Auto merge of rust-lang#126126 - matthiaskrgr:rollup-541x5a6, r=matthiaskrgr

Rollup of 10 pull requests

Successful merges:

 - rust-lang#116088 (Stabilise `c_unwind`)
 - rust-lang#124012 (Stabilize `binary_heap_as_slice`)
 - rust-lang#124214 (Parse unsafe attributes)
 - rust-lang#125572 (Detect pub structs never constructed and unused associated constants)
 - rust-lang#125781 (prefer `compile::stream_cargo` for building tools)
 - rust-lang#126030 (Update `./x fmt` command in library/std/src/sys/pal/windows/c/README.md)
 - rust-lang#126047 (Simplify the rayon calls in the installer)
 - rust-lang#126089 (Stabilize Option::take_if)
 - rust-lang#126112 (Clean up source root in run-make tests)
 - rust-lang#126119 (Improve docs for using custom paths with `--emit`)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_expand/src/build.rs

@@ -666,20 +666,34 @@ impl<'a> ExtCtxt<'a> {
     // Builds `#[name]`.
     pub fn attr_word(&self, name: Symbol, span: Span) -> ast::Attribute {
         let g = &self.sess.psess.attr_id_generator;
-        attr::mk_attr_word(g, ast::AttrStyle::Outer, name, span)
+        attr::mk_attr_word(g, ast::AttrStyle::Outer, ast::Safety::Default, name, span)
     }
 
     // Builds `#[name = val]`.
     //
     // Note: `span` is used for both the identifier and the value.
     pub fn attr_name_value_str(&self, name: Symbol, val: Symbol, span: Span) -> ast::Attribute {
         let g = &self.sess.psess.attr_id_generator;
-        attr::mk_attr_name_value_str(g, ast::AttrStyle::Outer, name, val, span)
+        attr::mk_attr_name_value_str(
+            g,
+            ast::AttrStyle::Outer,
+            ast::Safety::Default,
+            name,
+            val,
+            span,
+        )
     }
 
     // Builds `#[outer(inner)]`.
     pub fn attr_nested_word(&self, outer: Symbol, inner: Symbol, span: Span) -> ast::Attribute {
         let g = &self.sess.psess.attr_id_generator;
-        attr::mk_attr_nested_word(g, ast::AttrStyle::Outer, outer, inner, span)
+        attr::mk_attr_nested_word(
+            g,
+            ast::AttrStyle::Outer,
+            ast::Safety::Default,
+            outer,
+            inner,
+            span,
+        )
     }
 }

compiler/rustc_expand/src/expand.rs

@@ -778,7 +778,14 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     if let SyntaxExtensionKind::Derive(..) = ext {
                         self.gate_proc_macro_input(&item);
                     }
-                    let meta = ast::MetaItem { kind: MetaItemKind::Word, span, path };
+                    // The `MetaItem` representing the trait to derive can't
+                    // have an unsafe around it (as of now).
+                    let meta = ast::MetaItem {
+                        unsafety: ast::Safety::Default,
+                        kind: MetaItemKind::Word,
+                        span,
+                        path,
+                    };
                     let items = match expander.expand(self.cx, span, &meta, item, is_const) {
                         ExpandResult::Ready(items) => items,
                         ExpandResult::Retry(item) => {

compiler/rustc_feature/src/accepted.rs

@@ -80,6 +80,8 @@ declare_features! (
     (accepted, braced_empty_structs, "1.8.0", Some(29720)),
     /// Allows `c"foo"` literals.
     (accepted, c_str_literals, "1.77.0", Some(105723)),
+    /// Allows `extern "C-unwind" fn` to enable unwinding across ABI boundaries and treat `extern "C" fn` as nounwind.
+    (accepted, c_unwind, "CURRENT_RUSTC_VERSION", Some(74990)),
     /// Allows `#[cfg_attr(predicate, multiple, attributes, here)]`.
     (accepted, cfg_attr_multi, "1.33.0", Some(54881)),
     /// Allows the use of `#[cfg(doctest)]`, set when rustdoc is collecting doctests.