Auto merge of #125313 - matthiaskrgr:rollup-65etxv0, r=matthiaskrgr

Rollup of 5 pull requests

Successful merges:

 - #125034 (Weekly `cargo update`)
 - #125093 (Add `fn into_raw_with_allocator` to Rc/Arc/Weak.)
 - #125282 (Never type unsafe lint improvements)
 - #125301 (fix suggestion in E0373 for !Unpin coroutines)
 - #125302 (defrost `RUST_MIN_STACK=ice rustc hello.rs`)

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

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -3343,6 +3343,10 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 } else if string.starts_with("gen") {
                     // `gen` is 3 chars long
                     Some(3)
+                } else if string.starts_with("static") {
+                    // `static` is 6 chars long
+                    // This is used for `!Unpin` coroutines
+                    Some(6)
                 } else {
                     None
                 };

compiler/rustc_hir_typeck/src/fallback.rs

@@ -364,41 +364,11 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
             };
 
             let mut fallback_to = |ty| {
-                let unsafe_infer_vars = unsafe_infer_vars.get_or_init(|| {
-                    let unsafe_infer_vars = compute_unsafe_infer_vars(self.root_ctxt, self.body_id);
-                    debug!(?unsafe_infer_vars);
-                    unsafe_infer_vars
-                });
-
-                let affected_unsafe_infer_vars =
-                    graph::depth_first_search_as_undirected(&coercion_graph, root_vid)
-                        .filter_map(|x| unsafe_infer_vars.get(&x).copied())
-                        .collect::<Vec<_>>();
-
-                for (hir_id, span, reason) in affected_unsafe_infer_vars {
-                    self.tcx.emit_node_span_lint(
-                        lint::builtin::NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE,
-                        hir_id,
-                        span,
-                        match reason {
-                            UnsafeUseReason::Call => {
-                                errors::NeverTypeFallbackFlowingIntoUnsafe::Call
-                            }
-                            UnsafeUseReason::Method => {
-                                errors::NeverTypeFallbackFlowingIntoUnsafe::Method
-                            }
-                            UnsafeUseReason::Path => {
-                                errors::NeverTypeFallbackFlowingIntoUnsafe::Path
-                            }
-                            UnsafeUseReason::UnionField => {
-                                errors::NeverTypeFallbackFlowingIntoUnsafe::UnionField
-                            }
-                            UnsafeUseReason::Deref => {
-                                errors::NeverTypeFallbackFlowingIntoUnsafe::Deref
-                            }
-                        },
-                    );
-                }
+                self.lint_never_type_fallback_flowing_into_unsafe_code(
+                    &unsafe_infer_vars,
+                    &coercion_graph,
+                    root_vid,
+                );
 
                 diverging_fallback.insert(diverging_ty, ty);
             };
@@ -464,6 +434,41 @@ impl<'tcx> FnCtxt<'_, 'tcx> {
         diverging_fallback
     }
 
+    fn lint_never_type_fallback_flowing_into_unsafe_code(
+        &self,
+        unsafe_infer_vars: &OnceCell<UnordMap<ty::TyVid, (HirId, Span, UnsafeUseReason)>>,
+        coercion_graph: &VecGraph<ty::TyVid, true>,
+        root_vid: ty::TyVid,
+    ) {
+        let unsafe_infer_vars = unsafe_infer_vars.get_or_init(|| {
+            let unsafe_infer_vars = compute_unsafe_infer_vars(self.root_ctxt, self.body_id);
+            debug!(?unsafe_infer_vars);
+            unsafe_infer_vars
+        });
+
+        let affected_unsafe_infer_vars =
+            graph::depth_first_search_as_undirected(&coercion_graph, root_vid)
+                .filter_map(|x| unsafe_infer_vars.get(&x).copied())
+                .collect::<Vec<_>>();
+
+        for (hir_id, span, reason) in affected_unsafe_infer_vars {
+            self.tcx.emit_node_span_lint(
+                lint::builtin::NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE,
+                hir_id,
+                span,
+                match reason {
+                    UnsafeUseReason::Call => errors::NeverTypeFallbackFlowingIntoUnsafe::Call,
+                    UnsafeUseReason::Method => errors::NeverTypeFallbackFlowingIntoUnsafe::Method,
+                    UnsafeUseReason::Path => errors::NeverTypeFallbackFlowingIntoUnsafe::Path,
+                    UnsafeUseReason::UnionField => {
+                        errors::NeverTypeFallbackFlowingIntoUnsafe::UnionField
+                    }
+                    UnsafeUseReason::Deref => errors::NeverTypeFallbackFlowingIntoUnsafe::Deref,
+                },
+            );
+        }
+    }
+
     /// Returns a graph whose nodes are (unresolved) inference variables and where
     /// an edge `?A -> ?B` indicates that the variable `?A` is coerced to `?B`.
     fn create_coercion_graph(&self) -> VecGraph<ty::TyVid, true> {

