3663 - fix a refcounting bug: '(type)' != 'type'

This was a large commit, and most of it is a follow-up to commit 3309,
undoing what is probably the final ill-considered optimization I added
to s-expressions in Mu: I was always representing (a b c) as (a b . c),
etc. That is now gone.

Why did I need to take it out? The key problem was the error silently
ignored in layer 30. That was causing size_of("(type)") to silently
return garbage rather than loudly complain (assuming 'type' was a simple
type).

But to take it out I had to modify types_strictly_match (layer 21) to
actually strictly match and not just do a prefix match.

In the process of removing the prefix match, I had to make extracting
recipe types from recipe headers more robust. So far it only matched the
first element of each ingredient's type; these matched:

  (recipe address:number -> address:number)
  (recipe address -> address)

I didn't notice because the dotted notation optimization was actually
representing this as:

  (recipe address:number -> address number)

---

One final little thing in this commit: I added an alias for 'assert'
called 'assert_for_now', to indicate that I'm not sure something's
really an invariant, that it might be triggered by (invalid) user
programs, and so require more thought on error handling down the road.

But this may well be an ill-posed distinction. It may be overwhelmingly
uneconomic to continually distinguish between model invariants and error
states for input. I'm starting to grow sympathetic to Google Analytics's
recent approach of just banning assertions altogether. We'll see..

1 files changed, 26 insertions, 0 deletions

diff --git a/056shape_shifting_recipe.cc b/056shape_shifting_recipe.cc
index c867a12a..457febb8 100644
--- a/056shape_shifting_recipe.cc
+++ b/056shape_shifting_recipe.cc
@@ -177,6 +177,7 @@ bool concrete_type_names_strictly_match(const type_tree* to, const type_tree* fr
   if (!to) return !from;
   if (!from) return !to;
   if (to->atom && is_type_ingredient_name(to->name)) return true;  // type ingredient matches anything
+  if (!to->atom && to->right == NULL && to->left != NULL && to->left->atom && is_type_ingredient_name(to->left->name)) return true;
   if (from->atom && is_mu_address(to))
     return from->name == "literal" && rhs_reagent.name == "0";
   if (!from->atom && !to->atom)
@@ -328,6 +329,10 @@ void accumulate_type_ingredients(const type_tree* exemplar_type, const type_tree
     raise << "  (called from '" << to_original_string(call_instruction) << "')\n" << end();
     return;
   }
+  if (!exemplar_type->atom && exemplar_type->right == NULL && !refinement_type->atom && refinement_type->right != NULL) {
+    exemplar_type = exemplar_type->left;
+    assert_for_now(exemplar_type->atom);
+  }
   if (exemplar_type->atom) {
     if (is_type_ingredient_name(exemplar_type->name)) {
       const type_tree* curr_refinement_type = NULL;  // temporary heap allocation; must always be deleted before it goes out of scope
@@ -402,6 +407,10 @@ void replace_type_ingredients(reagent& x, const map<string, const type_tree*>& m
 void replace_type_ingredients(type_tree* type, const map<string, const type_tree*>& mappings) {
   if (!type) return;
   if (!type->atom) {
+    if (type->right == NULL && type->left != NULL && type->left->atom && contains_key(mappings, type->left->name) && !get(mappings, type->left->name)->atom && get(mappings, type->left->name)->right != NULL) {
+      *type = *get(mappings, type->left->name);
+      return;
+    }
     replace_type_ingredients(type->left, mappings);
     replace_type_ingredients(type->right, mappings);
     return;
@@ -656,6 +665,7 @@ void test_shape_shifting_new_ingredient_does_not_pollute_global_namespace() {
   CHECK(!element.type->right);
 }
 
+//: specializing a type ingredient with a compound type
 :(scenario shape_shifting_recipe_supports_compound_types)
 def main [
   1:&:point <- new point:type
@@ -670,6 +680,22 @@ def bar a:_t -> result:_t [
 ]
 +mem: storing 34 in location 5
 
+//: specializing a type ingredient with a compound type -- while *inside* another compound type
+:(scenario shape_shifting_recipe_supports_compound_types_2)
+container foo:_t [
+  value:_t
+]
+def bar x:&:foo:_t -> result:_t [
+  local-scope
+  load-ingredients
+  result <- get *x, value:offset
+]
+def main [
+  1:&:foo:&:point <- new {(foo address point): type}
+  2:&:point <- bar 1:&:foo:&:point
+]
+# no errors; call to 'bar' successfully specialized
+
 :(scenario shape_shifting_recipe_error)
 % Hide_errors = true;
 def main [