3 files changed, 53 insertions, 29 deletions

diff --git a/crates/ide/src/diagnostics/field_shorthand.rs b/crates/ide/src/diagnostics/field_shorthand.rs
index 5c89e2170..2b1787f9b 100644
--- a/crates/ide/src/diagnostics/field_shorthand.rs
+++ b/crates/ide/src/diagnostics/field_shorthand.rs
@@ -5,7 +5,7 @@ use ide_db::{base_db::FileId, source_change::SourceChange};
 use syntax::{ast, match_ast, AstNode, SyntaxNode};
 use text_edit::TextEdit;
 
-use crate::{Diagnostic, Fix};
+use crate::{diagnostics::fix, Diagnostic};
 
 pub(super) fn check(acc: &mut Vec<Diagnostic>, file_id: FileId, node: &SyntaxNode) {
     match_ast! {
@@ -47,7 +47,8 @@ fn check_expr_field_shorthand(
         let field_range = record_field.syntax().text_range();
         acc.push(
             Diagnostic::hint(field_range, "Shorthand struct initialization".to_string()).with_fix(
-                Some(Fix::new(
+                Some(fix(
+                    "use_expr_field_shorthand",
                     "Use struct shorthand initialization",
                     SourceChange::from_text_edit(file_id, edit),
                     field_range,
@@ -86,7 +87,8 @@ fn check_pat_field_shorthand(
 
         let field_range = record_pat_field.syntax().text_range();
         acc.push(Diagnostic::hint(field_range, "Shorthand struct pattern".to_string()).with_fix(
-            Some(Fix::new(
+            Some(fix(
+                "use_pat_field_shorthand",
                 "Use struct field shorthand",
                 SourceChange::from_text_edit(file_id, edit),
                 field_range,
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index 5fb3e2d91..7be8b3459 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -20,20 +20,30 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{diagnostics::Fix, references::rename::rename_with_semantics, FilePosition};
+use crate::{
+    diagnostics::{fix, unresolved_fix},
+    references::rename::rename_with_semantics,
+    Assist, FilePosition,
+};
 
 /// A [Diagnostic] that potentially has a fix available.
 ///
 /// [Diagnostic]: hir::diagnostics::Diagnostic
 pub(crate) trait DiagnosticWithFix: Diagnostic {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix>;
+    /// `resolve` determines if the diagnostic should fill in the `edit` field
+    /// of the assist.
+    ///
+    /// If `resolve` is false, the edit will be computed later, on demand, and
+    /// can be omitted.
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist>;
 }
 
 impl DiagnosticWithFix for UnresolvedModule {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let unresolved_module = self.decl.to_node(&root);
-        Some(Fix::new(
+        Some(fix(
+            "create_module",
             "Create module",
             FileSystemEdit::CreateFile {
                 dst: AnchoredPathBuf {
@@ -49,7 +59,7 @@ impl DiagnosticWithFix for UnresolvedModule {
 }
 
 impl DiagnosticWithFix for NoSuchField {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         missing_record_expr_field_fix(
             &sema,
@@ -60,7 +70,7 @@ impl DiagnosticWithFix for NoSuchField {
 }
 
 impl DiagnosticWithFix for MissingFields {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         // Note that although we could add a diagnostics to
         // fill the missing tuple field, e.g :
         // `struct A(usize);`
@@ -86,7 +96,8 @@ impl DiagnosticWithFix for MissingFields {
                 .into_text_edit(&mut builder);
             builder.finish()
         };
-        Some(Fix::new(
+        Some(fix(
+            "fill_missing_fields",
             "Fill struct fields",
             SourceChange::from_text_edit(self.file.original_file(sema.db), edit),
             sema.original_range(&field_list_parent.syntax()).range,
@@ -95,7 +106,7 @@ impl DiagnosticWithFix for MissingFields {
 }
 
 impl DiagnosticWithFix for MissingOkOrSomeInTailExpr {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let tail_expr = self.expr.to_node(&root);
         let tail_expr_range = tail_expr.syntax().text_range();
@@ -103,12 +114,12 @@ impl DiagnosticWithFix for MissingOkOrSomeInTailExpr {
         let edit = TextEdit::replace(tail_expr_range, replacement);
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
         let name = if self.required == "Ok" { "Wrap with Ok" } else { "Wrap with Some" };
-        Some(Fix::new(name, source_change, tail_expr_range))
+        Some(fix("wrap_tail_expr", name, source_change, tail_expr_range))
     }
 }
 
 impl DiagnosticWithFix for RemoveThisSemicolon {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
 
         let semicolon = self
@@ -123,12 +134,12 @@ impl DiagnosticWithFix for RemoveThisSemicolon {
         let edit = TextEdit::delete(semicolon);
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
 
