Auto merge of rust-lang#140335 - matthiaskrgr:rollup-aa0aqxv, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - rust-lang#123239 (Implement a lint for implicit autoref of raw pointer dereference - take 2)
 - rust-lang#140215 (transmutability: Support char, NonZeroXxx)
 - rust-lang#140226 (Update wasm-component-ld to 0.5.13)
 - rust-lang#140317 (Remove redundant check)
 - rust-lang#140318 (Simply try to unpeel AsyncFnKindHelper goal in `emit_specialized_closure_kind_error`)
 - rust-lang#140325 (Grammar fixes for BufRead::has_data_left docs)

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

Author: bors

Cargo.lock

@@ -4918,15 +4918,6 @@ dependencies = [
  "color-eyre",
 ]
 
-[[package]]
-name = "spdx"
-version = "0.10.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58b69356da67e2fc1f542c71ea7e654a361a79c938e4424392ecf4fa065d2193"
-dependencies = [
- "smallvec",
-]
-
 [[package]]
 name = "spdx-expression"
 version = "0.5.2"
@@ -5746,9 +5737,9 @@ dependencies = [
 
 [[package]]
 name = "wasi-preview1-component-adapter-provider"
-version = "29.0.1"
+version = "31.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcd9f21bbde82ba59e415a8725e6ad0d0d7e9e460b1a3ccbca5bdee952c1a324"
+checksum = "86fabda09a0d89ffd1615b297b4a5d4b4d99df9598aeb24685837e63019e927b"
 
 [[package]]
 name = "wasm-bindgen"
@@ -5810,17 +5801,17 @@ dependencies = [
 
 [[package]]
 name = "wasm-component-ld"
-version = "0.5.12"
+version = "0.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "580305a8e3f1b7a79859a8db897de643533b2851c5eb080fe5800233f16dec88"
+checksum = "a60a07a994a3538b57d8c5f8caba19f4793fb4c7156276e5e90e90acbb829e20"
 dependencies = [
  "anyhow",
  "clap",
  "lexopt",
  "libc",
  "tempfile",
  "wasi-preview1-component-adapter-provider",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
  "wat",
  "windows-sys 0.59.0",
  "winsplit",
@@ -5847,39 +5838,24 @@ dependencies = [
 
 [[package]]
 name = "wasm-encoder"
-version = "0.223.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a0a96fdeaee8fbeb4bd917fb8157d48c0d61c3b1f4ee4c363c8e8d68b2f4fe8"
-dependencies = [
- "leb128",
- "wasmparser 0.223.1",
-]
-
-[[package]]
-name = "wasm-encoder"
-version = "0.228.0"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "05d30290541f2d4242a162bbda76b8f2d8b1ac59eab3568ed6f2327d52c9b2c4"
+checksum = "38ba1d491ecacb085a2552025c10a675a6fddcbd03b1fc9b36c536010ce265d2"
 dependencies = [
  "leb128fmt",
- "wasmparser 0.228.0",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]
 name = "wasm-metadata"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e2e7e37883181704d96b89dbd8f1291be13694c71cd0663aebb94b46d235a377"
+checksum = "78fdb7d29a79191ab363dc90c1ddd3a1e880ffd5348d92d48482393a9e6c5f4d"
 dependencies = [
  "anyhow",
  "indexmap",
- "serde",
- "serde_derive",
- "serde_json",
- "spdx",
- "url",
- "wasm-encoder 0.223.1",
- "wasmparser 0.223.1",
+ "wasm-encoder 0.229.0",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]
@@ -5903,9 +5879,9 @@ dependencies = [
 
 [[package]]
 name = "wasmparser"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "664b980991ed9a8c834eb528a8979ab1109edcf52dc05dd5751e2cc3fb31035d"
+checksum = "0cc3b1f053f5d41aa55640a1fa9b6d1b8a9e4418d118ce308d20e24ff3575a8c"
 dependencies = [
  "bitflags",
  "hashbrown",
@@ -5914,35 +5890,24 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "wasmparser"
-version = "0.228.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4abf1132c1fdf747d56bbc1bb52152400c70f336870f968b85e89ea422198ae3"
-dependencies = [
- "bitflags",
- "indexmap",
- "semver",
-]
-
 [[package]]
 name = "wast"
-version = "228.0.0"
+version = "229.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e5aae124478cb51439f6587f074a3a5e835afd22751c59a87b2e2a882727c97"
+checksum = "63fcaff613c12225696bb163f79ca38ffb40e9300eff0ff4b8aa8b2f7eadf0d9"
 dependencies = [
  "bumpalo",
  "leb128fmt",
  "memchr",
  "unicode-width 0.2.0",
- "wasm-encoder 0.228.0",
+ "wasm-encoder 0.229.0",
 ]
 
 [[package]]
 name = "wat"
-version = "1.228.0"
+version = "1.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ec29c89a8d055df988de7236483bf569988ac3d6905899f6af5ef920f9385ad"
+checksum = "4189bad08b70455a9e9e67dc126d2dcf91fac143a80f1046747a5dde6d4c33e0"
 dependencies = [
  "wast",
 ]
@@ -6401,9 +6366,9 @@ dependencies = [
 
