Allow merging all libcore/alloc doctests into a single binary

compiler/rustc_error_codes/src/error_codes/E0636.md

@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 The same feature is enabled multiple times with `#![feature]` attributes
 
 Erroneous code example:
 
-```compile_fail,E0636
+```
 #![allow(stable_features)]
 #![feature(rust1)]
 #![feature(rust1)] // error: the feature `rust1` has already been enabled

compiler/rustc_lint_defs/src/builtin.rs

@@ -39,6 +39,7 @@ declare_lint_pass! {
         DEPRECATED_IN_FUTURE,
         DEPRECATED_SAFE_2024,
         DEPRECATED_WHERE_CLAUSE_LOCATION,
+        DUPLICATE_FEATURES,
         DUPLICATE_MACRO_ATTRIBUTES,
         ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
         ELIDED_LIFETIMES_IN_PATHS,
@@ -1098,6 +1099,16 @@ declare_lint! {
     "unused features found in crate-level `#[feature]` directives"
 }
 
+declare_lint! {
+    /// The `duplicate_features` lint detects duplicate features found in
+    /// crate-level [`feature` attributes].
+    ///
+    /// [`feature` attributes]: https://doc.rust-lang.org/nightly/unstable-book/
+    pub DUPLICATE_FEATURES,
+    Warn,
+    "duplicate features found in crate-level `#[feature]` directives"
+}
+
 declare_lint! {
     /// The `stable_features` lint detects a [`feature` attribute] that
     /// has since been made stable.

compiler/rustc_passes/src/errors.rs

@@ -1012,14 +1012,6 @@ pub(crate) struct ImpliedFeatureNotExist {
     pub implied_by: Symbol,
 }
 
-#[derive(Diagnostic)]
-#[diag("the feature `{$feature}` has already been enabled", code = E0636)]
-pub(crate) struct DuplicateFeatureErr {
-    #[primary_span]
-    pub span: Span,
-    pub feature: Symbol,
-}
-
 #[derive(Diagnostic)]
 #[diag(
     "attributes `#[rustc_const_unstable]`, `#[rustc_const_stable]` and `#[rustc_const_stable_indirect]` require the function or method to be `const`"
@@ -1169,6 +1161,12 @@ pub(crate) struct ProcMacroBadSig {
     pub kind: ProcMacroKind,
 }
 
+#[derive(LintDiagnostic)]
+#[diag("the feature `{$feature}` has already been enabled")]
+pub(crate) struct DuplicateFeature {
+    pub feature: Symbol,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(
     "the feature `{$feature}` has been stable since {$since} and no longer requires an attribute to enable"

compiler/rustc_passes/src/stability.rs

@@ -969,7 +969,7 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
         }
         if !lang_features.insert(gate_name) {
             // Warn if the user enables a lang feature multiple times.
-            tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *attr_sp, feature: *gate_name });
+            duplicate_feature_lint(tcx, *attr_sp, *gate_name);
         }
     }
 
@@ -978,7 +978,7 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
     for EnabledLibFeature { gate_name, attr_sp } in enabled_lib_features {
         if remaining_lib_features.contains_key(gate_name) {
             // Warn if the user enables a lib feature multiple times.
-            tcx.dcx().emit_err(errors::DuplicateFeatureErr { span: *attr_sp, feature: *gate_name });
+            duplicate_feature_lint(tcx, *attr_sp, *gate_name);
         }
         remaining_lib_features.insert(*gate_name, *attr_sp);
     }
@@ -1160,3 +1160,12 @@ fn unnecessary_stable_feature_lint(
         errors::UnnecessaryStableFeature { feature, since },
     );
 }
+
+fn duplicate_feature_lint(tcx: TyCtxt<'_>, span: Span, feature: Symbol) {
+    tcx.emit_node_span_lint(
+        lint::builtin::DUPLICATE_FEATURES,
+        hir::CRATE_HIR_ID,
+        span,
+        errors::DuplicateFeature { feature },
+    );
+}

compiler/rustc_span/src/symbol.rs

@@ -1073,6 +1073,7 @@ symbols! {
         include_bytes,
         include_str,
         inclusive_range_syntax,
+        incomplete_features,
         index,
         index_mut,
         infer_outlives_requirements,

library/alloc/src/lib.rs

@@ -63,7 +63,7 @@
 #![doc(
     html_playground_url = "https://play.rust-lang.org/",
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
-    test(no_crate_inject, attr(allow(unused_variables), deny(warnings)))
+    test(no_crate_inject, attr(allow(unused_variables, duplicate_features), deny(warnings)))
 )]
 #![doc(auto_cfg(hide(no_global_oom_handling, no_rc, no_sync, target_has_atomic = "ptr")))]
 #![doc(rust_logo)]

