Increase the size of the last hole if the new hole aligns to it

Author: rafalmiel

src/hole.rs

@@ -240,13 +240,6 @@ fn deallocate(mut hole: &mut Hole, addr: usize, mut size: usize) {
                 hole.size += size + next.size; // merge the F and Y blocks to this X block
                 hole.next = hole.next_unwrap().next.take(); // remove the Y block
             }
-            Some(_) if hole_addr + hole.size == addr => {
-                // block is right behind this hole but there is used memory after it
-                // before:  ___XXX______YYYYY____    where X is this hole and Y the next hole
-                // after:   ___XXXFFFF__YYYYY____    where F is the freed block
-
-                hole.size += size; // merge the F block to this X block
-            }
             Some(next) if addr + size == next.addr => {
                 // block is right before the next hole but there is used memory before it
                 // before:  ___XXX______YYYYY____    where X is this hole and Y the next hole
@@ -264,6 +257,17 @@ fn deallocate(mut hole: &mut Hole, addr: usize, mut size: usize) {
                 hole = move_helper(hole).next_unwrap(); // start next iteration at next hole
                 continue;
             }
+            _ if hole_addr + hole.size == addr => {
+                // block is right behind this hole but there is used memory after it
+                // before:  ___XXX______YYYYY____    where X is this hole and Y the next hole
+                // after:   ___XXXFFFF__YYYYY____    where F is the freed block
+
+                // or: block is right behind this hole and this is the last hole
+                // before:  ___XXX_______________    where X is this hole and Y the next hole
+                // after:   ___XXXFFFF___________    where F is the freed block
+
+                hole.size += size; // merge the F block to this X block
+            }
             _ => {
                 // block is between this and the next hole
                 // before:  ___XXX________YYYYY_    where X is this hole and Y the next hole