Auto merge of #149603 - matthiaskrgr:rollup-qvo8q9s, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #147841 (Fix ICE when applying test macro to crate root)
 - #149501 (CTFE: avoid emitting a hard error on generic normalization failures)
 - #149517 (Implement blessing for tidy alphabetical check)
 - #149521 (Improve `io::Error::downcast`)
 - #149545 (fix the check for which expressions read never type)
 - #149549 (Regression test for system register `ttbr0_el2`)
 - #149579 (Motor OS: fix compile error)
 - #149595 (Tidying up `tests/ui/issues` tests [2/N])
 - #149597 (Revert "implement and test `Iterator::{exactly_one, collect_array}`")

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

Author: bors

Cargo.lock

@@ -5615,6 +5615,7 @@ dependencies = [
  "semver",
  "serde",
  "similar",
+ "tempfile",
  "termcolor",
  "toml 0.7.8",
  "walkdir",

compiler/rustc_builtin_macros/src/test.rs

@@ -34,10 +34,6 @@ pub(crate) fn expand_test_case(
     check_builtin_macro_attribute(ecx, meta_item, sym::test_case);
     warn_on_duplicate_attribute(ecx, &anno_item, sym::test_case);
 
-    if !ecx.ecfg.should_test {
-        return vec![];
-    }
-
     let sp = ecx.with_def_site_ctxt(attr_sp);
     let (mut item, is_stmt) = match anno_item {
         Annotatable::Item(item) => (item, false),
@@ -54,6 +50,10 @@ pub(crate) fn expand_test_case(
         }
     };
 
+    if !ecx.ecfg.should_test {
+        return vec![];
+    }
+
     // `#[test_case]` is valid on functions, consts, and statics. Only modify
     // the item in those cases.
     match &mut item.kind {
@@ -113,29 +113,29 @@ pub(crate) fn expand_test_or_bench(
     item: Annotatable,
     is_bench: bool,
 ) -> Vec<Annotatable> {
-    // If we're not in test configuration, remove the annotated item
-    if !cx.ecfg.should_test {
-        return vec![];
-    }
-
     let (item, is_stmt) = match item {
         Annotatable::Item(i) => (i, false),
         Annotatable::Stmt(box ast::Stmt { kind: ast::StmtKind::Item(i), .. }) => (i, true),
         other => {
-            not_testable_error(cx, attr_sp, None);
+            not_testable_error(cx, is_bench, attr_sp, None);
             return vec![other];
         }
     };
 
     let ast::ItemKind::Fn(fn_) = &item.kind else {
-        not_testable_error(cx, attr_sp, Some(&item));
+        not_testable_error(cx, is_bench, attr_sp, Some(&item));
         return if is_stmt {
             vec![Annotatable::Stmt(Box::new(cx.stmt_item(item.span, item)))]
         } else {
             vec![Annotatable::Item(item)]
         };
     };
 
+    // If we're not in test configuration, remove the annotated item
+    if !cx.ecfg.should_test {
+        return vec![];
+    }
+
     if let Some(attr) = attr::find_by_name(&item.attrs, sym::naked) {
         cx.dcx().emit_err(errors::NakedFunctionTestingAttribute {
             testing_span: attr_sp,
@@ -405,9 +405,10 @@ pub(crate) fn expand_test_or_bench(
     }
 }
 
-fn not_testable_error(cx: &ExtCtxt<'_>, attr_sp: Span, item: Option<&ast::Item>) {
+fn not_testable_error(cx: &ExtCtxt<'_>, is_bench: bool, attr_sp: Span, item: Option<&ast::Item>) {
     let dcx = cx.dcx();
-    let msg = "the `#[test]` attribute may only be used on a non-associated function";
+    let name = if is_bench { "bench" } else { "test" };
+    let msg = format!("the `#[{name}]` attribute may only be used on a free function");
     let level = match item.map(|i| &i.kind) {
         // These were a warning before #92959 and need to continue being that to avoid breaking
         // stable user code (#94508).
@@ -426,12 +427,16 @@ fn not_testable_error(cx: &ExtCtxt<'_>, attr_sp: Span, item: Option<&ast::Item>)
             ),
         );
     }
-    err.with_span_label(attr_sp, "the `#[test]` macro causes a function to be run as a test and has no effect on non-functions")
-        .with_span_suggestion(attr_sp,
+    err.span_label(attr_sp, format!("the `#[{name}]` macro causes a function to be run as a test and has no effect on non-functions"));
+
+    if !is_bench {
+        err.with_span_suggestion(attr_sp,
             "replace with conditional compilation to make the item only exist when tests are being run",
             "#[cfg(test)]",
-            Applicability::MaybeIncorrect)
-        .emit();
+            Applicability::MaybeIncorrect).emit();
+    } else {
+        err.emit();
+    }
 }
 
 fn get_location_info(cx: &ExtCtxt<'_>, fn_: &ast::Fn) -> (Symbol, usize, usize, usize, usize) {

compiler/rustc_codegen_ssa/src/back/metadata.rs

@@ -86,8 +86,7 @@ impl MetadataLoader for DefaultMetadataLoader {
                     format!("failed to parse aix dylib '{}': {}", path.display(), e)
                 })?;
 
-                // FIXME: rewrite in terms of `#![feature(exact_length_collection)]`. See: #149266
-                match Itertools::exactly_one(archive.members()) {
+                match archive.members().exactly_one() {
                     Ok(lib) => {
                         let lib = lib.map_err(|e| {
                             format!("failed to parse aix dylib '{}': {}", path.display(), e)

