From 6941fdc49f0cc68955c07c80f0817b991f4dc495 Mon Sep 17 00:00:00 2001
From: Yoshua Wuyts <yoshuawuyts@gmail.com>
Date: Tue, 12 Oct 2021 14:18:08 +0200
Subject: [PATCH] impl PartialOrd codegen for tuple records

---
 .../replace_derive_with_manual_impl.rs        | 37 +++++++++++++++++++
 .../src/utils/gen_trait_fn_body.rs            | 37 +++++++++++++++++--
 2 files changed, 70 insertions(+), 4 deletions(-)

diff --git a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
index c0b7db332e2..1dc8dd95abd 100644
--- a/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/ide_assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -675,6 +675,43 @@ impl Clone for Foo {
         )
     }
 
+    #[test]
+    fn add_custom_impl_partial_ord_record_struct() {
+        check_assist(
+            replace_derive_with_manual_impl,
+            r#"
+//- minicore: ord
+#[derive(Partial$0Ord)]
+struct Foo {
+    bin: usize,
+    bar: usize,
+    baz: usize,
+}
+"#,
+            r#"
+struct Foo {
+    bin: usize,
+    bar: usize,
+    baz: usize,
+}
+
+impl PartialOrd for Foo {
+    $0fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+        match self.bin.partial_cmp(other.bin) {
+            Some(core::cmp::Ordering::Eq) => {}
+            ord => return ord,
+        }
+        match self.bar.partial_cmp(other.bar) {
+            Some(core::cmp::Ordering::Eq) => {}
+            ord => return ord,
+        }
+        self.baz.partial_cmp(other.baz)
+    }
+}
+"#,
+        )
+    }
+
     #[test]
     fn add_custom_impl_partial_eq_record_struct() {
         check_assist(
diff --git a/crates/ide_assists/src/utils/gen_trait_fn_body.rs b/crates/ide_assists/src/utils/gen_trait_fn_body.rs
index 5ec8adc2d4c..aa0d9bc76bd 100644
--- a/crates/ide_assists/src/utils/gen_trait_fn_body.rs
+++ b/crates/ide_assists/src/utils/gen_trait_fn_body.rs
@@ -581,6 +581,29 @@ fn gen_partial_ord(adt: &ast::Adt, func: &ast::Fn) -> Option<()> {
         }
     }
 
+    fn gen_partial_eq_match(match_target: ast::Expr) -> Option<ast::Stmt> {
+        let mut arms = vec![];
+
+        let variant_name =
+            make::path_pat(make::ext::path_from_idents(["core", "cmp", "Ordering", "Eq"])?);
+        let lhs = make::tuple_struct_pat(make::ext::path_from_idents(["Some"])?, [variant_name]);
+        arms.push(make::match_arm(Some(lhs.into()), None, make::expr_empty_block()));
+
+        arms.push(make::match_arm(
+            [make::ident_pat(false, false, make::name("ord")).into()],
+            None,
+            make::expr_return(Some(make::expr_path(make::ext::ident_path("ord")))),
+        ));
+        // let rhs = make::expr_path(make::ext::ident_path("other"));
+        let list = make::match_arm_list(arms).indent(ast::edit::IndentLevel(1));
+        Some(make::expr_stmt(make::expr_match(match_target, list)).into())
+    }
+
+    fn gen_partial_cmp_call(lhs: ast::Expr, rhs: ast::Expr) -> ast::Expr {
+        let method = make::name_ref("partial_cmp");
+        make::expr_method_call(lhs, method, make::arg_list(Some(rhs)))
+    }
+
     fn gen_record_pat_field(field_name: &str, pat_name: &str) -> ast::RecordPatField {
         let pat = make::ext::simple_ident_pat(make::name(&pat_name));
         let name_ref = make::name_ref(field_name);
@@ -700,16 +723,22 @@ fn gen_partial_ord(adt: &ast::Adt, func: &ast::Fn) -> Option<()> {
         }
         ast::Adt::Struct(strukt) => match strukt.field_list() {
             Some(ast::FieldList::RecordFieldList(field_list)) => {
-                let mut expr = None;
+                let mut exprs = vec![];
                 for field in field_list.fields() {
                     let lhs = make::expr_path(make::ext::ident_path("self"));
                     let lhs = make::expr_field(lhs, &field.name()?.to_string());
                     let rhs = make::expr_path(make::ext::ident_path("other"));
                     let rhs = make::expr_field(rhs, &field.name()?.to_string());
-                    let cmp = make::expr_op(ast::BinOp::EqualityTest, lhs, rhs);
-                    expr = gen_eq_chain(expr, cmp);
+                    let ord = gen_partial_cmp_call(lhs, rhs);
+                    exprs.push(ord);
                 }
-                make::block_expr(None, expr).indent(ast::edit::IndentLevel(1))
+
+                let tail = exprs.pop();
+                let stmts = exprs
+                    .into_iter()
+                    .map(gen_partial_eq_match)
+                    .collect::<Option<Vec<ast::Stmt>>>()?;
+                make::block_expr(stmts.into_iter(), tail).indent(ast::edit::IndentLevel(1))
             }
 
             Some(ast::FieldList::TupleFieldList(field_list)) => {