From acab1f4fd875d928ab015e6c9df7f2fe8830a339 Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Tue, 10 Sep 2024 16:34:24 -0400
Subject: [PATCH] Remove allocation from
 `ruff_python_stdlib::builtins::python_builtins` (#13317)

---
 crates/ruff_linter/src/checkers/ast/mod.rs | 25 +++++++-----
 crates/ruff_python_stdlib/src/builtins.rs  | 45 ++++++++++++++--------
 2 files changed, 45 insertions(+), 25 deletions(-)

diff --git a/crates/ruff_linter/src/checkers/ast/mod.rs b/crates/ruff_linter/src/checkers/ast/mod.rs
index a79b1031e1..3d4ab46a6d 100644
--- a/crates/ruff_linter/src/checkers/ast/mod.rs
+++ b/crates/ruff_linter/src/checkers/ast/mod.rs
@@ -1951,20 +1951,25 @@ impl<'a> Checker<'a> {
     }
 
     fn bind_builtins(&mut self) {
-        let standard_builtins = python_builtins(
-            self.settings.target_version.minor(),
-            self.source_type.is_ipynb(),
-        );
-        for builtin in standard_builtins
-            .iter()
-            .chain(MAGIC_GLOBALS.iter())
-            .copied()
-            .chain(self.settings.builtins.iter().map(String::as_str))
-        {
+        let mut bind_builtin = |builtin| {
             // Add the builtin to the scope.
             let binding_id = self.semantic.push_builtin();
             let scope = self.semantic.global_scope_mut();
             scope.add(builtin, binding_id);
+        };
+
+        let standard_builtins = python_builtins(
+            self.settings.target_version.minor(),
+            self.source_type.is_ipynb(),
+        );
+        for builtin in standard_builtins {
+            bind_builtin(builtin);
+        }
+        for builtin in MAGIC_GLOBALS {
+            bind_builtin(builtin);
+        }
+        for builtin in &self.settings.builtins {
+            bind_builtin(builtin);
         }
     }
 
diff --git a/crates/ruff_python_stdlib/src/builtins.rs b/crates/ruff_python_stdlib/src/builtins.rs
index f8ba9a3530..020029de9e 100644
--- a/crates/ruff_python_stdlib/src/builtins.rs
+++ b/crates/ruff_python_stdlib/src/builtins.rs
@@ -184,21 +184,36 @@ static PY313_PLUS_BUILTINS: &[&str] = &["PythonFinalizationError"];
 /// Return the list of builtins for the given Python minor version.
 ///
 /// Intended to be kept in sync with [`is_python_builtin`].
-pub fn python_builtins(minor_version: u8, is_notebook: bool) -> Vec<&'static str> {
-    let mut builtins = ALWAYS_AVAILABLE_BUILTINS.to_vec();
-    if minor_version >= 10 {
-        builtins.extend(PY310_PLUS_BUILTINS);
-    }
-    if minor_version >= 11 {
-        builtins.extend(PY311_PLUS_BUILTINS);
-    }
-    if minor_version >= 13 {
-        builtins.extend(PY313_PLUS_BUILTINS);
-    }
-    if is_notebook {
-        builtins.extend(IPYTHON_BUILTINS);
-    }
-    builtins
+pub fn python_builtins(minor_version: u8, is_notebook: bool) -> impl Iterator<Item = &'static str> {
+    let py310_builtins = if minor_version >= 10 {
+        Some(PY310_PLUS_BUILTINS)
+    } else {
+        None
+    };
+    let py311_builtins = if minor_version >= 11 {
+        Some(PY311_PLUS_BUILTINS)
+    } else {
+        None
+    };
+    let py313_builtins = if minor_version >= 13 {
+        Some(PY313_PLUS_BUILTINS)
+    } else {
+        None
+    };
+    let ipython_builtins = if is_notebook {
+        Some(IPYTHON_BUILTINS)
+    } else {
+        None
+    };
+
+    py310_builtins
+        .into_iter()
+        .chain(py311_builtins)
+        .chain(py313_builtins)
+        .chain(ipython_builtins)
+        .flatten()
+        .chain(ALWAYS_AVAILABLE_BUILTINS)
+        .copied()
 }
 
 /// Returns `true` if the given name is that of a Python builtin.