library/core/src/alloc/global.rs

@@ -19,7 +19,7 @@ use crate::{cmp, ptr};
 ///
 /// # Example
 ///
-/// ```
+/// ```standalone_crate
 /// use std::alloc::{GlobalAlloc, Layout};
 /// use std::cell::UnsafeCell;
 /// use std::ptr::null_mut;

library/core/src/hint.rs

@@ -514,7 +514,7 @@ pub const fn black_box<T>(dummy: T) -> T {
 /// macro_rules! make_error {
 ///     ($($args:expr),*) => {
 ///         core::hint::must_use({
-///             let error = $crate::make_error(core::format_args!($($args),*));
+///             let error = make_error(core::format_args!($($args),*));
 ///             error
 ///         })
 ///     };

library/core/src/intrinsics/mir.rs

@@ -62,7 +62,9 @@
 //!
 //! # Examples
 //!
-//! ```rust
+#![cfg_attr(panic = "unwind", doc = "```rust")]
+// This test can't support panic=abort because it generates an UnwindContinue MIR terminator.
+#![cfg_attr(panic = "abort", doc = "```ignore")]
 //! #![feature(core_intrinsics, custom_mir)]
 //! #![allow(internal_features)]
 //! #![allow(unused_assignments)]

library/core/src/lib.rs

@@ -48,7 +48,7 @@
     html_playground_url = "https://play.rust-lang.org/",
     issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
     test(no_crate_inject, attr(deny(warnings))),
-    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
+    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut, duplicate_features)))
 )]
 #![doc(rust_logo)]
 #![doc(auto_cfg(hide(

library/core/src/range.rs

@@ -572,7 +572,7 @@ impl<T> const From<legacy::RangeFrom<T>> for RangeFrom<T> {
 ///
 /// The `..=last` syntax is a `RangeToInclusive`:
 ///
-/// ```
+/// ```standalone_crate
 /// #![feature(new_range_api)]
 /// #![feature(new_range)]
 /// assert_eq!((..=5), std::range::RangeToInclusive{ last: 5 });

src/librustdoc/core.rs

@@ -232,6 +232,9 @@ pub(crate) fn create_config(
         rustc_lint::builtin::RENAMED_AND_REMOVED_LINTS.name.to_string(),
         rustc_lint::builtin::UNKNOWN_LINTS.name.to_string(),
         rustc_lint::builtin::UNEXPECTED_CFGS.name.to_string(),
+        rustc_lint::builtin::DUPLICATE_FEATURES.name.to_string(),
+        rustc_lint::builtin::UNUSED_FEATURES.name.to_string(),
+        rustc_lint::builtin::STABLE_FEATURES.name.to_string(),
         // this lint is needed to support `#[expect]` attributes
         rustc_lint::builtin::UNFULFILLED_LINT_EXPECTATIONS.name.to_string(),
     ];

src/librustdoc/doctest.rs

@@ -32,7 +32,7 @@ use rustc_span::edition::Edition;
 use rustc_span::{FileName, RemapPathScopeComponents, Span};
 use rustc_target::spec::{Target, TargetTuple};
 use tempfile::{Builder as TempFileBuilder, TempDir};
-use tracing::debug;
+use tracing::{debug, info};
 
 use self::rust::HirCollector;
 use crate::config::{MergeDoctests, Options as RustdocOptions, OutputFormat};
@@ -692,7 +692,7 @@ fn run_test(
         compiler.stderr(Stdio::piped());
     }
 
-    debug!("compiler invocation for doctest: {compiler:?}");
+    info!("compiler invocation for doctest: {compiler:?}");
 
     let mut child = match compiler.spawn() {
         Ok(child) => child,
@@ -759,7 +759,7 @@ fn run_test(
             runner_compiler.stderr(Stdio::inherit());
         }
         runner_compiler.arg("--error-format=short");
-        debug!("compiler invocation for doctest runner: {runner_compiler:?}");
+        info!("compiler invocation for doctest runner: {runner_compiler:?}");
 
         let status = if !status.success() {
             status
@@ -859,6 +859,8 @@ fn run_test(
         cmd.current_dir(run_directory);
     }
 
