Auto merge of rust-lang#138486 - jhpratt:rollup-765wijj, r=jhpratt

Rollup of 6 pull requests

Successful merges:

 - rust-lang#134720 (Display valid crate types in error message for --crate-type flag)
 - rust-lang#137424 (uefi: helpers: Add DevicePathNode abstractions)
 - rust-lang#137736 (Don't attempt to export compiler-builtins symbols from rust dylibs)
 - rust-lang#138451 (Build GCC on CI with GCC, not Clang)
 - rust-lang#138454 (Improve post-merge workflow)
 - rust-lang#138477 (Deny impls for `BikeshedGuaranteedNoDrop`)

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

Author: bors

.github/workflows/post-merge.yml

@@ -35,8 +35,13 @@ jobs:
 
           cd src/ci/citool
 
-          echo "Post-merge analysis result" > output.log
+          printf "*This is an experimental post-merge analysis report. You can ignore it.*\n\n" > output.log
+          printf "<details>\n<summary>Post-merge report</summary>\n\n" >> output.log
+
           cargo run --release post-merge-report ${PARENT_COMMIT} ${{ github.sha }} >> output.log
+
+          printf "</details>\n" >> output.log
+
           cat output.log
 
           gh pr comment ${HEAD_PR} -F output.log

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -1784,7 +1784,10 @@ fn exported_symbols_for_non_proc_macro(tcx: TyCtxt<'_>, crate_type: CrateType) -
     let mut symbols = Vec::new();
     let export_threshold = symbol_export::crates_export_threshold(&[crate_type]);
     for_each_exported_symbols_include_dep(tcx, crate_type, |symbol, info, cnum| {
-        if info.level.is_below_threshold(export_threshold) {
+        // Do not export mangled symbols from cdylibs and don't attempt to export compiler-builtins
+        // from any cdylib. The latter doesn't work anyway as we use hidden visibility for
+        // compiler-builtins. Most linkers silently ignore it, but ld64 gives a warning.
+        if info.level.is_below_threshold(export_threshold) && !tcx.is_compiler_builtins(cnum) {
             symbols.push(symbol_export::exporting_symbol_name_for_instance_in_crate(
                 tcx, symbol, cnum,
             ));

compiler/rustc_passes/messages.ftl

@@ -811,8 +811,8 @@ passes_unused_duplicate =
 passes_unused_empty_lints_note =
     attribute `{$name}` with an empty list has no effect
 
-passes_unused_linker_warnings_note =
-    the `linker_warnings` lint can only be controlled at the root of a crate that needs to be linked
+passes_unused_linker_messages_note =
+    the `linker_messages` lint can only be controlled at the root of a crate that needs to be linked
 
 passes_unused_multiple =
     multiple `{$name}` attributes

compiler/rustc_passes/src/check_attr.rs

@@ -2387,7 +2387,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     .iter()
                     .all(|kind| matches!(kind, CrateType::Rlib | CrateType::Staticlib));
                 if never_needs_link {
-                    errors::UnusedNote::LinkerWarningsBinaryCrateOnly
+                    errors::UnusedNote::LinkerMessagesBinaryCrateOnly
                 } else {
                     return;
                 }

compiler/rustc_passes/src/errors.rs

@@ -770,8 +770,8 @@ pub(crate) enum UnusedNote {
     NoLints { name: Symbol },
     #[note(passes_unused_default_method_body_const_note)]
     DefaultMethodBodyConst,
-    #[note(passes_unused_linker_warnings_note)]
-    LinkerWarningsBinaryCrateOnly,
+    #[note(passes_unused_linker_messages_note)]
+    LinkerMessagesBinaryCrateOnly,
 }
 
 #[derive(LintDiagnostic)]

compiler/rustc_session/src/config.rs

@@ -2709,7 +2709,12 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
                 "cdylib" => CrateType::Cdylib,
                 "bin" => CrateType::Executable,
                 "proc-macro" => CrateType::ProcMacro,
-                _ => return Err(format!("unknown crate type: `{part}`")),
+                _ => {
+                    return Err(format!(
+                        "unknown crate type: `{part}`, expected one of: \
+                        `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`",
+                    ));
+                }
             };
             if !crate_types.contains(&new_part) {
                 crate_types.push(new_part)

library/core/src/marker.rs

@@ -465,9 +465,13 @@ impl<T: ?Sized> Copy for &T {}
 /// Notably, this doesn't include all trivially-destructible types for semver
 /// reasons.
 ///
-/// Bikeshed name for now.
+/// Bikeshed name for now. This trait does not do anything other than reflect the
+/// set of types that are allowed within unions for field validity.
 #[unstable(feature = "bikeshed_guaranteed_no_drop", issue = "none")]
 #[lang = "bikeshed_guaranteed_no_drop"]
+#[rustc_deny_explicit_impl]
+#[rustc_do_not_implement_via_object]
+#[doc(hidden)]
 pub trait BikeshedGuaranteedNoDrop {}
 
