Add stage 06: Lua bootstrap

The goal of stage 06 is to try parse zig synax in lua. I pulled in
lpeglable 1.2.0 and parser-gen off github to get started. All of this
needs to be cleaned up rather soon.

Lua boostraps using tcc and musl from the previous stage. Since musl
0.6.0 doesn't support dynamic linking this build of lua doesn't support
shared libraries. I couldn't easily patch musl with dlopen and friends
so instead I link statically and call deps with c api.

06/parser-gen/parsers/lua-5.3.4-tests/goto.lua

@@ -0,0 +1,232 @@
+-- $Id: goto.lua,v 1.13 2016/11/07 13:11:28 roberto Exp $
+-- See Copyright Notice in file all.lua
+
+collectgarbage()
+
+local function errmsg (code, m)
+  local st, msg = load(code)
+  assert(not st and string.find(msg, m))
+end
+
+-- cannot see label inside block
+errmsg([[ goto l1; do ::l1:: end ]], "label 'l1'")
+errmsg([[ do ::l1:: end goto l1; ]], "label 'l1'")
+
+-- repeated label
+errmsg([[ ::l1:: ::l1:: ]], "label 'l1'")
+
+
+-- undefined label
+errmsg([[ goto l1; local aa ::l1:: ::l2:: print(3) ]], "local 'aa'")
+
+-- jumping over variable definition
+errmsg([[
+do local bb, cc; goto l1; end
+local aa
+::l1:: print(3)
+]], "local 'aa'")
+
+-- jumping into a block
+errmsg([[ do ::l1:: end goto l1 ]], "label 'l1'")
+errmsg([[ goto l1 do ::l1:: end ]], "label 'l1'")
+
+-- cannot continue a repeat-until with variables
+errmsg([[
+  repeat
+    if x then goto cont end
+    local xuxu = 10
+    ::cont::
+  until xuxu < x
+]], "local 'xuxu'")
+
+-- simple gotos
+local x
+do
+  local y = 12
+  goto l1
+  ::l2:: x = x + 1; goto l3
+  ::l1:: x = y; goto l2
+end
+::l3:: ::l3_1:: assert(x == 13)
+
+
+-- long labels
+do
+  local prog = [[
+  do
+    local a = 1
+    goto l%sa; a = a + 1
+   ::l%sa:: a = a + 10
+    goto l%sb; a = a + 2
+   ::l%sb:: a = a + 20
+    return a
+  end
+  ]]
+  local label = string.rep("0123456789", 40)
+  prog = string.format(prog, label, label, label, label)
+  assert(assert(load(prog))() == 31)
+end
+
+-- goto to correct label when nested
+do goto l3; ::l3:: end   -- does not loop jumping to previous label 'l3'
+
+-- ok to jump over local dec. to end of block
+do
+  goto l1
+  local a = 23
+  x = a
+  ::l1::;
+end
+
+while true do
+  goto l4
+  goto l1  -- ok to jump over local dec. to end of block
+  goto l1  -- multiple uses of same label
+  local x = 45
+  ::l1:: ;;;
+end
+::l4:: assert(x == 13)
+
+if print then
+  goto l1   -- ok to jump over local dec. to end of block
+  error("should not be here")
+  goto l2   -- ok to jump over local dec. to end of block
+  local x
+  ::l1:: ; ::l2:: ;;
+else end
+
+-- to repeat a label in a different function is OK
+local function foo ()
+  local a = {}
+  goto l3
+  ::l1:: a[#a + 1] = 1; goto l2;
+  ::l2:: a[#a + 1] = 2; goto l5;
+  ::l3::
+  ::l3a:: a[#a + 1] = 3; goto l1;
+  ::l4:: a[#a + 1] = 4; goto l6;
+  ::l5:: a[#a + 1] = 5; goto l4;
+  ::l6:: assert(a[1] == 3 and a[2] == 1 and a[3] == 2 and
+              a[4] == 5 and a[5] == 4)
+  if not a[6] then a[6] = true; goto l3a end   -- do it twice
+end
+
+::l6:: foo()
+
+
+do   -- bug in 5.2 -> 5.3.2
+  local x
+  ::L1::
+  local y             -- cannot join this SETNIL with previous one
+  assert(y == nil)
+  y = true
+  if x == nil then
+    x = 1
+    goto L1
+  else
+    x = x + 1
+  end
+  assert(x == 2 and y == true)
+end
+
+--------------------------------------------------------------------------------
+-- testing closing of upvalues
+
+local debug = require 'debug'
+
+local function foo ()
+  local t = {}
+  do
+  local i = 1
+  local a, b, c, d
+  t[1] = function () return a, b, c, d end
+  ::l1::
+  local b
+  do
+    local c
+    t[#t + 1] = function () return a, b, c, d end    -- t[2], t[4], t[6]
+    if i > 2 then goto l2 end
+    do
+      local d
+      t[#t + 1] = function () return a, b, c, d end   -- t[3], t[5]
+      i = i + 1
+      local a
+      goto l1
+    end
+  end
+  end
+  ::l2:: return t
+end
+
+local a = foo()
+assert(#a == 6)
+
+-- all functions share same 'a'
+for i = 2, 6 do
+  assert(debug.upvalueid(a[1], 1) == debug.upvalueid(a[i], 1))
+end
+
+-- 'b' and 'c' are shared among some of them
+for i = 2, 6 do
+  -- only a[1] uses external 'b'/'b'
+  assert(debug.upvalueid(a[1], 2) ~= debug.upvalueid(a[i], 2))
+  assert(debug.upvalueid(a[1], 3) ~= debug.upvalueid(a[i], 3))
+end
+
+for i = 3, 5, 2 do
+  -- inner functions share 'b'/'c' with previous ones
+  assert(debug.upvalueid(a[i], 2) == debug.upvalueid(a[i - 1], 2))
+  assert(debug.upvalueid(a[i], 3) == debug.upvalueid(a[i - 1], 3))
+  -- but not with next ones
+  assert(debug.upvalueid(a[i], 2) ~= debug.upvalueid(a[i + 1], 2))
+  assert(debug.upvalueid(a[i], 3) ~= debug.upvalueid(a[i + 1], 3))
+end
+
+-- only external 'd' is shared
+for i = 2, 6, 2 do
+  assert(debug.upvalueid(a[1], 4) == debug.upvalueid(a[i], 4))
+end
+
+-- internal 'd's are all different
+for i = 3, 5, 2 do
+  for j = 1, 6 do
+    assert((debug.upvalueid(a[i], 4) == debug.upvalueid(a[j], 4))
+      == (i == j))
+  end
+end
+
+--------------------------------------------------------------------------------
+-- testing if x goto optimizations
+
+local function testG (a)
+  if a == 1 then
+    goto l1
+    error("should never be here!")
+  elseif a == 2 then goto l2
+  elseif a == 3 then goto l3
+  elseif a == 4 then
+    goto l1  -- go to inside the block
+    error("should never be here!")
+    ::l1:: a = a + 1   -- must go to 'if' end
+  else
+    goto l4
+    ::l4a:: a = a * 2; goto l4b
+    error("should never be here!")
+    ::l4:: goto l4a
+    error("should never be here!")
+    ::l4b::
+  end
+  do return a end
+  ::l2:: do return "2" end
+  ::l3:: do return "3" end
+  ::l1:: return "1"
+end
+
+assert(testG(1) == "1")
+assert(testG(2) == "2")
+assert(testG(3) == "3")
+assert(testG(4) == 5)
+assert(testG(5) == 10)
+--------------------------------------------------------------------------------
+
+
+print'OK'