tidy: Check that cargo and compiletest share the same rustfix.

src/tools/tidy/src/deps.rs

@@ -287,6 +287,7 @@ pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
     check_exceptions(&metadata, EXCEPTIONS, runtime_ids, bad);
     check_dependencies(&metadata, PERMITTED_DEPENDENCIES, RESTRICTED_DEPENDENCY_CRATES, bad);
     check_crate_duplicate(&metadata, FORBIDDEN_TO_HAVE_DUPLICATES, bad);
+    check_rustfix(&metadata, bad);
 
     // Check rustc_codegen_cranelift independently as it has it's own workspace.
     let mut cmd = cargo_metadata::MetadataCommand::new();
@@ -547,3 +548,22 @@ fn normal_deps_of_r<'a>(
         normal_deps_of_r(resolve, &dep.pkg, result);
     }
 }
+
+fn check_rustfix(metadata: &Metadata, bad: &mut bool) {
+    let cargo = pkg_from_name(metadata, "cargo");
+    let compiletest = pkg_from_name(metadata, "compiletest");
+    let cargo_deps = deps_of(metadata, &cargo.id);
+    let compiletest_deps = deps_of(metadata, &compiletest.id);
+    let cargo_rustfix = cargo_deps.iter().find(|p| p.name == "rustfix").unwrap();
+    let compiletest_rustfix = compiletest_deps.iter().find(|p| p.name == "rustfix").unwrap();
+    if cargo_rustfix.version != compiletest_rustfix.version {
+        tidy_error!(
+            bad,
+            "cargo's rustfix version {} does not match compiletest's rustfix version {}\n\
+             rustfix should be kept in sync, update the cargo side first, and then update \
+             compiletest along with cargo.",
+            cargo_rustfix.version,
+            compiletest_rustfix.version
+        );
+    }
+}