 /// Types for which it is safe to share references between threads.

library/std/src/sys/pal/uefi/helpers.rs

@@ -216,6 +216,60 @@ pub(crate) fn device_path_to_text(path: NonNull<device_path::Protocol>) -> io::R
     Err(io::const_error!(io::ErrorKind::NotFound, "no device path to text protocol found"))
 }
 
+fn device_node_to_text(path: NonNull<device_path::Protocol>) -> io::Result<OsString> {
+    fn node_to_text(
+        protocol: NonNull<device_path_to_text::Protocol>,
+        path: NonNull<device_path::Protocol>,
+    ) -> io::Result<OsString> {
+        let path_ptr: *mut r_efi::efi::Char16 = unsafe {
+            ((*protocol.as_ptr()).convert_device_node_to_text)(
+                path.as_ptr(),
+                // DisplayOnly
+                r_efi::efi::Boolean::FALSE,
+                // AllowShortcuts
+                r_efi::efi::Boolean::FALSE,
+            )
+        };
+
+        let path = os_string_from_raw(path_ptr)
+            .ok_or(io::const_error!(io::ErrorKind::InvalidData, "Invalid path"))?;
+
+        if let Some(boot_services) = crate::os::uefi::env::boot_services() {
+            let boot_services: NonNull<r_efi::efi::BootServices> = boot_services.cast();
+            unsafe {
+                ((*boot_services.as_ptr()).free_pool)(path_ptr.cast());
+            }
+        }
+
+        Ok(path)
+    }
+
+    static LAST_VALID_HANDLE: AtomicPtr<crate::ffi::c_void> =
+        AtomicPtr::new(crate::ptr::null_mut());
+
+    if let Some(handle) = NonNull::new(LAST_VALID_HANDLE.load(Ordering::Acquire)) {
+        if let Ok(protocol) = open_protocol::<device_path_to_text::Protocol>(
+            handle,
+            device_path_to_text::PROTOCOL_GUID,
+        ) {
+            return node_to_text(protocol, path);
+        }
+    }
+
+    let device_path_to_text_handles = locate_handles(device_path_to_text::PROTOCOL_GUID)?;
+    for handle in device_path_to_text_handles {
+        if let Ok(protocol) = open_protocol::<device_path_to_text::Protocol>(
+            handle,
+            device_path_to_text::PROTOCOL_GUID,
+        ) {
+            LAST_VALID_HANDLE.store(handle.as_ptr(), Ordering::Release);
+            return node_to_text(protocol, path);
+        }
+    }
+
+    Err(io::const_error!(io::ErrorKind::NotFound, "No device path to text protocol found"))
+}
+
 /// Gets RuntimeServices.
 pub(crate) fn runtime_services() -> Option<NonNull<r_efi::efi::RuntimeServices>> {
     let system_table: NonNull<r_efi::efi::SystemTable> =
@@ -319,6 +373,11 @@ impl<'a> BorrowedDevicePath<'a> {
     pub(crate) fn to_text(&self) -> io::Result<OsString> {
         device_path_to_text(self.protocol)
     }
+
+    #[expect(dead_code)]
+    pub(crate) const fn iter(&'a self) -> DevicePathIterator<'a> {
+        DevicePathIterator::new(DevicePathNode::new(self.protocol))
+    }
 }
 
 impl<'a> crate::fmt::Debug for BorrowedDevicePath<'a> {
@@ -330,6 +389,126 @@ impl<'a> crate::fmt::Debug for BorrowedDevicePath<'a> {
     }
 }
 