compiler/rustc_interface/src/interface.rs

@@ -389,6 +389,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
     let hash_kind = config.opts.unstable_opts.src_hash_algorithm(&target);
 
     util::run_in_thread_pool_with_globals(
+        &early_dcx,
         config.opts.edition,
         config.opts.unstable_opts.threads,
         SourceMapInputs { file_loader, path_mapping, hash_kind },

compiler/rustc_interface/src/util.rs

@@ -51,20 +51,38 @@ pub fn add_configuration(cfg: &mut Cfg, sess: &mut Session, codegen_backend: &dy
 pub static STACK_SIZE: OnceLock<usize> = OnceLock::new();
 pub const DEFAULT_STACK_SIZE: usize = 8 * 1024 * 1024;
 
-fn init_stack_size() -> usize {
+fn init_stack_size(early_dcx: &EarlyDiagCtxt) -> usize {
     // Obey the environment setting or default
     *STACK_SIZE.get_or_init(|| {
         env::var_os("RUST_MIN_STACK")
-            .map(|os_str| os_str.to_string_lossy().into_owned())
-            // ignore if it is set to nothing
-            .filter(|s| s.trim() != "")
-            .map(|s| s.trim().parse::<usize>().unwrap())
+            .as_ref()
+            .map(|os_str| os_str.to_string_lossy())
+            // if someone finds out `export RUST_MIN_STACK=640000` isn't enough stack
+            // they might try to "unset" it by running `RUST_MIN_STACK=  rustc code.rs`
+            // this is wrong, but std would nonetheless "do what they mean", so let's do likewise
+            .filter(|s| !s.trim().is_empty())
+            // rustc is a batch program, so error early on inputs which are unlikely to be intended
+            // so no one thinks we parsed them setting `RUST_MIN_STACK="64 megabytes"`
+            // FIXME: we could accept `RUST_MIN_STACK=64MB`, perhaps?
+            .map(|s| {
+                let s = s.trim();
+                // FIXME(workingjubilee): add proper diagnostics when we factor out "pre-run" setup
+                #[allow(rustc::untranslatable_diagnostic, rustc::diagnostic_outside_of_impl)]
+                s.parse::<usize>().unwrap_or_else(|_| {
+                    let mut err = early_dcx.early_struct_fatal(format!(
+                        r#"`RUST_MIN_STACK` should be a number of bytes, but was "{s}""#,
+                    ));
+                    err.note("you can also unset `RUST_MIN_STACK` to use the default stack size");
+                    err.emit()
+                })
+            })
             // otherwise pick a consistent default
             .unwrap_or(DEFAULT_STACK_SIZE)
     })
 }
 
 fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
+    thread_stack_size: usize,
     edition: Edition,
     sm_inputs: SourceMapInputs,
     f: F,
@@ -75,7 +93,7 @@ fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
     // the parallel compiler, in particular to ensure there is no accidental
     // sharing of data between the main thread and the compilation thread
     // (which might cause problems for the parallel compiler).
-    let builder = thread::Builder::new().name("rustc".to_string()).stack_size(init_stack_size());
+    let builder = thread::Builder::new().name("rustc".to_string()).stack_size(thread_stack_size);
 
     // We build the session globals and run `f` on the spawned thread, because
     // `SessionGlobals` does not impl `Send` in the non-parallel compiler.
@@ -100,16 +118,19 @@ fn run_in_thread_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
 
 #[cfg(not(parallel_compiler))]
 pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
+    thread_builder_diag: &EarlyDiagCtxt,
     edition: Edition,
     _threads: usize,
     sm_inputs: SourceMapInputs,
     f: F,
 ) -> R {
-    run_in_thread_with_globals(edition, sm_inputs, f)
+    let thread_stack_size = init_stack_size(thread_builder_diag);
+    run_in_thread_with_globals(thread_stack_size, edition, sm_inputs, f)
 }
 
 #[cfg(parallel_compiler)]
 pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send, R: Send>(
+    thread_builder_diag: &EarlyDiagCtxt,
     edition: Edition,
     threads: usize,
     sm_inputs: SourceMapInputs,
@@ -121,10 +142,12 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
     use rustc_query_system::query::{break_query_cycles, QueryContext};
     use std::process;
 
