From 5e1ffef03c79a92143b87edd660a147d889e17d9 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 24 Jul 2025 09:14:46 +0000
Subject: [PATCH 1/3] Improve unit_tests tidy lint

Make it clearer where unit tests are allowed and restrict standard
library unit tests inside the same package to std_detect, std and test.
---
 src/tools/tidy/src/main.rs       |  6 +--
 src/tools/tidy/src/unit_tests.rs | 84 ++++++++++++++++++++------------
 2 files changed, 57 insertions(+), 33 deletions(-)

diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 13b20f33bd0f7..1a32372d2093f 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -127,9 +127,9 @@ fn main() {
         check!(pal, &library_path);
 
         // Checks that need to be done for both the compiler and std libraries.
-        check!(unit_tests, &src_path);
-        check!(unit_tests, &compiler_path);
-        check!(unit_tests, &library_path);
+        check!(unit_tests, &src_path, false);
+        check!(unit_tests, &compiler_path, false);
+        check!(unit_tests, &library_path, true);
 
         if bins::check_filesystem_support(&[&root_path], &output_directory) {
             check!(bins, &root_path);
diff --git a/src/tools/tidy/src/unit_tests.rs b/src/tools/tidy/src/unit_tests.rs
index df9146b51474c..90da1bc765a9d 100644
--- a/src/tools/tidy/src/unit_tests.rs
+++ b/src/tools/tidy/src/unit_tests.rs
@@ -1,44 +1,60 @@
 //! Tidy check to ensure `#[test]` and `#[bench]` are not used directly inside
-//! `core` or `alloc`.
+//! of the standard library.
 //!
 //! `core` and `alloc` cannot be tested directly due to duplicating lang items.
 //! All tests and benchmarks must be written externally in
 //! `{coretests,alloctests}/{tests,benches}`.
 //!
-//! Outside of `core` and `alloc`, tests and benchmarks should be outlined into
-//! separate files named `tests.rs` or `benches.rs`, or directories named
+//! Outside of the standard library, tests and benchmarks should be outlined
+//! into separate files named `tests.rs` or `benches.rs`, or directories named
 //! `tests` or `benches` unconfigured during normal build.
 
 use std::path::Path;
 
 use crate::walk::{filter_dirs, walk};
 
-pub fn check(root_path: &Path, bad: &mut bool) {
-    let core = root_path.join("core");
-    let core_copy = core.clone();
-    let is_core = move |path: &Path| path.starts_with(&core);
-    let alloc = root_path.join("alloc");
-    let alloc_copy = alloc.clone();
-    let is_alloc = move |path: &Path| path.starts_with(&alloc);
-
+pub fn check(root_path: &Path, stdlib: bool, bad: &mut bool) {
     let skip = move |path: &Path, is_dir| {
         let file_name = path.file_name().unwrap_or_default();
+
+        // Skip excluded directories and non-rust files
         if is_dir {
-            filter_dirs(path)
-                || path.ends_with("src/doc")
-                || (file_name == "tests" || file_name == "benches")
-                    && !is_core(path)
-                    && !is_alloc(path)
+            if filter_dirs(path) || path.ends_with("src/doc") {
+                return true;
+            }
         } else {
             let extension = path.extension().unwrap_or_default();
-            extension != "rs"
-                || (file_name == "tests.rs" || file_name == "benches.rs")
-                    && !is_core(path)
-                    && !is_alloc(path)
-                // Tests which use non-public internals and, as such, need to
-                // have the types in the same crate as the tests themselves. See
-                // the comment in alloctests/lib.rs.
-                || path.ends_with("library/alloc/src/collections/btree/borrow/tests.rs")
+            if extension != "rs" {
+                return true;
+            }
+        }
+
+        // Tests in a separate package are always allowed
+        if is_dir && file_name != "tests" && file_name.as_encoded_bytes().ends_with(b"tests") {
+            return true;
+        }
+
+        if !stdlib {
+            // Outside of the standard library tests may also be in separate files in the same crate
+            if is_dir {
+                if file_name == "tests" || file_name == "benches" {
+                    return true;
+                }
+            } else {
+                if file_name == "tests.rs" || file_name == "benches.rs" {
+                    return true;
+                }
+            }
+        }
+
+        if is_dir {
+            // FIXME remove those exceptions once no longer necessary
+            file_name == "std_detect" || file_name == "std" || file_name == "test"
+        } else {
+            // Tests which use non-public internals and, as such, need to
+            // have the types in the same crate as the tests themselves. See
+            // the comment in alloctests/lib.rs.
+            path.ends_with("library/alloc/src/collections/btree/borrow/tests.rs")
                 || path.ends_with("library/alloc/src/collections/btree/map/tests.rs")
                 || path.ends_with("library/alloc/src/collections/btree/node/tests.rs")
                 || path.ends_with("library/alloc/src/collections/btree/set/tests.rs")
@@ -50,22 +66,30 @@ pub fn check(root_path: &Path, bad: &mut bool) {
 
