From 1d40867fc8b7f9ff85aa5fe7a8c03a6a4a3531cd Mon Sep 17 00:00:00 2001
From: A4-Tacks <wdsjxhno1001@163.com>
Date: Tue, 25 Nov 2025 16:13:59 +0800
Subject: [PATCH] Fix invalid completion arg nr

Example
---
```rust
fn foo() { bar(, $0); }
fn bar(x: u32, y: i32) {}
```

**Before this PR**

```text
ty: u32, name: x
```

**After this PR**

```text
ty: i32, name: y
```
---
 crates/ide-completion/src/context/analysis.rs |  2 +-
 crates/ide-completion/src/context/tests.rs    | 14 ++++++++++++++
 crates/ide-db/src/active_parameter.rs         | 17 ++++++++++++-----
 3 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/crates/ide-completion/src/context/analysis.rs b/crates/ide-completion/src/context/analysis.rs
index d6d3978385d9..d5a1d2113674 100644
--- a/crates/ide-completion/src/context/analysis.rs
+++ b/crates/ide-completion/src/context/analysis.rs
@@ -657,7 +657,7 @@ fn expected_type_and_name<'db>(
                     cov_mark::hit!(expected_type_fn_param);
                     ActiveParameter::at_token(
                         sema,
-                       token.clone(),
+                        token.clone(),
                     ).map(|ap| {
                         let name = ap.ident().map(NameOrNameRef::Name);
                         (Some(ap.ty), name)
diff --git a/crates/ide-completion/src/context/tests.rs b/crates/ide-completion/src/context/tests.rs
index 51d28bd4ff98..41f0db3c5282 100644
--- a/crates/ide-completion/src/context/tests.rs
+++ b/crates/ide-completion/src/context/tests.rs
@@ -90,6 +90,20 @@ fn bar(x: u32) {}
 "#,
         expect![[r#"ty: u32, name: x"#]],
     );
+    check_expected_type_and_name(
+        r#"
+fn foo() { bar(, $0); }
+fn bar(x: u32, y: i32) {}
+"#,
+        expect![[r#"ty: i32, name: y"#]],
+    );
+    check_expected_type_and_name(
+        r#"
+fn foo() { bar(, c$0); }
+fn bar(x: u32, y: i32) {}
+"#,
+        expect![[r#"ty: i32, name: y"#]],
+    );
 }
 
 #[test]
diff --git a/crates/ide-db/src/active_parameter.rs b/crates/ide-db/src/active_parameter.rs
index 4fb7d142ed5f..f5a5b76c336a 100644
--- a/crates/ide-db/src/active_parameter.rs
+++ b/crates/ide-db/src/active_parameter.rs
@@ -5,7 +5,7 @@ use hir::{InFile, Semantics, Type};
 use parser::T;
 use span::TextSize;
 use syntax::{
-    AstNode, NodeOrToken, SyntaxToken,
+    AstNode, NodeOrToken, SyntaxKind, SyntaxNode, SyntaxToken,
     ast::{self, AstChildren, HasArgList, HasAttrs, HasName},
     match_ast,
 };
@@ -102,8 +102,7 @@ pub fn callable_for_node<'db>(
         arg_list
             .syntax()
             .children_with_tokens()
-            .filter_map(NodeOrToken::into_token)
-            .filter(|t| t.kind() == T![,])
+            .filter_map(into_comma)
             .take_while(|t| t.text_range().start() <= offset)
             .count()
     });
@@ -162,8 +161,7 @@ pub fn generic_def_for_node(
     let active_param = generic_arg_list
         .syntax()
         .children_with_tokens()
-        .filter_map(NodeOrToken::into_token)
-        .filter(|t| t.kind() == T![,])
+        .filter_map(into_comma)
         .take_while(|t| t.text_range().start() <= token.text_range().start())
         .count();
 
@@ -174,3 +172,12 @@ pub fn generic_def_for_node(
 
     Some((def, active_param, first_arg_is_non_lifetime, variant))
 }
+
+fn into_comma(it: NodeOrToken<SyntaxNode, SyntaxToken>) -> Option<SyntaxToken> {
+    let token = match it {
+        NodeOrToken::Token(it) => it,
+        NodeOrToken::Node(node) if node.kind() == SyntaxKind::ERROR => node.first_token()?,
+        NodeOrToken::Node(_) => return None,
+    };
+    (token.kind() == T![,]).then_some(token)
+}