Improve debug str generator

Generates more optimized code per https://rust-lang.github.io/rust-clippy/master/index.html#format_collect
rust-lang · Dec 1, 2024 · d9576ea · d9576ea
1 parent 0c3ae5c
commit d9576ea
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Showing 4 changed files with 48 additions and 25 deletions.
diff --git a/bindgen-tests/tests/expectations/tests/derive-bitfield-method-same-name.rs b/bindgen-tests/tests/expectations/tests/derive-bitfield-method-same-name.rs
diff --git a/bindgen-tests/tests/expectations/tests/derive-debug-bitfield.rs b/bindgen-tests/tests/expectations/tests/derive-debug-bitfield.rs
diff --git a/bindgen-tests/tests/expectations/tests/derive-debug-function-pointer.rs b/bindgen-tests/tests/expectations/tests/derive-debug-function-pointer.rs
diff --git a/bindgen/codegen/impl_debug.rs b/bindgen/codegen/impl_debug.rs
@@ -186,13 +186,18 @@ impl<'a> ImplDebug<'a> for Item {
                     // Let's implement our own print function
                     Some((
                         format!("{name}: [{{}}]"),
-                        vec![quote! {
-                            self.#name_ident
-                                .iter()
-                                .enumerate()
-                                .map(|(i, v)| format!("{}{:?}", if i > 0 { ", " } else { "" }, v))
-                                .collect::<String>()
-                        }],
+                        vec![quote! {{
+                            use std::fmt::Write as _;
+                            let mut output = String::new();
+                            let mut iter = self.#name_ident.iter();
+                            if let Some(value) = iter.next() {
+                                let _ = write!(output, "{value:?}");
+                                for value in iter {
+                                    let _ = write!(output, ", {value:?}");
+                                }
+                            }
+                            output
+                        }}],
                     ))
                 }
             }