-        Some(Fix::new("Remove this semicolon", source_change, semicolon))
+        Some(fix("remove_semicolon", "Remove this semicolon", source_change, semicolon))
     }
 }
 
 impl DiagnosticWithFix for IncorrectCase {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let name_node = self.ident.to_node(&root);
 
@@ -136,16 +147,19 @@ impl DiagnosticWithFix for IncorrectCase {
         let frange = name_node.original_file_range(sema.db);
         let file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
 
-        let rename_changes =
-            rename_with_semantics(sema, file_position, &self.suggested_text).ok()?;
-
         let label = format!("Rename to {}", self.suggested_text);
-        Some(Fix::new(&label, rename_changes, frange.range))
+        let mut res = unresolved_fix("change_case", &label, frange.range);
+        if resolve {
+            let source_change = rename_with_semantics(sema, file_position, &self.suggested_text);
+            res.source_change = Some(source_change.ok().unwrap_or_default());
+        }
+
+        Some(res)
     }
 }
 
 impl DiagnosticWithFix for ReplaceFilterMapNextWithFindMap {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let next_expr = self.next_expr.to_node(&root);
         let next_call = ast::MethodCallExpr::cast(next_expr.syntax().clone())?;
@@ -163,7 +177,8 @@ impl DiagnosticWithFix for ReplaceFilterMapNextWithFindMap {
 
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
 
-        Some(Fix::new(
+        Some(fix(
+            "replace_with_find_map",
             "Replace filter_map(..).next() with find_map()",
             source_change,
             trigger_range,
@@ -175,7 +190,7 @@ fn missing_record_expr_field_fix(
     sema: &Semantics<RootDatabase>,
     usage_file_id: FileId,
     record_expr_field: &ast::RecordExprField,
-) -> Option<Fix> {
+) -> Option<Assist> {
     let record_lit = ast::RecordExpr::cast(record_expr_field.syntax().parent()?.parent()?)?;
     let def_id = sema.resolve_variant(record_lit)?;
     let module;
@@ -233,7 +248,12 @@ fn missing_record_expr_field_fix(
         def_file_id,
         TextEdit::insert(last_field_syntax.text_range().end(), new_field),
     );
-    return Some(Fix::new("Create field", source_change, record_expr_field.syntax().text_range()));
+    return Some(fix(
+        "create_field",
+        "Create field",
+        source_change,
+        record_expr_field.syntax().text_range(),
+    ));
 
     fn record_field_list(field_def_list: ast::FieldList) -> Option<ast::RecordFieldList> {
         match field_def_list {
diff --git a/crates/ide/src/diagnostics/unlinked_file.rs b/crates/ide/src/diagnostics/unlinked_file.rs
index e174fb767..7d39f4fbe 100644
--- a/crates/ide/src/diagnostics/unlinked_file.rs
+++ b/crates/ide/src/diagnostics/unlinked_file.rs
@@ -16,9 +16,10 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::Fix;
-
-use super::fixes::DiagnosticWithFix;
+use crate::{
+    diagnostics::{fix, fixes::DiagnosticWithFix},
+    Assist,
+};
 
 // Diagnostic: unlinked-file
 //
@@ -49,7 +50,7 @@ impl Diagnostic for UnlinkedFile {
 }
 
 impl DiagnosticWithFix for UnlinkedFile {
-    fn fix(&self, sema: &hir::Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &hir::Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         // If there's an existing module that could add a `mod` item to include the unlinked file,
         // suggest that as a fix.
 
@@ -100,7 +101,7 @@ fn make_fix(
     parent_file_id: FileId,
     new_mod_name: &str,
     added_file_id: FileId,
-) -> Option<Fix> {
+) -> Option<Assist> {
     fn is_outline_mod(item: &ast::Item) -> bool {
         matches!(item, ast::Item::Module(m) if m.item_list().is_none())
     }
@@ -152,7 +153,8 @@ fn make_fix(
 
     let edit = builder.finish();
     let trigger_range = db.parse(added_file_id).tree().syntax().text_range();
-    Some(Fix::new(
+    Some(fix(
+        "add_mod_declaration",
         &format!("Insert `{}`", mod_decl),
         SourceChange::from_text_edit(parent_file_id, edit),
         trigger_range,