diff --git a/Cargo.lock b/Cargo.lock
index 266a93605bde7..06576c703e295 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -405,9 +405,9 @@ version = "0.1.0"
 
 [[package]]
 name = "cc"
-version = "1.2.5"
+version = "1.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c31a0499c1dc64f458ad13872de75c0eb7e3fdb0e67964610c914b034fc5956e"
+checksum = "8d6dbb628b8f8555f86d0323c2eb39e3ec81901f4b83e091db8a6a76d316a333"
 dependencies = [
  "shlex",
 ]
diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml
index 3a9b4d3680782..f0456e62442a6 100644
--- a/compiler/rustc_codegen_ssa/Cargo.toml
+++ b/compiler/rustc_codegen_ssa/Cargo.toml
@@ -10,7 +10,7 @@ arrayvec = { version = "0.7", default-features = false }
 bitflags = "2.4.1"
 # Pinned so `cargo update` bumps don't cause breakage. Please also update the
 # `cc` in `rustc_llvm` if you update the `cc` here.
-cc = "=1.2.5"
+cc = "=1.2.6"
 either = "1.5.0"
 itertools = "0.12"
 pathdiff = "0.2.0"
diff --git a/compiler/rustc_llvm/Cargo.toml b/compiler/rustc_llvm/Cargo.toml
index 79a6454dbb94a..b2a14a0022e8b 100644
--- a/compiler/rustc_llvm/Cargo.toml
+++ b/compiler/rustc_llvm/Cargo.toml
@@ -12,5 +12,5 @@ libc = "0.2.73"
 # tidy-alphabetical-start
 # Pinned so `cargo update` bumps don't cause breakage. Please also update the
 # pinned `cc` in `rustc_codegen_ssa` if you update `cc` here.
-cc = "=1.2.5"
+cc = "=1.2.6"
 # tidy-alphabetical-end
diff --git a/library/alloc/src/ffi/mod.rs b/library/alloc/src/ffi/mod.rs
index 4f9dc40a3cfc9..695d7ad07cf76 100644
--- a/library/alloc/src/ffi/mod.rs
+++ b/library/alloc/src/ffi/mod.rs
@@ -83,7 +83,7 @@
 #[doc(inline)]
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::CString;
-#[doc(no_inline)]
+#[doc(inline)]
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::{FromVecWithNulError, IntoStringError, NulError};
 
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 95192efda9887..fe2dd9cc5f3ee 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -1133,69 +1133,21 @@ fn testdir(builder: &Builder<'_>, host: TargetSelection) -> PathBuf {
     builder.out.join(host).join("test")
 }
 
-macro_rules! default_test {
-    ($name:ident { path: $path:expr, mode: $mode:expr, suite: $suite:expr }) => {
-        test!($name { path: $path, mode: $mode, suite: $suite, default: true, host: false });
-    };
-}
-
-macro_rules! default_test_with_compare_mode {
-    ($name:ident { path: $path:expr, mode: $mode:expr, suite: $suite:expr,
-                   compare_mode: $compare_mode:expr }) => {
-        test_with_compare_mode!($name {
-            path: $path,
-            mode: $mode,
-            suite: $suite,
-            default: true,
-            host: false,
-            compare_mode: $compare_mode
-        });
-    };
-}
-
-macro_rules! host_test {
-    ($name:ident { path: $path:expr, mode: $mode:expr, suite: $suite:expr }) => {
-        test!($name { path: $path, mode: $mode, suite: $suite, default: true, host: true });
-    };
-}
-
+/// Declares a test step that invokes compiletest on a particular test suite.
 macro_rules! test {
-    ($name:ident { path: $path:expr, mode: $mode:expr, suite: $suite:expr, default: $default:expr,
-                   host: $host:expr }) => {
-        test_definitions!($name {
-            path: $path,
-            mode: $mode,
-            suite: $suite,
-            default: $default,
-            host: $host,
-            compare_mode: None
-        });
-    };
-}
-
-macro_rules! test_with_compare_mode {
-    ($name:ident { path: $path:expr, mode: $mode:expr, suite: $suite:expr, default: $default:expr,
-                   host: $host:expr, compare_mode: $compare_mode:expr }) => {
-        test_definitions!($name {
-            path: $path,
-            mode: $mode,
-            suite: $suite,
-            default: $default,
-            host: $host,
-            compare_mode: Some($compare_mode)
-        });
-    };
-}
-
-macro_rules! test_definitions {
-    ($name:ident {
-        path: $path:expr,
-        mode: $mode:expr,
-        suite: $suite:expr,
-        default: $default:expr,
-        host: $host:expr,
-        compare_mode: $compare_mode:expr
-    }) => {
+    (
+        $( #[$attr:meta] )* // allow docstrings and attributes
+        $name:ident {
+            path: $path:expr,
+            mode: $mode:expr,
+            suite: $suite:expr,
+            default: $default:expr
+            $( , only_hosts: $only_hosts:expr )? // default: false
+            $( , compare_mode: $compare_mode:expr )? // default: None
+            $( , )? // optional trailing comma
+        }
+    ) => {
+        $( #[$attr] )*
         #[derive(Debug, Clone, PartialEq, Eq, Hash)]
         pub struct $name {
             pub compiler: Compiler,
@@ -1205,7 +1157,12 @@ macro_rules! test_definitions {
         impl Step for $name {
             type Output = ();
             const DEFAULT: bool = $default;
-            const ONLY_HOSTS: bool = $host;
+            const ONLY_HOSTS: bool = (const {
+                #[allow(unused_assignments, unused_mut)]
+                let mut value = false;
+                $( value = $only_hosts; )?
+                value
+            });
 
             fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
                 run.suite_path($path)
@@ -1224,7 +1181,12 @@ macro_rules! test_definitions {
                     mode: $mode,
                     suite: $suite,
                     path: $path,
-                    compare_mode: $compare_mode,
+                    compare_mode: (const {
+                        #[allow(unused_assignments, unused_mut)]
+                        let mut value = None;
+                        $( value = $compare_mode; )?
+                        value
+                    }),
                 })
             }
         }
@@ -1232,13 +1194,18 @@ macro_rules! test_definitions {
 }
 
 /// Declares an alias for running the [`Coverage`] tests in only one mode.
-/// Adapted from [`test_definitions`].
+/// Adapted from [`test`].
 macro_rules! coverage_test_alias {
-    ($name:ident {
-        alias_and_mode: $alias_and_mode:expr, // &'static str
-        default: $default:expr, // bool
-        only_hosts: $only_hosts:expr $(,)? // bool
-    }) => {
+    (
+        $( #[$attr:meta] )* // allow docstrings and attributes
+        $name:ident {
+            alias_and_mode: $alias_and_mode:expr, // &'static str
+            default: $default:expr, // bool
+            only_hosts: $only_hosts:expr // bool
+            $( , )? // optional trailing comma
+        }
+    ) => {
+        $( #[$attr] )*
         #[derive(Debug, Clone, PartialEq, Eq, Hash)]
         pub struct $name {
             pub compiler: Compiler,
@@ -1410,37 +1377,74 @@ impl Step for CrateBuildHelper {
     }
 }
 
-default_test!(Ui { path: "tests/ui", mode: "ui", suite: "ui" });
+test!(Ui { path: "tests/ui", mode: "ui", suite: "ui", default: true });
 
-default_test!(Crashes { path: "tests/crashes", mode: "crashes", suite: "crashes" });
+test!(Crashes { path: "tests/crashes", mode: "crashes", suite: "crashes", default: true });
 
-default_test!(Codegen { path: "tests/codegen", mode: "codegen", suite: "codegen" });
+test!(Codegen { path: "tests/codegen", mode: "codegen", suite: "codegen", default: true });
 
-default_test!(CodegenUnits {
+test!(CodegenUnits {
     path: "tests/codegen-units",
     mode: "codegen-units",
-    suite: "codegen-units"
+    suite: "codegen-units",
+    default: true,
 });
 
-default_test!(Incremental { path: "tests/incremental", mode: "incremental", suite: "incremental" });
+test!(Incremental {
+    path: "tests/incremental",
+    mode: "incremental",
+    suite: "incremental",
+    default: true,
+});
 
-default_test_with_compare_mode!(Debuginfo {
+test!(Debuginfo {
     path: "tests/debuginfo",
     mode: "debuginfo",
     suite: "debuginfo",
-    compare_mode: "split-dwarf"
+    default: true,
+    compare_mode: Some("split-dwarf"),
 });
 
-host_test!(UiFullDeps { path: "tests/ui-fulldeps", mode: "ui", suite: "ui-fulldeps" });
+test!(UiFullDeps {
+    path: "tests/ui-fulldeps",
+    mode: "ui",
+    suite: "ui-fulldeps",
+    default: true,
+    only_hosts: true,
+});
 
-host_test!(Rustdoc { path: "tests/rustdoc", mode: "rustdoc", suite: "rustdoc" });
-host_test!(RustdocUi { path: "tests/rustdoc-ui", mode: "ui", suite: "rustdoc-ui" });
+test!(Rustdoc {
+    path: "tests/rustdoc",
+    mode: "rustdoc",
+    suite: "rustdoc",
+    default: true,
+    only_hosts: true,
+});
+test!(RustdocUi {
+    path: "tests/rustdoc-ui",
+    mode: "ui",
+    suite: "rustdoc-ui",
+    default: true,
+    only_hosts: true,
+});
 
