Static INLINE_ALWAYS_MISMATCHING_TARGET_FEATURES 

pub static INLINE_ALWAYS_MISMATCHING_TARGET_FEATURES: &Lint

The inline_always_mismatching_target_features lint will trigger when a function with the #[inline(always)] and #[target_feature(enable = "...")] attributes is called and cannot be inlined due to missing target features in the caller.

Example

#[inline(always)]
#[target_feature(enable = "fp16")]
unsafe fn callee() {
    // operations using fp16 types
}

// Caller does not enable the required target feature
fn caller() {
    unsafe { callee(); }
}

fn main() {
    caller();
}

This will produce:

warning: call to `#[inline(always)]`-annotated `callee` requires the same target features. Function will not have `alwaysinline` attribute applied
  --> $DIR/builtin.rs:5192:14
   |
10 |     unsafe { callee(); }
   |              ^^^^^^^^
   |
note: `fp16` target feature enabled in `callee` here but missing from `caller`
  --> $DIR/builtin.rs:5185:1
   |
3  | #[target_feature(enable = "fp16")]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
4  | unsafe fn callee() {
   | ------------------
   = note: `#[warn(inline_always_mismatching_target_features)]` on by default
warning: 1 warning emitted

Explanation

Inlining a function with a target feature attribute into a caller that lacks the corresponding target feature can lead to unsound behavior. LLVM may select the wrong instructions or registers, or reorder operations, potentially resulting in runtime errors.