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -11,7 +11,9 @@ use rustc_middle::ty::layout::{
     self, FnAbiError, FnAbiOf, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOf,
     LayoutOfHelpers, TyAndLayout,
 };
-use rustc_middle::ty::{self, GenericArgsRef, Ty, TyCtxt, TypeFoldable, TypingEnv, Variance};
+use rustc_middle::ty::{
+    self, GenericArgsRef, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, TypingEnv, Variance,
+};
 use rustc_middle::{mir, span_bug};
 use rustc_span::Span;
 use rustc_target::callconv::FnAbi;
@@ -84,10 +86,31 @@ impl<'tcx, M: Machine<'tcx>> LayoutOfHelpers<'tcx> for InterpCx<'tcx, M> {
     #[inline]
     fn handle_layout_err(
         &self,
-        err: LayoutError<'tcx>,
+        mut err: LayoutError<'tcx>,
         _: Span,
         _: Ty<'tcx>,
     ) -> InterpErrorKind<'tcx> {
+        // FIXME(#149283): This is really hacky and is only used to hide type
+        // system bugs. We use it as a temporary fix for #149081.
+        //
+        // While it's expected that we sometimes get ambiguity errors when
+        // entering another generic environment while the current environment
+        // itself is still generic, we should never fail to entirely prove
+        // something.
+        match err {
+            LayoutError::NormalizationFailure(ty, _) => {
+                if ty.has_non_region_param() {
+                    err = LayoutError::TooGeneric(ty);
+                }
+            }
+
+            LayoutError::Unknown(_)
+            | LayoutError::SizeOverflow(_)
+            | LayoutError::InvalidSimd { .. }
+            | LayoutError::TooGeneric(_)
+            | LayoutError::ReferencesError(_)
+            | LayoutError::Cycle(_) => {}
+        }
         err_inval!(Layout(err))
     }
 }
@@ -112,7 +135,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// and allows wrapping the actual [LayoutOf::layout_of] with a tracing span.
     /// See [LayoutOf::layout_of] for the original documentation.
     #[inline(always)]
-    pub fn layout_of(&self, ty: Ty<'tcx>) -> <Self as LayoutOfHelpers<'tcx>>::LayoutOfResult {
+    pub fn layout_of(&self, ty: Ty<'tcx>) -> Result<TyAndLayout<'tcx>, InterpErrorKind<'tcx>> {
         let _trace = enter_trace_span!(M, layouting::layout_of, ty = ?ty.kind());
         LayoutOf::layout_of(self, ty)
     }

compiler/rustc_hir/src/hir.rs

@@ -1793,6 +1793,55 @@ impl<'hir> Pat<'hir> {
         });
         is_never_pattern
     }
+
+    /// Whether this pattern constitutes a read of value of the scrutinee that
+    /// it is matching against. This is used to determine whether we should
+    /// perform `NeverToAny` coercions.
+    ///
+    /// See [`expr_guaranteed_to_constitute_read_for_never`][m] for the nuances of
+    /// what happens when this returns true.
+    ///
+    /// [m]: ../../rustc_middle/ty/struct.TyCtxt.html#method.expr_guaranteed_to_constitute_read_for_never
+    pub fn is_guaranteed_to_constitute_read_for_never(&self) -> bool {
+        match self.kind {
+            // Does not constitute a read.
+            PatKind::Wild => false,
+
+            // The guard cannot affect if we make a read or not (it runs after the inner pattern
+            // has matched), therefore it's irrelevant.
+            PatKind::Guard(pat, _) => pat.is_guaranteed_to_constitute_read_for_never(),
+
+            // This is unnecessarily restrictive when the pattern that doesn't
+            // constitute a read is unreachable.
+            //
+            // For example `match *never_ptr { value => {}, _ => {} }` or
+            // `match *never_ptr { _ if false => {}, value => {} }`.
+            //
+            // It is however fine to be restrictive here; only returning `true`
+            // can lead to unsoundness.
+            PatKind::Or(subpats) => {
+                subpats.iter().all(|pat| pat.is_guaranteed_to_constitute_read_for_never())
+            }
+
+            // Does constitute a read, since it is equivalent to a discriminant read.
+            PatKind::Never => true,
+
+            // All of these constitute a read, or match on something that isn't `!`,
+            // which would require a `NeverToAny` coercion.
+            PatKind::Missing
+            | PatKind::Binding(_, _, _, _)
+            | PatKind::Struct(_, _, _)
+            | PatKind::TupleStruct(_, _, _)
+            | PatKind::Tuple(_, _)
+            | PatKind::Box(_)
+            | PatKind::Ref(_, _, _)
+            | PatKind::Deref(_)
+            | PatKind::Expr(_)
+            | PatKind::Range(_, _, _)
+            | PatKind::Slice(_, _, _)
+            | PatKind::Err(_) => true,
+        }
+    }
 }
 
 /// A single field in a struct pattern.

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1078,7 +1078,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             self,
             cause,
             allow_two_phase,
-            self.expr_guaranteed_to_constitute_read_for_never(expr),
+            self.tcx.expr_guaranteed_to_constitute_read_for_never(expr),
         );
         let ok = self.commit_if_ok(|_| coerce.coerce(source, target))?;