 [[package]]
 name = "wit-component"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3fc2fcc52a79f6f010a89c867e53e06d4227f86c58984add3e37f32b8e7af5f0"
+checksum = "7f550067740e223bfe6c4878998e81cdbe2529dd9a793dc49248dd6613394e8b"
 dependencies = [
  "anyhow",
  "bitflags",
@@ -6412,17 +6377,17 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "wasm-encoder 0.223.1",
+ "wasm-encoder 0.229.0",
  "wasm-metadata",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
  "wit-parser",
 ]
 
 [[package]]
 name = "wit-parser"
-version = "0.223.1"
+version = "0.229.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "263fde17f1fbe55a413f16eb59094bf751795c6da469a05c3d45ea6c77df6b40"
+checksum = "459c6ba62bf511d6b5f2a845a2a736822e38059c1cfa0b644b467bbbfae4efa6"
 dependencies = [
  "anyhow",
  "id-arena",
@@ -6433,7 +6398,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "unicode-xid",
- "wasmparser 0.223.1",
+ "wasmparser 0.229.0",
 ]
 
 [[package]]

compiler/rustc_feature/src/builtin_attrs.rs

@@ -918,6 +918,10 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         EncodeCrossCrate::Yes,
         "#[rustc_never_returns_null_ptr] is used to mark functions returning non-null pointers."
     ),
+    rustc_attr!(
+        rustc_no_implicit_autorefs, AttributeType::Normal, template!(Word), ErrorFollowing, EncodeCrossCrate::Yes,
+        "`#[rustc_no_implicit_autorefs]` is used to mark functions for which an autoref to the dereference of a raw pointer should not be used as an argument."
+    ),
     rustc_attr!(
         rustc_coherence_is_core, AttributeType::CrateLevel, template!(Word), ErrorFollowing, EncodeCrossCrate::No,
         "#![rustc_coherence_is_core] allows inherent methods on builtin types, only intended to be used in `core`."

compiler/rustc_hir_analysis/src/check/check.rs

@@ -730,7 +730,6 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     .is_ok()
                 {
                     check_impl_items_against_trait(tcx, def_id, impl_trait_header);
-                    check_on_unimplemented(tcx, def_id);
                 }
             }
         }

compiler/rustc_lint/messages.ftl

@@ -360,6 +360,10 @@ lint_impl_trait_overcaptures = `{$self_ty}` will capture more lifetimes than pos
 lint_impl_trait_redundant_captures = all possible in-scope parameters are already captured, so `use<...>` syntax is redundant
     .suggestion = remove the `use<...>` syntax
 
+lint_implicit_unsafe_autorefs = implicit autoref creates a reference to the dereference of a raw pointer
+    .note = creating a reference requires the pointer target to be valid and imposes aliasing requirements
+    .suggestion = try using a raw pointer method instead; or if this reference is intentional, make it explicit
+
 lint_improper_ctypes = `extern` {$desc} uses type `{$ty}`, which is not FFI-safe
     .label = not FFI-safe
     .note = the type is defined here

