Diagnostics for unnecessary assert

[ribru17]

[tomlau10]

Judging from the screenshot, the message expression of type `boolean` is always truthy from assert(true) seems a bit misleading 😕 .

• false is also a boolean type, but assert(false) won't cause problem

[ribru17]

Ah true, not sure why the printed type evaluates to boolean instead of true. I'll investigate

[ribru17]

Opted to just not print the expression type for now

[CppCXY]

is it test for multi return function?

---@return string?, string?
local function f() end

assert(f())

[CppCXY]

I think that if it is always falsy is also an unnecessary assertion. right?

assert(nil and 5) -- always falsy

[ribru17]

I think that if it is always falsy is also an unnecessary assertion. right?

assert(nil and 5) -- always falsy

True, but this PR only handles unnecessary if true. I'll add that as well, but wanted to keep the scope small at first.

is it test for multi return function?

---@return string?, string?
local function f() end

assert(f())

Works here as well, I added a test

[sumneko]

Thank you!