3963

Narrow the scope of implicit type conversions. Now only numbers can be
freely converted to from other scalars (booleans, characters). We want
in particular to make this an error:

  x:character <- new [abc]

1 files changed, 18 insertions, 7 deletions

diff --git a/021check_instruction.cc b/021check_instruction.cc
index b8aa3663..a32c6178 100644
--- a/021check_instruction.cc
+++ b/021check_instruction.cc
@@ -79,6 +79,14 @@ def main [
 +mem: storing 12 in location 2
 $error: 0
 
+:(scenario write_address_to_character_disallowed)
+% Hide_errors = true;
+def main [
+  1:address:num <- copy 12/unsafe
+  2:char <- copy 1:address:num
+]
++error: main: can't copy '1:address:num' to '2:char'; types don't match
+
 :(scenario write_boolean_to_number_allowed)
 def main [
   1:bool <- copy 1/true
@@ -87,21 +95,20 @@ def main [
 +mem: storing 1 in location 2
 $error: 0
 
-:(scenario write_number_to_boolean_allowed)
+:(scenario write_number_to_boolean_disallowed)
+% Hide_errors = true;
 def main [
   1:num <- copy 34
   2:bool <- copy 1:num
 ]
-+mem: storing 34 in location 2
-$error: 0
++error: main: can't copy '1:num' to '2:bool'; types don't match
 
 :(code)
 // types_match with some leniency
 bool types_coercible(const reagent& to, const reagent& from) {
   if (types_match(to, from)) return true;
-  if (is_mu_address(from) && is_mu_number(to)) return true;
-  if (is_mu_boolean(from) && is_mu_number(to)) return true;
-  if (is_mu_number(from) && is_mu_boolean(to)) return true;
+  if (is_mu_address(from) && is_real_mu_number(to)) return true;
+  if (is_mu_boolean(from) && is_real_mu_number(to)) return true;
   // End types_coercible Special-cases
   return false;
 }
@@ -223,6 +230,11 @@ bool is_mu_boolean(reagent/*copy*/ r) {
 }
 
 bool is_mu_number(reagent/*copy*/ r) {
+  if (is_mu_character(r.type)) return true;  // permit arithmetic on unicode code points
+  return is_real_mu_number(r);
+}
+
+bool is_real_mu_number(reagent/*copy*/ r) {
   // End Preprocess is_mu_number(reagent r)
   if (!r.type) return false;
   if (!r.type->atom) return false;
@@ -230,7 +242,6 @@ bool is_mu_number(reagent/*copy*/ r) {
     return r.type->name == "literal-fractional-number"
         || r.type->name == "literal";
   }
-  if (r.type->value == get(Type_ordinal, "character")) return true;  // permit arithmetic on unicode code points
   return r.type->value == get(Type_ordinal, "number");
 }