Fix compilation when using gcc 9:

  - Include header file for atomic when needed.
  - Use normal function template instead of abbreviated function template.

1 files changed, 2 insertions, 1 deletions

diff --git a/searchlib/src/vespa/searchlib/common/unique_issues.h b/searchlib/src/vespa/searchlib/common/unique_issues.h
index 79cb7a9aa23..17c42da060c 100644
--- a/searchlib/src/vespa/searchlib/common/unique_issues.h
+++ b/searchlib/src/vespa/searchlib/common/unique_issues.h
@@ -18,7 +18,8 @@ private:
 public:
     using UP = std::unique_ptr<UniqueIssues>;
     void handle(const vespalib::Issue &issue) override;
-    void for_each_message(auto fun) const {
+    template <class Function>
+    void for_each_message(Function fun) const {
         for (const auto &msg: _messages) {
             fun(msg);
         }