AK+Everywhere: Disallow returning a reference from a fallible expression

This will silently make a copy. Rather than masking this behavior, let's
explicitly disallow it.

1 files changed, 8 insertions, 6 deletions

diff --git a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
index d0117b3c2c..b3a8c92401 100644
--- a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
@@ -42,12 +42,14 @@
 
 namespace Web::Fetch::Fetching {
 
-#define TRY_OR_IGNORE(expression)              \
-    ({                                         \
-        auto _temporary_result = (expression); \
-        if (_temporary_result.is_error())      \
-            return;                            \
-        _temporary_result.release_value();     \
+#define TRY_OR_IGNORE(expression)                                                      \
+    ({                                                                                 \
+        auto _temporary_result = (expression);                                         \
+        if (_temporary_result.is_error())                                              \
+            return;                                                                    \
+        static_assert(!IsLvalueReference<decltype(_temporary_result.release_value())>, \
+            "Do not return a reference from a fallible expression");                   \
+        _temporary_result.release_value();                                             \
     })
 
 // https://fetch.spec.whatwg.org/#concept-fetch