fix feature gates

src/data/byte_str.rs

@@ -21,7 +21,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
+#[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 use core::borrow::{Borrow, BorrowMut};
 use core::convert::TryFrom;

src/data/number.rs

@@ -24,7 +24,9 @@
 //! Module defining number layout (integer, signed/unsigned, float etc) and universal in-memory
 //! number representation.
 
+#[cfg(feature = "alloc")]
 use alloc::format;
+#[cfg(feature = "alloc")]
 use alloc::string::{String, ToString};
 use core::fmt::{
     self, Debug, Display, Formatter, LowerExp, LowerHex, Octal, UpperExp, UpperHex, Write,
@@ -1495,8 +1497,6 @@ impl_number_int_conv!(u1024, 128, false);
 
 mod _float_impl {
     use amplify::num::apfloat::ieee::*;
-    use amplify::num::apfloat::Float;
-    use half::bf16;
 
     use super::*;
 

src/isa/bytecode.rs

@@ -23,6 +23,7 @@
 
 //! Instruction serialization and deserialization from bytecode.
 
+#[cfg(feature = "alloc")]
 use alloc::boxed::Box;
 use core::ops::RangeInclusive;