Auto merge of rust-lang#101946 - matthiaskrgr:rollup-jqkhsku, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#101672 (array docs - advertise how to get array from slice)
 - rust-lang#101781 (Extend list of targets that support dyanmic linking for llvm tools)
 - rust-lang#101783 (Improve handing of env vars during bootstrap process)
 - rust-lang#101801 (add note for `layout_of` when query depth overflows)
 - rust-lang#101824 (rustdoc: add test cases for turning ``[Vec<T>]`` into ``[`Vec<T>`]``)
 - rust-lang#101861 (Update stdarch)
 - rust-lang#101873 (Allow building `rust-analyzer-proc-macro-srv` as a standalone tool)
 - rust-lang#101918 (rustdoc: clean up CSS for All Items and All Crates lists)
 - rust-lang#101934 (Continue migration of CSS themes)

Failed merges:

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

Author: bors

Cargo.lock

@@ -507,6 +507,10 @@ name = "cfg-if"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+dependencies = [
+ "compiler_builtins",
+ "rustc-std-workspace-core",
+]
 
 [[package]]
 name = "chalk-derive"
@@ -4613,7 +4617,7 @@ version = "0.0.0"
 dependencies = [
  "addr2line 0.16.0",
  "alloc",
- "cfg-if 0.1.10",
+ "cfg-if 1.0.0",
  "compiler_builtins",
  "core",
  "dlmalloc",
@@ -4637,7 +4641,7 @@ dependencies = [
 name = "std_detect"
 version = "0.1.5"
 dependencies = [
- "cfg-if 0.1.10",
+ "cfg-if 1.0.0",
  "compiler_builtins",
  "libc",
  "rustc-std-workspace-alloc",

compiler/rustc_error_messages/locales/en-US/query_system.ftl

@@ -23,3 +23,6 @@ query_system_cycle_recursive_trait_alias = trait aliases cannot be recursive
 query_system_cycle_which_requires = ...which requires {$desc}...
 
 query_system_query_overflow = queries overflow the depth limit!
+    .help = consider increasing the recursion limit by adding a `#![recursion_limit = "{$suggested_limit}"]` attribute to your crate (`{$crate_name}`)
+
+query_system_layout_of_depth = query depth increased by {$depth} when {$desc}

compiler/rustc_query_impl/src/plumbing.rs

@@ -19,8 +19,10 @@ use rustc_query_system::query::{
     force_query, QueryConfig, QueryContext, QueryDescription, QueryJobId, QueryMap,
     QuerySideEffects, QueryStackFrame,
 };
-use rustc_query_system::Value;
+use rustc_query_system::{LayoutOfDepth, QueryOverflow, Value};
 use rustc_serialize::Decodable;
+use rustc_session::Limit;
+use rustc_span::def_id::LOCAL_CRATE;
 use std::any::Any;
 use std::num::NonZeroU64;
 use thin_vec::ThinVec;
@@ -109,7 +111,7 @@ impl QueryContext for QueryCtxt<'_> {
         // when accessing the `ImplicitCtxt`.
         tls::with_related_context(**self, move |current_icx| {
             if depth_limit && !self.recursion_limit().value_within_limit(current_icx.query_depth) {
-                self.depth_limit_error();
+                self.depth_limit_error(token);
             }
 
             // Update the `ImplicitCtxt` to point to our new query job.
@@ -127,6 +129,29 @@ impl QueryContext for QueryCtxt<'_> {
             })
         })
     }
+
+    fn depth_limit_error(&self, job: QueryJobId) {
+        let mut span = None;
+        let mut layout_of_depth = None;
+        if let Some(map) = self.try_collect_active_jobs() {
+            if let Some((info, depth)) = job.try_find_layout_root(map) {
+                span = Some(info.job.span);
+                layout_of_depth = Some(LayoutOfDepth { desc: info.query.description, depth });
+            }
+        }
+
+        let suggested_limit = match self.recursion_limit() {
+            Limit(0) => Limit(2),
+            limit => limit * 2,
+        };
+
+        self.sess.emit_fatal(QueryOverflow {
+            span,
+            layout_of_depth,
+            suggested_limit,
+            crate_name: self.crate_name(LOCAL_CRATE),
+        });
+    }
 }
 
 impl<'tcx> QueryCtxt<'tcx> {

compiler/rustc_query_system/src/error.rs

@@ -1,5 +1,6 @@
 use rustc_errors::AddSubdiagnostic;
-use rustc_span::Span;
+use rustc_session::Limit;
+use rustc_span::{Span, Symbol};
 
 pub struct CycleStack {
     pub span: Span,
@@ -76,5 +77,20 @@ pub struct IncrementCompilation {
 }
 
