Prevent PYI025 from clashing with isort-required check

remove new line

crates/ruff/tests/cli/lint.rs

@@ -3652,3 +3652,33 @@ fn supported_file_extensions_preview_enabled() -> Result<()> {
     ");
     Ok(())
 }
+
+// Regression test for https://github.com/astral-sh/ruff/issues/20891
+#[test]
+fn required_import_skips_pyi025() {
+    assert_cmd_snapshot!(
+        Command::new(get_cargo_bin(BIN_NAME))
+            .arg("--isolated")
+            .arg("check")
+            .args(["--select", "F401,I002,PYI025"])
+            .arg("--config")
+            .arg(r#"lint.isort.required-imports=["from collections.abc import Set"]"#)
+            .arg("-")
+            .arg("--unsafe-fixes")
+            .arg("--no-cache")
+            .pass_stdin("1"),
+        @r"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+    I002 [*] Missing required import: `from collections.abc import Set`
+    --> -:1:1
+    help: Insert required import: `from collections.abc import Set`
+
+    Found 1 error.
+    [*] 1 fixable with the --fix option.
+
+    ----- stderr -----
+    "
+    );
+}

crates/ruff_linter/src/rules/flake8_pyi/rules/unaliased_collections_abc_set_import.rs

@@ -1,10 +1,12 @@
 use ruff_macros::{ViolationMetadata, derive_message_formats};
+use ruff_python_ast::{Stmt, StmtImportFrom};
 use ruff_python_semantic::Imported;
 use ruff_python_semantic::{Binding, BindingKind, Scope};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
 use crate::renamer::Renamer;
+use crate::rules::pyupgrade::rules::is_import_required_by_isort;
 use crate::{Applicability, Fix, FixAvailability, Violation};
 
 /// ## What it does
@@ -73,6 +75,20 @@ pub(crate) fn unaliased_collections_abc_set_import(checker: &Checker, binding: &
         return;
     }
 
+    // Skip if this import is required by isort to prevent infinite loops with I002 and F401
+    if let Some(stmt @ Stmt::ImportFrom(StmtImportFrom { names, .. })) =
+        binding.statement(checker.semantic())
+        && names.iter().any(|alias| {
+            is_import_required_by_isort(
+                &checker.settings().isort.required_imports,
+                stmt.into(),
+                alias,
+            )
+        })
+    {
+        return;
+    }
+
     let mut diagnostic =
         checker.report_diagnostic(UnaliasedCollectionsAbcSetImport, binding.range());
     if checker.semantic().is_available("AbstractSet") {