+    let thread_stack_size = init_stack_size(thread_builder_diag);
+
     let registry = sync::Registry::new(std::num::NonZero::new(threads).unwrap());
 
     if !sync::is_dyn_thread_safe() {
-        return run_in_thread_with_globals(edition, sm_inputs, |current_gcx| {
+        return run_in_thread_with_globals(thread_stack_size, edition, sm_inputs, |current_gcx| {
             // Register the thread for use with the `WorkerLocal` type.
             registry.register();
 
@@ -167,7 +190,7 @@ pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce(CurrentGcx) -> R + Send,
                 })
                 .unwrap();
         })
-        .stack_size(init_stack_size());
+        .stack_size(thread_stack_size);
 
     // We create the session globals on the main thread, then create the thread
     // pool. Upon creation, each worker thread created gets a copy of the

compiler/rustc_lint_defs/src/builtin.rs

@@ -4263,8 +4263,7 @@ declare_lint! {
     ///
     /// // where absurd is a function with the following signature
     /// // (it's sound, because `!` always marks unreachable code):
-    /// fn absurd<T>(_: !) -> T { ... }
-    // FIXME: use `core::convert::absurd` here instead, once it's merged
+    /// fn absurd<T>(never: !) -> T { ... }
     /// ```
     ///
     /// While it's convenient to be able to use non-diverging code in one of the branches (like
@@ -4321,7 +4320,12 @@ declare_lint! {
     /// [`()`]: https://doc.rust-lang.org/core/primitive.unit.html
     pub NEVER_TYPE_FALLBACK_FLOWING_INTO_UNSAFE,
     Warn,
-    "never type fallback affecting unsafe function calls"
+    "never type fallback affecting unsafe function calls",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
+        reference: "issue #123748 <https://github.com/rust-lang/rust/issues/123748>",
+    };
+    report_in_external_macro
 }
 
 declare_lint! {

library/alloc/src/rc.rs

@@ -1356,6 +1356,33 @@ impl<T: ?Sized, A: Allocator> Rc<T, A> {
         ptr
     }
 
+    /// Consumes the `Rc`, returning the wrapped pointer and allocator.
+    ///
+    /// To avoid a memory leak the pointer must be converted back to an `Rc` using
+    /// [`Rc::from_raw_in`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    /// use std::rc::Rc;
+    /// use std::alloc::System;
+    ///
+    /// let x = Rc::new_in("hello".to_owned(), System);
+    /// let (ptr, alloc) = Rc::into_raw_with_allocator(x);
+    /// assert_eq!(unsafe { &*ptr }, "hello");
+    /// let x = unsafe { Rc::from_raw_in(ptr, alloc) };
+    /// assert_eq!(&*x, "hello");
+    /// ```
+    #[unstable(feature = "allocator_api", issue = "32838")]
+    pub fn into_raw_with_allocator(this: Self) -> (*const T, A) {
+        let this = mem::ManuallyDrop::new(this);
+        let ptr = Self::as_ptr(&this);
+        // Safety: `this` is ManuallyDrop so the allocator will not be double-dropped
+        let alloc = unsafe { ptr::read(&this.alloc) };
+        (ptr, alloc)
+    }
+
     /// Provides a raw pointer to the data.
     ///
     /// The counts are not affected in any way and the `Rc` is not consumed. The pointer is valid
@@ -3024,39 +3051,42 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> {
         result
     }
 
-    /// Consumes the `Weak<T>` and turns it into a raw pointer.
+    /// Consumes the `Weak<T>`, returning the wrapped pointer and allocator.
     ///
     /// This converts the weak pointer into a raw pointer, while still preserving the ownership of
     /// one weak reference (the weak count is not modified by this operation). It can be turned
-    /// back into the `Weak<T>` with [`from_raw`].
+    /// back into the `Weak<T>` with [`from_raw_in`].
     ///
     /// The same restrictions of accessing the target of the pointer as with
     /// [`as_ptr`] apply.
     ///
     /// # Examples
     ///
     /// ```
+    /// #![feature(allocator_api)]
     /// use std::rc::{Rc, Weak};
+    /// use std::alloc::System;
     ///
-    /// let strong = Rc::new("hello".to_owned());
+    /// let strong = Rc::new_in("hello".to_owned(), System);
     /// let weak = Rc::downgrade(&strong);
-    /// let raw = weak.into_raw();
+    /// let (raw, alloc) = weak.into_raw_with_allocator();
     ///
     /// assert_eq!(1, Rc::weak_count(&strong));
     /// assert_eq!("hello", unsafe { &*raw });
     ///
-    /// drop(unsafe { Weak::from_raw(raw) });
+    /// drop(unsafe { Weak::from_raw_in(raw, alloc) });
     /// assert_eq!(0, Rc::weak_count(&strong));
     /// ```
     ///
-    /// [`from_raw`]: Weak::from_raw
+    /// [`from_raw_in`]: Weak::from_raw_in
     /// [`as_ptr`]: Weak::as_ptr
     #[inline]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    pub fn into_raw_and_alloc(self) -> (*const T, A) {
-        let rc = mem::ManuallyDrop::new(self);
-        let result = rc.as_ptr();
-        let alloc = unsafe { ptr::read(&rc.alloc) };
+    pub fn into_raw_with_allocator(self) -> (*const T, A) {
+        let this = mem::ManuallyDrop::new(self);
+        let result = this.as_ptr();
+        // Safety: `this` is ManuallyDrop so the allocator will not be double-dropped
+        let alloc = unsafe { ptr::read(&this.alloc) };
         (result, alloc)
     }
 

