Check nargs for builtins (fixes #217)

Author: timholy

src/generate_builtins.jl

@@ -31,11 +31,9 @@ end
 function generate_fcall_nargs(fname, minarg, maxarg)
     # Generate a separate call for each number of arguments
     maxarg < typemax(Int) || error("call this only for constrained number of arguments")
-    wrapper = minarg == maxarg ? "" : "if nargs == "
+    wrapper = "if nargs == "
     for nargs = minarg:maxarg
-        if minarg < maxarg
-            wrapper *= "$nargs\n            "
-        end
+        wrapper *= "$nargs\n            "
         argcall = ""
         for i = 1:nargs
             argcall *= "@lookup(frame, args[$(i+1)])"
@@ -48,9 +46,9 @@ function generate_fcall_nargs(fname, minarg, maxarg)
             wrapper *= "\n        elseif nargs == "
         end
     end
-    if minarg < maxarg
-        wrapper *= "\n        end"
-    end
+    wrapper *= "\n        else"
+    wrapper *= "\n            return Some{Any}($fname(getargs(args, frame)...))"  # to throw the correct error
+    wrapper *= "\n        end"
     return wrapper
 end
 

test/interpret.jl

@@ -441,4 +441,8 @@ try
     @test occursin("[4] g_1(::Float64) at $(@__FILE__):$(line_g - 3)", stacktrace_lines[6])
 finally
     break_off(:error)
-end
+end
+
+# Check #args for builtins (#217)
+f217() =  Core._typevar(:foo, Union{}, Any, "foo")
+@test_throws ArgumentError @interpret(f217())