fix: fix stack overflow for methods using symbolic_container to define a fallback

Author: AayushSabharwal

src/index_provider_interface.jl

@@ -59,8 +59,8 @@ parameter_index(indp, sym) = parameter_index(symbolic_container(indp), sym)
 Check whether the given `sym` is a timeseries parameter in `indp`.
 """
 function is_timeseries_parameter(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
-        is_timeseries_parameter(symbolic_container(indp), sym)
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) && (sc = symbolic_container(indp)) !== indp
+        is_timeseries_parameter(sc, sym)
     else
         return false
     end
@@ -91,7 +91,7 @@ parameter in `indp`. Defaults to returning `nothing`. Respects the
 [`symbolic_container`](@ref) fallback for `indp` if present.
 """
 function timeseries_parameter_index(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) && (sc = symbolic_container(indp)) !== indp
         timeseries_parameter_index(symbolic_container(indp), sym)
     else
         return nothing
@@ -111,7 +111,7 @@ By default, this function returns `nothing`, indicating that the index provider
 support generating parameter observed functions.
 """
 function parameter_observed(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) && (sc = symbolic_container(indp)) !== indp
         return parameter_observed(symbolic_container(indp), sym)
     else
         return nothing
@@ -143,7 +143,7 @@ variable.
 By default, this function returns `Set([ContinuousTimeseries()])`.
 """
 function get_all_timeseries_indexes(indp, sym)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) && (sc = symbolic_container(indp)) !== indp
         return get_all_timeseries_indexes(symbolic_container(indp), sym)
     else
         return Set([ContinuousTimeseries()])
@@ -240,7 +240,7 @@ Return a dictionary mapping symbols in the index provider to their default value
 This includes parameter symbols. The dictionary must be mutable.
 """
 function default_values(indp)
-    if hasmethod(symbolic_container, Tuple{typeof(indp)})
+    if hasmethod(symbolic_container, Tuple{typeof(indp)}) && (sc = symbolic_container(indp)) !== indp
         default_values(symbolic_container(indp))
     else
         Dict()

src/symbol_cache.jl

@@ -71,6 +71,8 @@ function SymbolCache(vars = nothing, params = nothing, indepvars = nothing;
         defaults)
 end
 
+symbolic_container(sc::SymbolCache) = sc
+
 function is_variable(sc::SymbolCache, sym)
     sc.variables === nothing && return false
     if symbolic_type(sym) == NotSymbolic()