Don't find unbound type parameter in main code inside generic type (#…

…6292)
crystal-lang · Jun 29, 2018 · 2bbf72f · 2bbf72f
1 parent bfd9e6d
commit 2bbf72f
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Showing 3 changed files with 27 additions and 5 deletions.
diff --git a/spec/compiler/semantic/generic_class_spec.cr b/spec/compiler/semantic/generic_class_spec.cr
@@ -1054,4 +1054,13 @@ describe "Semantic: generic class" do
       ),
       "undefined constant "
   end
+
+  it "doesn't find unbound type parameter in main code inside generic type (#6168)" do
+    assert_error %(
+      class Foo(T)
+        Foo(T)
+      end
+      ),
+      "undefined constant T"
+  end
 end
diff --git a/src/compiler/crystal/semantic/main_visitor.cr b/src/compiler/crystal/semantic/main_visitor.cr
@@ -170,7 +170,20 @@ module Crystal
     end
 
     def visit(node : Path)
-      type = (@path_lookup || @scope || @current_type).lookup_type_var(node, free_vars: free_vars)
+      lookup_scope = @path_lookup || @scope || @current_type
+
+      # If the lookup scope is a generic type, like Foo(T), we don't
+      # want to find T in main code. For example:
+      #
+      # class Foo(T)
+      #   Bar(T) # This T is unbound and it shouldn't be found in the lookup
+      # end
+      find_root_generic_type_parameters = !lookup_scope.is_a?(GenericType)
+
+      type = lookup_scope.lookup_type_var(node,
+        free_vars: free_vars,
+        find_root_generic_type_parameters: find_root_generic_type_parameters)
+
       case type
       when Const
         if !type.value.type? && !type.visited?

diff --git a/src/compiler/crystal/semantic/type_lookup.cr b/src/compiler/crystal/semantic/type_lookup.cr
@@ -52,13 +52,13 @@ class Crystal::Type
 
   # Similar to `lookup_type`, but the result might also be an ASTNode, for example when
   # looking `N` relative to a StaticArray.
-  def lookup_type_var(node : Path, free_vars : Hash(String, TypeVar)? = nil) : Type | ASTNode
-    TypeLookup.new(self, self.instance_type, true, false, false, free_vars).lookup_type_var(node).not_nil!
+  def lookup_type_var(node : Path, free_vars : Hash(String, TypeVar)? = nil, find_root_generic_type_parameters = true) : Type | ASTNode
+    TypeLookup.new(self, self.instance_type, true, false, false, free_vars, find_root_generic_type_parameters).lookup_type_var(node).not_nil!
   end
 
   # Similar to `lookup_type_var`, but might return `nil`.
-  def lookup_type_var?(node : Path, free_vars : Hash(String, TypeVar)? = nil, raise = false) : Type | ASTNode | Nil
-    TypeLookup.new(self, self.instance_type, raise, false, false, free_vars).lookup_type_var?(node)
+  def lookup_type_var?(node : Path, free_vars : Hash(String, TypeVar)? = nil, raise = false, find_root_generic_type_parameters = true) : Type | ASTNode | Nil
+    TypeLookup.new(self, self.instance_type, raise, false, false, free_vars, find_root_generic_type_parameters).lookup_type_var?(node)
   end
 
   private struct TypeLookup