2 files changed, 517 insertions, 0 deletions

diff --git a/crates/ide_assists/src/handlers/convert_tuple_variant_to_named_variant.rs b/crates/ide_assists/src/handlers/convert_tuple_variant_to_named_variant.rs
new file mode 100644
index 000000000..586ad9809
--- /dev/null
+++ b/crates/ide_assists/src/handlers/convert_tuple_variant_to_named_variant.rs
@@ -0,0 +1,515 @@
+use ide_db::defs::{Definition, NameRefClass};
+use syntax::{
+    ast::{self, AstNode, VisibilityOwner},
+    match_ast, SyntaxNode,
+};
+
+use crate::{assist_context::AssistBuilder, AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: convert_tuple_variant_to_named_variant
+//
+// Converts tuple variant to variant with named fields.
+//
+// ```
+// enum A {
+//     Variant(usize),
+// }
+//
+// impl A {
+//     fn new(value: usize) -> A {
+//         A::Variant(value)
+//     }
+//
+//     fn new_with_default() -> A {
+//         A::new(Default::default())
+//     }
+//
+//     fn value(self) -> usize {
+//         match self {
+//             A::Variant(value) => value,
+//         }
+//     }
+// }
+// ```
+// ->
+// ```
+// enum A {
+//     Variant {
+//         field1: usize
+//     },
+// }
+//
+// impl A {
+//     fn new(value: usize) -> A {
+//         A::Variant {
+//             field1: value,
+//         }
+//     }
+//
+//     fn new_with_default() -> A {
+//         A::new(Default::default())
+//     }
+//
+//     fn value(self) -> usize {
+//         match self {
+//             A::Variant { field1: value } => value,
+//         }
+//     }
+// }
+// ```
+pub(crate) fn convert_tuple_variant_to_named_variant(
+    acc: &mut Assists,
+    ctx: &AssistContext,
+) -> Option<()> {
+    let variant = ctx.find_node_at_offset::<ast::Variant>()?;
+    let tuple_fields = match variant.field_list()? {
+        ast::FieldList::TupleFieldList(it) => it,
+        ast::FieldList::RecordFieldList(_) => return None,
+    };
+    let variant_def = ctx.sema.to_def(&variant)?;
+
+    let target = variant.syntax().text_range();
+    acc.add(
+        AssistId("convert_tuple_variant_to_named_variant", AssistKind::RefactorRewrite),
+        "Convert to named struct",
+        target,
+        |edit| {
+            let names = generate_names(tuple_fields.fields());
+            edit_field_references(ctx, edit, tuple_fields.fields(), &names); // TODO: is this needed?
+            edit_variant_references(ctx, edit, variant_def, &names);
+            edit_variant_def(ctx, edit, tuple_fields, names);
+        },
+    )
+}
+
+fn edit_variant_def(
+    ctx: &AssistContext,
+    edit: &mut AssistBuilder,
+    tuple_fields: ast::TupleFieldList,
+    names: Vec<ast::Name>,
+) {
+    let record_fields = tuple_fields
+        .fields()
+        .zip(names)
+        .filter_map(|(f, name)| Some(ast::make::record_field(f.visibility(), name, f.ty()?)));
+    let record_fields = ast::make::record_field_list(record_fields);
+    let tuple_fields_text_range = tuple_fields.syntax().text_range();
+
+    edit.edit_file(ctx.frange.file_id);
+
+    edit.insert(tuple_fields_text_range.start(), ast::make::tokens::single_space().text());
+
+    edit.replace(tuple_fields_text_range, record_fields.to_string());
+}
+
+fn edit_variant_references(
+    ctx: &AssistContext,
+    edit: &mut AssistBuilder,
+    variant: hir::Variant,
+    names: &[ast::Name],
+) {
+    let variant_def = Definition::ModuleDef(hir::ModuleDef::Variant(variant));
+    let usages = variant_def.usages(&ctx.sema).include_self_refs().all();
+
+    let edit_node = |edit: &mut AssistBuilder, node: SyntaxNode| -> Option<()> {
+        match_ast! {
+            match node {
+                ast::TupleStructPat(tuple_struct_pat) => {
+                    edit.replace(
+                        tuple_struct_pat.syntax().text_range(),
+                        ast::make::record_pat_with_fields(
+                            tuple_struct_pat.path()?,
+                            ast::make::record_pat_field_list(tuple_struct_pat.fields().zip(names).map(
+                                |(pat, name)| {
+                                    ast::make::record_pat_field(
+                                        ast::make::name_ref(&name.to_string()),
+                                        pat,
+                                    )
+                                },
+                            )),
+                        )
+                        .to_string(),
+                    );
+                },
+                // for tuple struct creations like Foo(42)
