2 files changed, 78 insertions, 16 deletions

diff --git a/crates/ide_assists/src/handlers/apply_demorgan.rs b/crates/ide_assists/src/handlers/apply_demorgan.rs
index 3cd6699c3..6997ea048 100644
--- a/crates/ide_assists/src/handlers/apply_demorgan.rs
+++ b/crates/ide_assists/src/handlers/apply_demorgan.rs
@@ -61,10 +61,77 @@ fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
 
 #[cfg(test)]
 mod tests {
+    use ide_db::helpers::FamousDefs;
+
     use super::*;
 
     use crate::tests::{check_assist, check_assist_not_applicable};
 
+    const ORDABLE_FIXTURE: &'static str = r"
+//- /lib.rs deps:core crate:ordable
+struct NonOrderable;
+struct Orderable;
+impl core::cmp::Ord for Orderable {}
+";
+
+    fn check(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let before = &format!(
+            "//- /main.rs crate:main deps:core,ordable\n{}\n{}{}",
+            ra_fixture_before,
+            FamousDefs::FIXTURE,
+            ORDABLE_FIXTURE
+        );
+        check_assist(apply_demorgan, before, &format!("{}\n", ra_fixture_after));
+    }
+
+    #[test]
+    fn demorgan_handles_leq() {
+        check(
+            r"use ordable::Orderable;
+fn f() {
+    Orderable < Orderable &&$0 Orderable <= Orderable
+}",
+            r"use ordable::Orderable;
+fn f() {
+    !(Orderable >= Orderable || Orderable > Orderable)
+}",
+        );
+        check(
+            r"use ordable::NonOrderable;
+fn f() {
+    NonOrderable < NonOrderable &&$0 NonOrderable <= NonOrderable
+}",
+            r"use ordable::NonOrderable;
+fn f() {
+    !(!(NonOrderable < NonOrderable) || !(NonOrderable <= NonOrderable))
+}",
+        );
+    }
+
+    #[test]
+    fn demorgan_handles_geq() {
+        check(
+            r"use ordable::Orderable;
+fn f() {
+    Orderable > Orderable &&$0 Orderable >= Orderable
+}",
+            r"use ordable::Orderable;
+fn f() {
+    !(Orderable <= Orderable || Orderable < Orderable)
+}",
+        );
+        check(
+            r"use ordable::NonOrderable;
+fn f() {
+    Orderable > Orderable &&$0 Orderable >= Orderable
+}",
+            r"use ordable::NonOrderable;
+fn f() {
+    !(!(Orderable > Orderable) || !(Orderable >= Orderable))
+}",
+        );
+    }
+
     #[test]
     fn demorgan_turns_and_into_or() {
         check_assist(apply_demorgan, "fn f() { !x &&$0 !x }", "fn f() { !(x || x) }")
diff --git a/crates/ide_assists/src/utils.rs b/crates/ide_assists/src/utils.rs
index 38ed74673..276792bc1 100644
--- a/crates/ide_assists/src/utils.rs
+++ b/crates/ide_assists/src/utils.rs
@@ -267,24 +267,19 @@ fn invert_special_case(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Opti
 }
 
 fn bin_impls_ord(sema: &Semantics<RootDatabase>, bin: &ast::BinExpr) -> bool {
-    if let (Some(lhs), Some(rhs)) = (bin.lhs(), bin.rhs()) {
-        return sema.type_of_expr(&lhs) == sema.type_of_expr(&rhs)
-            && impls_ord(sema, &lhs)
-            && impls_ord(sema, &rhs);
-    }
-    false
-}
-
-fn impls_ord(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> bool {
-    let krate = sema.scope(expr.syntax()).module().map(|it| it.krate());
-    let famous_defs = FamousDefs(&sema, krate);
-
-    if let Some(ty) = sema.type_of_expr(expr) {
-        if let Some(ord_trait) = famous_defs.core_cmp_Ord() {
-            return ty.autoderef(sema.db).any(|ty| ty.impls_trait(sema.db, ord_trait, &[]));
+    match (
+        bin.lhs().and_then(|lhs| sema.type_of_expr(&lhs)),
+        bin.rhs().and_then(|rhs| sema.type_of_expr(&rhs)),
+    ) {
+        (Some(lhs_ty), Some(rhs_ty)) if lhs_ty == rhs_ty => {
+            let krate = sema.scope(bin.syntax()).module().map(|it| it.krate());
+            let ord_trait = FamousDefs(sema, krate).core_cmp_Ord();
+            ord_trait.map_or(false, |ord_trait| {
+                lhs_ty.autoderef(sema.db).any(|ty| ty.impls_trait(sema.db, ord_trait, &[]))
+            })
         }
+        _ => false,
     }
-    false
 }
 
 pub(crate) fn next_prev() -> impl Iterator<Item = Direction> {