Support bitwise operations in luaL_loadbuffer_proto

[ligurio]

No description provided.

[Buristan]

Hi, Sergey!
Thanks for the patch-set!
I'll proceed with the review per-patch below.

---

[PATCH 1/3] extra: add more errors found in PUC Rio Lua

LGTM.

[Buristan]

[PATCH 2/3] tests/capi: support floor division operation

Thanks for the patch!
Please consider my comment below.

[Buristan]

This will break parsing for Lua versions below 5.3:

luajit: /tmp/t5.3.lua:2: unexpected symbol near '/'

It is possible to workaround it via loadstring().

[ligurio]

Fixed:

diff --git a/tests/capi/luaL_loadbuffer_proto/preamble.lua b/tests/capi/luaL_loadbuffer_proto/preamble.lua
index 06912a0..edb56a8 100644
--- a/tests/capi/luaL_loadbuffer_proto/preamble.lua
+++ b/tests/capi/luaL_loadbuffer_proto/preamble.lua
@@ -91,7 +91,10 @@ local __unm = function(v)
     return - always_number(v)
 end
 local __idiv = function(v1, v2)
-    return always_number(v1) // always_number(v2)
+    -- `//` breaks parsing in PUC Rio Lua 5.1 and 5.1:
+    -- `unexpected symbol near '/'`.
+    local chunk = ('%d // %d'):format(always_number(v1), always_number(v2))
+    return assert(loadstring(chunk))()
 end
 local __band = function(v1, v2)
     local band = bitwise_op('&')

[Buristan]

loadstring() is undefined for the Lua 5.4:

lua5.4 -e 'loadstring""'
lua5.4: (command line):1: attempt to call a nil value (global 'loadstring')
stack traceback:
        (command line):1: in main chunk
        [C]: in ?

Plus, IMO, It is better to do something like the following:

_G.always_number = always_number

local __idiv = load[[
  local v1, v2 = ...
  return always_number(v1) // always_number(v2)
]]

In this key this metamethod will be uninitialized for the incorrect syntax cases.

Also, this helps to avoid calls to load on every invokation.

[Buristan]

[PATCH 3/3] tests/capi: support bitwise operations in luaL_loadbuffer_proto

Thanks for the patch!
Please consider my comment below.

[Buristan]

This will break parsing for Lua versions below 5.3.

[ligurio]

Fixed:

diff --git a/tests/capi/luaL_loadbuffer_proto/preamble.lua b/tests/capi/luaL_loadbuffer_proto/preamble.lua
index eea7336..edb56a8 100644
--- a/tests/capi/luaL_loadbuffer_proto/preamble.lua
+++ b/tests/capi/luaL_loadbuffer_proto/preamble.lua
@@ -8,6 +8,26 @@ local not_nan_and_nil = function(val)
     return (val ~= val or val == nil) and DEFAULT_NUMBER or val
 end
 
+local function bitwise_op(op_name)
+    return function(...)
+        local n = select('#', ...)
+        local chunk
+        -- Bitwise exclusive OR and bitwise NOT have the same
+        -- operator.
+        if (op_name == '&' or op_name == '|') then
+            assert(n > 1)
+        end
+        if n == 1 then
+            local x = ...
+            chunk = ('return %s %d'):format(op_name, x)
+        else
+            local op_name_ws = (' %s '):format(op_name)
+            chunk = 'return ' .. table.concat({...}, op_name_ws)
+        end
+        return assert(load(chunk))()
+    end
+end
+
 local __add = function(v1, v2)
     return always_number(v1) + always_number(v2)
 end
@@ -77,22 +97,28 @@ local __idiv = function(v1, v2)
     return assert(loadstring(chunk))()
 end
 local __band = function(v1, v2)
-    return always_number(v1) & always_number(v2)
+    local band = bitwise_op('&')
+    return band(always_number(v1), always_number(v2))
 end
 local __bor = function(v1, v2)
-    return always_number(v1) | always_number(v2)
+    local bor = bitwise_op('|')
+    return bor(always_number(v1), always_number(v2))
 end
 local __bxor = function(v1, v2)
-    return always_number(v1) ~ always_number(v2)
+    local bxor = bitwise_op('~')
+    return bxor(always_number(v1), always_number(v2))
 end
 local __bnot = function(v)
-    return ~always_number(v)
+    local bnot = bitwise_op('~')
+    return bnot(always_number(v))
 end
 local __shl = function(v1, v2)
-    return always_number(v1) << always_number(v2)
+    local shl = bitwise_op('<<')
+    return shl(always_number(v1), always_number(v2))
 end
 local __shr = function(v1, v2)
-    return always_number(v1) >> always_number(v2)
+    local shr = bitwise_op('>>')
+    return shr(always_number(v1), always_number(v2))
 end
 
 debug.setmetatable('string', {

[Buristan]

I suggest using the same approach as I mentioned for the // above.
Also, the n value is always either 1 or 2.