tests still failing, but logic working

Author: ZuseZ4

library/core/Cargo.toml

@@ -23,6 +23,7 @@ optimize_for_size = []
 # Make `RefCell` store additional debugging information, which is printed out when
 # a borrow error occurs
 debug_refcell = []
+llvm_enzyme = []
 
 [lints.rust.unexpected_cfgs]
 level = "warn"

library/core/src/macros/mod.rs

@@ -1513,8 +1513,8 @@ pub(crate) mod builtin {
     ///
     /// ### Usage examples:
     ///
-    #[cfg_attr(llvm_enzyme, doc = " ```rust")]
-    #[cfg_attr(not(llvm_enzyme), doc = " ```rust,compile_fail")]
+    #[cfg_attr(feature = "llvm_enzyme", doc = " ```rust")]
+    #[cfg_attr(not(feature = "llvm_enzyme"), doc = " ```rust,compile_fail")]
     /// use std::autodiff::*;
     /// #[autodiff_forward(rb_fwd1, Dual, Const, Dual)]
     /// #[autodiff_forward(rb_fwd2, Const, Dual, Dual)]
@@ -1538,6 +1538,8 @@ pub(crate) mod builtin {
     ///   let mut dout = 0.0;
     ///   let x4 = rb_inp_fwd(1.0, 1.0, 3.0, 1.0, &mut out, &mut dout);
     ///   // (out, dout) == (400.0, -400.0)
+    ///   //assert_eq!(x0, x1);
+    ///   //assert_eq!(x0, dxy);
     /// }
     /// ```
     ///
@@ -1584,8 +1586,8 @@ pub(crate) mod builtin {
     ///
     /// ### Usage examples:
     ///
-    #[cfg_attr(llvm_enzyme, doc = " ```rust")]
-    #[cfg_attr(not(llvm_enzyme), doc = " ```rust,compile_fail")]
+    #[cfg_attr(feature = "llvm_enzyme", doc = " ```rust")]
+    #[cfg_attr(not(feature = "llvm_enzyme"), doc = " ```rust,compile_fail")]
     /// use std::autodiff::*;
     /// #[autodiff_reverse(rb_rev, Active, Active, Active)]
     /// fn rosenbrock(x: f64, y: f64) -> f64 {

library/std/Cargo.toml

@@ -126,6 +126,7 @@ optimize_for_size = ["core/optimize_for_size", "alloc/optimize_for_size"]
 # a borrow error occurs
 debug_refcell = ["core/debug_refcell"]
 
+llvm_enzyme = ["core/llvm_enzyme"]
 
 # Enable std_detect features:
 std_detect_file_io = ["std_detect/std_detect_file_io"]

library/sysroot/Cargo.toml

@@ -35,3 +35,4 @@ profiler = ["dep:profiler_builtins"]
 std_detect_file_io = ["std/std_detect_file_io"]
 std_detect_dlsym_getauxval = ["std/std_detect_dlsym_getauxval"]
 windows_raw_dylib = ["std/windows_raw_dylib"]
+llvm_enzyme = ["std/llvm_enzyme"]

src/bootstrap/src/lib.rs

@@ -846,6 +846,10 @@ impl Build {
             features.insert("compiler-builtins-mem");
         }
 
+        if self.config.llvm_enzyme {
+            features.insert("llvm_enzyme");
+        }
+
         features.into_iter().collect::<Vec<_>>().join(" ")
     }