Auto merge of #115615 - matthiaskrgr:rollup-49fosdf, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #114511 (Remove the unhelpful let binding diag comes from FormatArguments)
 - #115473 (Add explanatory note to 'expected item' error)
 - #115574 (Replace `rustc_data_structures` dependency with `rustc_index` in `rustc_parse_format`)
 - #115578 (Clarify cryptic comments)
 - #115587 (fix #115348)
 - #115596 (A small change)
 - #115598 (Fix log formatting in bootstrap)
 - #115605 (Better Debug for `Ty` in smir)
 - #115614 (Fix minor grammar typo)

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

Author: bors

Cargo.lock

@@ -4175,7 +4175,7 @@ dependencies = [
 name = "rustc_parse_format"
 version = "0.0.0"
 dependencies = [
- "rustc_data_structures",
+ "rustc_index",
  "rustc_lexer",
 ]
 

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -2130,21 +2130,27 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 /// misleading users in cases like `tests/ui/nll/borrowed-temporary-error.rs`.
                 /// We could expand the analysis to suggest hoising all of the relevant parts of
                 /// the users' code to make the code compile, but that could be too much.
-                struct NestedStatementVisitor {
+                /// We found the `prop_expr` by the way to check whether the expression is a `FormatArguments`,
+                /// which is a special case since it's generated by the compiler.
+                struct NestedStatementVisitor<'tcx> {
                     span: Span,
                     current: usize,
                     found: usize,
+                    prop_expr: Option<&'tcx hir::Expr<'tcx>>,
                 }
 
-                impl<'tcx> Visitor<'tcx> for NestedStatementVisitor {
-                    fn visit_block(&mut self, block: &hir::Block<'tcx>) {
+                impl<'tcx> Visitor<'tcx> for NestedStatementVisitor<'tcx> {
+                    fn visit_block(&mut self, block: &'tcx hir::Block<'tcx>) {
                         self.current += 1;
                         walk_block(self, block);
                         self.current -= 1;
                     }
-                    fn visit_expr(&mut self, expr: &hir::Expr<'tcx>) {
+                    fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
                         if self.span == expr.span.source_callsite() {
                             self.found = self.current;
+                            if self.prop_expr.is_none() {
+                                self.prop_expr = Some(expr);
+                            }
                         }
                         walk_expr(self, expr);
                     }
@@ -2162,22 +2168,40 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                             span: proper_span,
                             current: 0,
                             found: 0,
+                            prop_expr: None,
                         };
                         visitor.visit_stmt(stmt);
+
+                        let typeck_results = self.infcx.tcx.typeck(self.mir_def_id());
+                        let expr_ty: Option<Ty<'_>> = visitor.prop_expr.map(|expr| typeck_results.expr_ty(expr).peel_refs());
+
+                        let is_format_arguments_item =
+                            if let Some(expr_ty) = expr_ty
+                               && let ty::Adt(adt, _) = expr_ty.kind() {
+                                    self.infcx.tcx.lang_items().get(LangItem::FormatArguments) == Some(adt.did())
+                               } else {
+                                   false
+                               };
+
                         if visitor.found == 0
                             && stmt.span.contains(proper_span)
                             && let Some(p) = sm.span_to_margin(stmt.span)
                             && let Ok(s) = sm.span_to_snippet(proper_span)
                         {
-                            let addition = format!("let binding = {};\n{}", s, " ".repeat(p));
-                            err.multipart_suggestion_verbose(
-                                msg,
-                                vec![
-                                    (stmt.span.shrink_to_lo(), addition),
-                                    (proper_span, "binding".to_string()),
-                                ],
-                                Applicability::MaybeIncorrect,
-                            );
+                            if !is_format_arguments_item {
+                                let addition = format!("let binding = {};\n{}", s, " ".repeat(p));
+                                err.multipart_suggestion_verbose(
+                                    msg,
+                                    vec![
+                                        (stmt.span.shrink_to_lo(), addition),
+                                        (proper_span, "binding".to_string()),
+                                    ],
+                                    Applicability::MaybeIncorrect,
+                                );
+                            } else {
+                                err.note("the result of `format_args!` can only be assigned directly if no placeholders in it's arguments are used");
+                                err.note("to learn more, visit <https://doc.rust-lang.org/std/macro.format_args.html>");
+                            }
                             suggested = true;
                             break;
                         }