     walk(root_path, skip, &mut |entry, contents| {
         let path = entry.path();
-        let is_core = path.starts_with(&core_copy);
-        let is_alloc = path.starts_with(&alloc_copy);
+        let package = path
+            .strip_prefix(root_path)
+            .unwrap()
+            .components()
+            .next()
+            .unwrap()
+            .as_os_str()
+            .to_str()
+            .unwrap();
         for (i, line) in contents.lines().enumerate() {
             let line = line.trim();
             let is_test = || line.contains("#[test]") && !line.contains("`#[test]");
             let is_bench = || line.contains("#[bench]") && !line.contains("`#[bench]");
             let manual_skip = line.contains("//tidy:skip");
             if !line.starts_with("//") && (is_test() || is_bench()) && !manual_skip {
-                let explanation = if is_core {
-                    "`core` unit tests and benchmarks must be placed into `coretests`"
-                } else if is_alloc {
-                    "`alloc` unit tests and benchmarks must be placed into `alloctests`"
+                let explanation = if stdlib {
+                    format!(
+                        "`{package}` unit tests and benchmarks must be placed into `{package}tests`"
+                    )
                 } else {
                     "unit tests and benchmarks must be placed into \
                          separate files or directories named \
                          `tests.rs`, `benches.rs`, `tests` or `benches`"
+                        .to_owned()
                 };
                 let name = if is_test() { "test" } else { "bench" };
                 tidy_error!(

From c5d7021cddd97a4ec8dd64f878711ec983986fcd Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 24 Jul 2025 09:15:28 +0000
Subject: [PATCH 2/3] Disable unit tests for stdlib packages that don't contain
 any

---
 library/rustc-std-workspace-alloc/Cargo.toml | 3 +++
 library/rustc-std-workspace-core/Cargo.toml  | 3 +++
 library/rustc-std-workspace-std/Cargo.toml   | 3 +++
 library/sysroot/Cargo.toml                   | 2 ++
 library/windows_targets/Cargo.toml           | 5 +++++
 5 files changed, 16 insertions(+)

diff --git a/library/rustc-std-workspace-alloc/Cargo.toml b/library/rustc-std-workspace-alloc/Cargo.toml
index 5a177808d1bd8..a5b51059119c0 100644
--- a/library/rustc-std-workspace-alloc/Cargo.toml
+++ b/library/rustc-std-workspace-alloc/Cargo.toml
@@ -9,6 +9,9 @@ edition = "2024"
 
 [lib]
 path = "lib.rs"
+test = false
+bench = false
+doc = false
 
 [dependencies]
 alloc = { path = "../alloc" }
diff --git a/library/rustc-std-workspace-core/Cargo.toml b/library/rustc-std-workspace-core/Cargo.toml
index 1ddc112380f16..d68965c634578 100644
--- a/library/rustc-std-workspace-core/Cargo.toml
+++ b/library/rustc-std-workspace-core/Cargo.toml
@@ -11,6 +11,9 @@ edition = "2024"
 
 [lib]
 path = "lib.rs"
+test = false
+bench = false
+doc = false
 
 [dependencies]
 core = { path = "../core", public = true }
diff --git a/library/rustc-std-workspace-std/Cargo.toml b/library/rustc-std-workspace-std/Cargo.toml
index f70994e1f8868..6079dc85d906b 100644
--- a/library/rustc-std-workspace-std/Cargo.toml
+++ b/library/rustc-std-workspace-std/Cargo.toml
@@ -9,6 +9,9 @@ edition = "2024"
 
