fix(discretization): fold symbolic initial conditions for MTK v1.45 compatibility

src/MethodOfLines.jl

@@ -8,7 +8,8 @@ using ModelingToolkit: get_unknowns,
     get_ivs
 using SymbolicIndexingInterface
 using SymbolicUtils, Symbolics
-using Symbolics: unwrap, symbolic_linear_solve, expand_derivatives, diff2term
+using Symbolics: unwrap, symbolic_linear_solve, expand_derivatives, diff2term,
+    symbolic_to_float
 using SymbolicUtils: operation, arguments, iscall, getmetadata, unwrap_const
 using IfElse
 using StaticArrays

src/discretization/generate_ic_defaults.jl

@@ -14,14 +14,12 @@ function PDEBase.generate_ic_defaults(
             D = ic.order == 0 ? identity : (Differential(t)^ic.order)
             defaultvars = D.(s.discvars[depvar(ic.u, s)])
             broadcastable_rhs = [symbolic_linear_solve(ic.eq, D(ic.u))]
-            out = pde_substitute.(
+            rhs_vals = pde_substitute.(
                 broadcastable_rhs, Dict.(valmaps(s, depvar(ic.u, s), ic.depvars, indexmap))
             )
-            vec(
-                defaultvars .=> pde_substitute.(
-                    broadcastable_rhs, Dict.(valmaps(s, depvar(ic.u, s), ic.depvars, indexmap))
-                )
-            )
+
+            fold(v) = v isa Number ? v : symbolic_to_float(v)
+            vec(defaultvars .=> fold.(rhs_vals))
         end
     else
         u0 = []

test/qa/qa.jl

@@ -44,7 +44,7 @@ run_qa(
                 :Interval, :add_metadata!, :error_analysis, :get_ops, :insert, :remove,
                 :sym_dot, :unitindex, :unitindices, :update_varmap!, :vcat!,
                 # non-public in Symbolics:
-                :diff2term,
+                :diff2term, :symbolic_to_float,
             ),
         ),
         all_qualified_accesses_are_public = (;