Compiler: require free vars to be specified with forall

Ary Borenszweig · Ary Borenszweig · commit 991e39b0a34d · 2016-12-23T11:30:12.000-03:00
diff --git a/spec/compiler/semantic/restrictions_spec.cr b/spec/compiler/semantic/restrictions_spec.cr
@@ -407,4 +407,15 @@ describe "Restrictions" do
       ),
       "no overload matches"
   end
+
+  it "errors if using free var without forall" do
+    assert_error %(
+      def foo(x : T)
+        T
+      end
+
+      foo(1)
+      ),
+      "undefined constant T"
+  end
 end
diff --git a/src/compiler/crystal/semantic/default_arguments.cr b/src/compiler/crystal/semantic/default_arguments.cr
@@ -128,7 +128,7 @@ class Crystal::Def
             # a temporary variable (tmp_var) and then replace all ocurrences of that free var with typeof(tmp_var)
             # to achieve the same effect, since we can't define a type alias inside a method.
             restriction = arg.restriction
-            if restriction.is_a?(Path) && restriction.names.size == 1 && (Parser.free_var_name?(restriction.names.first) || free_vars.try(&.includes?(restriction.names.first)))
+            if restriction.is_a?(Path) && restriction.names.size == 1 && free_vars.try(&.includes?(restriction.names.first))
               restriction_name = program.new_temp_var_name
               new_body << Assign.new(Var.new(restriction_name), Var.new(arg.name))
               body = body.transform(ReplaceFreeVarTransformer.new(restriction.names.first, restriction_name))
diff --git a/src/compiler/crystal/semantic/restrictions.cr b/src/compiler/crystal/semantic/restrictions.cr
@@ -377,7 +377,7 @@ module Crystal
 
       if single_name
         first_name = other.names.first
-        if context.defining_type.type_var?(first_name) || Parser.free_var_name?(first_name)
+        if context.defining_type.type_var?(first_name)
           return context.set_free_var(first_name, self)
         end
       end
@@ -856,7 +856,7 @@ module Crystal
         single_name = other.names.size == 1
         if single_name
           first_name = other.names.first
-          if context.defining_type.type_var?(first_name) || Parser.free_var_name?(first_name)
+          if context.defining_type.type_var?(first_name)
             return context.set_free_var(first_name, self)
           else
             other.raise_undefined_constant(context.defining_type)
diff --git a/src/compiler/crystal/syntax/parser.cr b/src/compiler/crystal/syntax/parser.cr
@@ -5359,9 +5359,5 @@ module Crystal
       @visibility = old_visibility
       value
     end
-
-    def self.free_var_name?(name)
-      name.size == 1 || (name.size == 2 && name[1].ascii_number?)
-    end
   end
 end
diff --git a/src/enumerable.cr b/src/enumerable.cr
@@ -91,7 +91,7 @@ module Enumerable(T)
   # * `Enumerable::Chunk::Alone` specifies that the element should be chunked by itself
   #
   # See also: `Iterator#chunk`
-  def chunks(&block : T -> U)
+  def chunks(&block : T -> U) forall U
     res = [] of Tuple(U, Array(T))
     chunks_internal(block) { |k, v| res << {k, v} }
     res
@@ -160,7 +160,7 @@ module Enumerable(T)
     end
   end
 
-  private def chunks_internal(original_block : T -> U)
+  private def chunks_internal(original_block : T -> U) forall U
     acc = Chunk::Accumulator(T, U).new
     each do |val|
       key = original_block.call(val)