+                ast::CallExpr(call_expr) => {
+                    let path = call_expr.syntax().descendants().find_map(ast::PathExpr::cast).and_then(|expr| expr.path())?;
+
+                    // this also includes method calls like Foo::new(42), we should skip them
+                    if let Some(name_ref) = path.segment().and_then(|s| s.name_ref()) {
+                        match NameRefClass::classify(&ctx.sema, &name_ref) {
+                            Some(NameRefClass::Definition(Definition::SelfType(_))) => {},
+                            Some(NameRefClass::Definition(def)) if def == variant_def => {},
+                            _ => return None,
+                        };
+                    }
+
+                    let arg_list = call_expr.syntax().descendants().find_map(ast::ArgList::cast)?;
+
+                    edit.replace(
+                        call_expr.syntax().text_range(),
+                        ast::make::record_expr(
+                            path,
+                            ast::make::record_expr_field_list(arg_list.args().zip(names).map(
+                                |(expr, name)| {
+                                    ast::make::record_expr_field(
+                                        ast::make::name_ref(&name.to_string()),
+                                        Some(expr),
+                                    )
+                                },
+                            )),
+                        )
+                        .to_string(),
+                    );
+                },
+                _ => return None,
+            }
+        }
+        Some(())
+    };
+
+    for (file_id, refs) in usages {
+        edit.edit_file(file_id);
+        for r in refs {
+            for node in r.name.syntax().ancestors() {
+                if edit_node(edit, node).is_some() {
+                    break;
+                }
+            }
+        }
+    }
+}
+
+fn edit_field_references(
+    ctx: &AssistContext,
+    edit: &mut AssistBuilder,
+    fields: impl Iterator<Item = ast::TupleField>,
+    names: &[ast::Name],
+) {
+    for (field, name) in fields.zip(names) {
+        let field = match ctx.sema.to_def(&field) {
+            Some(it) => it,
+            None => continue,
+        };
+        let def = Definition::Field(field);
+        let usages = def.usages(&ctx.sema).all();
+        for (file_id, refs) in usages {
+            edit.edit_file(file_id);
+            for r in refs {
+                if let Some(name_ref) = r.name.as_name_ref() {
+                    edit.replace(name_ref.syntax().text_range(), name.text());
+                }
+            }
+        }
+    }
+}
+
+fn generate_names(fields: impl Iterator<Item = ast::TupleField>) -> Vec<ast::Name> {
+    fields.enumerate().map(|(i, _)| ast::make::name(&format!("field{}", i + 1))).collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn not_applicable_other_than_tuple_variant() {
+        check_assist_not_applicable(
+            convert_tuple_variant_to_named_variant,
+            r#"enum Enum { Variant$0 { value: usize } };"#,
+        );
+        check_assist_not_applicable(convert_tuple_variant_to_named_variant, r#"enum Enum { Variant$0 }"#);
+    }
+
+    #[test]
+    fn convert_simple_variant() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+enum A {
+    $0Variant(usize),
+}
+
+impl A {
+    fn new(value: usize) -> A {
+        A::Variant(value)
+    }
+
+    fn new_with_default() -> A {
+        A::new(Default::default())
+    }
+
+    fn value(self) -> usize {
+        match self {
+            A::Variant(value) => value,
+        }
+    }
+}"#,
+            r#"
+enum A {
+    Variant { field1: usize },
+}
+
+impl A {
+    fn new(value: usize) -> A {
+        A::Variant { field1: value }
+    }
+
+    fn new_with_default() -> A {
+        A::new(Default::default())
+    }
+
+    fn value(self) -> usize {
+        match self {
+            A::Variant { field1: value } => value,
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn convert_variant_referenced_via_self_kw() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+enum A {
+    $0Variant(usize),
+}
+
+impl A {
+    fn new(value: usize) -> A {
+        Self::Variant(value)
+    }
+
+    fn new_with_default() -> A {
+        Self::new(Default::default())
+    }
+
+    fn value(self) -> usize {
+        match self {
+            Self::Variant(value) => value,
+        }
+    }
+}"#,
+            r#"
+enum A {
