Feature-gate block support in objc_foundation

.github/workflows/ci.yml

@@ -113,4 +113,6 @@ jobs:
       uses: actions-rs/cargo@v1
       with:
         command: test
-        args: --verbose --no-fail-fast
+        # TODO: `objc/exception` feature is broken in objc_foundation
+        # TODO: `objc_foundation/block` feature doesn't work on GNUStep
+        args: --verbose --no-fail-fast --no-default-features

objc_foundation/Cargo.toml

@@ -12,7 +12,10 @@ license = "MIT"
 
 exclude = [".gitignore"]
 
+[features]
+default = ["block"]
+
 [dependencies]
-block = "0.1"
+block = { optional = true, version = "0.1" }
 objc = { path = "../objc", version = "0.2.7" }
 objc_id = { path = "../objc_id", version = "0.1" }

objc_foundation/src/data.rs

@@ -1,9 +1,9 @@
-use std::mem;
 use std::ops::Range;
 use std::os::raw::c_void;
 use std::slice;
 
 use super::{INSCopying, INSMutableCopying, INSObject, NSRange};
+#[cfg(feature = "block")]
 use block::{Block, ConcreteBlock};
 use objc::msg_send;
 use objc_id::Id;
@@ -39,6 +39,7 @@ pub trait INSData: INSObject {
         }
     }
 
+    #[cfg(feature = "block")]
     fn from_vec(bytes: Vec<u8>) -> Id<Self> {
         let capacity = bytes.capacity();
         let dealloc = ConcreteBlock::new(move |bytes: *mut c_void, len: usize| unsafe {
@@ -56,7 +57,7 @@ pub trait INSData: INSObject {
             let obj: *mut Self = msg_send![obj, initWithBytesNoCopy:bytes_ptr
                                                              length:bytes.len()
                                                         deallocator:dealloc];
-            mem::forget(bytes);
+            std::mem::forget(bytes);
             Id::from_retained_ptr(obj)
         }
     }
@@ -192,6 +193,7 @@ mod tests {
         assert!(data.bytes() == [8, 17]);
     }
 
+    #[cfg(feature = "block")]
     #[test]
     fn test_from_vec() {
         let bytes = vec![3, 7, 16];