-host_test!(RustdocJson { path: "tests/rustdoc-json", mode: "rustdoc-json", suite: "rustdoc-json" });
+test!(RustdocJson {
+    path: "tests/rustdoc-json",
+    mode: "rustdoc-json",
+    suite: "rustdoc-json",
+    default: true,
+    only_hosts: true,
+});
 
-host_test!(Pretty { path: "tests/pretty", mode: "pretty", suite: "pretty" });
+test!(Pretty {
+    path: "tests/pretty",
+    mode: "pretty",
+    suite: "pretty",
+    default: true,
+    only_hosts: true,
+});
 
-/// Special-handling is needed for `run-make`, so don't use `default_test` for defining `RunMake`
+/// Special-handling is needed for `run-make`, so don't use `test!` for defining `RunMake`
 /// tests.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub struct RunMake {
@@ -1475,7 +1479,7 @@ impl Step for RunMake {
     }
 }
 
-default_test!(Assembly { path: "tests/assembly", mode: "assembly", suite: "assembly" });
+test!(Assembly { path: "tests/assembly", mode: "assembly", suite: "assembly", default: true });
 
 /// Coverage tests are a bit more complicated than other test suites, because
 /// we want to run the same set of test files in multiple different modes,
@@ -1552,27 +1556,33 @@ impl Step for Coverage {
     }
 }
 
-// Runs `tests/coverage` in "coverage-map" mode only.
-// Used by `x test` and `x test coverage-map`.
-coverage_test_alias!(CoverageMap {
-    alias_and_mode: "coverage-map",
-    default: true,
-    only_hosts: false,
-});
-// Runs `tests/coverage` in "coverage-run" mode only.
-// Used by `x test` and `x test coverage-run`.
-coverage_test_alias!(CoverageRun {
-    alias_and_mode: "coverage-run",
-    default: true,
-    // Compiletest knows how to automatically skip these tests when cross-compiling,
-    // but skipping the whole step here makes it clearer that they haven't run at all.
-    only_hosts: true,
-});
+coverage_test_alias! {
+    /// Runs the `tests/coverage` test suite in "coverage-map" mode only.
+    /// Used by `x test` and `x test coverage-map`.
+    CoverageMap {
+        alias_and_mode: "coverage-map",
+        default: true,
+        only_hosts: false,
+    }
+}
+coverage_test_alias! {
+    /// Runs the `tests/coverage` test suite in "coverage-run" mode only.
+    /// Used by `x test` and `x test coverage-run`.
+    CoverageRun {
+        alias_and_mode: "coverage-run",
+        default: true,
+        // Compiletest knows how to automatically skip these tests when cross-compiling,
+        // but skipping the whole step here makes it clearer that they haven't run at all.
+        only_hosts: true,
+    }
+}
 
-host_test!(CoverageRunRustdoc {
+test!(CoverageRunRustdoc {
     path: "tests/coverage-run-rustdoc",
     mode: "coverage-run",
-    suite: "coverage-run-rustdoc"
+    suite: "coverage-run-rustdoc",
+    default: true,
+    only_hosts: true,
 });
 
 // For the mir-opt suite we do not use macros, as we need custom behavior when blessing.
diff --git a/src/bootstrap/src/utils/mod.rs b/src/bootstrap/src/utils/mod.rs
index 53b41f1578060..b5f5e2ba6dc8b 100644
--- a/src/bootstrap/src/utils/mod.rs
+++ b/src/bootstrap/src/utils/mod.rs
@@ -14,3 +14,5 @@ pub(crate) mod metrics;
 pub(crate) mod render_tests;
 pub(crate) mod shared_helpers;
 pub(crate) mod tarball;
+#[cfg(test)]
+mod tests;
diff --git a/src/bootstrap/src/utils/shared_helpers.rs b/src/bootstrap/src/utils/shared_helpers.rs
index 6d3c276cc056d..7b206c3ffe826 100644
--- a/src/bootstrap/src/utils/shared_helpers.rs
+++ b/src/bootstrap/src/utils/shared_helpers.rs
@@ -13,8 +13,9 @@ use std::io::Write;
 use std::process::Command;
 use std::str::FromStr;
 
-#[cfg(test)]
-mod tests;
+// If we were to declare a tests submodule here, the shim binaries that include this
+// module via `#[path]` would fail to find it, which breaks `./x check bootstrap`.
+// So instead the unit tests for this module are in `super::tests::shared_helpers_tests`.
 
