From 69d98b07ff9aec906691853dd76b6eea5f892c37 Mon Sep 17 00:00:00 2001
From: Linwei Shang <linwei.shang@dfinity.org>
Date: Fri, 11 Oct 2024 13:18:27 -0700
Subject: [PATCH] fix: update/query macro could not handle function arguments
 with the same name as the function itself (#525)

* add a test case to reveal the bug

* fix: update/query macro could not handle function arguments with the same name as the function itself

* changelog
---
 ic-cdk-macros/src/export.rs               | 17 ++++++++++-------
 ic-cdk/CHANGELOG.md                       |  4 ++++
 ic-cdk/tests/pass/method_arg_same_name.rs | 13 +++++++++++++
 3 files changed, 27 insertions(+), 7 deletions(-)
 create mode 100644 ic-cdk/tests/pass/method_arg_same_name.rs

diff --git a/ic-cdk-macros/src/export.rs b/ic-cdk-macros/src/export.rs
index 6d087d398..b38c0ed27 100644
--- a/ic-cdk-macros/src/export.rs
+++ b/ic-cdk-macros/src/export.rs
@@ -81,14 +81,17 @@ fn get_args(method: MethodType, signature: &Signature) -> Result<Vec<(Ident, Box
                 ));
             }
             FnArg::Typed(PatType { pat, ty, .. }) => {
-                if let Pat::Ident(PatIdent { ident, .. }) = pat.as_ref() {
-                    (ident.clone(), ty.clone())
+                let ident = if let Pat::Ident(PatIdent { ident, .. }) = pat.as_ref() {
+                    // If the argument is named the same as the function, we need to rename it.
+                    if ident == &signature.ident {
+                        format_ident!("__arg_{}", ident, span = pat.span())
+                    } else {
+                        ident.clone()
+                    }
                 } else {
-                    (
-                        format_ident!("__unnamed_arg_{i}", span = pat.span()),
-                        ty.clone(),
-                    )
-                }
+                    format_ident!("__unnamed_arg_{i}", span = pat.span())
+                };
+                (ident, ty.clone())
             }
         };
 
diff --git a/ic-cdk/CHANGELOG.md b/ic-cdk/CHANGELOG.md
index 2c58efa9d..9476bd1dc 100644
--- a/ic-cdk/CHANGELOG.md
+++ b/ic-cdk/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [unreleased]
 
+### Fixed
+
+- Fix update/query macro could not handle function arguments with the same name as the function itself. (#525)
+
 ### Changed
 
 - Add `AllowedViewers` variant to `LogVisibility` enum. (#512)
diff --git a/ic-cdk/tests/pass/method_arg_same_name.rs b/ic-cdk/tests/pass/method_arg_same_name.rs
new file mode 100644
index 000000000..749db8d54
--- /dev/null
+++ b/ic-cdk/tests/pass/method_arg_same_name.rs
@@ -0,0 +1,13 @@
+use ic_cdk::{query, update};
+
+#[update]
+fn foo(foo: i32) -> i32 {
+    foo
+}
+
+#[query]
+fn bar(bar: i32) -> i32 {
+    bar
+}
+
+fn main() {}