 [lib]
 path = "lib.rs"
+test = false
+bench = false
+doc = false
 
 [dependencies]
 std = { path = "../std" }
diff --git a/library/sysroot/Cargo.toml b/library/sysroot/Cargo.toml
index 032f5272a9cd4..2952556f699d8 100644
--- a/library/sysroot/Cargo.toml
+++ b/library/sysroot/Cargo.toml
@@ -6,6 +6,8 @@ version = "0.0.0"
 edition = "2024"
 
 [lib]
+test = false
+bench = false
 # make sure this crate isn't included in public standard library docs
 doc = false
 
diff --git a/library/windows_targets/Cargo.toml b/library/windows_targets/Cargo.toml
index 705c9e0438119..1c804a0ab391f 100644
--- a/library/windows_targets/Cargo.toml
+++ b/library/windows_targets/Cargo.toml
@@ -4,6 +4,11 @@ description = "A drop-in replacement for the real windows-targets crate for use
 version = "0.0.0"
 edition = "2024"
 
+[lib]
+test = false
+bench = false
+doc = false
+
 [features]
 # Enable using raw-dylib for Windows imports.
 # This will eventually be the default.

From b481c5b8ba322612fb3bc167e323f7a548a2390c Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 24 Jul 2025 13:01:08 +0000
Subject: [PATCH 3/3] std_detect testing improvements

* Fix riscv testing. Previously the mod tests; would be looking for
  src/detect/os/tests.rs.
* Replace a test with an unnamed const item. It is testing that no
  warnings are emitted. It doesn't contain any checks that need to run
  at runtime. Replacing the test allows removing the tidy:skip directive
  for test locations.
---
 library/std_detect/src/detect/macros.rs   | 5 ++---
 library/std_detect/src/detect/os/riscv.rs | 1 +
 src/tools/tidy/src/unit_tests.rs          | 3 +--
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/library/std_detect/src/detect/macros.rs b/library/std_detect/src/detect/macros.rs
index c2a006d3753a1..17140e15653d2 100644
--- a/library/std_detect/src/detect/macros.rs
+++ b/library/std_detect/src/detect/macros.rs
@@ -131,14 +131,13 @@ macro_rules! features {
             };
         }
 
-        #[test] //tidy:skip
         #[deny(unexpected_cfgs)]
         #[deny(unfulfilled_lint_expectations)]
-        fn unexpected_cfgs() {
+        const _: () = {
             $(
                 check_cfg_feature!($feature, $feature_lit $(, without cfg check: $feature_cfg_check)? $(: $($target_feature_lit),*)?);
             )*
-        }
+        };
 
         /// Each variant denotes a position in a bitset for a particular feature.
         ///
diff --git a/library/std_detect/src/detect/os/riscv.rs b/library/std_detect/src/detect/os/riscv.rs
index 46b7dd71eb351..dc9a4036d86a1 100644
--- a/library/std_detect/src/detect/os/riscv.rs
+++ b/library/std_detect/src/detect/os/riscv.rs
@@ -135,4 +135,5 @@ pub(crate) fn imply_features(mut value: cache::Initializer) -> cache::Initialize
 }
 
 #[cfg(test)]
+#[path = "riscv/tests.rs"]
 mod tests;
diff --git a/src/tools/tidy/src/unit_tests.rs b/src/tools/tidy/src/unit_tests.rs
index 90da1bc765a9d..3d14a46731932 100644
--- a/src/tools/tidy/src/unit_tests.rs
+++ b/src/tools/tidy/src/unit_tests.rs
@@ -79,8 +79,7 @@ pub fn check(root_path: &Path, stdlib: bool, bad: &mut bool) {
             let line = line.trim();
             let is_test = || line.contains("#[test]") && !line.contains("`#[test]");
             let is_bench = || line.contains("#[bench]") && !line.contains("`#[bench]");
-            let manual_skip = line.contains("//tidy:skip");
-            if !line.starts_with("//") && (is_test() || is_bench()) && !manual_skip {
+            if !line.starts_with("//") && (is_test() || is_bench()) {
                 let explanation = if stdlib {
                     format!(
                         "`{package}` unit tests and benchmarks must be placed into `{package}tests`"