Auto merge of #147449 - matthiaskrgr:rollup-njyi5yr, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #145943 (stdlib docs: document lifetime extension for `format_args!`'s arguments)
 - #147243 (cmse: disallow `impl Trait` in `cmse-nonsecure-entry` return types)
 - #147402 ([rustdoc] Don't serialize & deserialize data that doesn't go OTW)
 - #147418 (Fix target list of `link_section`)
 - #147429 (Print tip for human error format in runtest)
 - #147441 (Fix comments error for Provenance impls)
 - #147442 (c-variadic: fix thir-print for `...` without a pattern)

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

Author: bors

compiler/rustc_attr_parsing/src/attributes/link_attrs.rs

@@ -467,8 +467,14 @@ impl<S: Stage> SingleAttributeParser<S> for LinkSectionParser {
     const PATH: &[Symbol] = &[sym::link_section];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
-    const ALLOWED_TARGETS: AllowedTargets =
-        AllowedTargets::AllowListWarnRest(&[Allow(Target::Static), Allow(Target::Fn)]);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Static),
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         NameValueStr: "name",
         "https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"

compiler/rustc_hir_analysis/src/hir_ty_lowering/cmse.rs

@@ -1,9 +1,9 @@
-use rustc_abi::ExternAbi;
+use rustc_abi::{BackendRepr, ExternAbi, Float, Integer, Primitive, Scalar};
 use rustc_errors::{DiagCtxtHandle, E0781, struct_span_code_err};
 use rustc_hir::{self as hir, HirId};
 use rustc_middle::bug;
-use rustc_middle::ty::layout::LayoutError;
-use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::layout::{LayoutError, TyAndLayout};
+use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
 
 use crate::errors;
 
@@ -164,44 +164,48 @@ fn is_valid_cmse_output<'tcx>(
 ) -> Result<bool, &'tcx LayoutError<'tcx>> {
     // this type is only used for layout computation, which does not rely on regions
     let fn_sig = tcx.instantiate_bound_regions_with_erased(fn_sig);
+    let fn_sig = tcx.erase_and_anonymize_regions(fn_sig);
+    let return_type = fn_sig.output();
+
+    // `impl Trait` is already disallowed with `cmse-nonsecure-call`, because that ABI is only
+    // allowed on function pointers, and function pointers cannot contain `impl Trait` in their
+    // signature.
+    //
+    // Here we explicitly disallow `impl Trait` in the `cmse-nonsecure-entry` return type too, to
+    // prevent query cycles when calculating the layout. This ABI is meant to be used with
+    // `#[no_mangle]` or similar, so generics in the type really don't make sense.
+    //
+    // see also https://github.com/rust-lang/rust/issues/147242.
+    if return_type.has_opaque_types() {
+        return Err(tcx.arena.alloc(LayoutError::TooGeneric(return_type)));
+    }
 
     let typing_env = ty::TypingEnv::fully_monomorphized();
+    let layout = tcx.layout_of(typing_env.as_query_input(return_type))?;
+
+    Ok(is_valid_cmse_output_layout(layout))
+}
 
-    let mut ret_ty = fn_sig.output();
-    let layout = tcx.layout_of(typing_env.as_query_input(ret_ty))?;
+/// Returns whether the output will fit into the available registers
+fn is_valid_cmse_output_layout<'tcx>(layout: TyAndLayout<'tcx>) -> bool {
     let size = layout.layout.size().bytes();
 
     if size <= 4 {
-        return Ok(true);
+        return true;
     } else if size > 8 {
-        return Ok(false);
+        return false;
     }
 
-    // next we need to peel any repr(transparent) layers off
-    'outer: loop {
-        let ty::Adt(adt_def, args) = ret_ty.kind() else {
-            break;
-        };
-
-        if !adt_def.repr().transparent() {
-            break;
-        }
-
-        // the first field with non-trivial size and alignment must be the data
-        for variant_def in adt_def.variants() {
-            for field_def in variant_def.fields.iter() {
-                let ty = field_def.ty(tcx, args);
-                let layout = tcx.layout_of(typing_env.as_query_input(ty))?;
+    // Accept scalar 64-bit types.
+    let BackendRepr::Scalar(scalar) = layout.layout.backend_repr else {
+        return false;
+    };
 
