Add tests for allocation of variable-sized cdata

test/lib/ffi/cdata_var.lua

@@ -0,0 +1,41 @@
+local ffi = require("ffi")
+
+do --- byte array allocations
+  local typ = ffi.typeof"uint8_t[?]"
+  for i = 4, 20 do
+    for d = -3, 3 do
+      local sz = 2^i + d
+      assert(ffi.sizeof(typ, sz) == sz)
+      local mem = ffi.new(typ, sz)
+      assert(ffi.sizeof(mem) == sz)
+      mem[0] = 0x21
+      mem[1] = 0x32
+      mem[2] = 0x43
+      mem[sz-3] = 0x54
+      mem[sz-2] = 0x65
+      mem[sz-1] = 0x76
+      assert(mem[0] == 0x21)
+      assert(mem[1] == 0x32)
+      assert(mem[2] == 0x43)
+      assert(mem[sz-3] == 0x54)
+      assert(mem[sz-2] == 0x65)
+      assert(mem[sz-1] == 0x76)
+    end
+  end
+end
+
+do --- int array allocations
+  local typ = ffi.typeof"int32_t[?]"
+  for i = 2, 17 do
+    for d = -2, 2 do
+      local sz = 2^i + d
+      assert(ffi.sizeof(typ, sz) == sz*4)
+      local mem = ffi.new(typ, sz)
+      assert(ffi.sizeof(mem) == sz*4)
+      mem[0] = -3
+      mem[sz-1] = -4
+      assert(mem[0] == -3)
+      assert(mem[sz-1] == -4)
+    end
+  end
+end

test/lib/ffi/index

@@ -1,4 +1,5 @@
 bit64.lua +luajit>=2.1
+cdata_var.lua
 copy_fill.lua
 err.lua
 istype.lua