fix(util/buffer): bug in expand method

fixes #385

src/tests/util/buffer.cpp

@@ -81,10 +81,26 @@ static void tst3() {
     check(b, {1000, 2000, 0, 1, 2, 3, 100, 4, 300});
 }
 
+static void tst4() {
+    buffer<buffer<int>> b;
+    for (unsigned j = 38; j < 40; j++) {
+        for (unsigned i = 0; i < j; i++) {
+            b.push_back(buffer<int>());
+            for (unsigned k = 0; k < 10; k++) {
+                b.back().push_back(k);
+            }
+        }
+        lean_assert(b.size() == j);
+        b.clear();
+        lean_assert(b.size() == 0);
+    }
+}
+
 int main() {
     loop<buffer<int>>(100);
     tst1();
     tst2();
     tst3();
+    tst4();
     return has_violations() ? 1 : 0;
 }

src/util/buffer.h

@@ -30,11 +30,12 @@ protected:
     }
 
     void expand() {
-        unsigned new_capacity = m_capacity << 1;
-        char * new_buffer        = new char[sizeof(T) * new_capacity];
-        std::memcpy(new_buffer, static_cast<void*>(m_buffer), m_pos * sizeof(T));
-        free_memory();
-        m_buffer              = reinterpret_cast<T*>(new_buffer);
+        unsigned new_capacity  = m_capacity << 1;
+        char * new_buffer_char = new char[sizeof(T) * new_capacity];
+        T * new_buffer         = reinterpret_cast<T*>(new_buffer_char);
+        std::uninitialized_copy(m_buffer, m_buffer + m_pos, new_buffer);
+        destroy();
+        m_buffer              = new_buffer;
         m_capacity            = new_capacity;
     }
 

tests/lean/hott/crash1.hlean

@@ -0,0 +1,23 @@
+import types.sigma types.prod
+import algebra.binary algebra.group
+open eq eq.ops
+
+namespace path_algebra
+
+variable {A : Type}
+
+structure distrib [class] (A : Type) extends has_mul A, has_add A :=
+(left_distrib : ∀a b c, mul a (add b c) = add (mul a b) (mul a c))
+(right_distrib : ∀a b c, mul (add a b) c = add (mul a c) (mul b c))
+
+structure mul_zero_class [class] (A : Type) extends has_mul A, has_zero A :=
+(zero_mul : Πa, mul zero a = zero)
+(mul_zero : Πa, mul a zero = zero)
+
+structure zero_ne_one_class [class] (A : Type) extends has_zero A, has_one A :=
+(zero_ne_one : zero ≠ one)
+
+structure semiring [class] (A : Type) extends add_comm_monoid A, monoid A,
+  distrib A, mul_zero_class A, zero_ne_one_class A
+
+end path_algebra