+pub(crate) struct DevicePathIterator<'a>(Option<DevicePathNode<'a>>);
+
+impl<'a> DevicePathIterator<'a> {
+    const fn new(node: DevicePathNode<'a>) -> Self {
+        if node.is_end() { Self(None) } else { Self(Some(node)) }
+    }
+}
+
+impl<'a> Iterator for DevicePathIterator<'a> {
+    type Item = DevicePathNode<'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let cur_node = self.0?;
+
+        let next_node = unsafe { cur_node.next_node() };
+        self.0 = if next_node.is_end() { None } else { Some(next_node) };
+
+        Some(cur_node)
+    }
+}
+
+#[derive(Copy, Clone)]
+pub(crate) struct DevicePathNode<'a> {
+    protocol: NonNull<r_efi::protocols::device_path::Protocol>,
+    phantom: PhantomData<&'a r_efi::protocols::device_path::Protocol>,
+}
+
+impl<'a> DevicePathNode<'a> {
+    pub(crate) const fn new(protocol: NonNull<r_efi::protocols::device_path::Protocol>) -> Self {
+        Self { protocol, phantom: PhantomData }
+    }
+
+    pub(crate) const fn length(&self) -> u16 {
+        let len = unsafe { (*self.protocol.as_ptr()).length };
+        u16::from_le_bytes(len)
+    }
+
+    pub(crate) const fn node_type(&self) -> u8 {
+        unsafe { (*self.protocol.as_ptr()).r#type }
+    }
+
+    pub(crate) const fn sub_type(&self) -> u8 {
+        unsafe { (*self.protocol.as_ptr()).sub_type }
+    }
+
+    pub(crate) fn data(&self) -> &[u8] {
+        let length: usize = self.length().into();
+
+        // Some nodes do not have any special data
+        if length > 4 {
+            let raw_ptr: *const u8 = self.protocol.as_ptr().cast();
+            let data = unsafe { raw_ptr.add(4) };
+            unsafe { crate::slice::from_raw_parts(data, length - 4) }
+        } else {
+            &[]
+        }
+    }
+
+    pub(crate) const fn is_end(&self) -> bool {
+        self.node_type() == r_efi::protocols::device_path::TYPE_END
+            && self.sub_type() == r_efi::protocols::device_path::End::SUBTYPE_ENTIRE
+    }
+
+    #[expect(dead_code)]
+    pub(crate) const fn is_end_instance(&self) -> bool {
+        self.node_type() == r_efi::protocols::device_path::TYPE_END
+            && self.sub_type() == r_efi::protocols::device_path::End::SUBTYPE_INSTANCE
+    }
+
+    pub(crate) unsafe fn next_node(&self) -> Self {
+        let node = unsafe {
+            self.protocol
+                .cast::<u8>()
+                .add(self.length().into())
+                .cast::<r_efi::protocols::device_path::Protocol>()
+        };
+        Self::new(node)
+    }
+
+    #[expect(dead_code)]
+    pub(crate) fn to_path(&'a self) -> BorrowedDevicePath<'a> {
+        BorrowedDevicePath::new(self.protocol)
+    }
+
+    pub(crate) fn to_text(&self) -> io::Result<OsString> {
+        device_node_to_text(self.protocol)
+    }
+}
+
+impl<'a> PartialEq for DevicePathNode<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        let self_len = self.length();
+        let other_len = other.length();
+
+        self_len == other_len
+            && unsafe {
+                compiler_builtins::mem::memcmp(
+                    self.protocol.as_ptr().cast(),
+                    other.protocol.as_ptr().cast(),
+                    usize::from(self_len),
+                ) == 0
+            }
+    }
+}
+
+impl<'a> crate::fmt::Debug for DevicePathNode<'a> {
+    fn fmt(&self, f: &mut crate::fmt::Formatter<'_>) -> crate::fmt::Result {
+        match self.to_text() {
+            Ok(p) => p.fmt(f),
+            Err(_) => f
+                .debug_struct("DevicePathNode")
+                .field("type", &self.node_type())
+                .field("sub_type", &self.sub_type())
+                .field("length", &self.length())
+                .field("specific_device_path_data", &self.data())
+                .finish(),
+        }
+    }
+}
+
 pub(crate) struct OwnedProtocol<T> {
     guid: r_efi::efi::Guid,
     handle: NonNull<crate::ffi::c_void>,

src/bootstrap/src/core/build_steps/dist.rs

@@ -2481,7 +2481,7 @@ impl Step for Gcc {
     fn run(self, builder: &Builder<'_>) -> Self::Output {
         let tarball = Tarball::new(builder, "gcc", &self.target.triple);
         let output = builder.ensure(super::gcc::Gcc { target: self.target });
-        tarball.add_file(output.libgccjit, ".", 0o644);
+        tarball.add_file(output.libgccjit, "lib", 0o644);
         tarball.generate()
     }
 }

src/bootstrap/src/core/build_steps/gcc.rs

@@ -63,18 +63,23 @@ impl Step for Gcc {
         }
 
         build_gcc(&metadata, builder, target);
-
-        let lib_alias = metadata.install_dir.join("lib/libgccjit.so.0");
-        if !lib_alias.exists() {
-            t!(builder.symlink_file(&libgccjit_path, lib_alias));
-        }
+        create_lib_alias(builder, &libgccjit_path);
 
         t!(metadata.stamp.write());
 
