Auto merge of #128650 - matthiaskrgr:rollup-gvrnowj, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #127655 (turn `invalid_type_param_default` into a `FutureReleaseErrorReportInDeps`)
 - #127974 (force compiling std from source if modified)
 - #128026 (std::thread: available_parallelism implementation for vxWorks proposal.)
 - #128362 (add test for symbol visibility of `#[naked]` functions)
 - #128500 (Add test for updating enum discriminant through pointer)
 - #128630 (docs(resolve): more explain about `target`)
 - #128638 (run-make: enable msvc for `link-dedup`)

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

Author: bors

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

library/std/src/sys/pal/unix/thread.rs

@@ -455,8 +455,18 @@ pub fn available_parallelism() -> io::Result<NonZero<usize>> {
 
                 Ok(NonZero::new_unchecked(sinfo.cpu_count as usize))
             }
+        } else if #[cfg(target_os = "vxworks")] {
+            // Note: there is also `vxCpuConfiguredGet`, closer to _SC_NPROCESSORS_CONF
+            // expectations than the actual cores availability.
+            extern "C" {
+                fn vxCpuEnabledGet() -> libc::cpuset_t;
+            }
+
+            // always fetches a valid bitmask
+            let set = unsafe { vxCpuEnabledGet() };
+            Ok(NonZero::new_unchecked(set.count_ones() as usize))
         } else {
-            // FIXME: implement on vxWorks, Redox, l4re
+            // FIXME: implement on Redox, l4re
             Err(io::const_io_error!(io::ErrorKind::Unsupported, "Getting the number of hardware threads is not supported on the target platform"))
         }
     }

src/bootstrap/src/core/build_steps/compile.rs

@@ -26,7 +26,8 @@ use crate::core::builder::{
 use crate::core::config::{DebuginfoLevel, LlvmLibunwind, RustcLto, TargetSelection};
 use crate::utils::exec::command;
 use crate::utils::helpers::{
-    exe, get_clang_cl_resource_dir, is_debug_info, is_dylib, symlink_dir, t, up_to_date,
+    self, exe, get_clang_cl_resource_dir, get_closest_merge_base_commit, is_debug_info, is_dylib,
+    symlink_dir, t, up_to_date,
 };
 use crate::{CLang, Compiler, DependencyType, GitRepo, Mode, LLVM_TOOLS};
 
@@ -114,21 +115,43 @@ impl Step for Std {
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        // When downloading stage1, the standard library has already been copied to the sysroot, so
-        // there's no need to rebuild it.
-        let builder = run.builder;
-        run.crate_or_deps("sysroot")
-            .path("library")
-            .lazy_default_condition(Box::new(|| !builder.download_rustc()))
+        run.crate_or_deps("sysroot").path("library")
     }
 
     fn make_run(run: RunConfig<'_>) {
         let crates = std_crates_for_run_make(&run);
+        let builder = run.builder;
+
+        // Force compilation of the standard library from source if the `library` is modified. This allows
+        // library team to compile the standard library without needing to compile the compiler with
+        // the `rust.download-rustc=true` option.
+        let force_recompile =
+            if builder.rust_info().is_managed_git_subrepository() && builder.download_rustc() {
+                let closest_merge_commit = get_closest_merge_base_commit(
+                    Some(&builder.src),
+                    &builder.config.git_config(),
+                    &builder.config.stage0_metadata.config.git_merge_commit_email,
+                    &[],
+                )
+                .unwrap();
+
+                // Check if `library` has changes (returns false otherwise)
+                !t!(helpers::git(Some(&builder.src))
+                    .args(["diff-index", "--quiet", &closest_merge_commit])
+                    .arg("--")
+                    .arg(builder.src.join("library"))
+                    .as_command_mut()
+                    .status())
+                .success()
+            } else {
+                false
+            };
+
         run.builder.ensure(Std {
             compiler: run.builder.compiler(run.builder.top_stage, run.build_triple()),
             target: run.target,
             crates,
-            force_recompile: false,
+            force_recompile,
             extra_rust_args: &[],
             is_for_mir_opt_tests: false,
         });

tests/codegen/issues/issue-122600-ptr-discriminant-update.rs

@@ -0,0 +1,19 @@
+//@ compile-flags: -O
+//@ min-llvm-version: 19
+
+#![crate_type = "lib"]
+
+pub enum State {
+    A([u8; 753]),
+    B([u8; 753]),
+}
+
+// CHECK-LABEL: @update
+#[no_mangle]
+pub unsafe fn update(s: *mut State) {
+    // CHECK-NEXT: start:
+    // CHECK-NEXT: store i8
+    // CHECK-NEXT: ret
+    let State::A(v) = s.read() else { std::hint::unreachable_unchecked() };
+    s.write(State::B(v));
+}

tests/run-make/link-dedup/rmake.rs

@@ -5,20 +5,37 @@
 // Without the --cfg flag, there should be a single -ltesta, no more, no less.
 // See https://github.com/rust-lang/rust/pull/84794
 
-//@ ignore-msvc
+use std::fmt::Write;
 
-use run_make_support::rustc;
+use run_make_support::{is_msvc, rustc};
 
 fn main() {
     rustc().input("depa.rs").run();
     rustc().input("depb.rs").run();
     rustc().input("depc.rs").run();
+
     let output = rustc().input("empty.rs").cfg("bar").run_fail();
-    output.assert_stderr_contains(r#""-ltesta" "-ltestb" "-ltesta""#);
-    let output = rustc().input("empty.rs").run_fail();
-    output.assert_stderr_contains(r#""-ltesta""#);
-    let output = rustc().input("empty.rs").run_fail();
-    output.assert_stderr_not_contains(r#""-ltestb""#);
+    output.assert_stderr_contains(needle_from_libs(&["testa", "testb", "testa"]));
+
     let output = rustc().input("empty.rs").run_fail();
-    output.assert_stderr_not_contains(r#""-ltesta" "-ltesta" "-ltesta""#);
+    output.assert_stderr_contains(needle_from_libs(&["testa"]));
+    output.assert_stderr_not_contains(needle_from_libs(&["testb"]));
+    output.assert_stderr_not_contains(needle_from_libs(&["testa", "testa", "testa"]));
+    // Adjacent identical native libraries are no longer deduplicated if
+    // they come from different crates (https://github.com/rust-lang/rust/pull/103311)
+    // so the following will fail:
+    //output.assert_stderr_not_contains(needle_from_libs(&["testa", "testa"]));
+}
+
+fn needle_from_libs(libs: &[&str]) -> String {
+    let mut needle = String::new();
+    for lib in libs {
+        if is_msvc() {
+            let _ = needle.write_fmt(format_args!(r#""{lib}.lib" "#));
+        } else {
+            let _ = needle.write_fmt(format_args!(r#""-l{lib}" "#));
+        }
+    }
+    needle.pop(); // remove trailing space
+    needle
 }