3760 - force functions to use dependency-injection

This is the kind of check I want Mu to be anal about, not whitespace or
unused variables.

012transform.cc

@@ -45,6 +45,7 @@ void initialize_transforms() {
 
 void transform_all() {
   trace(9990, "transform") << "=== transform_all()" << end();
+  // Begin transform_all
   for (int t = 0;  t < SIZE(Transform);  ++t) {
     for (map<recipe_ordinal, recipe>::iterator p = Recipe.begin();  p != Recipe.end();  ++p) {
       recipe& r = p->second;

099hardware_checks.cc

@@ -0,0 +1,63 @@
+//: Let's raise errors when students use real hardware in any functions
+//: besides 'main'. Part of the goal is to teach them testing hygiene and
+//: dependency injection.
+//:
+//: This is easy to sidestep, it's for feedback rather than safety.
+
+:(before "End Globals")
+vector<type_tree*> Real_hardware_types;
+:(before "Begin transform_all")
+setup_real_hardware_types();
+:(before "End transform_all")
+teardown_real_hardware_types();
+:(code)
+void setup_real_hardware_types() {
+  Real_hardware_types.push_back(parse_type("address:screen"));
+  Real_hardware_types.push_back(parse_type("address:console"));
+  Real_hardware_types.push_back(parse_type("address:resources"));
+}
+type_tree* parse_type(string s) {
+  reagent x("x:"+s);
+  type_tree* result = x.type;
+  x.type = NULL;  // don't deallocate on return
+  return result;
+}
+void teardown_real_hardware_types() {
+  for (int i = 0;  i < SIZE(Real_hardware_types);  ++i)
+    delete Real_hardware_types.at(i);
+  Real_hardware_types.clear();
+}
+
+:(before "End Checks")
+Transform.push_back(check_for_misuse_of_real_hardware);
+:(code)
+void check_for_misuse_of_real_hardware(const recipe_ordinal r) {
+  const recipe& caller = get(Recipe, r);
+  if (caller.name == "main") return;
+  if (starts_with(caller.name, "scenario_")) return;
+  trace(9991, "transform") << "--- check if recipe " << caller.name << " has any dependency-injection mistakes" << end();
+  for (int index = 0;  index < SIZE(caller.steps);  ++index) {
+    const instruction& inst = caller.steps.at(index);
+    if (inst.operation < MAX_PRIMITIVE_RECIPES) continue;
+    for (int i = 0;  i < SIZE(inst.ingredients);  ++i) {
+      const reagent& ing = inst.ingredients.at(i);
+      if (!is_literal(ing) || ing.name != "0") continue;
+      const recipe& callee = get(Recipe, inst.operation);
+      if (!callee.has_header) continue;
+      if (i >= SIZE(callee.ingredients)) continue;
+      const reagent& expected_ing = callee.ingredients.at(i);
+      for (int j = 0;  j < SIZE(Real_hardware_types);  ++j) {
+        if (*Real_hardware_types.at(j) == *expected_ing.type)
+          raise << maybe(caller.name) << "'" << inst.original_string << "': only 'main' can pass 0 into a " << to_string(expected_ing.type) << '\n' << end();
+      }
+    }
+  }
+}
+
+:(scenarios transform)
+:(scenario warn_on_using_real_screen_directly_in_non_main_recipe)
+% Hide_errors = true;
+def foo [
+  print 0, 34
+]
++error: foo: 'print 0, 34': only 'main' can pass 0 into a (address screen)