Auto merge of #140646 - tgross35:rollup-z3hjbm6, r=tgross35

Rollup of 6 pull requests

Successful merges:

 - #137280 (stabilize ptr::swap_nonoverlapping in const)
 - #140457 (Use target-cpu=z13 on s390x codegen const vector test)
 - #140619 (Small adjustments to `check_attribute_safety` to make the logic more obvious)
 - #140625 (Suggest `retain_mut` over `retain` as `Vec::extract_if` alternative)
 - #140627 (Allow linking rustc and rustdoc against the same single tracing crate)
 - #140630 (Async drop source info fix for proxy-drop-coroutine)

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

Author: bors

compiler/rustc_expand/src/config.rs

@@ -276,7 +276,7 @@ impl<'a> StripUnconfigured<'a> {
     pub(crate) fn expand_cfg_attr(&self, cfg_attr: &Attribute, recursive: bool) -> Vec<Attribute> {
         validate_attr::check_attribute_safety(
             &self.sess.psess,
-            AttributeSafety::Normal,
+            Some(AttributeSafety::Normal),
             &cfg_attr,
             ast::CRATE_NODE_ID,
         );

compiler/rustc_log/src/lib.rs

@@ -37,6 +37,7 @@ use std::env::{self, VarError};
 use std::fmt::{self, Display};
 use std::io::{self, IsTerminal};
 
+use tracing::dispatcher::SetGlobalDefaultError;
 use tracing_core::{Event, Subscriber};
 use tracing_subscriber::filter::{Directive, EnvFilter, LevelFilter};
 use tracing_subscriber::fmt::FmtContext;
@@ -131,10 +132,10 @@ pub fn init_logger(cfg: LoggerConfig) -> Result<(), Error> {
                 .without_time()
                 .event_format(BacktraceFormatter { backtrace_target });
             let subscriber = subscriber.with(fmt_layer);
-            tracing::subscriber::set_global_default(subscriber).unwrap();
+            tracing::subscriber::set_global_default(subscriber)?;
         }
         Err(_) => {
-            tracing::subscriber::set_global_default(subscriber).unwrap();
+            tracing::subscriber::set_global_default(subscriber)?;
         }
     };
 
@@ -180,6 +181,7 @@ pub enum Error {
     InvalidColorValue(String),
     NonUnicodeColorValue,
     InvalidWraptree(String),
+    AlreadyInit(SetGlobalDefaultError),
 }
 
 impl std::error::Error for Error {}
@@ -199,6 +201,13 @@ impl Display for Error {
                 formatter,
                 "invalid log WRAPTREE value '{value}': expected a non-negative integer",
             ),
+            Error::AlreadyInit(tracing_error) => Display::fmt(tracing_error, formatter),
         }
     }
 }
+
+impl From<SetGlobalDefaultError> for Error {
+    fn from(tracing_error: SetGlobalDefaultError) -> Self {
+        Error::AlreadyInit(tracing_error)
+    }
+}

compiler/rustc_middle/src/ty/mod.rs

@@ -1929,13 +1929,17 @@ impl<'tcx> TyCtxt<'tcx> {
             if arg_cor_ty.is_coroutine() {
                 let span = self.def_span(def_id);
                 let source_info = SourceInfo::outermost(span);
+                // Even minimal, empty coroutine has 3 states (RESERVED_VARIANTS),
+                // so variant_fields and variant_source_info should have 3 elements.
                 let variant_fields: IndexVec<VariantIdx, IndexVec<FieldIdx, CoroutineSavedLocal>> =
                     iter::repeat(IndexVec::new()).take(CoroutineArgs::RESERVED_VARIANTS).collect();
+                let variant_source_info: IndexVec<VariantIdx, SourceInfo> =
+                    iter::repeat(source_info).take(CoroutineArgs::RESERVED_VARIANTS).collect();
                 let proxy_layout = CoroutineLayout {
                     field_tys: [].into(),
                     field_names: [].into(),
                     variant_fields,
-                    variant_source_info: [source_info].into(),
+                    variant_source_info,
                     storage_conflicts: BitMatrix::new(0, 0),
                 };
                 return Some(self.arena.alloc(proxy_layout));

compiler/rustc_parse/src/validate_attr.rs

@@ -22,15 +22,13 @@ pub fn check_attr(psess: &ParseSess, attr: &Attribute, id: NodeId) {
         return;
     }
 
-    let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
-    let attr_item = attr.get_normal_item();
+    let builtin_attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
 
-    // All non-builtin attributes are considered safe
-    let safety = attr_info.map(|x| x.safety).unwrap_or(AttributeSafety::Normal);
-    check_attribute_safety(psess, safety, attr, id);
+    let builtin_attr_safety = builtin_attr_info.map(|x| x.safety);
+    check_attribute_safety(psess, builtin_attr_safety, attr, id);
 
