Prevent type infer hang of "simple" recursive functions

Compiler/src/typeinfer.jl

@@ -613,18 +613,17 @@ function finishinfer!(me::InferenceState, interp::AbstractInterpreter, cycleid::
     istoplevel = !(me.linfo.def isa Method)
     istoplevel || compute_edges!(me) # don't add backedges to toplevel method instance
 
-    if limited_ret
-        # a parent may be cached still, but not this intermediate work:
-        # we can throw everything else away now
+    if limited_ret || limited_src
+        # A parent may be cached still, but not this intermediate work:
+        # we can throw everything else away now. Caching anything can confuse later
+        # heuristics to consider it worth trying to pursue compiling this further and
+        # finding infinite work as a result. Avoiding caching helps to ensure there is only
+        # a finite amount of work that can be discovered later (although potentially still a
+        # large multiplier on it).
         result.src = nothing
         result.tombstone = true
         me.cache_mode = CACHE_MODE_NULL
         set_inlineable!(me.src, false)
-    elseif limited_src
-        # a type result will be cached still, but not this intermediate work:
-        # we can throw everything else away now
-        result.src = nothing
-        set_inlineable!(me.src, false)
     else
         # annotate fulltree with type information,
         # either because we are the outermost code, or we might use this later

Compiler/test/inference.jl

@@ -6445,4 +6445,29 @@ A58257.B58257.get!    # Creates binding partition in A.B, N+1:∞
 Base.invoke_in_world(UInt(38678), getglobal, A58257, :get!) # Expands binding partition in A through <N
 @test Base.infer_return_type(A58257.f) == typeof(Base.get!) # Attempt to lookup A.B in world age N hangs
 
+function tt57873(a::Vector{String}, pref)
+    ret = String[]
+    for j in a
+        append!(ret, tt57873(a[2:end], (pref..., "")))
+    end
+    return ret
+end
+let code = Compiler.typeinf_ext_toplevel(Any[Core.svec(Any,Tuple{typeof(tt57873),Vector{String},Tuple{String}})], [Base.get_world_counter()], Base.Compiler.TRIM_NO)
+    @test !isempty(code)
+    ## If we were to run trim here, we should fail with:
+    #    Verifier error #1: unresolved invoke from statement tt57873(::Vector{String}, ::Tuple{String, String})::Vector{String}
+    #Stacktrace:
+    # [1] tt57873(a::Vector{String}, pref::Tuple{String})
+    #   @ Main REPL[1]:4
+end
+
+function ss57873(a::Vector{String}, pref)
+    ret = String[]
+    for j in a
+        append!(ret, ss57873(a[2:end], (pref..., "")))
+    end
+    return ret
+end
+@test ss57873(["a", "b", "c"], ("",)) == String[]
+
 end # module inference