-                if !layout.layout.is_1zst() {
-                    ret_ty = ty;
-                    continue 'outer;
-                }
-            }
-        }
-    }
+    let Scalar::Initialized { value, .. } = scalar else {
+        return false;
+    };
 
-    Ok(ret_ty == tcx.types.i64 || ret_ty == tcx.types.u64 || ret_ty == tcx.types.f64)
+    matches!(value, Primitive::Int(Integer::I64, _) | Primitive::Float(Float::F64))
 }
 
 fn should_emit_generic_error<'tcx>(abi: ExternAbi, layout_err: &'tcx LayoutError<'tcx>) -> bool {

compiler/rustc_middle/src/mir/interpret/pointer.rs

@@ -167,7 +167,7 @@ impl CtfeProvenance {
 }
 
 impl Provenance for CtfeProvenance {
-    // With the `AllocId` as provenance, the `offset` is interpreted *relative to the allocation*,
+    // With the `CtfeProvenance` as provenance, the `offset` is interpreted *relative to the allocation*,
     // so ptr-to-int casts are not possible (since we do not know the global physical offset).
     const OFFSET_IS_ADDR: bool = false;
 

compiler/rustc_mir_build/src/thir/print.rs

@@ -689,7 +689,9 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
         print_indented!(self, "kind: PatKind {", depth_lvl);
 
         match pat_kind {
-            PatKind::Missing => unreachable!(),
+            PatKind::Missing => {
+                print_indented!(self, "Missing", depth_lvl + 1);
+            }
             PatKind::Wild => {
                 print_indented!(self, "Wild", depth_lvl + 1);
             }

library/core/src/macros/mod.rs

@@ -951,8 +951,9 @@ pub(crate) mod builtin {
     /// format string in `format_args!`.
     ///
     /// ```rust
-    /// let debug = format!("{:?}", format_args!("{} foo {:?}", 1, 2));
-    /// let display = format!("{}", format_args!("{} foo {:?}", 1, 2));
+    /// let args = format_args!("{} foo {:?}", 1, 2);
+    /// let debug = format!("{args:?}");
+    /// let display = format!("{args}");
     /// assert_eq!("1 foo 2", display);
     /// assert_eq!(display, debug);
     /// ```
@@ -976,13 +977,17 @@ pub(crate) mod builtin {
     /// assert_eq!(s, format!("hello {}", "world"));
     /// ```
     ///
-    /// # Lifetime limitation
+    /// # Argument lifetimes
     ///
     /// Except when no formatting arguments are used,
-    /// the produced `fmt::Arguments` value borrows temporary values,
-    /// which means it can only be used within the same expression
-    /// and cannot be stored for later use.
-    /// This is a known limitation, see [#92698](https://github.com/rust-lang/rust/issues/92698).
+    /// the produced `fmt::Arguments` value borrows temporary values.
+    /// To allow it to be stored for later use, the arguments' lifetimes, as well as those of
+    /// temporaries they borrow, may be [extended] when `format_args!` appears in the initializer
+    /// expression of a `let` statement. The syntactic rules used to determine when temporaries'
+    /// lifetimes are extended are documented in the [Reference].
+    ///
+    /// [extended]: ../reference/destructors.html#temporary-lifetime-extension
+    /// [Reference]: ../reference/destructors.html#extending-based-on-expressions
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_diagnostic_item = "format_args_macro"]
     #[allow_internal_unsafe]

src/librustdoc/html/render/mod.rs

@@ -144,7 +144,7 @@ pub(crate) struct IndexItem {
 }
 
 /// A type used for the search index.
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 struct RenderType {
     id: Option<RenderTypeId>,
     generics: Option<Vec<RenderType>>,
@@ -301,7 +301,7 @@ impl RenderTypeId {
 }
 
 /// Full type of functions/methods in the search index.
-#[derive(Debug, Eq, PartialEq)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 pub(crate) struct IndexItemFunctionType {
     inputs: Vec<RenderType>,
     output: Vec<RenderType>,