Expand fuzzing coverage (#95)

* Also cover reserve, reserve_exact and shrink_to_fit by fuzzing. SmallVec had a use-after-free bug in shrink_to_fit inlining so we'd better test this

* Also test extend_from_slice on tinyvec and arrayvec

fuzz/src/bin/arrayish.rs

@@ -26,6 +26,7 @@ arbitrary_stateful_operations! {
             fn as_slice(&self) -> &[T];
             fn clear(&mut self);
             fn dedup(&mut self);
+            fn extend_from_slice(&mut self, sli: &Box<[T]>);
             fn insert(&mut self, index: usize, item: T);
             fn is_empty(&self) -> bool;
             fn len(&self) -> usize;
@@ -56,7 +57,9 @@ arbitrary_stateful_operations! {
             Self::resize { new_len, .. } if new_len > CAPACITY => {
                 return;
             }
-
+            Self::extend_from_slice { sli } if model.len().saturating_add(sli.len()) > CAPACITY => {
+                return;
+            }
             _ => {}
         }
     }

fuzz/src/bin/tinyvec.rs

@@ -26,13 +26,17 @@ arbitrary_stateful_operations! {
             fn as_slice(&self) -> &[T];
             fn clear(&mut self);
             fn dedup(&mut self);
+            fn extend_from_slice(&mut self, sli: &Box<[T]>);
             fn insert(&mut self, index: usize, item: T);
             fn is_empty(&self) -> bool;
             fn len(&self) -> usize;
             fn pop(&mut self) -> Option<T>;
             fn push(&mut self, item: T);
             fn remove(&mut self, index: usize) -> T;
+            fn reserve(&mut self, n: usize);
+            fn reserve_exact(&mut self, n: usize);
             fn resize(&mut self, new_len: usize, new_val: T);
+            fn shrink_to_fit(&mut self);
             fn swap_remove(&mut self, index: usize) -> T;
             fn truncate(&mut self, new_len: usize);
         }
@@ -50,7 +54,16 @@ arbitrary_stateful_operations! {
             // Arbitrary limit to avoid allocating too large a buffer
             Self::resize { new_len, .. } if new_len > 4 * CAPACITY => {
                 return;
-            }
+            },
+            Self::reserve { n } if model.capacity().saturating_add(n) > 4 * CAPACITY => {
+                return;
+            },
+            Self::reserve_exact { n } if model.capacity().saturating_add(n) > 4 * CAPACITY => {
+                return;
+            },
+            Self::extend_from_slice { sli } if model.len().saturating_add(sli.len()) > 4 * CAPACITY => {
+                return;
+            },
             _ => {}
         }
     }