 #[derive(SessionDiagnostic)]
+#[help]
 #[diag(query_system::query_overflow)]
-pub struct QueryOverflow;
+pub struct QueryOverflow {
+    #[primary_span]
+    pub span: Option<Span>,
+    #[subdiagnostic]
+    pub layout_of_depth: Option<LayoutOfDepth>,
+    pub suggested_limit: Limit,
+    pub crate_name: Symbol,
+}
+
+#[derive(SessionSubdiagnostic)]
+#[note(query_system::layout_of_depth)]
+pub struct LayoutOfDepth {
+    pub desc: String,
+    pub depth: usize,
+}

compiler/rustc_query_system/src/lib.rs

@@ -23,4 +23,6 @@ pub mod query;
 mod values;
 
 pub use error::HandleCycleError;
+pub use error::LayoutOfDepth;
+pub use error::QueryOverflow;
 pub use values::Value;

compiler/rustc_query_system/src/query/job.rs

@@ -59,6 +59,7 @@ impl QueryJobId {
     }
 }
 
+#[derive(Clone)]
 pub struct QueryJobInfo {
     pub query: QueryStackFrame,
     pub job: QueryJob,
@@ -116,10 +117,10 @@ impl QueryJob {
     }
 }
 
-#[cfg(not(parallel_compiler))]
 impl QueryJobId {
     #[cold]
     #[inline(never)]
+    #[cfg(not(parallel_compiler))]
     pub(super) fn find_cycle_in_stack(
         &self,
         query_map: QueryMap,
@@ -156,6 +157,24 @@ impl QueryJobId {
 
         panic!("did not find a cycle")
     }
+
+    #[cold]
+    #[inline(never)]
+    pub fn try_find_layout_root(&self, query_map: QueryMap) -> Option<(QueryJobInfo, usize)> {
+        let mut last_layout = None;
+        let mut current_id = Some(*self);
+        let mut depth = 0;
+
+        while let Some(id) = current_id {
+            let info = query_map.get(&id).unwrap();
+            if info.query.name == "layout_of" {
+                depth += 1;
+                last_layout = Some((info.clone(), depth));
+            }
+            current_id = info.job.parent;
+        }
+        last_layout
+    }
 }
 
 #[cfg(parallel_compiler)]

compiler/rustc_query_system/src/query/mod.rs

@@ -14,7 +14,7 @@ pub use self::caches::{
 mod config;
 pub use self::config::{QueryConfig, QueryDescription, QueryVTable};
 
-use crate::dep_graph::{DepContext, DepNodeIndex, HasDepContext, SerializedDepNodeIndex};
+use crate::dep_graph::{DepNodeIndex, HasDepContext, SerializedDepNodeIndex};
 use rustc_data_structures::sync::Lock;
 use rustc_errors::Diagnostic;
 use rustc_hir::def::DefKind;
@@ -123,7 +123,5 @@ pub trait QueryContext: HasDepContext {
         compute: impl FnOnce() -> R,
     ) -> R;
 
-    fn depth_limit_error(&self) {
-        self.dep_context().sess().emit_fatal(crate::error::QueryOverflow);
-    }
+    fn depth_limit_error(&self, job: QueryJobId);
 }

library/core/src/array/mod.rs

@@ -184,6 +184,18 @@ impl<T, const N: usize> const BorrowMut<[T]> for [T; N] {
     }
 }
 
+/// Tries to create an array `[T; N]` by copying from a slice `&[T]`. Succeeds if
+/// `slice.len() == N`.
+///
+/// ```
+/// let bytes: [u8; 3] = [1, 0, 2];
+///
+/// let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&bytes[0..2]).unwrap();
+/// assert_eq!(1, u16::from_le_bytes(bytes_head));
+///
+/// let bytes_tail: [u8; 2] = bytes[1..3].try_into().unwrap();
+/// assert_eq!(512, u16::from_le_bytes(bytes_tail));
+/// ```
 #[stable(feature = "try_from", since = "1.34.0")]
 impl<T, const N: usize> TryFrom<&[T]> for [T; N]
 where
@@ -196,6 +208,18 @@ where
     }
 }
 
