Add ide-assist: remove else branches

Author: A4-Tacks

src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_else_branches.rs

@@ -0,0 +1,90 @@
+use syntax::{AstNode, SyntaxKind, T, TextRange, ast};
+
+use crate::{AssistContext, AssistId, Assists};
+
+// Assist: remove_else_branches
+//
+// Removes the `else` keyword and else branches.
+//
+// ```
+// fn main() {
+//     if true {
+//         let _ = 2;
+//     } $0else {
+//         unreachable!();
+//     }
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     if true {
+//         let _ = 2;
+//     }
+// }
+// ```
+// ---
+// ```
+// fn main() {
+//     let _x = 2 $0else { unreachable!() };
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     let _x = 2;
+// }
+// ```
+pub(crate) fn remove_else_branches(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
+    let else_token = ctx.find_token_syntax_at_offset(T![else])?;
+    let else_branches = ctx
+        .find_node_at_range::<ast::IfExpr>()
+        .and_then(|if_expr| if_expr.else_branch()?.syntax().clone().into())
+        .or_else(|| {
+            ctx.find_node_at_range::<ast::LetStmt>()?
+                .let_else()?
+                .block_expr()?
+                .syntax()
+                .clone()
+                .into()
+        })?;
+
+    let target = TextRange::cover(else_token.text_range(), else_branches.text_range());
+    acc.add(
+        AssistId::refactor("remove_else_branches"),
+        "Remove `else` branches",
+        target,
+        |builder| {
+            let mut editor = builder.make_editor(&else_token.parent().unwrap());
+            match else_token.prev_token() {
+                Some(it) if it.kind() == SyntaxKind::WHITESPACE => editor.delete(it),
+                _ => (),
+            }
+            match else_token.next_token() {
+                Some(it) if it.kind() == SyntaxKind::WHITESPACE => editor.delete(it),
+                _ => (),
+            }
+            editor.delete(else_token);
+            editor.delete(else_branches);
+            builder.add_file_edits(ctx.vfs_file_id(), editor);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tests::check_assist_not_applicable;
+
+    #[test]
+    fn test_remove_else_branches_not_on_else_token() {
+        check_assist_not_applicable(
+            remove_else_branches,
+            r#"
+fn main() {
+    let _x = 2 else {$0 unreachable!() };
+}
+"#,
+        );
+    }
+}

src/tools/rust-analyzer/crates/ide-assists/src/lib.rs

@@ -199,6 +199,7 @@ mod handlers {
     mod qualify_path;
     mod raw_string;
     mod remove_dbg;
+    mod remove_else_branches;
     mod remove_mut;
     mod remove_parentheses;
     mod remove_underscore;
@@ -337,6 +338,7 @@ mod handlers {
             raw_string::remove_hash,
             remove_dbg::remove_dbg,
             remove_mut::remove_mut,
+            remove_else_branches::remove_else_branches,
             remove_parentheses::remove_parentheses,
             remove_underscore::remove_underscore,
             remove_unused_imports::remove_unused_imports,

src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs

@@ -2738,6 +2738,46 @@ fn main() {
     )
 }
 
+#[test]
+fn doctest_remove_else_branches() {
+    check_doc_test(
+        "remove_else_branches",
+        r#####"
+fn main() {
+    if true {
+        let _ = 2;
+    } $0else {
+        unreachable!();
+    }
+}
+"#####,
+        r#####"
+fn main() {
+    if true {
+        let _ = 2;
+    }
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_remove_else_branches_1() {
+    check_doc_test(
+        "remove_else_branches",
+        r#####"
+fn main() {
+    let _x = 2 $0else { unreachable!() };
+}
+"#####,
+        r#####"
+fn main() {
+    let _x = 2;
+}
+"#####,
+    )
+}
+
 #[test]
 fn doctest_remove_hash() {
     check_doc_test(