Add tests for 99866 and 99852

src/test/ui/mir/issue-99852.rs

@@ -0,0 +1,16 @@
+// check-pass
+// compile-flags: -C opt-level=3
+
+#![crate_type = "lib"]
+
+fn lambda<T: Default>() -> T {
+    if true && let Some(bar) = transform() {
+        bar
+    } else {
+        T::default()
+    }
+}
+
+fn transform<T>() -> Option<T> {
+    None
+}

src/test/ui/mir/issue-99866.rs

@@ -0,0 +1,27 @@
+// check-pass
+// compile-flags: -C opt-level=3
+
+#![crate_type = "lib"]
+
+pub trait Backend {
+    type DescriptorSetLayout;
+}
+
+pub struct Back;
+
+impl Backend for Back {
+    type DescriptorSetLayout = u32;
+}
+
+pub struct HalSetLayouts {
+    vertex_layout: <Back as Backend>::DescriptorSetLayout,
+}
+
+impl HalSetLayouts {
+    pub fn iter<DSL>(self) -> DSL
+    where
+        Back: Backend<DescriptorSetLayout = DSL>,
+    {
+        self.vertex_layout
+    }
+}