compiler/rustc_lint/src/traits.rs

@@ -96,7 +96,7 @@ impl<'tcx> LateLintPass<'tcx> for DropTraitConstraints {
             };
             let def_id = trait_predicate.trait_ref.def_id;
             if cx.tcx.lang_items().drop_trait() == Some(def_id) {
-                // Explicitly allow `impl Drop`, a drop-guards-as-Voldemort-type pattern.
+                // Explicitly allow `impl Drop`, a drop-guards-as-unnameable-type pattern.
                 if trait_predicate.trait_ref.self_ty().is_impl_trait() {
                     continue;
                 }

compiler/rustc_lint_defs/src/builtin.rs

@@ -4363,7 +4363,7 @@ declare_lint! {
     ///     pub struct S;
     /// }
     ///
-    /// pub fn get_voldemort() -> m::S { m::S }
+    /// pub fn get_unnameable() -> m::S { m::S }
     /// # fn main() {}
     /// ```
     ///

compiler/rustc_middle/src/ty/sty.rs

@@ -2857,7 +2857,7 @@ impl<'tcx> Ty<'tcx> {
             | ty::Uint(..)
             | ty::Float(..) => true,
 
-            // The voldemort ZSTs are fine.
+            // ZST which can't be named are fine.
             ty::FnDef(..) => true,
 
             ty::Array(element_ty, _len) => element_ty.is_trivially_pure_clone_copy(),

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -483,7 +483,7 @@ fn unsafety_check_result(tcx: TyCtxt<'_>, def: LocalDefId) -> &UnsafetyCheckResu
     // `mir_built` force this.
     let body = &tcx.mir_built(def).borrow();
 
-    if body.is_custom_mir() {
+    if body.is_custom_mir() || body.tainted_by_errors.is_some() {
         return tcx.arena.alloc(UnsafetyCheckResult {
             violations: Vec::new(),
             used_unsafe_blocks: Default::default(),

compiler/rustc_parse/src/parser/attr_wrapper.rs

@@ -106,7 +106,7 @@ impl ToAttrTokenStream for LazyAttrTokenStreamImpl {
         let mut cursor_snapshot = self.cursor_snapshot.clone();
         let tokens =
             std::iter::once((FlatToken::Token(self.start_token.0.clone()), self.start_token.1))
-                .chain((0..self.num_calls).map(|_| {
+                .chain(std::iter::repeat_with(|| {
                     let token = cursor_snapshot.next();
                     (FlatToken::Token(token.0), token.1)
                 }))

compiler/rustc_parse/src/parser/item.rs

@@ -73,12 +73,16 @@ impl<'a> Parser<'a> {
             if !self.maybe_consume_incorrect_semicolon(&items) {
                 let msg = format!("expected item, found {token_str}");
                 let mut err = self.struct_span_err(self.token.span, msg);
-                let label = if self.is_kw_followed_by_ident(kw::Let) {
-                    "consider using `const` or `static` instead of `let` for global variables"
+                let span = self.token.span;
+                if self.is_kw_followed_by_ident(kw::Let) {
+                    err.span_label(
+                        span,
+                        "consider using `const` or `static` instead of `let` for global variables",
+                    );
                 } else {
-                    "expected item"
+                    err.span_label(span, "expected item")
+                        .note("for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>");
                 };
-                err.span_label(self.token.span, label);
                 return Err(err);
             }
         }

compiler/rustc_parse_format/Cargo.toml

@@ -5,4 +5,4 @@ edition = "2021"
 
 [dependencies]
 rustc_lexer = { path = "../rustc_lexer" }
-rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_index = { path = "../rustc_index", default-features = false }

compiler/rustc_parse_format/src/lib.rs

@@ -1011,7 +1011,7 @@ fn unescape_string(string: &str) -> Option<string::String> {
 
 // Assert a reasonable size for `Piece`
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Piece<'_>, 16);
+rustc_index::static_assert_size!(Piece<'_>, 16);
 
 #[cfg(test)]
 mod tests;