+    info!("running doctest executable: {cmd:?}");
+
     let result = if doctest.is_multiple_tests() || rustdoc_options.no_capture {
         cmd.status().map(|status| process::Output {
             status,

src/librustdoc/doctest/make.rs

@@ -555,7 +555,10 @@ fn parse_source(
                     // consider it only as a crate-level attribute.
                     if attr.has_name(sym::allow)
                         && let Some(list) = attr.meta_item_list()
-                        && list.iter().any(|sub_attr| sub_attr.has_name(sym::internal_features))
+                        && list.iter().any(|sub_attr| {
+                            sub_attr.has_name(sym::internal_features)
+                                || sub_attr.has_name(sym::incomplete_features)
+                        })
                     {
                         push_to_s(&mut info.crate_attrs, source, attr.span, &mut prev_span_hi);
                     } else {

tests/rustdoc-html/assoc/assoc-type-bindings-20646.rs

@@ -3,7 +3,6 @@
 
 // https://github.com/rust-lang/rust/issues/20646
 #![crate_name="issue_20646"]
-#![feature(associated_types)]
 
 extern crate issue_20646;
 

tests/rustdoc-html/doc-cfg/doc-cfg.rs

@@ -1,5 +1,4 @@
 #![feature(doc_cfg)]
-#![feature(target_feature, cfg_target_feature)]
 
 //@ has doc_cfg/struct.Portable.html
 //@ !has - '//*[@id="main-content"]/*[@class="item-info"]/*[@class="stab portability"]' ''

tests/rustdoc-ui/issues/issue-79494.rs

@@ -1,6 +1,4 @@
 //@ only-64bit
 
-#![feature(const_transmute)]
-
 pub const ZST: &[u8] = unsafe { std::mem::transmute(1usize) };
 //~^ ERROR transmuting from 8-byte type to 16-byte type

tests/rustdoc-ui/issues/issue-79494.stderr

@@ -1,5 +1,5 @@
 error[E0080]: transmuting from 8-byte type to 16-byte type: `usize` -> `&[u8]`
-  --> $DIR/issue-79494.rs:5:33
+  --> $DIR/issue-79494.rs:3:33
    |
 LL | pub const ZST: &[u8] = unsafe { std::mem::transmute(1usize) };
    |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `ZST` failed here

tests/rustdoc-ui/rustc-check-passes.rs

@@ -1,4 +1,6 @@
+//@ check-pass
+
 #![feature(rustdoc_internals)]
-#![feature(rustdoc_internals)] //~ ERROR
+#![feature(rustdoc_internals)] //~ WARN duplicate
 
 pub fn foo() {}

tests/rustdoc-ui/rustc-check-passes.stderr

@@ -1,9 +1,10 @@
-error[E0636]: the feature `rustdoc_internals` has already been enabled
-  --> $DIR/rustc-check-passes.rs:2:12
+warning: the feature `rustdoc_internals` has already been enabled
+  --> $DIR/rustc-check-passes.rs:4:12
    |
 LL | #![feature(rustdoc_internals)]
    |            ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(duplicate_features)]` on by default
 
-error: aborting due to 1 previous error
+warning: 1 warning emitted
 
-For more information about this error, try `rustc --explain E0636`.

tests/ui/feature-gates/duplicate-features.rs

@@ -1,9 +1,11 @@
+//@ check-pass
+
 #![allow(stable_features)]
 
 #![feature(rust1)]
-#![feature(rust1)] //~ ERROR the feature `rust1` has already been enabled
+#![feature(rust1)] //~ WARN the feature `rust1` has already been enabled
 
 #![feature(if_let)]
-#![feature(if_let)] //~ ERROR the feature `if_let` has already been enabled
+#![feature(if_let)] //~ WARN the feature `if_let` has already been enabled
 
 fn main() {}

tests/ui/feature-gates/duplicate-features.stderr

@@ -1,15 +1,16 @@
-error[E0636]: the feature `if_let` has already been enabled
-  --> $DIR/duplicate-features.rs:7:12
+warning: the feature `if_let` has already been enabled
+  --> $DIR/duplicate-features.rs:9:12
    |
 LL | #![feature(if_let)]
    |            ^^^^^^
+   |
+   = note: `#[warn(duplicate_features)]` on by default
 
-error[E0636]: the feature `rust1` has already been enabled
-  --> $DIR/duplicate-features.rs:4:12
+warning: the feature `rust1` has already been enabled
+  --> $DIR/duplicate-features.rs:6:12
    |
 LL | #![feature(rust1)]
    |            ^^^^^
 
-error: aborting due to 2 previous errors
+warning: 2 warnings emitted
 
-For more information about this error, try `rustc --explain E0636`.