Replace short preconditions in the main package

source/tanya/range/adapter.d

@@ -170,7 +170,11 @@ if (isArray!Array)
 
         void opCall(T)(auto ref T data)
         if (is(T : E))
-        in (!this.data.empty)
+        in
+        {
+            assert(!this.data.empty);
+        }
+        do
         {
             put(this.data, data);
         }

source/tanya/range/array.d

@@ -55,7 +55,11 @@ module tanya.range.array;
  * Precondition: $(D_INLINECODE array.length > 0).
  */
 @property ref inout(T) front(T)(return scope inout(T)[] array)
-in (array.length > 0)
+in
+{
+    assert(array.length > 0);
+}
+do
 {
     return array[0];
 }
@@ -91,7 +95,11 @@ in (array.length > 0)
  * Precondition: $(D_INLINECODE array.length > 0).
  */
 @property ref inout(T) back(T)(return scope inout(T)[] array)
-in (array.length > 0)
+in
+{
+    assert(array.length > 0);
+}
+do
 {
     return array[$ - 1];
 }
@@ -126,14 +134,22 @@ in (array.length > 0)
  * Precondition: $(D_INLINECODE array.length > 0).
  */
 void popFront(T)(scope ref inout(T)[] array)
-in (array.length > 0)
+in
+{
+    assert(array.length > 0);
+}
+do
 {
     array = array[1 .. $];
 }
 
 /// ditto
 void popBack(T)(scope ref inout(T)[] array)
-in (array.length > 0)
+in
+{
+    assert(array.length > 0);
+}
+do
 {
     array = array[0 .. $ - 1];
 }

source/tanya/range/primitive.d

@@ -1556,7 +1556,11 @@ if (isInputRange!Range && hasLvalueElements!Range)
  */
 ElementType!R getAndPopFront(R)(ref R range)
 if (isInputRange!R)
-in (!range.empty)
+in
+{
+    assert(!range.empty);
+}
+do
 {
     static if (hasLvalueElements!R)
     {
@@ -1609,7 +1613,11 @@ in (!range.empty)
  */
 auto ref getAndPopBack(R)(ref R range)
 if (isBidirectionalRange!R)
-in (!range.empty)
+in
+{
+    assert(!range.empty);
+}
+do
 {
     static if (hasLvalueElements!R)
     {