     // Check input tokens for built-in and key-value attributes.
-    match attr_info {
+    match builtin_attr_info {
         // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
         Some(BuiltinAttribute { name, template, .. }) if *name != sym::rustc_dummy => {
             match parse_meta(psess, attr) {
@@ -44,6 +42,7 @@ pub fn check_attr(psess: &ParseSess, attr: &Attribute, id: NodeId) {
             }
         }
         _ => {
+            let attr_item = attr.get_normal_item();
             if let AttrArgs::Eq { .. } = attr_item.args {
                 // All key-value attributes are restricted to meta-item syntax.
                 match parse_meta(psess, attr) {
@@ -157,14 +156,21 @@ fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaIte
 
 pub fn check_attribute_safety(
     psess: &ParseSess,
-    safety: AttributeSafety,
+    builtin_attr_safety: Option<AttributeSafety>,
     attr: &Attribute,
     id: NodeId,
 ) {
     let attr_item = attr.get_normal_item();
+    match (builtin_attr_safety, attr_item.unsafety) {
+        // - Unsafe builtin attribute
+        // - User wrote `#[unsafe(..)]`, which is permitted on any edition
+        (Some(AttributeSafety::Unsafe { .. }), Safety::Unsafe(..)) => {
+            // OK
+        }
 
-    if let AttributeSafety::Unsafe { unsafe_since } = safety {
-        if let ast::Safety::Default = attr_item.unsafety {
+        // - Unsafe builtin attribute
+        // - User did not write `#[unsafe(..)]`
+        (Some(AttributeSafety::Unsafe { unsafe_since }), Safety::Default) => {
             let path_span = attr_item.path.span;
 
             // If the `attr_item`'s span is not from a macro, then just suggest
@@ -199,11 +205,38 @@ pub fn check_attribute_safety(
                 );
             }
         }
-    } else if let Safety::Unsafe(unsafe_span) = attr_item.unsafety {
-        psess.dcx().emit_err(errors::InvalidAttrUnsafe {
-            span: unsafe_span,
-            name: attr_item.path.clone(),
-        });
+
+        // - Normal builtin attribute, or any non-builtin attribute
+        // - All non-builtin attributes are currently considered safe; writing `#[unsafe(..)]` is
+        //   not permitted on non-builtin attributes or normal builtin attributes
+        (Some(AttributeSafety::Normal) | None, Safety::Unsafe(unsafe_span)) => {
+            psess.dcx().emit_err(errors::InvalidAttrUnsafe {
+                span: unsafe_span,
+                name: attr_item.path.clone(),
+            });
+        }
+
+        // - Normal builtin attribute
+        // - No explicit `#[unsafe(..)]` written.
+        (Some(AttributeSafety::Normal), Safety::Default) => {
+            // OK
+        }
+
+        // - Non-builtin attribute
+        // - No explicit `#[unsafe(..)]` written.
+        (None, Safety::Default) => {
+            // OK
+        }
+
+        (
+            Some(AttributeSafety::Unsafe { .. } | AttributeSafety::Normal) | None,
+            Safety::Safe(..),
+        ) => {
+            psess.dcx().span_delayed_bug(
+                attr_item.span(),
+                "`check_attribute_safety` does not expect `Safety::Safe` on attributes",
+            );
+        }
     }
 }
 

library/alloc/src/vec/mod.rs

@@ -3659,9 +3659,9 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// If the returned `ExtractIf` is not exhausted, e.g. because it is dropped without iterating
     /// or the iteration short-circuits, then the remaining elements will be retained.
-    /// Use [`retain`] with a negated predicate if you do not need the returned iterator.
+    /// Use [`retain_mut`] with a negated predicate if you do not need the returned iterator.
     ///
-    /// [`retain`]: Vec::retain
+    /// [`retain_mut`]: Vec::retain_mut
     ///
     /// Using this method is equivalent to the following code:
     ///

library/core/src/intrinsics/mod.rs

@@ -3320,7 +3320,6 @@ pub const fn is_val_statically_known<T: Copy>(_arg: T) -> bool {
 #[inline]
 #[rustc_intrinsic]
 #[rustc_intrinsic_const_stable_indirect]
-#[rustc_allow_const_fn_unstable(const_swap_nonoverlapping)] // this is anyway not called since CTFE implements the intrinsic
 pub const unsafe fn typed_swap_nonoverlapping<T>(x: *mut T, y: *mut T) {
     // SAFETY: The caller provided single non-overlapping items behind
     // pointers, so swapping them with `count: 1` is fine.