compiler/rustc_lint/src/autorefs.rs

@@ -0,0 +1,153 @@
+use rustc_ast::{BorrowKind, UnOp};
+use rustc_hir::{Expr, ExprKind, Mutability};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, OverloadedDeref};
+use rustc_session::{declare_lint, declare_lint_pass};
+use rustc_span::sym;
+
+use crate::lints::{ImplicitUnsafeAutorefsDiag, ImplicitUnsafeAutorefsSuggestion};
+use crate::{LateContext, LateLintPass, LintContext};
+
+declare_lint! {
+    /// The `dangerous_implicit_autorefs` lint checks for implicitly taken references
+    /// to dereferences of raw pointers.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// unsafe fn fun(ptr: *mut [u8]) -> *mut [u8] {
+    ///     &raw mut (*ptr)[..16]
+    ///     //             ^^^^^^ this calls `IndexMut::index_mut(&mut ..., ..16)`,
+    ///     //                    implicitly creating a reference
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// When working with raw pointers it's usually undesirable to create references,
+    /// since they inflict additional safety requirements. Unfortunately, it's possible
+    /// to take a reference to the dereference of a raw pointer implicitly, which inflicts
+    /// the usual reference requirements.
+    ///
+    /// If you are sure that you can soundly take a reference, then you can take it explicitly:
+    ///
+    /// ```rust
+    /// unsafe fn fun(ptr: *mut [u8]) -> *mut [u8] {
+    ///     &raw mut (&mut *ptr)[..16]
+    /// }
+    /// ```
+    ///
+    /// Otherwise try to find an alternative way to achive your goals using only raw pointers:
+    ///
+    /// ```rust
+    /// use std::slice;
+    ///
+    /// unsafe fn fun(ptr: *mut [u8]) -> *mut [u8] {
+    ///     slice::from_raw_parts_mut(ptr.cast(), 16)
+    /// }
+    /// ```
+    pub DANGEROUS_IMPLICIT_AUTOREFS,
+    Warn,
+    "implicit reference to a dereference of a raw pointer",
+    report_in_external_macro
+}
+
+declare_lint_pass!(ImplicitAutorefs => [DANGEROUS_IMPLICIT_AUTOREFS]);
+
+impl<'tcx> LateLintPass<'tcx> for ImplicitAutorefs {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        // This logic has mostly been taken from
+        // <https://github.com/rust-lang/rust/pull/103735#issuecomment-1370420305>
+
+        // 5. Either of the following:
+        //   a. A deref followed by any non-deref place projection (that intermediate
+        //      deref will typically be auto-inserted).
+        //   b. A method call annotated with `#[rustc_no_implicit_refs]`.
+        //   c. A deref followed by a `&raw const` or `&raw mut`.
+        let mut is_coming_from_deref = false;
+        let inner = match expr.kind {
+            ExprKind::AddrOf(BorrowKind::Raw, _, inner) => match inner.kind {
+                ExprKind::Unary(UnOp::Deref, inner) => {
+                    is_coming_from_deref = true;
+                    inner
+                }
+                _ => return,
+            },
+            ExprKind::Index(base, _, _) => base,
+            ExprKind::MethodCall(_, inner, _, _)
+                if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
+                    && cx.tcx.has_attr(def_id, sym::rustc_no_implicit_autorefs) =>
+            {
+                inner
+            }
+            ExprKind::Field(inner, _) => inner,
+            _ => return,
+        };
+
+        let typeck = cx.typeck_results();
+        let adjustments_table = typeck.adjustments();
+
+        if let Some(adjustments) = adjustments_table.get(inner.hir_id)
+            // 4. Any number of automatically inserted deref/derefmut calls.
+            && let adjustments = peel_derefs_adjustments(&**adjustments)
+            // 3. An automatically inserted reference (might come from a deref).
+            && let [adjustment] = adjustments
+            && let Some(borrow_mutbl) = has_implicit_borrow(adjustment)
+            && let ExprKind::Unary(UnOp::Deref, dereferenced) =
+                // 2. Any number of place projections.
+                peel_place_mappers(inner).kind
+            // 1. Deref of a raw pointer.
+            && typeck.expr_ty(dereferenced).is_raw_ptr()
+        {
+            cx.emit_span_lint(
+                DANGEROUS_IMPLICIT_AUTOREFS,
+                expr.span.source_callsite(),
+                ImplicitUnsafeAutorefsDiag {
+                    suggestion: ImplicitUnsafeAutorefsSuggestion {
+                        mutbl: borrow_mutbl.ref_prefix_str(),
+                        deref: if is_coming_from_deref { "*" } else { "" },
+                        start_span: inner.span.shrink_to_lo(),
+                        end_span: inner.span.shrink_to_hi(),
+                    },
+                },
+            )
+        }
+    }
+}
+
+/// Peels expressions from `expr` that can map a place.
+fn peel_place_mappers<'tcx>(mut expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
+    loop {
+        match expr.kind {
+            ExprKind::Index(base, _idx, _) => expr = &base,
+            ExprKind::Field(e, _) => expr = &e,
+            _ => break expr,
+        }
+    }
+}
+
+/// Peel derefs adjustments until the last last element.
+fn peel_derefs_adjustments<'a>(mut adjs: &'a [Adjustment<'a>]) -> &'a [Adjustment<'a>] {
+    while let [Adjustment { kind: Adjust::Deref(_), .. }, end @ ..] = adjs
+        && !end.is_empty()
+    {
+        adjs = end;
+    }
+    adjs
+}
+
+/// Test if some adjustment has some implicit borrow.
+///
+/// Returns `Some(mutability)` if the argument adjustment has implicit borrow in it.
+fn has_implicit_borrow(Adjustment { kind, .. }: &Adjustment<'_>) -> Option<Mutability> {
+    match kind {
+        &Adjust::Deref(Some(OverloadedDeref { mutbl, .. })) => Some(mutbl),
+        &Adjust::Borrow(AutoBorrow::Ref(mutbl)) => Some(mutbl.into()),
+        Adjust::NeverToAny
+        | Adjust::Pointer(..)
+        | Adjust::ReborrowPin(..)
+        | Adjust::Deref(None)
+        | Adjust::Borrow(AutoBorrow::RawPtr(..)) => None,
+    }
+}

compiler/rustc_lint/src/lib.rs

@@ -36,6 +36,7 @@
 
 mod async_closures;
 mod async_fn_in_trait;
+mod autorefs;
 pub mod builtin;
 mod context;
 mod dangling;
@@ -83,6 +84,7 @@ mod utils;
 
 use async_closures::AsyncClosureUsage;
 use async_fn_in_trait::AsyncFnInTrait;
+use autorefs::*;
 use builtin::*;
 use dangling::*;
 use default_could_be_derived::DefaultCouldBeDerived;
@@ -200,6 +202,7 @@ late_lint_methods!(
             PathStatements: PathStatements,
             LetUnderscore: LetUnderscore,
             InvalidReferenceCasting: InvalidReferenceCasting,
+            ImplicitAutorefs: ImplicitAutorefs,
             // Depends on referenced function signatures in expressions
             UnusedResults: UnusedResults,
             UnitBindings: UnitBindings,