Fix printing of complex coefficients in expressions (#3112)

Author: odow

src/print.jl

@@ -51,9 +51,7 @@ function _is_one_for_printing(coef)
     return _is_zero_for_printing(abs(coef) - oneunit(coef))
 end
 
-function _is_one_for_printing(coef::Complex)
-    return _is_one_for_printing(real(coef)) && _is_zero_for_printing(imag(coef))
-end
+_is_one_for_printing(coef::Complex{T}) where {T} = coef == one(T)
 
 function _is_zero_for_printing(coef::Complex)
     return _is_zero_for_printing(real(coef)) &&

test/print.jl

@@ -965,6 +965,14 @@ function test_show_latex_parameter()
     return
 end
 
+function test_minus_one_complex_aff_expr()
+    model = Model()
+    @variable(model, x)
+    f = 1.0im * x + 1.0im
+    @test sprint(show, im * f) == "(-1.0 + 0.0im) x + (-1.0 + 0.0im)"
+    return
+end
+
 end
 
 TestPrint.runtests()