Merge branch 'rust-lang:master' into bibliography.md

src/SUMMARY.md

@@ -120,6 +120,7 @@
         - [Interactions with turbofishing](./turbofishing-and-early-late-bound.md)
     - [Higher-ranked trait bounds](./traits/hrtb.md)
     - [Caching subtleties](./traits/caching.md)
+    - [Implied bounds](./traits/implied-bounds.md)
     - [Specialization](./traits/specialization.md)
     - [Chalk-based trait solving](./traits/chalk.md)
         - [Lowering to logic](./traits/lowering-to-logic.md)
@@ -131,8 +132,10 @@
         - [The solver](./solve/the-solver.md)
         - [Canonicalization](./solve/canonicalization.md)
         - [Coinduction](./solve/coinduction.md)
+        - [Caching](./solve/caching.md)
         - [Proof trees](./solve/proof-trees.md)
         - [Normalization](./solve/normalization.md)
+        - [Opaque types](./solve/opaque-types.md)
     - [`Unsize` and `CoerceUnsized` traits](./traits/unsize.md)
 - [Type checking](./type-checking.md)
     - [Method Lookup](./method-lookup.md)

src/building/suggested.md

@@ -276,67 +276,34 @@ If you're using nix, you can use the following nix-shell to work on Rust:
 
 ```nix
 { pkgs ? import <nixpkgs> {} }:
-
-# This file contains a development shell for working on rustc.
-let
-  # Build configuration for rust-lang/rust. Based on `config.example.toml` (then called
-  # `config.toml.example`) from `1bd30ce2aac40c7698aa4a1b9520aa649ff2d1c5`
-  config = pkgs.writeText "rustc-config" ''
-    profile = "compiler" # you may want to choose a different profile, like `library` or `tools`
-
-    [build]
-    patch-binaries-for-nix = true
-    # The path to (or name of) the GDB executable to use. This is only used for
-    # executing the debuginfo test suite.
-    gdb = "${pkgs.gdb}/bin/gdb"
-    python = "${pkgs.python3Full}/bin/python"
-
-    [rust]
-    debug = true
-    incremental = true
-    deny-warnings = false
-
-    # Indicates whether some LLVM tools, like llvm-objdump, will be made available in the
-    # sysroot.
-    llvm-tools = true
-
-    # Print backtrace on internal compiler errors during bootstrap
-    backtrace-on-ice = true
-  '';
-
-  ripgrepConfig =
-    let
-      # Files that are ignored by ripgrep when searching.
-      ignoreFile = pkgs.writeText "rustc-rgignore" ''
-        configure
-        config.example.toml
-        x.py
-        LICENSE-MIT
-        LICENSE-APACHE
-        COPYRIGHT
-        **/*.txt
-        **/*.toml
-        **/*.yml
-        **/*.nix
-        *.md
-        src/ci
-        src/etc/
-        src/llvm-emscripten/
-        src/llvm-project/
-        src/rtstartup/
-        src/rustllvm/
-        src/stdsimd/
-        src/tools/rls/rls-analysis/test_data/
-      '';
-    in
-    pkgs.writeText "rustc-ripgreprc" "--ignore-file=${ignoreFile}";
-in
 pkgs.mkShell {
   name = "rustc";
   nativeBuildInputs = with pkgs; [
-    gcc_multi binutils cmake ninja openssl pkgconfig python39 git curl cacert patchelf nix psutils
+    binutils cmake ninja pkg-config python3 git curl cacert patchelf nix
+  ];
+  buildInputs = with pkgs; [
+    openssl glibc.out glibc.static
   ];
-  RIPGREP_CONFIG_PATH = ripgrepConfig;
+  # Avoid creating text files for ICEs.
+  RUSTC_ICE = "0";
+}
+```
+
+Note that when using nix on a not-NixOS distribution, it may be necessary to set
+**`patch-binaries-for-nix = true` in `config.toml`**.
+Bootstrap tries to detect whether it's running in nix and enable patching automatically,
+but this detection can have false negatives.
+
+You can also use your nix shell to manage `config.toml`:
+
+```nix
+let
+  config = pkgs.writeText "rustc-config" ''
+    # Your config.toml content goes here
+  ''
+pkgs.mkShell {
+  /* ... */
+  # This environment varaible tells bootstrap where our config.toml is.
   RUST_BOOTSTRAP_CONFIG = config;
 }
 ```

src/implementing_new_features.md

@@ -123,6 +123,8 @@ a new unstable feature:
 
 1. Add the feature name to `rustc_span/src/symbol.rs` in the `Symbols {...}` block.
 
+   Note that this block must be in alphbetical order.
+
 1. Add a feature gate declaration to `rustc_feature/src/unstable.rs` in the unstable
    `declare_features` block.
 
@@ -171,9 +173,13 @@ a new unstable feature:
     For an example of adding an error, see [#81015].
 
    For features introducing new syntax, pre-expansion gating should be used instead.
-   To do so, extend the [`GatedSpans`] struct, add spans to it during parsing,
-   and then finally feature-gate all the spans in
-   [`rustc_ast_passes::feature_gate::check_crate`].
+   During parsing, when the new syntax is parsed, the symbol must be inserted to the
+   current crate's [`GatedSpans`] via `self.sess.gated_span.gate(sym::my_feature, span)`. 
+
+   After being inserted to the gated spans, the span must be checked in the 
+   [`rustc_ast_passes::feature_gate::check_crate`] function, which actually denies
+   features. Exactly how it is gated depends on the exact type of feature, but most 
+   likely will use the `gate_all!()` macro. 
 
 1. Add a test to ensure the feature cannot be used without
    a feature gate, by creating `tests/ui/feature-gates/feature-gate-$feature_name.rs`.