Fixed smallvec ToBoundedStatic, IntoBoundedStatic to process elements…

… inside.

Now there's one drawback that in some case SmallVec<A> won't be
supported where A is still smallvec::Array but isn't [T; N]. However, it
should be OK in reality, given smallvec itself is going to be SmallVec<T, N>
instead of SmallVec<[T; N]> with removing this.

Context: servo/rust-smallvec#183

bounded-static/src/lib.rs

@@ -824,29 +824,33 @@ impl IntoBoundedStatic for smol_str::SmolStr {
 
 /// [`ToBoundedStatic`] impl for `smallvec::SmallVec`.
 #[cfg(feature = "smallvec")]
-impl<A> ToBoundedStatic for smallvec::SmallVec<A>
+impl<T, const N: usize> ToBoundedStatic for smallvec::SmallVec<[T; N]>
 where
-    A: smallvec::Array + 'static,
-    A::Item: Clone,
+    [T; N]: smallvec::Array<Item = T>,
+    [T::Static; N]: smallvec::Array<Item = T::Static>,
+    T: ToBoundedStatic,
 {
-    type Static = Self;
+    type Static = smallvec::SmallVec<[T::Static; N]>;
 
     fn to_static(&self) -> Self::Static {
-        self.clone()
+        self.iter().map(ToBoundedStatic::to_static).collect()
     }
 }
 
-/// No-op [`IntoBoundedStatic`] impl for `smallvec::SmallVec`.
+/// [`IntoBoundedStatic`] impl for `smallvec::SmallVec`.
 #[cfg(feature = "smallvec")]
-impl<A> IntoBoundedStatic for smallvec::SmallVec<A>
+impl<T, const N: usize> IntoBoundedStatic for smallvec::SmallVec<[T; N]>
 where
-    A: smallvec::Array + 'static,
-    A::Item: Clone,
+    [T; N]: smallvec::Array<Item = T>,
+    [T::Static; N]: smallvec::Array<Item = T::Static>,
+    T: IntoBoundedStatic,
 {
-    type Static = Self;
+    type Static = smallvec::SmallVec<[T::Static; N]>;
 
     fn into_static(self) -> Self::Static {
-        self
+        self.into_iter()
+            .map(IntoBoundedStatic::into_static)
+            .collect()
     }
 }
 
@@ -1706,6 +1710,23 @@ mod smallvec_tests {
         ensure_static(small_vec.to_static());
         ensure_static(small_vec.into_static());
     }
+
+    #[cfg(feature = "alloc")]
+    mod alloc_smallvec_tests {
+        use super::*;
+
+        use crate::std::string::ToString;
+
+        #[test]
+        fn test_smallvec3() {
+            let x = "foo".to_string();
+            let y = "bar".to_string();
+            let buf = [Cow::Borrowed(x.as_str()), Cow::Borrowed(y.as_str())];
+            let small_vec: smallvec::SmallVec<_> = smallvec::SmallVec::from_buf(buf);
+            ensure_static(small_vec.to_static());
+            ensure_static(small_vec.into_static());
+        }
+    }
 }
 
 #[cfg(feature = "smartstring")]