fix: ide-assists, gen from impl for enum indent

Author: A4-Tacks

crates/ide-assists/src/handlers/generate_from_impl_for_enum.rs

@@ -1,7 +1,10 @@
 use ide_db::{RootDatabase, famous_defs::FamousDefs};
-use syntax::ast::{self, AstNode, HasName};
+use syntax::ast::{self, AstNode, HasName, edit::AstNodeEdit};
 
-use crate::{AssistContext, AssistId, Assists, utils::generate_trait_impl_text_intransitive};
+use crate::{
+    AssistContext, AssistId, Assists,
+    utils::{generate_trait_impl_text_intransitive, indent_string},
+};
 
 // Assist: generate_from_impl_for_enum
 //
@@ -71,7 +74,7 @@ pub(crate) fn generate_from_impl_for_enum(
                 )
             };
             let from_impl = generate_trait_impl_text_intransitive(&enum_, &from_trait, &impl_code);
-            edit.insert(start_offset, from_impl);
+            edit.insert(start_offset, indent_string(&from_impl, enum_.indent_level()));
         },
     )
 }
@@ -295,6 +298,54 @@ impl<'a> From<&'a i32> for Generic<'a> {
         Self::One(v)
     }
 }
+"#,
+        );
+    }
+
+    #[test]
+    fn test_non_zero_indent() {
+        check_assist(
+            generate_from_impl_for_enum,
+            r#"
+//- minicore: from
+mod foo {
+    enum Generic<'a> { $0One(&'a i32) }
+}
+"#,
+            r#"
+mod foo {
+    enum Generic<'a> { One(&'a i32) }
+
+    impl<'a> From<&'a i32> for Generic<'a> {
+        fn from(v: &'a i32) -> Self {
+            Self::One(v)
+        }
+    }
+}
+"#,
+        );
+        check_assist(
+            generate_from_impl_for_enum,
+            r#"
+//- minicore: from
+mod foo {
+    mod bar {
+        enum Generic<'a> { $0One(&'a i32) }
+    }
+}
+"#,
+            r#"
+mod foo {
+    mod bar {
+        enum Generic<'a> { One(&'a i32) }
+
+        impl<'a> From<&'a i32> for Generic<'a> {
+            fn from(v: &'a i32) -> Self {
+                Self::One(v)
+            }
+        }
+    }
+}
 "#,
         );
     }

crates/ide-assists/src/utils.rs

@@ -1,5 +1,7 @@
 //! Assorted functions shared by several assists.
 
+use std::borrow::Cow;
+
 pub(crate) use gen_trait_fn_body::gen_trait_fn_body;
 use hir::{
     DisplayTarget, HasAttrs as HirHasAttrs, HirDisplay, InFile, ModuleDef, PathResolution,
@@ -250,6 +252,35 @@ pub fn add_trait_assoc_items_to_impl(
     first_item.unwrap()
 }
 
+pub(crate) fn indent_string(mut s: &str, indent_level: IndentLevel) -> Cow<'_, str> {
+    if indent_level.is_zero() || s.is_empty() {
+        return s.into();
+    }
+    let level = indent_level.0 as usize;
+
+    let indent = indent_level.to_string();
+    let mut buf = String::with_capacity(s.len() + level * 3 * 4);
+
+    if !s.starts_with('\n') {
+        buf.push_str(&indent);
+    }
+
+    while let Some((line, rest)) = s.split_once('\n') {
+        buf.push_str(line);
+        buf.push('\n');
+
+        if !rest.split_once('\n').map_or(rest, |s| s.0).is_empty() {
+            buf.push_str(&indent);
+        }
+
+        s = rest;
+    }
+
+    buf.push_str(s);
+
+    buf.into()
+}
+
 pub(crate) fn vis_offset(node: &SyntaxNode) -> TextSize {
     node.children_with_tokens()
         .find(|it| !matches!(it.kind(), WHITESPACE | COMMENT | ATTR))