Matouš Jan Fialka
8cecd0985c
`tostring()` was delegating to `luaToString()` which calls `__tostring` with a dead stack frame, breaking metamethods that call back into globals. Now `tostringFunction` receives the live stack frame, looks up `__tostring` via `rawGet`, calls it through `luaCall` with the live frame, and validates the return is a string. Also add tests covering the basic case, the nested-call case, and the error path for a non-string return. Signed-off-by: Matouš Jan Fialka <mjf@mjf.cz>
55 lines
1.6 KiB
Lua
55 lines
1.6 KiB
Lua
local function assertEqual(a, b)
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if a ~= b then
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error("Assertion failed: " .. a .. " is not equal to " .. b)
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end
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end
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-- Logic values, shouldn't be affected
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assertEqual(some(nil), nil)
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assertEqual(some(true), true)
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assertEqual(some(false), false)
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-- Numbers
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assertEqual(some(1), 1)
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assertEqual(some(0), 0) -- 0 is not falsy unlike C
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assertEqual(some(-1), -1)
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assertEqual(some(1/0), nil) -- inf
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assertEqual(some(0/0), nil) -- nan
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-- Strings
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assertEqual(some("foo bar"), "foo bar")
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assertEqual(some(""), nil)
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assertEqual(some(" \n"), nil)
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-- Tables
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assertEqual(some({}), nil)
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assertEqual(some({"baz"})[1], "baz") -- compare an element to ensure passthrough
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assertEqual(some({foo="bar"})["foo"], "bar")
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-- tostring: primitives
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assertEqual(tostring(nil), "nil")
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assertEqual(tostring(true), "true")
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assertEqual(tostring(false), "false")
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assertEqual(tostring(42), "42")
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assertEqual(tostring(3.14), "3.14")
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-- tostring: `__tostring` metamethod is called with the live SF
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local mt = { __tostring = function(t) return "custom:" .. t.name end }
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local obj = setmetatable({ name = "lua" }, mt)
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assertEqual(tostring(obj), "custom:lua")
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-- tostring: `__tostring` returning non-string must error
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local bad_mt = { __tostring = function(_) return 99 end }
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local bad_obj = setmetatable({}, bad_mt)
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local ok, err = pcall(tostring, bad_obj)
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assertEqual(ok, false)
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-- tostring: `__tostring` on a nested call (SF propagation via `luaCall`)
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local inner_mt = {
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__tostring = function(t)
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return "inner:" .. tostring(t.val)
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end
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}
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local inner = setmetatable({ val = 7 }, inner_mt)
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assertEqual(tostring(inner), "inner:7")
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