Merge pull request #1030 from SciML/revert-1025-dg/trim

Revert "Make `get_initial_values` differentiate"

Author: ChrisRackauckas

src/initialization.jl

@@ -260,7 +260,7 @@ function get_initial_values(prob, valp, f, alg::OverrideInit,
     end
 
     if is_trivial_initialization(initdata)
-        nlsol = initdata
+        nlsol = initprob
         success = true
     else
         nlsolve_alg = something(nlsolve_alg, alg.nlsolve, Some(nothing))
@@ -295,13 +295,18 @@ function get_initial_values(prob, valp, f, alg::OverrideInit,
     end
 
     if initdata.initializeprobmap !== nothing
-        u0 = initdata.initializeprobmap(choose_branch(nlsol))
+        u02 = initdata.initializeprobmap(nlsol)
     end
     if initdata.initializeprobpmap !== nothing
-        p = initdata.initializeprobpmap(valp, choose_branch(nlsol))
+        p2 = initdata.initializeprobpmap(valp, nlsol)
     end
 
-    return u0, p, success
+    # specifically needs to be written this way for Zygote
+    # See https://github.com/SciML/ModelingToolkit.jl/pull/3585#issuecomment-2883919162
+    u03 = isnothing(initdata.initializeprobmap) ? u0 : u02
+    p3 = isnothing(initdata.initializeprobpmap) ? p : p2
+
+    return u03, p3, success
 end
 
 """

src/utils.jl

@@ -550,6 +550,3 @@ Strips a SciMLSolution object and its interpolation of their functions to better
 function strip_solution(sol::AbstractSciMLSolution)
     sol
 end
-
-choose_branch(x::OverrideInitData) = x.initializeprob
-choose_branch(sol::AbstractSciMLSolution) = sol