Auto merge of rust-lang#128665 - matthiaskrgr:rollup-zumm3fk, r=matth…

…iaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang#127655 (turn `invalid_type_param_default` into a `FutureReleaseErrorReportInDeps`)
 - rust-lang#127974 (force compiling std from source if modified)
 - rust-lang#128026 (std::thread: available_parallelism implementation for vxWorks proposal.)
 - rust-lang#128309 (Implement cursors for `BTreeSet`)
 - rust-lang#128500 (Add test for updating enum discriminant through pointer)
 - rust-lang#128630 (docs(resolve): more explain about `target`)
 - rust-lang#128638 (run-make: enable msvc for `link-dedup`)

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

compiler/rustc_feature/src/removed.rs

@@ -82,6 +82,9 @@ declare_features! (
     /// Allows the use of `#[derive(Anything)]` as sugar for `#[derive_Anything]`.
     (removed, custom_derive, "1.32.0", Some(29644),
      Some("subsumed by `#[proc_macro_derive]`")),
+    /// Allows default type parameters to influence type inference.
+    (removed, default_type_parameter_fallback, "CURRENT_RUSTC_VERSION", Some(27336),
+     Some("never properly implemented; requires significant design work")),
     /// Allows using `#[doc(keyword = "...")]`.
     (removed, doc_keyword, "1.28.0", Some(51315),
      Some("merged into `#![feature(rustdoc_internals)]`")),

compiler/rustc_feature/src/unstable.rs

@@ -431,8 +431,6 @@ declare_features! (
     (unstable, custom_test_frameworks, "1.30.0", Some(50297)),
     /// Allows declarative macros 2.0 (`macro`).
     (unstable, decl_macro, "1.17.0", Some(39412)),
-    /// Allows default type parameters to influence type inference.
-    (unstable, default_type_parameter_fallback, "1.3.0", Some(27336)),
     /// Allows using `#[deprecated_safe]` to deprecate the safeness of a function or trait
     (unstable, deprecated_safe, "1.61.0", Some(94978)),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.

compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -338,8 +338,6 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
             if default.is_some() {
                 match allow_defaults {
                     Defaults::Allowed => {}
-                    Defaults::FutureCompatDisallowed
-                        if tcx.features().default_type_parameter_fallback => {}
                     Defaults::FutureCompatDisallowed => {
                         tcx.node_span_lint(
                             lint::builtin::INVALID_TYPE_PARAM_DEFAULT,

compiler/rustc_lint_defs/src/builtin.rs

@@ -1267,7 +1267,7 @@ declare_lint! {
     Deny,
     "type parameter default erroneously allowed in invalid location",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
         reference: "issue #36887 <https://github.com/rust-lang/rust/issues/36887>",
     };
 }

compiler/rustc_resolve/src/imports.rs

@@ -48,6 +48,7 @@ pub(crate) enum ImportKind<'a> {
         /// `source` in `use prefix::source as target`.
         source: Ident,
         /// `target` in `use prefix::source as target`.
+        /// It will directly use `source` when the format is `use prefix::source`.
         target: Ident,
         /// Bindings to which `source` refers to.
         source_bindings: PerNS<Cell<Result<NameBinding<'a>, Determinacy>>>,

config.example.toml

@@ -472,7 +472,8 @@
 # This is mostly useful for tools; if you have changes to `compiler/` or `library/` they will be ignored.
 #
 # Set this to "if-unchanged" to only download if the compiler and standard library have not been modified.
-# Set this to `true` to download unconditionally (useful if e.g. you are only changing doc-comments).
+# Set this to `true` to download unconditionally. This is useful if you are working on tools, doc-comments,
+# or library (you will be able to build the standard library without needing to build the compiler).
 #download-rustc = false
 
 # Number of codegen units to use for each compiler invocation. A value of 0