Fix handling generated clauses without a line

Author: Premwoik

lib/gradient/ast_specifier.ex

@@ -145,6 +145,7 @@ defmodule Gradient.AstSpecifier do
 
   def mapper({:function, anno, name, arity, clauses}, tokens, opts) do
     # anno has line
+    opts = Keyword.put(opts, :line, :erl_anno.line(anno))
     {clauses, tokens} = context_mapper_fold(clauses, tokens, opts)
 
     {:function, anno, name, arity, clauses}

test/gradient/ast_specifier_test.exs

@@ -1362,6 +1362,19 @@ defmodule Gradient.AstSpecifierTest do
              ]}} = missing_type
   end
 
+  test "clauses without a line" do
+    forms = [
+      {:function, 8, :__impl__, 1,
+       [
+         {:clause, [generated: true, location: 0],
+          [{:atom, [generated: true, location: 0], :for}], [],
+          [{:atom, [generated: true, location: 0], TypedSchemaTest}]}
+       ]}
+    ]
+
+    assert [_] = AstSpecifier.run_mappers(forms, [])
+  end
+
   # Helpers
 
   def filter_specs(ast) do