Add "type_name" support in emulate_intrinsic()

src/librustc_mir/interpret/intrinsics.rs

@@ -78,6 +78,13 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tcx, M>
                 let id_val = Scalar::from_uint(type_id, dest.layout.size);
                 self.write_scalar(id_val, dest)?;
             }
+
+            "type_name" => {
+                let ty = substs.type_at(0);
+                let ty_name = ty.to_string();
+                let name_val = self.str_to_immediate(&ty_name)?;
+                self.write_immediate(name_val, dest)?;
+            }
             | "ctpop"
             | "cttz"
             | "cttz_nonzero"

src/test/run-pass/ctfe/const-fn-type-name.rs

@@ -0,0 +1,38 @@
+// run-pass
+
+#![feature(core_intrinsics)]
+#![feature(const_fn)]
+#![allow(dead_code)]
+
+const fn type_name_wrapper<T>(_: &T) -> &'static str {
+    unsafe { std::intrinsics::type_name::<T>() }
+}
+
+struct Struct<TA, TB, TC> {
+    a: TA,
+    b: TB,
+    c: TC,
+}
+
+type StructInstantiation = Struct<i8, f64, bool>;
+
+const CONST_STRUCT: StructInstantiation = StructInstantiation {
+    a: 12,
+    b: 13.7,
+    c: false,
+};
+
+const CONST_STRUCT_NAME: &'static str = type_name_wrapper(&CONST_STRUCT);
+
+fn main() {
+    println!("{}", CONST_STRUCT_NAME);
+
+    let non_const_struct = StructInstantiation {
+        a: 87,
+        b: 65.99,
+        c: true,
+    };
+    let non_const_struct_name = type_name_wrapper(&non_const_struct);
+
+    println!("{}", non_const_struct_name);
+}