@variable macro fails to resolve variables in 1.18.0

[ianfiske]

Here's a MWE:

using JuMP

m = Model()
x = (lower_bound=5.0,)
@variable(m, set = MOI.GreaterThan(x.lower_bound))

With JuMP 1.18.0, this fails with the error

ERROR: UndefVarError: `x` not defined
Stacktrace:
 [1] macro expansion
   @ ~/.julia/packages/JuMP/9tYtW/src/macros/@variable.jl:313 [inlined]
 [2] macro expansion
   @ ~/.julia/packages/JuMP/9tYtW/src/macros.jl:375 [inlined]
 [3] top-level scope
   @ ~/julia-envs/jump-bug/minrepro.jl:6

In JuMP 1.17 and below, there is no error.

[odow]

I'll take a look. I recently refactored our macro handling, so this is my fault.

I guess I was right #3629 (comment)

The main risk is probably esc scoping bugs

[odow]

See #3647

I guess the lesson is that when writing tests, we should prefer to use variables rather than literals so that we can check for scoping bugs like this.