Rollup of 9 pull requests

compiler/rustc_ast_lowering/src/item.rs

@@ -172,7 +172,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         id: NodeId,
         hir_id: hir::HirId,
         ident: &mut Ident,
-        attrs: Option<&'hir [Attribute]>,
+        attrs: &'hir [Attribute],
         vis_span: Span,
         i: &ItemKind,
     ) -> hir::ItemKind<'hir> {
@@ -488,7 +488,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         id: NodeId,
         vis_span: Span,
         ident: &mut Ident,
-        attrs: Option<&'hir [Attribute]>,
+        attrs: &'hir [Attribute],
     ) -> hir::ItemKind<'hir> {
         let path = &tree.prefix;
         let segments = prefix.segments.iter().chain(path.segments.iter()).cloned().collect();
@@ -566,7 +566,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         // `ItemLocalId` and the new owner. (See `lower_node_id`)
                         let kind =
                             this.lower_use_tree(use_tree, &prefix, id, vis_span, &mut ident, attrs);
-                        if let Some(attrs) = attrs {
+                        if !attrs.is_empty() {
                             this.attrs.insert(hir::ItemLocalId::ZERO, attrs);
                         }
 

compiler/rustc_ast_lowering/src/lib.rs

@@ -913,15 +913,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         ret
     }
 
-    fn lower_attrs(&mut self, id: HirId, attrs: &[Attribute]) -> Option<&'hir [Attribute]> {
+    fn lower_attrs(&mut self, id: HirId, attrs: &[Attribute]) -> &'hir [Attribute] {
         if attrs.is_empty() {
-            None
+            &[]
         } else {
             debug_assert_eq!(id.owner, self.current_hir_id_owner);
             let ret = self.arena.alloc_from_iter(attrs.iter().map(|a| self.lower_attr(a)));
             debug_assert!(!ret.is_empty());
             self.attrs.insert(id.local_id, ret);
-            Some(ret)
+            ret
         }
     }
 

compiler/rustc_builtin_macros/messages.ftl

@@ -216,6 +216,11 @@ builtin_macros_multiple_defaults = multiple declared defaults
     .note = only one variant can be default
     .suggestion = make `{$ident}` default
 
+builtin_macros_naked_functions_testing_attribute =
+    cannot use `#[naked]` with testing attributes
+    .label = function marked with testing attribute here
+    .naked_attribute = `#[naked]` is incompatible with testing attributes
+
 builtin_macros_no_default_variant = no default declared
     .help = make a unit variant default by placing `#[default]` above it
     .suggestion = make `{$ident}` default

compiler/rustc_builtin_macros/src/errors.rs

@@ -912,3 +912,13 @@ pub(crate) struct ExpectedItem<'a> {
     pub span: Span,
     pub token: &'a str,
 }
+
+#[derive(Diagnostic)]
+#[diag(builtin_macros_naked_functions_testing_attribute, code = E0736)]
+pub struct NakedFunctionTestingAttribute {
+    #[primary_span]
+    #[label(builtin_macros_naked_attribute)]
+    pub naked_span: Span,
+    #[label]
+    pub testing_span: Span,
+}

compiler/rustc_builtin_macros/src/test.rs

@@ -133,6 +133,14 @@ pub(crate) fn expand_test_or_bench(
         };
     };
 
+    if let Some(attr) = attr::find_by_name(&item.attrs, sym::naked) {
+        cx.dcx().emit_err(errors::NakedFunctionTestingAttribute {
+            testing_span: attr_sp,
+            naked_span: attr.span,
+        });
+        return vec![Annotatable::Item(item)];
+    }
+
     // check_*_signature will report any errors in the type so compilation
     // will fail. We shouldn't try to expand in this case because the errors
     // would be spurious.

compiler/rustc_error_codes/src/error_codes/E0736.md

@@ -1,14 +1,20 @@
-`#[track_caller]` and `#[naked]` cannot both be applied to the same function.
+Functions marked with the `#[naked]` attribute are restricted in what other
+attributes they may be marked with.
+
+Notable attributes that are incompatible with `#[naked]` are:
+
+* `#[inline]`
+* `#[track_caller]`
+* `#[test]`, `#[ignore]`, `#[should_panic]`
 
 Erroneous code example:
 
 ```compile_fail,E0736
+#[inline]
 #[naked]
-#[track_caller]
 fn foo() {}
 ```
 
-This is primarily due to ABI incompatibilities between the two attributes.
-See [RFC 2091] for details on this and other limitations.
-
-[RFC 2091]: https://github.com/rust-lang/rfcs/blob/master/text/2091-inline-semantic.md
+These incompatibilities are due to the fact that naked functions deliberately
+impose strict restrictions regarding the code that the compiler is
+allowed to produce for this function.