 /// Returns the environment variable which the dynamic library lookup path
 /// resides in for this platform.
diff --git a/src/bootstrap/src/utils/tests/mod.rs b/src/bootstrap/src/utils/tests/mod.rs
new file mode 100644
index 0000000000000..0791f7a6e2074
--- /dev/null
+++ b/src/bootstrap/src/utils/tests/mod.rs
@@ -0,0 +1 @@
+mod shared_helpers_tests;
diff --git a/src/bootstrap/src/utils/shared_helpers/tests.rs b/src/bootstrap/src/utils/tests/shared_helpers_tests.rs
similarity index 69%
rename from src/bootstrap/src/utils/shared_helpers/tests.rs
rename to src/bootstrap/src/utils/tests/shared_helpers_tests.rs
index da7924276f7c8..6c47e7f24387e 100644
--- a/src/bootstrap/src/utils/shared_helpers/tests.rs
+++ b/src/bootstrap/src/utils/tests/shared_helpers_tests.rs
@@ -1,4 +1,11 @@
-use super::parse_value_from_args;
+//! The `shared_helpers` module can't have its own tests submodule, because
+//! that would cause problems for the shim binaries that include it via
+//! `#[path]`, so instead those unit tests live here.
+//!
+//! To prevent tidy from complaining about this file not being named `tests.rs`,
+//! it lives inside a submodule directory named `tests`.
+
+use crate::utils::shared_helpers::parse_value_from_args;
 
 #[test]
 fn test_parse_value_from_args() {
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 27b7d55f4d08b..3c9e0914b59d7 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -268,7 +268,7 @@ fn clean_poly_trait_ref_with_constraints<'tcx>(
     )
 }
 
-fn clean_lifetime(lifetime: &hir::Lifetime, cx: &mut DocContext<'_>) -> Lifetime {
+fn clean_lifetime(lifetime: &hir::Lifetime, cx: &DocContext<'_>) -> Lifetime {
     if let Some(
         rbv::ResolvedArg::EarlyBound(did)
         | rbv::ResolvedArg::LateBound(_, _, did)
@@ -362,9 +362,9 @@ pub(crate) fn clean_predicate<'tcx>(
     let bound_predicate = predicate.kind();
     match bound_predicate.skip_binder() {
         ty::ClauseKind::Trait(pred) => clean_poly_trait_predicate(bound_predicate.rebind(pred), cx),
-        ty::ClauseKind::RegionOutlives(pred) => clean_region_outlives_predicate(pred),
+        ty::ClauseKind::RegionOutlives(pred) => Some(clean_region_outlives_predicate(pred)),
         ty::ClauseKind::TypeOutlives(pred) => {
-            clean_type_outlives_predicate(bound_predicate.rebind(pred), cx)
+            Some(clean_type_outlives_predicate(bound_predicate.rebind(pred), cx))
         }
         ty::ClauseKind::Projection(pred) => {
             Some(clean_projection_predicate(bound_predicate.rebind(pred), cx))
@@ -396,32 +396,30 @@ fn clean_poly_trait_predicate<'tcx>(
     })
 }
 
-fn clean_region_outlives_predicate(
-    pred: ty::RegionOutlivesPredicate<'_>,
-) -> Option<WherePredicate> {
+fn clean_region_outlives_predicate(pred: ty::RegionOutlivesPredicate<'_>) -> WherePredicate {
     let ty::OutlivesPredicate(a, b) = pred;
 
-    Some(WherePredicate::RegionPredicate {
+    WherePredicate::RegionPredicate {
         lifetime: clean_middle_region(a).expect("failed to clean lifetime"),
         bounds: vec![GenericBound::Outlives(
             clean_middle_region(b).expect("failed to clean bounds"),
         )],
-    })
+    }
 }
 
 fn clean_type_outlives_predicate<'tcx>(
     pred: ty::Binder<'tcx, ty::TypeOutlivesPredicate<'tcx>>,
     cx: &mut DocContext<'tcx>,
-) -> Option<WherePredicate> {
+) -> WherePredicate {
     let ty::OutlivesPredicate(ty, lt) = pred.skip_binder();
 
-    Some(WherePredicate::BoundPredicate {
+    WherePredicate::BoundPredicate {
         ty: clean_middle_ty(pred.rebind(ty), cx, None, None),
         bounds: vec![GenericBound::Outlives(
             clean_middle_region(lt).expect("failed to clean lifetimes"),
         )],
         bound_params: Vec::new(),
-    })
+    }
 }
 
 fn clean_middle_term<'tcx>(
@@ -1860,7 +1858,7 @@ pub(crate) fn clean_ty<'tcx>(ty: &hir::Ty<'tcx>, cx: &mut DocContext<'tcx>) -> T
 
 /// Returns `None` if the type could not be normalized
 fn normalize<'tcx>(
-    cx: &mut DocContext<'tcx>,
+    cx: &DocContext<'tcx>,
     ty: ty::Binder<'tcx, Ty<'tcx>>,
 ) -> Option<ty::Binder<'tcx, Ty<'tcx>>> {
     // HACK: low-churn fix for #79459 while we wait for a trait normalization fix