
+                    &[] => {}
+                    &[x] => {
+                        diag.span_label(
+                            self.span,
+                            format!("the only valid argument here is {quote}{x}{quote}"),
+                        );
+                    }
+                    [first, second] => {
+                        diag.span_label(self.span, format!("valid arguments are {quote}{first}{quote} or {quote}{second}{quote}"));
+                    }
+                    [first @ .., second_to_last, last] => {
+                        let mut res = String::new();
+                        for i in first {
+                            res.push_str(&format!("{quote}{i}{quote}, "));
+                        }
+                        res.push_str(&format!(
+                            "{quote}{second_to_last}{quote} or {quote}{last}{quote}"
+                        ));
+
+                        diag.span_label(self.span, format!("valid arguments are {res}"));
+                    }
+                }
+            }
+        }
+
+        let suggestions = self.template.suggestions(false, &name);
+        diag.span_suggestions(
+            self.attr_span,
+            if suggestions.len() == 1 {
+                "must be of the form"
+            } else {
+                "try changing it to one of the following valid forms of the attribute"
+            },
+            suggestions,
+            Applicability::HasPlaceholders,
+        );
+
+        diag
+    }
+}