compiler/rustc_error_codes/src/error_codes/E0739.md

@@ -1,4 +1,4 @@
-`#[track_caller]` can not be applied on struct.
+`#[track_caller]` must  be applied to a function
 
 Erroneous code example:
 

compiler/rustc_parse/src/parser/attr.rs

@@ -457,14 +457,3 @@ impl<'a> Parser<'a> {
         Err(self.dcx().create_err(err))
     }
 }
-
-/// The attributes are complete if all attributes are either a doc comment or a
-/// builtin attribute other than `cfg_attr`.
-pub fn is_complete(attrs: &[ast::Attribute]) -> bool {
-    attrs.iter().all(|attr| {
-        attr.is_doc_comment()
-            || attr.ident().is_some_and(|ident| {
-                ident.name != sym::cfg_attr && rustc_feature::is_builtin_attr_name(ident.name)
-            })
-    })
-}

compiler/rustc_parse/src/parser/attr_wrapper.rs

@@ -60,10 +60,6 @@ impl AttrWrapper {
     pub fn is_empty(&self) -> bool {
         self.attrs.is_empty()
     }
-
-    pub fn is_complete(&self) -> bool {
-        crate::parser::attr::is_complete(&self.attrs)
-    }
 }
 
 /// Returns `true` if `attrs` contains a `cfg` or `cfg_attr` attribute
@@ -114,17 +110,15 @@ impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
             replace_ranges.sort_by_key(|(range, _)| range.start);
 
             #[cfg(debug_assertions)]
-            {
-                for [(range, tokens), (next_range, next_tokens)] in replace_ranges.array_windows() {
-                    assert!(
-                        range.end <= next_range.start || range.end >= next_range.end,
-                        "Replace ranges should either be disjoint or nested: ({:?}, {:?}) ({:?}, {:?})",
-                        range,
-                        tokens,
-                        next_range,
-                        next_tokens,
-                    );
-                }
+            for [(range, tokens), (next_range, next_tokens)] in replace_ranges.array_windows() {
+                assert!(
+                    range.end <= next_range.start || range.end >= next_range.end,
+                    "Replace ranges should either be disjoint or nested: ({:?}, {:?}) ({:?}, {:?})",
+                    range,
+                    tokens,
+                    next_range,
+                    next_tokens,
+                );
             }
 
             // Process the replace ranges, starting from the highest start
@@ -137,9 +131,9 @@ impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
             // `#[cfg(FALSE)] struct Foo { #[cfg(FALSE)] field: bool }`
             //
             // By starting processing from the replace range with the greatest
-            // start position, we ensure that any replace range which encloses
-            // another replace range will capture the *replaced* tokens for the inner
-            // range, not the original tokens.
+            // start position, we ensure that any (outer) replace range which
+            // encloses another (inner) replace range will fully overwrite the
+            // inner range's replacement.
             for (range, target) in replace_ranges.into_iter().rev() {
                 assert!(!range.is_empty(), "Cannot replace an empty range: {range:?}");
 
@@ -199,20 +193,20 @@ impl<'a> Parser<'a> {
         force_collect: ForceCollect,
         f: impl FnOnce(&mut Self, ast::AttrVec) -> PResult<'a, (R, bool)>,
     ) -> PResult<'a, R> {
-        // Skip collection when nothing could observe the collected tokens, i.e.
-        // all of the following conditions hold.
-        // - We are not force collecting tokens (because force collection
-        //   requires tokens by definition).
-        if matches!(force_collect, ForceCollect::No)
-            // - None of our outer attributes require tokens.
-            && attrs.is_complete()
-            // - Our target doesn't support custom inner attributes (custom
+        // We must collect if anything could observe the collected tokens, i.e.
+        // if any of the following conditions hold.
+        // - We are force collecting tokens (because force collection requires
+        //   tokens by definition).
+        let needs_collection = matches!(force_collect, ForceCollect::Yes)
+            // - Any of our outer attributes require tokens.
+            || needs_tokens(&attrs.attrs)
+            // - Our target supports custom inner attributes (custom
             //   inner attribute invocation might require token capturing).
-            && !R::SUPPORTS_CUSTOM_INNER_ATTRS
-            // - We are not in `capture_cfg` mode (which requires tokens if
+            || R::SUPPORTS_CUSTOM_INNER_ATTRS
+            // - We are in `capture_cfg` mode (which requires tokens if
             //   the parsed node has `#[cfg]` or `#[cfg_attr]` attributes).
-            && !self.capture_cfg
-        {
+            || self.capture_cfg;
+        if !needs_collection {
             return Ok(f(self, attrs.attrs)?.0);
         }
 