         GccOutput { libgccjit: libgccjit_path }
     }
 }
 
+/// Creates a libgccjit.so.0 alias next to libgccjit.so if it does not
+/// already exist
+fn create_lib_alias(builder: &Builder<'_>, libgccjit: &PathBuf) {
+    let lib_alias = libgccjit.parent().unwrap().join("libgccjit.so.0");
+    if !lib_alias.exists() {
+        t!(builder.symlink_file(libgccjit, lib_alias));
+    }
+}
+
 pub struct Meta {
     stamp: BuildStamp,
     out_dir: PathBuf,
@@ -109,8 +114,10 @@ fn try_download_gcc(builder: &Builder<'_>, target: TargetSelection) -> Option<Pa
         builder.config.download_ci_gcc(&sha, &root);
         t!(gcc_stamp.write());
     }
-    // FIXME: put libgccjit.so into a lib directory in dist::Gcc
-    Some(root.join("libgccjit.so"))
+
+    let libgccjit = root.join("lib").join("libgccjit.so");
+    create_lib_alias(builder, &libgccjit);
+    Some(libgccjit)
 }
 
 #[cfg(test)]
@@ -177,6 +184,14 @@ fn libgccjit_built_path(install_dir: &Path) -> PathBuf {
 }
 
 fn build_gcc(metadata: &Meta, builder: &Builder<'_>, target: TargetSelection) {
+    if builder.build.cc_tool(target).is_like_clang()
+        || builder.build.cxx_tool(target).is_like_clang()
+    {
+        panic!(
+            "Attempting to build GCC using Clang, which is known to misbehave. Please use GCC as the host C/C++ compiler. "
+        );
+    }
+
     let Meta { stamp: _, out_dir, install_dir, root } = metadata;
 
     t!(fs::create_dir_all(out_dir));
@@ -203,18 +218,13 @@ fn build_gcc(metadata: &Meta, builder: &Builder<'_>, target: TargetSelection) {
     let mut configure_cmd = command(src_dir.join("configure"));
     configure_cmd
         .current_dir(out_dir)
-        // On CI, we compile GCC with Clang.
-        // The -Wno-everything flag is needed to make GCC compile with Clang 19.
-        // `-g -O2` are the default flags that are otherwise used by Make.
-        // FIXME(kobzol): change the flags once we have [gcc] configuration in config.toml.
-        .env("CXXFLAGS", "-Wno-everything -g -O2")
-        .env("CFLAGS", "-Wno-everything -g -O2")
         .arg("--enable-host-shared")
-        .arg("--enable-languages=jit")
+        .arg("--enable-languages=c,jit,lto")
         .arg("--enable-checking=release")
         .arg("--disable-bootstrap")
         .arg("--disable-multilib")
         .arg(format!("--prefix={}", install_dir.display()));
+
     let cc = builder.build.cc(target).display().to_string();
     let cc = builder
         .build

src/bootstrap/src/lib.rs

@@ -27,6 +27,7 @@ use std::{env, fs, io, str};
 
 use build_helper::ci::gha;
 use build_helper::exit;
+use cc::Tool;
 use termcolor::{ColorChoice, StandardStream, WriteColor};
 use utils::build_stamp::BuildStamp;
 use utils::channel::GitInfo;
@@ -1218,6 +1219,16 @@ Executed at: {executed_at}"#,
         self.cc.borrow()[&target].path().into()
     }
 
+    /// Returns the internal `cc::Tool` for the C compiler.
+    fn cc_tool(&self, target: TargetSelection) -> Tool {
+        self.cc.borrow()[&target].clone()
+    }
+
+    /// Returns the internal `cc::Tool` for the C++ compiler.
+    fn cxx_tool(&self, target: TargetSelection) -> Tool {
+        self.cxx.borrow()[&target].clone()
+    }
+
     /// Returns C flags that `cc-rs` thinks should be enabled for the
     /// specified target by default.
     fn cc_handled_clags(&self, target: TargetSelection, c: CLang) -> Vec<String> {

src/ci/citool/src/merge_report.rs

@@ -1,8 +1,8 @@
-use std::cmp::Reverse;
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
+use std::path::PathBuf;
 
 use anyhow::Context;
-use build_helper::metrics::{JsonRoot, TestOutcome};
+use build_helper::metrics::{JsonRoot, TestOutcome, TestSuiteMetadata};
 
 use crate::jobs::JobDatabase;
 use crate::metrics::get_test_suites;
@@ -13,8 +13,10 @@ type JobName = String;
 /// Computes a post merge CI analysis report between the `parent` and `current` commits.
 pub fn post_merge_report(job_db: JobDatabase, parent: Sha, current: Sha) -> anyhow::Result<()> {
     let jobs = download_all_metrics(&job_db, &parent, &current)?;
-    let diffs = aggregate_test_diffs(&jobs)?;
-    report_test_changes(diffs);
+    let aggregated_test_diffs = aggregate_test_diffs(&jobs)?;
+
+    println!("Comparing {parent} (base) -> {current} (this PR)\n");
+    report_test_diffs(aggregated_test_diffs);
 
