Allow annotating class and global variables. Fixes #1838

spec/compiler/parser/parser_spec.cr

@@ -874,6 +874,8 @@ describe "Parser" do
   it_parses "@a :: Foo | Int32", TypeDeclaration.new("@a".instance_var, Union.new(["Foo".path, "Int32".path] of ASTNode))
   it_parses "a : Foo", TypeDeclaration.new("a".var, "Foo".path)
   it_parses "@a : Foo", TypeDeclaration.new("@a".instance_var, "Foo".path)
+  it_parses "@@a : Foo", TypeDeclaration.new("@@a".class_var, "Foo".path)
+  it_parses "$x : Foo", TypeDeclaration.new(Global.new("$x"), "Foo".path)
 
   it_parses "a = uninitialized Foo; a", [UninitializedVar.new("a".var, "Foo".path), "a".var]
   it_parses "@a = uninitialized Foo", UninitializedVar.new("@a".instance_var, "Foo".path)

spec/compiler/type_inference/class_var_spec.cr

@@ -41,19 +41,6 @@ describe "Type inference: class var" do
       ") { int32 }
   end
 
-  it "types class var as nil if assigned for the first time inside method" do
-    assert_type("
-      class Foo
-        def self.foo
-          @@foo = 1
-          @@foo
-        end
-      end
-
-      Foo.foo
-      ") { |mod| union_of(mod.nil, int32) }
-  end
-
   it "types class var of program" do
     assert_type("
       @@foo = 1

spec/compiler/type_inference/type_declaration_spec.cr

@@ -92,6 +92,52 @@ describe "Type inference: type declaration" do
       "can't declare variable of generic non-instantiated type Foo"
   end
 
+  it "declares global variable" do
+    assert_error %(
+      $x : Int32
+      $x = true
+      ),
+      "type must be Int32, not Bool"
+  end
+
+  it "declares global variable and reads it (nilable)" do
+    assert_error %(
+      $x : Int32
+      $x
+      ),
+      "type must be Int32, not Nil"
+  end
+
+  it "declares class variable" do
+    assert_error %(
+      class Foo
+        @@x : Int32
+
+        def self.x=(x)
+          @@x = x
+        end
+      end
+
+      Foo.x = true
+      ),
+      "type must be Int32, not Bool"
+  end
+
+  it "declares class variable (2)" do
+    assert_error %(
+      class Foo
+        @@x : Int32
+
+        def self.x
+          @@x
+        end
+      end
+
+      Foo.x
+      ),
+      "type must be Int32, not Nil"
+  end
+
   # TODO: remove these after 0.11
 
   it "declares as uninitialized" do

src/compiler/crystal/semantic/type_visitor.cr

@@ -157,6 +157,24 @@ module Crystal
         else
           node.raise "can only declare instance variables of a non-generic class, not a #{type.type_desc} (#{type})"
         end
+      when ClassVar
+        class_var = lookup_class_var(var, bind_to_nil_if_non_existent: false)
+
+        node.declared_type.accept self
+        var_type = check_declare_var_type node
+
+        class_var.freeze_type = var_type
+      when Global
+        global_var = mod.global_vars[var.name]?
+        unless global_var
+          global_var = Var.new(var.name)
+          mod.global_vars[var.name] = global_var
+        end
+
+        node.declared_type.accept self
+        var_type = check_declare_var_type node
+
+        global_var.freeze_type = var_type
       end
 
       node.type = @mod.nil
@@ -282,9 +300,9 @@ module Crystal
       var = mod.global_vars[node.name]?
       unless var
         var = Var.new(node.name)
-        var.bind_to mod.nil_var
         mod.global_vars[node.name] = var
       end
+      var.bind_to mod.nil_var unless var.dependencies?
       node.bind_to var
       var
     end
@@ -371,10 +389,8 @@ module Crystal
 
       class_var_owner = scope as ClassVarContainer
 
-      bind_to_nil = bind_to_nil_if_non_existent && !class_var_owner.has_class_var?(node.name)
-
       var = class_var_owner.lookup_class_var node.name
-      var.bind_to mod.nil_var if bind_to_nil
+      var.bind_to mod.nil_var if bind_to_nil_if_non_existent && !var.dependencies?
 
       node.owner = class_var_owner
       node.var = var
@@ -541,7 +557,7 @@ module Crystal
     end
 
     def type_assign(target : ClassVar, value, node)
-      var = lookup_class_var target, !!@typed_def
+      var = lookup_class_var target, bind_to_nil_if_non_existent: false
       check_valid_attributes var, ValidClassVarAttributes, "class variable"
 
       value.accept self

src/compiler/crystal/syntax/parser.cr

@@ -854,8 +854,7 @@ module Crystal
       when :SYMBOL
         node_and_next_token SymbolLiteral.new(@token.value.to_s)
       when :GLOBAL
-        @wants_regex = false
-        node_and_next_token Global.new(@token.value.to_s)
+        new_node_check_type_declaration Global
       when :"$~", :"$?"
         location = @token.location
         var = Var.new(@token.to_s).at(location)
@@ -1016,30 +1015,39 @@ module Crystal
       when :CONST
         parse_ident_or_literal
       when :INSTANCE_VAR
-        name = @token.value.to_s
-        add_instance_var name
-        ivar = InstanceVar.new(name).at(@token.location)
-        ivar.end_location = token_end_location
-        @wants_regex = false
-        next_token_skip_space
-
-        if (@token.type == :"::") || (@no_type_declaration == 0 && @token.type == :":")
-          next_token_skip_space
-          ivar_type = parse_single_type
-          TypeDeclaration.new(ivar, ivar_type).at(ivar.location)
-        else
-          ivar
+        new_node_check_type_declaration(InstanceVar) do |name|
+          add_instance_var(name)
         end
       when :CLASS_VAR
-        @wants_regex = false
-        node_and_next_token ClassVar.new(@token.value.to_s)
+        new_node_check_type_declaration ClassVar
       when :UNDERSCORE
         node_and_next_token Underscore.new
       else
         unexpected_token_in_atomic
       end
     end
 
+    def new_node_check_type_declaration(klass)
+      new_node_check_type_declaration(klass) { }
+    end
+
+    def new_node_check_type_declaration(klass)
+      name = @token.value.to_s
+      yield name
+      var = klass.new(name).at(@token.location)
+      var.end_location = token_end_location
+      @wants_regex = false
+      next_token_skip_space
+
+      if (@token.type == :"::") || (@no_type_declaration == 0 && @token.type == :":")
+        next_token_skip_space
+        var_type = parse_single_type
+        TypeDeclaration.new(var, var_type).at(var.location)
+      else
+        var
+      end
+    end
+
     def parse_ident_or_literal
       ident = parse_ident
       skip_space

src/concurrent/scheduler.cr

@@ -8,7 +8,7 @@ class Scheduler
     if runnable = @@runnables.pop?
       runnable.resume
     else
-      @@loop_fiber.resume
+      @@loop_fiber.not_nil!.resume
     end
     nil
   end