+    Variant { field1: usize },
+}
+
+impl A {
+    fn new(value: usize) -> A {
+        Self::Variant { field1: value }
+    }
+
+    fn new_with_default() -> A {
+        Self::new(Default::default())
+    }
+
+    fn value(self) -> usize {
+        match self {
+            Self::Variant { field1: value } => value,
+        }
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn convert_destructured_variant() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+enum A {
+    $0Variant(usize),
+}
+
+impl A {
+    fn into_inner(self) -> usize {
+        let A::Variant(first) = self;
+        first
+    }
+
+    fn into_inner_via_self(self) -> usize {
+        let Self::Variant(first) = self;
+        first
+    }
+}"#,
+            r#"
+enum A {
+    Variant { field1: usize },
+}
+
+impl A {
+    fn into_inner(self) -> usize {
+        let A::Variant { field1: first } = self;
+        first
+    }
+
+    fn into_inner_via_self(self) -> usize {
+        let Self::Variant { field1: first } = self;
+        first
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn convert_variant_with_wrapped_references() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+enum Inner {
+    $0Variant(usize),
+}
+enum Outer {
+    Variant(Inner),
+}
+
+impl Outer {
+    fn new() -> Self {
+        Self::Variant(Inner::Variant(42))
+    }
+
+    fn into_inner_destructed(self) -> u32 {
+        let Outer::Variant(Inner::Variant(x)) = self;
+        x
+    }
+}"#,
+            r#"
+enum Inner {
+    Variant { field1: usize },
+}
+enum Outer {
+    Variant(Inner),
+}
+
+impl Outer {
+    fn new() -> Self {
+        Self::Variant(Inner::Variant { field1: 42 })
+    }
+
+    fn into_inner_destructed(self) -> u32 {
+        let Outer::Variant(Inner::Variant { field1: x }) = self;
+        x
+    }
+}"#,
+        );
+
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+enum Inner {
+    Variant(usize),
+}
+enum Outer {
+    $0Variant(Inner),
+}
+
+impl Outer {
+    fn new() -> Self {
+        Self::Variant(Inner::Variant(42))
+    }
+
+    fn into_inner_destructed(self) -> u32 {
+        let Outer::Variant(Inner::Variant(x)) = self;
+        x
+    }
+}"#,
+            r#"
+enum Inner {
+    Variant(usize),
+}
+enum Outer {
+    Variant { field1: Inner },
+}
+
+impl Outer {
+    fn new() -> Self {
+        Self::Variant { field1: Inner::Variant(42) }
+    }
+
+    fn into_inner_destructed(self) -> u32 {
+        let Outer::Variant { field1: Inner::Variant(x) } = self;
+        x
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn convert_variant_with_multi_file_references() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+//- /main.rs
+struct Inner;
+enum A {
+    $0Variant(Inner),
+}
+
+mod foo;
+
+//- /foo.rs
+use crate::{A, Inner};
+fn f() {
+    let a = A::Variant(Inner);
+}
+"#,
+            r#"
+//- /main.rs
+struct Inner;
+enum A {
+    Variant { field1: Inner },
+}
+
+mod foo;
+
+//- /foo.rs
+use crate::{A, Inner};
+fn f() {
+    let a = A::Variant { field1: Inner };
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn convert_directly_used_variant() {
+        check_assist(
+            convert_tuple_variant_to_named_variant,
+            r#"
+//- /main.rs
+struct Inner;
+enum A {
+    $0Variant(Inner),
+}
+
+mod foo;
+
+//- /foo.rs
+use crate::{A::Variant, Inner};
+fn f() {
+    let a = Variant(Inner);
+}
+"#,
+            r#"
+//- /main.rs
+struct Inner;
+enum A {
+    Variant { field1: Inner },
+}
+
+mod foo;
+
+//- /foo.rs
+use crate::{A::Variant, Inner};
+fn f() {
+    let a = Variant { field1: Inner };
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index 16af72927..d64233315 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -186,6 +186,7 @@ mod handlers {
     mod convert_iter_for_each_to_for;
     mod convert_into_to_from;
     mod convert_tuple_struct_to_named_struct;
+    mod convert_tuple_variant_to_named_variant;
     mod early_return;
     mod expand_glob_import;
     mod extract_function;
@@ -256,6 +257,7 @@ mod handlers {
             convert_iter_for_each_to_for::convert_iter_for_each_to_for,
             convert_into_to_from::convert_into_to_from,
             convert_tuple_struct_to_named_struct::convert_tuple_struct_to_named_struct,
+            convert_tuple_variant_to_named_variant::convert_tuple_variant_to_named_variant,
             early_return::convert_to_guarded_return,
             expand_glob_import::expand_glob_import,
             extract_struct_from_enum_variant::extract_struct_from_enum_variant,