Merge pull request #307 from savi-lang/allow/non-sendable-params-iso-…

…constructor-empty-object Allow non-sendable params to an elevated constructor when the type has no fields.
savi-lang · Apr 22, 2022 · a3472d5 · a3472d5
2 parents 4d81979 + 0fccffa
commit a3472d5
Show file tree

Hide file tree

Showing 3 changed files with 37 additions and 21 deletions.
diff --git a/spec/compiler/type_check.validation.savi.spec.md b/spec/compiler/type_check.validation.savi.spec.md
@@ -2,9 +2,32 @@
 pass: type_check
 ---
 
+It complains if some params of an asynchronous function are not sendable:
+
+```savi
+:actor BadActor
+  :be bad_behavior(a String'ref, b String'val, c String'box)
+```
+```error
+An asynchronous function must only have sendable parameters:
+  :be bad_behavior(a String'ref, b String'val, c String'box)
+   ^~
+
+- this parameter type (String'ref) is not sendable:
+  :be bad_behavior(a String'ref, b String'val, c String'box)
+                   ^~~~~~~~~~~~
+
+- this parameter type (String'box) is not sendable:
+  :be bad_behavior(a String'ref, b String'val, c String'box)
+                                               ^~~~~~~~~~~~
+```
+
+---
+
 It complains if some params of an elevated constructor are not sendable:
 
 ```savi
+  :let field String'ref: String.new
   :new iso iso_constructor(a String'ref, b String'val, c String'box)
   :new val val_constructor(a String'ref, b String'val, c String'box)
   :new box box_constructor(a String'ref, b String'val, c String'box)
@@ -38,24 +61,11 @@ A constructor with elevated capability must only have sendable parameters:
 
 ---
 
-It complains if some params of an asynchronous function are not sendable:
+It allows non-sendable params to an elevated constructor if there are no fields:
 
 ```savi
-:actor BadActor
-  :be bad_behavior(a String'ref, b String'val, c String'box)
-```
-```error
-An asynchronous function must only have sendable parameters:
-  :be bad_behavior(a String'ref, b String'val, c String'box)
-   ^~
-
-- this parameter type (String'ref) is not sendable:
-  :be bad_behavior(a String'ref, b String'val, c String'box)
-                   ^~~~~~~~~~~~
-
-- this parameter type (String'box) is not sendable:
-  :be bad_behavior(a String'ref, b String'val, c String'box)
-                                               ^~~~~~~~~~~~
+  // (no fields)
+  :new iso iso_constructor(a String'ref, b String'val, c String'box)
 ```
 
 ---

diff --git a/src/savi/compiler/type_check.cr b/src/savi/compiler/type_check.cr
@@ -769,11 +769,13 @@ class Savi::Compiler::TypeCheck
       require_sendable =
         if @func.has_tag?(:async)
           "An asynchronous function"
-        elsif @func.has_tag?(:constructor) \
-        && !MetaType.cap(Cap::REF).subtype_of?(ctx,
-          resolve(ctx, @pre_infer[ret]).not_nil!.cap_only
-        )
-          "A constructor with elevated capability"
+        elsif @func.has_tag?(:constructor)
+          ret_mt = resolve(ctx, @pre_infer[ret]).not_nil!
+          ret_rt = ret_mt.single_rt?.not_nil!
+          if !MetaType.cap(Cap::REF).subtype_of?(ctx, ret_mt.cap_only) \
+          && ret_rt.defn(ctx).has_any_fields?
+            "A constructor with elevated capability"
+          end
         end
       if require_sendable
         @func.params.try do |params|

diff --git a/src/savi/program.cr b/src/savi/program.cr
@@ -267,6 +267,10 @@ class Savi::Program
       io << "#<#{self.class} #{@ident.value}>"
     end
 
+    def has_any_fields?
+      @functions.any?(&.has_tag?(:field))
+    end
+
     def find_func?(func_name)
       @functions
         .find { |f| f.ident.value == func_name && !f.has_tag?(:hygienic) }