library/core/src/ptr/mod.rs

@@ -1065,10 +1065,45 @@ pub const unsafe fn swap<T>(x: *mut T, y: *mut T) {
 /// assert_eq!(x, [7, 8, 3, 4]);
 /// assert_eq!(y, [1, 2, 9]);
 /// ```
+///
+/// # Const evaluation limitations
+///
+/// If this function is invoked during const-evaluation, the current implementation has a small (and
+/// rarely relevant) limitation: if `count` is at least 2 and the data pointed to by `x` or `y`
+/// contains a pointer that crosses the boundary of two `T`-sized chunks of memory, the function may
+/// fail to evaluate (similar to a panic during const-evaluation). This behavior may change in the
+/// future.
+///
+/// The limitation is illustrated by the following example:
+///
+/// ```
+/// use std::mem::size_of;
+/// use std::ptr;
+///
+/// const { unsafe {
+///     const PTR_SIZE: usize = size_of::<*const i32>();
+///     let mut data1 = [0u8; PTR_SIZE];
+///     let mut data2 = [0u8; PTR_SIZE];
+///     // Store a pointer in `data1`.
+///     data1.as_mut_ptr().cast::<*const i32>().write_unaligned(&42);
+///     // Swap the contents of `data1` and `data2` by swapping `PTR_SIZE` many `u8`-sized chunks.
+///     // This call will fail, because the pointer in `data1` crosses the boundary
+///     // between several of the 1-byte chunks that are being swapped here.
+///     //ptr::swap_nonoverlapping(data1.as_mut_ptr(), data2.as_mut_ptr(), PTR_SIZE);
+///     // Swap the contents of `data1` and `data2` by swapping a single chunk of size
+///     // `[u8; PTR_SIZE]`. That works, as there is no pointer crossing the boundary between
+///     // two chunks.
+///     ptr::swap_nonoverlapping(&mut data1, &mut data2, 1);
+///     // Read the pointer from `data2` and dereference it.
+///     let ptr = data2.as_ptr().cast::<*const i32>().read_unaligned();
+///     assert!(*ptr == 42);
+/// } }
+/// ```
 #[inline]
 #[stable(feature = "swap_nonoverlapping", since = "1.27.0")]
-#[rustc_const_unstable(feature = "const_swap_nonoverlapping", issue = "133668")]
+#[rustc_const_stable(feature = "const_swap_nonoverlapping", since = "CURRENT_RUSTC_VERSION")]
 #[rustc_diagnostic_item = "ptr_swap_nonoverlapping"]
+#[rustc_allow_const_fn_unstable(const_eval_select)] // both implementations behave the same
 pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) {
     ub_checks::assert_unsafe_precondition!(
         check_library_ub,

library/coretests/tests/lib.rs

@@ -15,7 +15,6 @@
 #![feature(char_max_len)]
 #![feature(clone_to_uninit)]
 #![feature(const_eval_select)]
-#![feature(const_swap_nonoverlapping)]
 #![feature(const_trait_impl)]
 #![feature(core_intrinsics)]
 #![feature(core_intrinsics_fallbacks)]

library/coretests/tests/ptr.rs

@@ -949,6 +949,10 @@ fn test_const_swap_ptr() {
         // Make sure they still work.
         assert!(*s1.0.ptr == 1);
         assert!(*s2.0.ptr == 666);
+
+        // This is where we'd swap again using a `u8` type and a `count` of `size_of::<T>()` if it
+        // were not for the limitation of `swap_nonoverlapping` around pointers crossing multiple
+        // elements.
     };
 }
 

src/librustdoc/lib.rs

@@ -170,12 +170,28 @@ pub fn main() {
     // NOTE: this compiles both versions of tracing unconditionally, because
     // - The compile time hit is not that bad, especially compared to rustdoc's incremental times, and
     // - Otherwise, there's no warning that logging is being ignored when `download-rustc` is enabled
-    // NOTE: The reason this doesn't show double logging when `download-rustc = false` and
-    // `debug_logging = true` is because all rustc logging goes to its version of tracing (the one
-    // in the sysroot), and all of rustdoc's logging goes to its version (the one in Cargo.toml).
 