@@ -250,28 +244,28 @@ impl<'a> Parser<'a> {
             return Ok(ret);
         }
 
-        // This is similar to the "skip collection" check at the start of this
-        // function, but now that we've parsed an AST node we have more
+        // This is similar to the `needs_collection` check at the start of this
+        // function, but now that we've parsed an AST node we have complete
         // information available. (If we return early here that means the
         // setup, such as cloning the token cursor, was unnecessary. That's
         // hard to avoid.)
         //
-        // Skip collection when nothing could observe the collected tokens, i.e.
-        // all of the following conditions hold.
-        // - We are not force collecting tokens.
-        if matches!(force_collect, ForceCollect::No)
-            // - None of our outer *or* inner attributes require tokens.
-            //   (`attrs` was just outer attributes, but `ret.attrs()` is outer
-            //   and inner attributes. That makes this check more precise than
-            //   `attrs.is_complete()` at the start of the function, and we can
-            //   skip the subsequent check on `R::SUPPORTS_CUSTOM_INNER_ATTRS`.
-            && crate::parser::attr::is_complete(ret.attrs())
-            // - We are not in `capture_cfg` mode, or we are but there are no
-            //   `#[cfg]` or `#[cfg_attr]` attributes. (During normal
-            //   non-`capture_cfg` parsing, we don't need any special capturing
-            //   for those attributes, because they're builtin.)
-            && (!self.capture_cfg || !has_cfg_or_cfg_attr(ret.attrs()))
-        {
+        // We must collect if anything could observe the collected tokens, i.e.
+        // if any of the following conditions hold.
+        // - We are force collecting tokens.
+        let needs_collection = matches!(force_collect, ForceCollect::Yes)
+            // - Any of our outer *or* inner attributes require tokens.
+            //   (`attr.attrs` was just outer attributes, but `ret.attrs()` is
+            //   outer and inner attributes. So this check is more precise than
+            //   the earlier `needs_tokens` check, and we don't need to
+            //   check `R::SUPPORTS_CUSTOM_INNER_ATTRS`.)
+            || needs_tokens(ret.attrs())
+            // - We are in `capture_cfg` mode and there are `#[cfg]` or
+            //   `#[cfg_attr]` attributes. (During normal non-`capture_cfg`
+            //   parsing, we don't need any special capturing for those
+            //   attributes, because they're builtin.)
+            || (self.capture_cfg && has_cfg_or_cfg_attr(ret.attrs()));
+        if !needs_collection {
             return Ok(ret);
         }
 
@@ -297,11 +291,13 @@ impl<'a> Parser<'a> {
         // with `None`, which means the relevant tokens will be removed. (More
         // details below.)
         let mut inner_attr_replace_ranges = Vec::new();
-        for inner_attr in ret.attrs().iter().filter(|a| a.style == ast::AttrStyle::Inner) {
-            if let Some(attr_range) = self.capture_state.inner_attr_ranges.remove(&inner_attr.id) {
-                inner_attr_replace_ranges.push((attr_range, None));
-            } else {
-                self.dcx().span_delayed_bug(inner_attr.span, "Missing token range for attribute");
+        for attr in ret.attrs() {
+            if attr.style == ast::AttrStyle::Inner {
+                if let Some(attr_range) = self.capture_state.inner_attr_ranges.remove(&attr.id) {
+                    inner_attr_replace_ranges.push((attr_range, None));
+                } else {
+                    self.dcx().span_delayed_bug(attr.span, "Missing token range for attribute");
+                }
             }
         }
 
@@ -337,8 +333,7 @@ impl<'a> Parser<'a> {
         // When parsing `m`:
         // - `start_pos..end_pos` is `0..34` (`mod m`, excluding the `#[cfg_eval]` attribute).
         // - `inner_attr_replace_ranges` is empty.
-        // - `replace_range_start..replace_ranges_end` has two entries.
-        //   - One to delete the inner attribute (`17..27`), obtained when parsing `g` (see above).
+        // - `replace_range_start..replace_ranges_end` has one entry.
         //   - One `AttrsTarget` (added below when parsing `g`) to replace all of `g` (`3..33`,
         //     including its outer attribute), with:
         //     - `attrs`: includes the outer and the inner attr.
@@ -369,12 +364,10 @@ impl<'a> Parser<'a> {
 
             // What is the status here when parsing the example code at the top of this method?
             //
-            // When parsing `g`, we add two entries:
+            // When parsing `g`, we add one entry:
             // - The `start_pos..end_pos` (`3..33`) entry has a new `AttrsTarget` with:
             //   - `attrs`: includes the outer and the inner attr.
             //   - `tokens`: lazy tokens for `g` (with its inner attr deleted).
-            // - `inner_attr_replace_ranges` contains the one entry to delete the inner attr's
-            //   tokens (`17..27`).
             //
             // When parsing `m`, we do nothing here.
 