+/// Tries to create an array `[T; N]` by copying from a mutable slice `&mut [T]`.
+/// Succeeds if `slice.len() == N`.
+///
+/// ```
+/// let mut bytes: [u8; 3] = [1, 0, 2];
+///
+/// let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
+/// assert_eq!(1, u16::from_le_bytes(bytes_head));
+///
+/// let bytes_tail: [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
+/// assert_eq!(512, u16::from_le_bytes(bytes_tail));
+/// ```
 #[stable(feature = "try_from_mut_slice_to_array", since = "1.59.0")]
 impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]
 where
@@ -208,6 +232,18 @@ where
     }
 }
 
+/// Tries to create an array ref `&[T; N]` from a slice ref `&[T]`. Succeeds if
+/// `slice.len() == N`.
+///
+/// ```
+/// let bytes: [u8; 3] = [1, 0, 2];
+///
+/// let bytes_head: &[u8; 2] = <&[u8; 2]>::try_from(&bytes[0..2]).unwrap();
+/// assert_eq!(1, u16::from_le_bytes(*bytes_head));
+///
+/// let bytes_tail: &[u8; 2] = bytes[1..3].try_into().unwrap();
+/// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
+/// ```
 #[stable(feature = "try_from", since = "1.34.0")]
 impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
     type Error = TryFromSliceError;
@@ -223,6 +259,18 @@ impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N] {
     }
 }
 
+/// Tries to create a mutable array ref `&mut [T; N]` from a mutable slice ref
+/// `&mut [T]`. Succeeds if `slice.len() == N`.
+///
+/// ```
+/// let mut bytes: [u8; 3] = [1, 0, 2];
+///
+/// let bytes_head: &mut [u8; 2] = <&mut [u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
+/// assert_eq!(1, u16::from_le_bytes(*bytes_head));
+///
+/// let bytes_tail: &mut [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
+/// assert_eq!(512, u16::from_le_bytes(*bytes_tail));
+/// ```
 #[stable(feature = "try_from", since = "1.34.0")]
 impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N] {
     type Error = TryFromSliceError;

library/core/src/primitive_docs.rs

@@ -611,7 +611,19 @@ mod prim_pointer {}
 ///
 /// Arrays coerce to [slices (`[T]`)][slice], so a slice method may be called on
 /// an array. Indeed, this provides most of the API for working with arrays.
-/// Slices have a dynamic size and do not coerce to arrays.
+///
+/// Slices have a dynamic size and do not coerce to arrays. Instead, use
+/// `slice.try_into().unwrap()` or `<ArrayType>::try_from(slice).unwrap()`.
+///
+/// Array's `try_from(slice)` implementations (and the corresponding `slice.try_into()`
+/// array implementations) succeed if the input slice length is the same as the result
+/// array length. They optimize especially well when the optimizer can easily determine
+/// the slice length, e.g. `<[u8; 4]>::try_from(&slice[4..8]).unwrap()`. Array implements
+/// [TryFrom](crate::convert::TryFrom) returning:
+///
+/// - `[T; N]` copies from the slice's elements
+/// - `&[T; N]` references the original slice's elements
+/// - `&mut [T; N]` references the original slice's elements
 ///
 /// You can move elements out of an array with a [slice pattern]. If you want
 /// one element, see [`mem::replace`].
@@ -640,6 +652,15 @@ mod prim_pointer {}
 /// for x in &array { }
 /// ```
 ///
+/// You can use `<ArrayType>::try_from(slice)` or `slice.try_into()` to get an array from
+/// a slice:
+///
+/// ```
+/// let bytes: [u8; 3] = [1, 0, 2];
+/// assert_eq!(1, u16::from_le_bytes(<[u8; 2]>::try_from(&bytes[0..2]).unwrap()));
+/// assert_eq!(512, u16::from_le_bytes(bytes[1..3].try_into().unwrap()));
+/// ```
+///
 /// You can use a [slice pattern] to move elements out of an array:
 ///
 /// ```

library/std/Cargo.toml

@@ -11,7 +11,7 @@ crate-type = ["dylib", "rlib"]
 
 [dependencies]
 alloc = { path = "../alloc" }
-cfg-if = { version = "0.1.8", features = ['rustc-dep-of-std'] }
+cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core" }