     Ok(())
 }
@@ -54,7 +56,16 @@ Maybe it was newly added?"#,
     Ok(jobs)
 }
 
+/// Downloads job metrics of the given job for the given commit.
+/// Caches the result on the local disk.
 fn download_job_metrics(job_name: &str, sha: &str) -> anyhow::Result<JsonRoot> {
+    let cache_path = PathBuf::from(".citool-cache").join(sha).join(job_name).join("metrics.json");
+    if let Some(cache_entry) =
+        std::fs::read_to_string(&cache_path).ok().and_then(|data| serde_json::from_str(&data).ok())
+    {
+        return Ok(cache_entry);
+    }
+
     let url = get_metrics_url(job_name, sha);
     let mut response = ureq::get(&url).call()?;
     if !response.status().is_success() {
@@ -68,6 +79,13 @@ fn download_job_metrics(job_name: &str, sha: &str) -> anyhow::Result<JsonRoot> {
         .body_mut()
         .read_json()
         .with_context(|| anyhow::anyhow!("cannot deserialize metrics from {url}"))?;
+
+    // Ignore errors if cache cannot be created
+    if std::fs::create_dir_all(cache_path.parent().unwrap()).is_ok() {
+        if let Ok(serialized) = serde_json::to_string(&data) {
+            let _ = std::fs::write(&cache_path, &serialized);
+        }
+    }
     Ok(data)
 }
 
@@ -76,81 +94,80 @@ fn get_metrics_url(job_name: &str, sha: &str) -> String {
     format!("https://ci-artifacts.rust-lang.org/rustc-builds{suffix}/{sha}/metrics-{job_name}.json")
 }
 
+/// Represents a difference in the outcome of tests between a base and a current commit.
+/// Maps test diffs to jobs that contained them.
+#[derive(Debug)]
+struct AggregatedTestDiffs {
+    diffs: HashMap<TestDiff, Vec<JobName>>,
+}
+
 fn aggregate_test_diffs(
     jobs: &HashMap<JobName, JobMetrics>,
-) -> anyhow::Result<Vec<AggregatedTestDiffs>> {
-    let mut job_diffs = vec![];
+) -> anyhow::Result<AggregatedTestDiffs> {
+    let mut diffs: HashMap<TestDiff, Vec<JobName>> = HashMap::new();
 
     // Aggregate test suites
     for (name, metrics) in jobs {
         if let Some(parent) = &metrics.parent {
             let tests_parent = aggregate_tests(parent);
             let tests_current = aggregate_tests(&metrics.current);
-            let test_diffs = calculate_test_diffs(tests_parent, tests_current);
-            if !test_diffs.is_empty() {
-                job_diffs.push((name.clone(), test_diffs));
+            for diff in calculate_test_diffs(tests_parent, tests_current) {
+                diffs.entry(diff).or_default().push(name.to_string());
             }
         }
     }
 
-    // Aggregate jobs with the same diff, as often the same diff will appear in many jobs
-    let job_diffs: HashMap<Vec<(Test, TestOutcomeDiff)>, Vec<String>> =
-        job_diffs.into_iter().fold(HashMap::new(), |mut acc, (job, diffs)| {
-            acc.entry(diffs).or_default().push(job);
-            acc
-        });
+    Ok(AggregatedTestDiffs { diffs })
+}
 
-    Ok(job_diffs
-        .into_iter()
-        .map(|(test_diffs, jobs)| AggregatedTestDiffs { jobs, test_diffs })
-        .collect())
+#[derive(Eq, PartialEq, Hash, Debug)]
+enum TestOutcomeDiff {
+    ChangeOutcome { before: TestOutcome, after: TestOutcome },
+    Missing { before: TestOutcome },
+    Added(TestOutcome),
 }
 
