1 files changed, 37 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/macros.rs b/compiler/rustc_data_structures/src/macros.rs
new file mode 100644
index 000000000..e05491f6f
--- /dev/null
+++ b/compiler/rustc_data_structures/src/macros.rs
@@ -0,0 +1,37 @@
+#[macro_export]
+macro_rules! enum_from_u32 {
+    ($(#[$attr:meta])* pub enum $name:ident {
+        $($(#[$var_attr:meta])* $variant:ident = $e:expr,)*
+    }) => {
+        $(#[$attr])*
+        pub enum $name {
+            $($(#[$var_attr])* $variant = $e),*
+        }
+
+        impl $name {
+            pub fn from_u32(u: u32) -> Option<$name> {
+                $(if u == $name::$variant as u32 {
+                    return Some($name::$variant)
+                })*
+                None
+            }
+        }
+    };
+    ($(#[$attr:meta])* pub enum $name:ident {
+        $($(#[$var_attr:meta])* $variant:ident,)*
+    }) => {
+        $(#[$attr])*
+        pub enum $name {
+            $($(#[$var_attr])* $variant,)*
+        }
+
+        impl $name {
+            pub fn from_u32(u: u32) -> Option<$name> {
+                $(if u == $name::$variant as u32 {
+                    return Some($name::$variant)
+                })*
+                None
+            }
+        }
+    }
+}