From be9e3fdf3690cb943aa35290049bbd77ddb0cde2 Mon Sep 17 00:00:00 2001
From: A4-Tacks <wdsjxhno1001@163.com>
Date: Tue, 23 Sep 2025 15:45:31 +0800
Subject: [PATCH] Add ide-assist: unwrap_destructure_assign_unpaired

Unwrap the tuple destructuration assignment to different variables.

Example
---
```rust
fn foo() {
    let (a, b);
    (a, b) $0= (2, 3);
}
```
->
```rust
fn foo() {
    let (a, b);
    a = 2;
    b = 3;
}
```
---
 .../src/handlers/unwrap_destructure_assign.rs | 109 ++++++++++++++++++
 crates/ide-assists/src/lib.rs                 |   2 +
 crates/ide-assists/src/tests/generated.rs     |  20 ++++
 3 files changed, 131 insertions(+)
 create mode 100644 crates/ide-assists/src/handlers/unwrap_destructure_assign.rs

diff --git a/crates/ide-assists/src/handlers/unwrap_destructure_assign.rs b/crates/ide-assists/src/handlers/unwrap_destructure_assign.rs
new file mode 100644
index 000000000000..6d1ecf3def6f
--- /dev/null
+++ b/crates/ide-assists/src/handlers/unwrap_destructure_assign.rs
@@ -0,0 +1,109 @@
+use itertools::Itertools;
+use syntax::{
+    AstNode, T,
+    ast::{self, Expr, edit::AstNodeEdit, syntax_factory::SyntaxFactory},
+    syntax_editor::Element,
+};
+
+use crate::{AssistContext, AssistId, Assists};
+
+pub(crate) fn unwrap_destructure_assign(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let eq_token = ctx.find_token_syntax_at_offset(T![=])?;
+    let assign = ast::BinExpr::cast(eq_token.parent()?)?;
+    let expr_stmt = ast::ExprStmt::cast(assign.syntax().parent()?)?;
+    let (lhs, rhs) = (assign.lhs()?, assign.rhs()?);
+
+    if !ctx.has_empty_selection() {
+        return None;
+    }
+
+    match (lhs, rhs) {
+        (Expr::TupleExpr(lhs), Expr::TupleExpr(rhs)) => {
+            unwrap_tuple_destructure_assign(acc, ctx, expr_stmt, lhs, rhs)
+        }
+        _ => None,
+    }
+}
+
+// Assist: unwrap_tuple_destructure_assign
+//
+// Unwrap the tuple destructuration assignment to different variables.
+//
+// ```
+// fn foo() {
+//     let (a, b);
+//     (a, b) $0= (2, 3);
+// }
+// ```
+// ->
+// ```
+// fn foo() {
+//     let (a, b);
+//     a = 2;
+//     b = 3;
+// }
+// ```
+fn unwrap_tuple_destructure_assign(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+    expr_stmt: ast::ExprStmt,
+    lhs: ast::TupleExpr,
+    rhs: ast::TupleExpr,
+) -> Option<()> {
+    if lhs.fields().count() != rhs.fields().count() {
+        cov_mark::hit!(unwrap_destructure_assign_unpaired);
+        return None;
+    }
+
+    acc.add(
+        AssistId::refactor_rewrite("unwrap_tuple_destructure_assign"),
+        "Unwrap tuple destructure assign",
+        expr_stmt.syntax().text_range(),
+        |builder| {
+            let mut edit = builder.make_editor(expr_stmt.syntax());
+            let make = SyntaxFactory::with_mappings();
+
+            let indent = expr_stmt.indent_level();
+            let whitespace = make.whitespace(&format!("\n{indent}")).syntax_element();
+            let pairs = lhs.fields().zip(rhs.fields()).map(|(lhs, rhs)| {
+                let assignment = make.expr_assignment(lhs, rhs);
+                make.expr_stmt(assignment.into()).syntax().syntax_element()
+            });
+            let pairs = Itertools::intersperse(pairs, whitespace);
+
+            edit.replace_with_many(expr_stmt.syntax(), pairs.collect());
+
+            edit.add_mappings(make.finish_with_mappings());
+            builder.add_file_edits(ctx.vfs_file_id(), edit);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::check_assist_not_applicable;
+
+    use super::*;
+
+    #[test]
+    fn tuple_not_applicable_not_on_eq_token() {
+        check_assist_not_applicable(
+            unwrap_destructure_assign,
+            "fn foo() { let (a, b); (a, b) = $0(1, 2); }",
+        );
+        check_assist_not_applicable(
+            unwrap_destructure_assign,
+            "fn foo() { let (a, b); ($0a, b) = (1, 2); }",
+        );
+    }
+
+    #[test]
+    fn not_applicable_with_unpaired() {
+        cov_mark::check!(unwrap_destructure_assign_unpaired);
+
+        check_assist_not_applicable(
+            unwrap_destructure_assign,
+            "fn foo() { let (a, b); (a, b, c) $0= (1, 2); }",
+        );
+    }
+}
diff --git a/crates/ide-assists/src/lib.rs b/crates/ide-assists/src/lib.rs
index 4682c0473238..92b6126e19ac 100644
--- a/crates/ide-assists/src/lib.rs
+++ b/crates/ide-assists/src/lib.rs
@@ -228,6 +228,7 @@ mod handlers {
     mod unnecessary_async;
     mod unqualify_method_call;
     mod unwrap_block;
+    mod unwrap_destructure_assign;
     mod unwrap_return_type;
     mod unwrap_tuple;
     mod unwrap_type_to_generic_arg;
@@ -371,6 +372,7 @@ mod handlers {
             unnecessary_async::unnecessary_async,
             unqualify_method_call::unqualify_method_call,
             unwrap_block::unwrap_block,
+            unwrap_destructure_assign::unwrap_destructure_assign,
             unwrap_return_type::unwrap_return_type,
             unwrap_tuple::unwrap_tuple,
             unwrap_type_to_generic_arg::unwrap_type_to_generic_arg,
diff --git a/crates/ide-assists/src/tests/generated.rs b/crates/ide-assists/src/tests/generated.rs
index 91348be97eb7..fb814d0bcf12 100644
--- a/crates/ide-assists/src/tests/generated.rs
+++ b/crates/ide-assists/src/tests/generated.rs
@@ -3552,6 +3552,26 @@ fn main() {
     )
 }
 
+#[test]
+fn doctest_unwrap_tuple_destructure_assign() {
+    check_doc_test(
+        "unwrap_tuple_destructure_assign",
+        r#####"
+fn foo() {
+    let (a, b);
+    (a, b) $0= (2, 3);
+}
+"#####,
+        r#####"
+fn foo() {
+    let (a, b);
+    a = 2;
+    b = 3;
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_unwrap_type_to_generic_arg() {
     check_doc_test(