-fn calculate_test_diffs(
-    reference: TestSuiteData,
-    current: TestSuiteData,
-) -> Vec<(Test, TestOutcomeDiff)> {
-    let mut diffs = vec![];
+#[derive(Eq, PartialEq, Hash, Debug)]
+struct TestDiff {
+    test: Test,
+    diff: TestOutcomeDiff,
+}
+
+fn calculate_test_diffs(parent: TestSuiteData, current: TestSuiteData) -> HashSet<TestDiff> {
+    let mut diffs = HashSet::new();
     for (test, outcome) in &current.tests {
-        match reference.tests.get(test) {
+        match parent.tests.get(test) {
             Some(before) => {
                 if before != outcome {
-                    diffs.push((
-                        test.clone(),
-                        TestOutcomeDiff::ChangeOutcome {
+                    diffs.insert(TestDiff {
+                        test: test.clone(),
+                        diff: TestOutcomeDiff::ChangeOutcome {
                             before: before.clone(),
                             after: outcome.clone(),
                         },
-                    ));
+                    });
                 }
             }
-            None => diffs.push((test.clone(), TestOutcomeDiff::Added(outcome.clone()))),
+            None => {
+                diffs.insert(TestDiff {
+                    test: test.clone(),
+                    diff: TestOutcomeDiff::Added(outcome.clone()),
+                });
+            }
         }
     }
-    for (test, outcome) in &reference.tests {
+    for (test, outcome) in &parent.tests {
         if !current.tests.contains_key(test) {
-            diffs.push((test.clone(), TestOutcomeDiff::Missing { before: outcome.clone() }));
+            diffs.insert(TestDiff {
+                test: test.clone(),
+                diff: TestOutcomeDiff::Missing { before: outcome.clone() },
+            });
         }
     }
 
     diffs
 }
 
-/// Represents a difference in the outcome of tests between a base and a current commit.
-#[derive(Debug)]
-struct AggregatedTestDiffs {
-    /// All jobs that had the exact same test diffs.
-    jobs: Vec<String>,
-    test_diffs: Vec<(Test, TestOutcomeDiff)>,
-}
-
-#[derive(Eq, PartialEq, Hash, Debug)]
-enum TestOutcomeDiff {
-    ChangeOutcome { before: TestOutcome, after: TestOutcome },
-    Missing { before: TestOutcome },
-    Added(TestOutcome),
-}
-
 /// Aggregates test suite executions from all bootstrap invocations in a given CI job.
 #[derive(Default)]
 struct TestSuiteData {
@@ -160,6 +177,7 @@ struct TestSuiteData {
 #[derive(Hash, PartialEq, Eq, Debug, Clone)]
 struct Test {
     name: String,
+    is_doctest: bool,
 }
 
 /// Extracts all tests from the passed metrics and map them to their outcomes.
@@ -168,7 +186,10 @@ fn aggregate_tests(metrics: &JsonRoot) -> TestSuiteData {
     let test_suites = get_test_suites(&metrics);
     for suite in test_suites {
         for test in &suite.tests {
-            let test_entry = Test { name: normalize_test_name(&test.name) };
+            // Poor man's detection of doctests based on the "(line XYZ)" suffix
+            let is_doctest = matches!(suite.metadata, TestSuiteMetadata::CargoPackage { .. })
+                && test.name.contains("(line");
+            let test_entry = Test { name: normalize_test_name(&test.name), is_doctest };
             tests.insert(test_entry, test.outcome.clone());
         }
     }
@@ -181,16 +202,13 @@ fn normalize_test_name(name: &str) -> String {
 }
 
 /// Prints test changes in Markdown format to stdout.
-fn report_test_changes(mut diffs: Vec<AggregatedTestDiffs>) {
+fn report_test_diffs(diff: AggregatedTestDiffs) {
     println!("## Test differences");
-    if diffs.is_empty() {
+    if diff.diffs.is_empty() {
         println!("No test diffs found");
         return;
     }
 
-    // Sort diffs in decreasing order by diff count
-    diffs.sort_by_key(|entry| Reverse(entry.test_diffs.len()));
-
     fn format_outcome(outcome: &TestOutcome) -> String {
         match outcome {
             TestOutcome::Passed => "pass".to_string(),
@@ -219,36 +237,79 @@ fn report_test_changes(mut diffs: Vec<AggregatedTestDiffs>) {
         }
     }
 
-    let max_diff_count = 10;
-    let max_job_count = 5;
-    let max_test_count = 10;
-
-    for diff in diffs.iter().take(max_diff_count) {
-        let mut jobs = diff.jobs.clone();
-        jobs.sort();
-
-        let jobs = jobs.iter().take(max_job_count).map(|j| format!("`{j}`")).collect::<Vec<_>>();
+    fn format_job_group(group: u64) -> String {
+        format!("**J{group}**")
+    }
 