-    init_logging(&early_dcx);
-    rustc_driver::init_logger(&early_dcx, rustc_log::LoggerConfig::from_env("RUSTDOC_LOG"));
+    crate::init_logging(&early_dcx);
+    match rustc_log::init_logger(rustc_log::LoggerConfig::from_env("RUSTDOC_LOG")) {
+        Ok(()) => {}
+        // With `download-rustc = true` there are definitely 2 distinct tracing crates in the
+        // dependency graph: one in the downloaded sysroot and one built just now as a dependency of
+        // rustdoc. So the sysroot's tracing is definitely not yet initialized here.
+        //
+        // But otherwise, depending on link style, there may or may not be 2 tracing crates in play.
+        // The one we just initialized in `crate::init_logging` above is rustdoc's direct dependency
+        // on tracing. When rustdoc is built by x.py using Cargo, rustc_driver's and rustc_log's
+        // tracing dependency is distinct from this one and also needs to be initialized (using the
+        // same RUSTDOC_LOG environment variable for both). Other build systems may use just a
+        // single tracing crate throughout the rustc and rustdoc build.
+        //
+        // The reason initializing 2 tracings does not show double logging when `download-rustc =
+        // false` and `debug_logging = true` is because all rustc logging goes only to its version
+        // of tracing (the one in the sysroot) and all of rustdoc's logging only goes to its version
+        // (the one in Cargo.toml).
+        Err(rustc_log::Error::AlreadyInit(_)) => {}
+        Err(error) => early_dcx.early_fatal(error.to_string()),
+    }
 
     let exit_code = rustc_driver::catch_with_exit_code(|| {
         let at_args = rustc_driver::args::raw_args(&early_dcx);

tests/codegen/const-vector.rs

@@ -1,4 +1,8 @@
-//@ compile-flags: -C no-prepopulate-passes -Copt-level=0
+//@ revisions: OPT0 OPT0_S390X
+//@ [OPT0] ignore-s390x
+//@ [OPT0_S390X] only-s390x
+//@ [OPT0] compile-flags: -C no-prepopulate-passes -Copt-level=0
+//@ [OPT0_S390X] compile-flags: -C no-prepopulate-passes -Copt-level=0 -C target-cpu=z13
 
 // This test checks that constants of SIMD type are passed as immediate vectors.
 // We ensure that both vector representations (struct with fields and struct wrapping array) work.

tests/ui/consts/missing_span_in_backtrace.rs

@@ -1,7 +1,5 @@
 //@ compile-flags: -Z ui-testing=no
 
-
-#![feature(const_swap_nonoverlapping)]
 use std::{
     mem::{self, MaybeUninit},
     ptr,

tests/ui/consts/missing_span_in_backtrace.stderr

@@ -1,11 +1,11 @@
 error[E0080]: evaluation of constant value failed
-  --> $DIR/missing_span_in_backtrace.rs:16:9
+  --> $DIR/missing_span_in_backtrace.rs:14:9
    |
-16 | /         ptr::swap_nonoverlapping(
-17 | |             &mut ptr1 as *mut _ as *mut MaybeUninit<u8>,
-18 | |             &mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
-19 | |             mem::size_of::<&i32>(),
-20 | |         );
+14 | /         ptr::swap_nonoverlapping(
+15 | |             &mut ptr1 as *mut _ as *mut MaybeUninit<u8>,
+16 | |             &mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
+17 | |             mem::size_of::<&i32>(),
+18 | |         );
    | |_________^ unable to copy parts of a pointer from memory at ALLOC0
    |
 note: inside `swap_nonoverlapping::<MaybeUninit<u8>>`

tests/ui/rust-2024/unsafe-attributes/auxiliary/safe_attr.rs

@@ -0,0 +1,7 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn safe(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    item
+}

tests/ui/rust-2024/unsafe-attributes/safe-proc-macro-attribute.rs

@@ -0,0 +1,22 @@
+//! Anti-regression test for `#[safe]` proc-macro attribute.
+
+//@ revisions: unknown_attr proc_macro_attr
+//@[proc_macro_attr] proc-macro: safe_attr.rs
+//@[proc_macro_attr] check-pass
+
+#![warn(unsafe_attr_outside_unsafe)]
+
+#[cfg(proc_macro_attr)]
+extern crate safe_attr;
+#[cfg(proc_macro_attr)]
+use safe_attr::safe;
+
+#[safe]
+//[unknown_attr]~^ ERROR cannot find attribute `safe` in this scope
+fn foo() {}
+
+#[safe(no_mangle)]
+//[unknown_attr]~^ ERROR cannot find attribute `safe` in this scope
+fn bar() {}
+
+fn main() {}

tests/ui/rust-2024/unsafe-attributes/safe-proc-macro-attribute.unknown_attr.stderr

@@ -0,0 +1,14 @@
+error: cannot find attribute `safe` in this scope
+  --> $DIR/safe-proc-macro-attribute.rs:18:3
+   |
+LL | #[safe(no_mangle)]
+   |   ^^^^
+
+error: cannot find attribute `safe` in this scope
+  --> $DIR/safe-proc-macro-attribute.rs:14:3
+   |
+LL | #[safe]
+   |   ^^^^
+
+error: aborting due to 2 previous errors
+