Fix Derivative Update Bug (#264)

* Fix derivative macro bug.

* fix tests

* regex fix

Author: pulsipher

docs/src/guide/derivative.md

@@ -191,6 +191,12 @@ dydt2(t, ξ)
 This will also support anonymous definition and multi-dimensional definition. 
 Please see [Macro Variable Definition](@ref) for more information.
 
+!!! warning
+    The same derivative should not be redefined with multiple `@variable` calls 
+    and using `@variable` to define derivatives should be avoided on derivatives 
+    that were already defined. This is because the latest `@variable` will 
+    overwrite any existing properties a derivative might already have. 
+
 Second, for more convenient definition we use [`@deriv`](@ref) (or [`@∂`](@ref)) 
 as shown in the Basic Usage section above. Unlike `@variable` this can handle any 
 `InfiniteOpt` expression as the argument input. It also can build derivatives 

docs/src/guide/variable.md

@@ -1,5 +1,5 @@
 ```@meta
-DocTestFilters = [r"≤|<=", r" == | = ", r" ∈ | in ", r" for all | ∀ "]
+DocTestFilters = [r"≤|<=", r" == | = ", r" ∈ | in ", r" for all | ∀ ", r"sin \(.*"]
 ```
 
 # [Variables](@id var_docs)

src/derivatives.jl

@@ -332,7 +332,13 @@ function add_derivative(
     else
         dref = DerivativeRef(model, existing_index)
         gvref = _make_variable_ref(model, existing_index)
+        old_info = _variable_info(dref)
+        if old_info.has_lb || old_info.has_ub || old_info.has_fix || old_info.has_start
+            @warn "Overwriting $dref, any previous properties (e.g., lower bound " * 
+                  "or start value) will be lost/changed."
+        end
         _update_info_constraints(d.info, gvref, dref)
+        _set_core_variable_object(dref, d)
         if !isempty(name)
             set_name(dref, name)
         end

test/derivatives.jl

@@ -206,7 +206,8 @@ end
     info = VariableInfo(false, num, false, num, false, num, false, NaN, false, false)
     info2 = VariableInfo(true, num, true, num, true, num, true, func1, false, false)
     info3 = VariableInfo(true, num, true, num, true, num, true, 42, false, true)
-    info4 = VariableInfo(true, num, false, num, false, num, false, s -> NaN, false, false)
+    info4 = VariableInfo(true, num, false, num, false, num, true, s -> NaN, false, false)
+    info5 = VariableInfo(false, num, false, num, false, num, false, s -> NaN, false, false)
     # build_derivative
     @testset "build_derivative" begin 
         # test errors 
@@ -302,12 +303,22 @@ end
         idx = DerivativeIndex(1)
         dref = DerivativeRef(m, idx)
         gvref = InfiniteOpt._make_variable_ref(m, idx)
-        d = Derivative(info4, true, x, pref)
+        d = Derivative(info4, false, x, pref)
         @test isequal(add_derivative(m, d, "name2"), gvref)
         @test haskey(InfiniteOpt._data_dictionary(dref), idx)
         @test InfiniteOpt._core_variable_object(dref) == d
         @test name(dref) == "name2"
         @test lower_bound(dref) == 0
+        # test redundant build with warning 
+        idx = DerivativeIndex(1)
+        dref = DerivativeRef(m, idx)
+        d = Derivative(info5, true, x, pref)
+        warn = "Overwriting name2(pref, prefs), any previous properties (e.g., lower bound " * 
+               "or start value) will be lost/changed."
+        @test_logs (:warn, warn) add_derivative(m, d, "name3")
+        @test haskey(InfiniteOpt._data_dictionary(dref), idx)
+        @test InfiniteOpt._core_variable_object(dref) == d
+        @test name(dref) == "name3"
     end
     # test JuMP.add_variable 
     @testset "JuMP.add_variable" begin