-        let extra_jobs = diff.jobs.len().saturating_sub(max_job_count);
-        let suffix = if extra_jobs > 0 {
-            format!(" (and {extra_jobs} {})", pluralize("other", extra_jobs))
-        } else {
-            String::new()
+    // It would be quite noisy to repeat the jobs that contained the test changes after/next to
+    // every test diff. At the same time, grouping the test diffs by
+    // [unique set of jobs that contained them] also doesn't work well, because the test diffs
+    // would have to be duplicated several times.
+    // Instead, we create a set of unique job groups, and then print a job group after each test.
+    // We then print the job groups at the end, as a sort of index.
+    let mut grouped_diffs: Vec<(&TestDiff, u64)> = vec![];
+    let mut job_list_to_group: HashMap<&[JobName], u64> = HashMap::new();
+    let mut job_index: Vec<&[JobName]> = vec![];
+
+    let original_diff_count = diff.diffs.len();
+    let diffs = diff
+        .diffs
+        .into_iter()
+        .filter(|(diff, _)| !diff.test.is_doctest)
+        .map(|(diff, mut jobs)| {
+            jobs.sort();
+            (diff, jobs)
+        })
+        .collect::<Vec<_>>();
+    let doctest_count = original_diff_count.saturating_sub(diffs.len());
+
+    let max_diff_count = 100;
+    for (diff, jobs) in diffs.iter().take(max_diff_count) {
+        let jobs = &*jobs;
+        let job_group = match job_list_to_group.get(jobs.as_slice()) {
+            Some(id) => *id,
+            None => {
+                let id = job_index.len() as u64;
+                job_index.push(jobs);
+                job_list_to_group.insert(jobs, id);
+                id
+            }
         };
-        println!("- {}{suffix}", jobs.join(","));
+        grouped_diffs.push((diff, job_group));
+    }
 
-        let extra_tests = diff.test_diffs.len().saturating_sub(max_test_count);
-        for (test, outcome_diff) in diff.test_diffs.iter().take(max_test_count) {
-            println!("  - {}: {}", test.name, format_diff(&outcome_diff));
-        }
-        if extra_tests > 0 {
-            println!("  - (and {extra_tests} additional {})", pluralize("tests", extra_tests));
-        }
+    // Sort diffs by job group and test name
+    grouped_diffs.sort_by(|(d1, g1), (d2, g2)| g1.cmp(&g2).then(d1.test.name.cmp(&d2.test.name)));
+
+    for (diff, job_group) in grouped_diffs {
+        println!(
+            "- `{}`: {} ({})",
+            diff.test.name,
+            format_diff(&diff.diff),
+            format_job_group(job_group)
+        );
     }
 
     let extra_diffs = diffs.len().saturating_sub(max_diff_count);
     if extra_diffs > 0 {
-        println!("\n(and {extra_diffs} additional {})", pluralize("diff", extra_diffs));
+        println!("\n(and {extra_diffs} additional {})", pluralize("test diff", extra_diffs));
+    }
+
+    if doctest_count > 0 {
+        println!(
+            "\nAdditionally, {doctest_count} doctest {} were found. These are ignored, as they are noisy.",
+            pluralize("diff", doctest_count)
+        );
+    }
+
+    // Now print the job group index
+    println!("\n**Job group index**\n");
+    for (group, jobs) in job_index.into_iter().enumerate() {
+        println!(
+            "- {}: {}",
+            format_job_group(group as u64),
+            jobs.iter().map(|j| format!("`{j}`")).collect::<Vec<_>>().join(", ")
+        );
     }
 }
 

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -101,7 +101,9 @@ ENV SCRIPT python3 ../x.py build --set rust.debug=true opt-dist && \
     ./build/$HOSTS/stage0-tools-bin/opt-dist linux-ci -- python3 ../x.py dist \
     --host $HOSTS --target $HOSTS \
     --include-default-paths \
-    build-manifest bootstrap gcc
+    build-manifest bootstrap && \
+    # Use GCC for building GCC, as it seems to behave badly when built with Clang
+    CC=/rustroot/bin/cc CXX=/rustroot/bin/c++ python3 ../x.py dist gcc
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=clang
 
 # This is the only builder which will create source tarballs

src/tools/opt-dist/src/tests.rs

@@ -1,3 +1,5 @@
+use std::path::Path;
+
 use anyhow::Context;
 use camino::{Utf8Path, Utf8PathBuf};
 
@@ -86,36 +88,57 @@ llvm-config = "{llvm_config}"
     log::info!("Using following `config.toml` for running tests:\n{config_content}");
 