@@ -384,7 +377,6 @@ impl<'a> Parser<'a> {
             let start_pos = if has_outer_attrs { attrs.start_pos } else { start_pos };
             let target = AttrsTarget { attrs: ret.attrs().iter().cloned().collect(), tokens };
             self.capture_state.replace_ranges.push((start_pos..end_pos, Some(target)));
-            self.capture_state.replace_ranges.extend(inner_attr_replace_ranges);
         } else if matches!(self.capture_state.capturing, Capturing::No) {
             // Only clear the ranges once we've finished capturing entirely, i.e. we've finished
             // the outermost call to this method.
@@ -461,6 +453,19 @@ fn make_attr_token_stream(
     AttrTokenStream::new(stack_top.inner)
 }
 
+/// Tokens are needed if:
+/// - any non-single-segment attributes (other than doc comments) are present; or
+/// - any `cfg_attr` attributes are present;
+/// - any single-segment, non-builtin attributes are present.
+fn needs_tokens(attrs: &[ast::Attribute]) -> bool {
+    attrs.iter().any(|attr| match attr.ident() {
+        None => !attr.is_doc_comment(),
+        Some(ident) => {
+            ident.name == sym::cfg_attr || !rustc_feature::is_builtin_attr_name(ident.name)
+        }
+    })
+}
+
 // Some types are used a lot. Make sure they don't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
 mod size_asserts {

compiler/rustc_parse/src/parser/item.rs

@@ -2483,12 +2483,15 @@ impl<'a> Parser<'a> {
     /// `check_pub` adds additional `pub` to the checks in case users place it
     /// wrongly, can be used to ensure `pub` never comes after `default`.
     pub(super) fn check_fn_front_matter(&mut self, check_pub: bool, case: Case) -> bool {
+        const ALL_QUALS: &[Symbol] =
+            &[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern];
+
         // We use an over-approximation here.
         // `const const`, `fn const` won't parse, but we're not stepping over other syntax either.
         // `pub` is added in case users got confused with the ordering like `async pub fn`,
         // only if it wasn't preceded by `default` as `default pub` is invalid.
         let quals: &[Symbol] = if check_pub {
-            &[kw::Pub, kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
+            ALL_QUALS
         } else {
             &[kw::Gen, kw::Const, kw::Async, kw::Unsafe, kw::Safe, kw::Extern]
         };
@@ -2518,9 +2521,9 @@ impl<'a> Parser<'a> {
             || self.check_keyword_case(kw::Extern, case)
                 && self.look_ahead(1, |t| t.can_begin_string_literal())
                 && (self.look_ahead(2, |t| t.is_keyword_case(kw::Fn, case)) ||
-                    // this branch is only for better diagnostic in later, `pub` is not allowed here
+                    // this branch is only for better diagnostics; `pub`, `unsafe`, etc. are not allowed here
                     (self.may_recover()
-                        && self.look_ahead(2, |t| t.is_keyword(kw::Pub))
+                        && self.look_ahead(2, |t| ALL_QUALS.iter().any(|&kw| t.is_keyword(kw)))
                         && self.look_ahead(3, |t| t.is_keyword_case(kw::Fn, case))))
     }
 

compiler/rustc_passes/messages.ftl

@@ -69,9 +69,6 @@ passes_break_non_loop =
     .suggestion = use `break` on its own without a value inside this `{$kind}` loop
     .break_expr_suggestion = alternatively, you might have meant to use the available loop label
 
-passes_cannot_inline_naked_function =
-    naked functions cannot be inlined
-
 passes_cannot_stabilize_deprecated =
     an API can't be stabilized after it is deprecated
     .label = invalid version
@@ -485,16 +482,18 @@ passes_naked_functions_asm_block =
 passes_naked_functions_asm_options =
     asm options unsupported in naked functions: {$unsupported_options}
 
+passes_naked_functions_incompatible_attribute =
+    attribute incompatible with `#[naked]`
+    .label = the `{$attr}` attribute is incompatible with `#[naked]`
+    .naked_attribute = function marked with `#[naked]` here
+
 passes_naked_functions_must_use_noreturn =
     asm in naked functions must use `noreturn` option
     .suggestion = consider specifying that the asm block is responsible for returning from the function
 
 passes_naked_functions_operands =
     only `const` and `sym` operands are supported in naked functions
 
-passes_naked_tracked_caller =
-    cannot use `#[track_caller]` with `#[naked]`
-
 passes_no_link =
     attribute should be applied to an `extern crate` item
     .label = not an `extern crate` item