Auto merge of #78350 - JohnTitor:rollup-vbbm5wf, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - #77984 (Compute proper module parent during resolution)
 - #78085 (MIR validation should check `SwitchInt` values are valid for the type)
 - #78208 (replace `#[allow_internal_unstable]` with `#[rustc_allow_const_fn_unstable]` for `const fn`s)
 - #78209 (Update `compiler_builtins` to 0.1.36)
 - #78276 (Bump backtrace-rs to enable Mach-O support on iOS.)
 - #78320 (Link to cargo's `build-std` feature instead of `xargo` in custom target docs)
 - #78322 (BTreeMap: stop mistaking node::MIN_LEN for a node level constraint)
 - #78326 (Split out statement attributes changes from #78306)

Failed merges:

r? `@ghost`

Author: bors

Cargo.lock

@@ -636,9 +636,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.35"
+version = "0.1.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e3fcd8aba10d17504c87ef12d4f62ef404c6a4703d16682a9eb5543e6cf24455"
+checksum = "7cd0782e0a7da7598164153173e5a5d4d9b1da094473c98dce0ff91406112369"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",

compiler/rustc_ast/src/attr/mod.rs

@@ -629,7 +629,8 @@ impl HasAttrs for StmtKind {
         match *self {
             StmtKind::Local(ref local) => local.attrs(),
             StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => expr.attrs(),
-            StmtKind::Empty | StmtKind::Item(..) => &[],
+            StmtKind::Item(ref item) => item.attrs(),
+            StmtKind::Empty => &[],
             StmtKind::MacCall(ref mac) => mac.attrs.attrs(),
         }
     }
@@ -638,7 +639,8 @@ impl HasAttrs for StmtKind {
         match self {
             StmtKind::Local(local) => local.visit_attrs(f),
             StmtKind::Expr(expr) | StmtKind::Semi(expr) => expr.visit_attrs(f),
-            StmtKind::Empty | StmtKind::Item(..) => {}
+            StmtKind::Item(item) => item.visit_attrs(f),
+            StmtKind::Empty => {}
             StmtKind::MacCall(mac) => {
                 mac.attrs.visit_attrs(f);
             }

compiler/rustc_attr/src/builtin.rs

@@ -1013,13 +1013,28 @@ pub fn allow_internal_unstable<'a>(
     sess: &'a Session,
     attrs: &'a [Attribute],
 ) -> Option<impl Iterator<Item = Symbol> + 'a> {
-    let attrs = sess.filter_by_name(attrs, sym::allow_internal_unstable);
+    allow_unstable(sess, attrs, sym::allow_internal_unstable)
+}
+
+pub fn rustc_allow_const_fn_unstable<'a>(
+    sess: &'a Session,
+    attrs: &'a [Attribute],
+) -> Option<impl Iterator<Item = Symbol> + 'a> {
+    allow_unstable(sess, attrs, sym::rustc_allow_const_fn_unstable)
+}
+
+fn allow_unstable<'a>(
+    sess: &'a Session,
+    attrs: &'a [Attribute],
+    symbol: Symbol,
+) -> Option<impl Iterator<Item = Symbol> + 'a> {
+    let attrs = sess.filter_by_name(attrs, symbol);
     let list = attrs
         .filter_map(move |attr| {
             attr.meta_item_list().or_else(|| {
                 sess.diagnostic().span_err(
                     attr.span,
-                    "`allow_internal_unstable` expects a list of feature names",
+                    &format!("`{}` expects a list of feature names", symbol.to_ident_string()),
                 );
                 None
             })
@@ -1029,8 +1044,10 @@ pub fn allow_internal_unstable<'a>(
     Some(list.into_iter().filter_map(move |it| {
         let name = it.ident().map(|ident| ident.name);
         if name.is_none() {
-            sess.diagnostic()
-                .span_err(it.span(), "`allow_internal_unstable` expects feature names");
+            sess.diagnostic().span_err(
+                it.span(),
+                &format!("`{}` expects feature names", symbol.to_ident_string()),
+            );
         }
         name
     }))

compiler/rustc_expand/src/expand.rs

@@ -1357,7 +1357,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         // we'll expand attributes on expressions separately
         if !stmt.is_expr() {
             let (attr, derives, after_derive) = if stmt.is_item() {
-                self.classify_item(&mut stmt)
+                // FIXME: Handle custom attributes on statements (#15701)
+                (None, vec![], false)
             } else {
                 // ignore derives on non-item statements so it falls through
                 // to the unused-attributes lint

compiler/rustc_feature/src/active.rs

@@ -210,6 +210,11 @@ declare_features! (
     /// it is not on path for eventual stabilization).
     (active, no_niche, "1.42.0", None, None),
 
