Rollup merge of #137885 - klensy:tidy-triagebot, r=jieyouxu

tidy: add triagebot checks

Validates triagebot.toml to have existing paths:

`[mentions."*"]` sections, i.e.
```toml
[mentions."compiler/rustc_const_eval/src/"]
```
or
```toml
[assign.owners]
"/.github/workflows" = ["infra-ci"]
```
or

```toml
trigger_files = [
 "src/librustdoc/html/static/js/search.js",
 "tests/rustdoc-js",
 "tests/rustdoc-js-std",
 ]
```
Looked at #137876 and implemented check.

4 files changed, 97 insertions, 0 deletions

diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index 9a4d0891b4a..dfdbc0878f2 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -17,6 +17,7 @@ termcolor = "1.1.3"
 rustc-hash = "2.0.0"
 fluent-syntax = "0.11.1"
 similar = "2.5.0"
+toml = "0.7.8"
 
 [features]
 build-metrics = ["dep:serde"]
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 9f6d563166e..66856f5247b 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -87,6 +87,7 @@ pub mod target_policy;
 pub mod target_specific_tests;
 pub mod tests_placement;
 pub mod tests_revision_unpaired_stdout_stderr;
+pub mod triagebot;
 pub mod ui_tests;
 pub mod unit_tests;
 pub mod unknown_revision;
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 1d8514ef4c9..bc3519142dd 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -144,6 +144,8 @@ fn main() {
 
         check!(x_version, &root_path, &cargo);
 
+        check!(triagebot, &root_path);
+
         let collected = {
             drain_handles(&mut handles);
 
diff --git a/src/tools/tidy/src/triagebot.rs b/src/tools/tidy/src/triagebot.rs
new file mode 100644
index 00000000000..7131c16ec30
--- /dev/null
+++ b/src/tools/tidy/src/triagebot.rs
@@ -0,0 +1,93 @@
+//! Tidy check to ensure paths mentioned in triagebot.toml exist in the project.
+
+use std::path::Path;
+
+use toml::Value;
+
+pub fn check(path: &Path, bad: &mut bool) {
+    let triagebot_path = path.join("triagebot.toml");
+    if !triagebot_path.exists() {
+        tidy_error!(bad, "triagebot.toml file not found");
+        return;
+    }
+
+    let contents = std::fs::read_to_string(&triagebot_path).unwrap();
+    let config: Value = toml::from_str(&contents).unwrap();
+
+    // Check [mentions."*"] sections, i.e. [mentions."compiler/rustc_const_eval/src/"]
+    if let Some(Value::Table(mentions)) = config.get("mentions") {
+        for path_str in mentions.keys() {
+            // Remove quotes from the path
+            let clean_path = path_str.trim_matches('"');
+            let full_path = path.join(clean_path);
+
+            if !full_path.exists() {
+                tidy_error!(
+                    bad,
+                    "triagebot.toml [mentions.*] contains path '{}' which doesn't exist",
+                    clean_path
+                );
+            }
+        }
+    } else {
+        tidy_error!(
+            bad,
+            "triagebot.toml missing [mentions.*] section, this wrong for rust-lang/rust repo."
+        );
+    }
+
+    // Check [assign.owners] sections, i.e.
+    // [assign.owners]
+    // "/.github/workflows" = ["infra-ci"]
+    if let Some(Value::Table(assign)) = config.get("assign") {
+        if let Some(Value::Table(owners)) = assign.get("owners") {
+            for path_str in owners.keys() {
+                // Remove quotes and leading slash from the path
+                let clean_path = path_str.trim_matches('"').trim_start_matches('/');
+                let full_path = path.join(clean_path);
+
+                if !full_path.exists() {
+                    tidy_error!(
+                        bad,
+                        "triagebot.toml [assign.owners] contains path '{}' which doesn't exist",
+                        clean_path
+                    );
+                }
+            }
+        } else {
+            tidy_error!(
+                bad,
+                "triagebot.toml missing [assign.owners] section, this wrong for rust-lang/rust repo."
+            );
+        }
+    }
+
+    // Verify that trigger_files in [autolabel."*"] exist in the project, i.e.
+    // [autolabel."A-rustdoc-search"]
+    // trigger_files = [
+    //    "src/librustdoc/html/static/js/search.js",
+    //    "tests/rustdoc-js",
+    //    "tests/rustdoc-js-std",
+    // ]
+    if let Some(Value::Table(autolabels)) = config.get("autolabel") {
+        for (label, content) in autolabels {
+            if let Some(trigger_files) = content.get("trigger_files").and_then(|v| v.as_array()) {
+                for file in trigger_files {
+                    if let Some(file_str) = file.as_str() {
+                        let full_path = path.join(file_str);
+
+                        // Handle both file and directory paths
+                        if !full_path.exists() {
+                            tidy_error!(
+                                bad,
+                                "triagebot.toml [autolabel.{}] contains trigger_files path '{}' which doesn't exist",
+                                label,
+                                file_str
+                            );
+                        }
+                    }
+                }
+            }
+        }
+    }
+}