library/alloc/src/sync.rs

@@ -1496,6 +1496,34 @@ impl<T: ?Sized, A: Allocator> Arc<T, A> {
         ptr
     }
 
+    /// Consumes the `Arc`, returning the wrapped pointer and allocator.
+    ///
+    /// To avoid a memory leak the pointer must be converted back to an `Arc` using
+    /// [`Arc::from_raw_in`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    /// use std::sync::Arc;
+    /// use std::alloc::System;
+    ///
+    /// let x = Arc::new_in("hello".to_owned(), System);
+    /// let (ptr, alloc) = Arc::into_raw_with_allocator(x);
+    /// assert_eq!(unsafe { &*ptr }, "hello");
+    /// let x = unsafe { Arc::from_raw_in(ptr, alloc) };
+    /// assert_eq!(&*x, "hello");
+    /// ```
+    #[must_use = "losing the pointer will leak memory"]
+    #[unstable(feature = "allocator_api", issue = "32838")]
+    pub fn into_raw_with_allocator(this: Self) -> (*const T, A) {
+        let this = mem::ManuallyDrop::new(this);
+        let ptr = Self::as_ptr(&this);
+        // Safety: `this` is ManuallyDrop so the allocator will not be double-dropped
+        let alloc = unsafe { ptr::read(&this.alloc) };
+        (ptr, alloc)
+    }
+
     /// Provides a raw pointer to the data.
     ///
     /// The counts are not affected in any way and the `Arc` is not consumed. The pointer is valid for
@@ -2740,6 +2768,45 @@ impl<T: ?Sized, A: Allocator> Weak<T, A> {
         result
     }
 
+    /// Consumes the `Weak<T>`, returning the wrapped pointer and allocator.
+    ///
+    /// This converts the weak pointer into a raw pointer, while still preserving the ownership of
+    /// one weak reference (the weak count is not modified by this operation). It can be turned
+    /// back into the `Weak<T>` with [`from_raw_in`].
+    ///
+    /// The same restrictions of accessing the target of the pointer as with
+    /// [`as_ptr`] apply.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(allocator_api)]
+    /// use std::sync::{Arc, Weak};
+    /// use std::alloc::System;
+    ///
+    /// let strong = Arc::new_in("hello".to_owned(), System);
+    /// let weak = Arc::downgrade(&strong);
+    /// let (raw, alloc) = weak.into_raw_with_allocator();
+    ///
+    /// assert_eq!(1, Arc::weak_count(&strong));
+    /// assert_eq!("hello", unsafe { &*raw });
+    ///
+    /// drop(unsafe { Weak::from_raw_in(raw, alloc) });
+    /// assert_eq!(0, Arc::weak_count(&strong));
+    /// ```
+    ///
+    /// [`from_raw_in`]: Weak::from_raw_in
+    /// [`as_ptr`]: Weak::as_ptr
+    #[must_use = "losing the pointer will leak memory"]
+    #[unstable(feature = "allocator_api", issue = "32838")]
+    pub fn into_raw_with_allocator(self) -> (*const T, A) {
+        let this = mem::ManuallyDrop::new(self);
+        let result = this.as_ptr();
+        // Safety: `this` is ManuallyDrop so the allocator will not be double-dropped
+        let alloc = unsafe { ptr::read(&this.alloc) };
+        (result, alloc)
+    }
+
     /// Converts a raw pointer previously created by [`into_raw`] back into `Weak<T>` in the provided
     /// allocator.
     ///