+    /// Allows using `#[rustc_allow_const_fn_unstable]`.
+    /// This is an attribute on `const fn` for the same
+    /// purpose as `#[allow_internal_unstable]`.
+    (active, rustc_allow_const_fn_unstable, "1.49.0", Some(69399), None),
+
     // no-tracking-issue-end
 
     // -------------------------------------------------------------------------

compiler/rustc_feature/src/builtin_attrs.rs

@@ -379,6 +379,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         allow_internal_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
         "allow_internal_unstable side-steps feature gating and stability checks",
     ),
+    gated!(
+        rustc_allow_const_fn_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
+        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
+    ),
     gated!(
         allow_internal_unsafe, Normal, template!(Word),
         "allow_internal_unsafe side-steps the unsafe_code lint",

compiler/rustc_hir/src/hir.rs

@@ -1101,11 +1101,11 @@ pub enum StmtKind<'hir> {
     Semi(&'hir Expr<'hir>),
 }
 
-impl StmtKind<'hir> {
-    pub fn attrs(&self) -> &'hir [Attribute] {
+impl<'hir> StmtKind<'hir> {
+    pub fn attrs(&self, get_item: impl FnOnce(ItemId) -> &'hir Item<'hir>) -> &'hir [Attribute] {
         match *self {
             StmtKind::Local(ref l) => &l.attrs,
-            StmtKind::Item(_) => &[],
+            StmtKind::Item(ref item_id) => &get_item(*item_id).attrs,
             StmtKind::Expr(ref e) | StmtKind::Semi(ref e) => &e.attrs,
         }
     }

compiler/rustc_lint/src/builtin.rs

@@ -994,7 +994,8 @@ impl EarlyLintPass for UnusedDocComment {
     fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
         let kind = match stmt.kind {
             ast::StmtKind::Local(..) => "statements",
-            ast::StmtKind::Item(..) => "inner items",
+            // Disabled pending discussion in #78306
+            ast::StmtKind::Item(..) => return,
             // expressions will be reported by `check_expr`.
             ast::StmtKind::Empty
             | ast::StmtKind::Semi(_)

compiler/rustc_lint/src/early.rs

@@ -18,6 +18,7 @@ use crate::context::{EarlyContext, LintContext, LintStore};
 use crate::passes::{EarlyLintPass, EarlyLintPassObject};
 use rustc_ast as ast;
 use rustc_ast::visit as ast_visit;
+use rustc_attr::HasAttrs;
 use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
 use rustc_session::Session;
 use rustc_span::symbol::Ident;
@@ -119,8 +120,22 @@ impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T>
     }
 
     fn visit_stmt(&mut self, s: &'a ast::Stmt) {
-        run_early_pass!(self, check_stmt, s);
-        self.check_id(s.id);
+        // Add the statement's lint attributes to our
+        // current state when checking the statement itself.
+        // This allows us to handle attributes like
+        // `#[allow(unused_doc_comments)]`, which apply to
+        // sibling attributes on the same target
+        //
+        // Note that statements get their attributes from
+        // the AST struct that they wrap (e.g. an item)
+        self.with_lint_attrs(s.id, s.attrs(), |cx| {
+            run_early_pass!(cx, check_stmt, s);
+            cx.check_id(s.id);
+        });
+        // The visitor for the AST struct wrapped
+        // by the statement (e.g. `Item`) will call
+        // `with_lint_attrs`, so do this walk
+        // outside of the above `with_lint_attrs` call
         ast_visit::walk_stmt(self, s);
     }
 

compiler/rustc_lint/src/late.rs

@@ -174,12 +174,13 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
     }
 
     fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
-        // statement attributes are actually just attributes on one of
-        // - item
-        // - local
-        // - expression
-        // so we keep track of lint levels there
-        lint_callback!(self, check_stmt, s);
+        let get_item = |id: hir::ItemId| self.context.tcx.hir().item(id.id);
+        let attrs = &s.kind.attrs(get_item);
+        // See `EarlyContextAndPass::visit_stmt` for an explanation
+        // of why we call `walk_stmt` outside of `with_lint_attrs`
+        self.with_lint_attrs(s.hir_id, attrs, |cx| {
+            lint_callback!(cx, check_stmt, s);
+        });
         hir_visit::walk_stmt(self, s);
     }