     // Simulate a stage 0 compiler with the extracted optimized dist artifacts.
-    std::fs::write("config.toml", config_content)?;
-
-    let x_py = env.checkout_path().join("x.py");
-    let mut args = vec![
-        env.python_binary(),
-        x_py.as_str(),
-        "test",
-        "--build",
-        env.host_tuple(),
-        "--stage",
-        "0",
-        "tests/assembly",
-        "tests/codegen",
-        "tests/codegen-units",
-        "tests/incremental",
-        "tests/mir-opt",
-        "tests/pretty",
-        "tests/run-make/glibc-symbols-x86_64-unknown-linux-gnu",
-        "tests/ui",
-        "tests/crashes",
-    ];
-    for test_path in env.skipped_tests() {
-        args.extend(["--skip", test_path]);
+    with_backed_up_file(Path::new("config.toml"), &config_content, || {
+        let x_py = env.checkout_path().join("x.py");
+        let mut args = vec![
+            env.python_binary(),
+            x_py.as_str(),
+            "test",
+            "--build",
+            env.host_tuple(),
+            "--stage",
+            "0",
+            "tests/assembly",
+            "tests/codegen",
+            "tests/codegen-units",
+            "tests/incremental",
+            "tests/mir-opt",
+            "tests/pretty",
+            "tests/run-make/glibc-symbols-x86_64-unknown-linux-gnu",
+            "tests/ui",
+            "tests/crashes",
+        ];
+        for test_path in env.skipped_tests() {
+            args.extend(["--skip", test_path]);
+        }
+        cmd(&args)
+            .env("COMPILETEST_FORCE_STAGE0", "1")
+            // Also run dist-only tests
+            .env("COMPILETEST_ENABLE_DIST_TESTS", "1")
+            .run()
+            .context("Cannot execute tests")
+    })
+}
+
+/// Backup `path` (if it exists), then write `contents` into it, and then restore the original
+/// contents of the file.
+fn with_backed_up_file<F>(path: &Path, contents: &str, func: F) -> anyhow::Result<()>
+where
+    F: FnOnce() -> anyhow::Result<()>,
+{
+    let original_contents =
+        if path.is_file() { Some(std::fs::read_to_string(path)?) } else { None };
+
+    // Overwrite it with new contents
+    std::fs::write(path, contents)?;
+
+    let ret = func();
+
+    if let Some(original_contents) = original_contents {
+        std::fs::write(path, original_contents)?;
     }
-    cmd(&args)
-        .env("COMPILETEST_FORCE_STAGE0", "1")
-        // Also run dist-only tests
-        .env("COMPILETEST_ENABLE_DIST_TESTS", "1")
-        .run()
-        .context("Cannot execute tests")
+
+    ret
 }
 
 /// Tries to find the version of the dist artifacts (either nightly, beta, or 1.XY.Z).

tests/ui/crate_type_flag.rs

@@ -0,0 +1,4 @@
+//@ compile-flags: --crate-type dynlib
+//@ error-pattern: unknown crate type: `dynlib`, expected one of: `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`
+
+fn main() {}

tests/ui/crate_type_flag.stderr

@@ -0,0 +1,2 @@
+error: unknown crate type: `dynlib`, expected one of: `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`
+

tests/ui/invalid-compile-flags/crate-type-flag.empty_crate_type.stderr

@@ -1,2 +1,2 @@
-error: unknown crate type: ``
+error: unknown crate type: ``, expected one of: `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`
 

tests/ui/invalid-compile-flags/crate-type-flag.proc_underscore_macro.stderr

@@ -1,2 +1,2 @@
-error: unknown crate type: `proc_macro`
+error: unknown crate type: `proc_macro`, expected one of: `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`
 

tests/ui/invalid-compile-flags/crate-type-flag.rs

@@ -45,16 +45,16 @@
 // `proc-macro` is accepted, but `proc_macro` is not.
 //@ revisions: proc_underscore_macro
 //@[proc_underscore_macro] compile-flags: --crate-type=proc_macro
-//@[proc_underscore_macro] error-pattern: "unknown crate type: `proc_macro`"
+//@[proc_underscore_macro] error-pattern: unknown crate type: `proc_macro`
 
 // Empty `--crate-type` not accepted.
 //@ revisions: empty_crate_type
 //@[empty_crate_type] compile-flags: --crate-type=
-//@[empty_crate_type] error-pattern: "unknown crate type: ``"
+//@[empty_crate_type] error-pattern: unknown crate type: ``
 
 // Random unknown crate type. Also check that we can handle non-ASCII.
 //@ revisions: unknown
 //@[unknown] compile-flags: --crate-type=🤡
-//@[unknown] error-pattern: "unknown crate type: `🤡`"
+//@[unknown] error-pattern: unknown crate type: `🤡`
 
 fn main() {}

tests/ui/invalid-compile-flags/crate-type-flag.unknown.stderr

@@ -1,2 +1,2 @@
-error: unknown crate type: `🤡`
+error: unknown crate type: `🤡`, expected one of: `lib`, `rlib`, `staticlib`, `dylib`, `cdylib`, `bin`, `proc-macro`
 

tests/ui/lint/linker-warning.stderr

@@ -16,7 +16,7 @@ warning: unused attribute
 LL | #![allow(linker_messages)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove this attribute
    |
-   = note: the `linker_warnings` lint can only be controlled at the root of a crate that needs to be linked
+   = note: the `linker_messages` lint can only be controlled at the root of a crate that needs to be linked
 
 warning: 2 warnings emitted