message: Move ExecutionContext logic to Guard
diff: @@ -18,7 +18,11 @@ class ExecutionContext
  ExecutionContext& m_execution_context; ///< Reference to the guarded execution context.
  public:
  - explicit Guard(ExecutionContext& ctx) noexcept : m_execution_context{ctx} {}
  + explicit Guard(ExecutionContext& ctx) noexcept : m_execution_context{ctx}
  + {
  + ++m_execution_context.depth;
  + }
  +
  ~Guard() noexcept { --m_execution_context.depth; }
  };
  @@ -27,10 +31,6 @@ public:
  /// Increments the call depth and returns the guard object which decrements
  /// the call depth back to the original value when going out of scope.
  - Guard increment_call_depth() noexcept
  - {
  - ++depth;
  - return Guard{*this};
  - }
  + Guard increment_call_depth() noexcept { return Guard{*this}; }
  };
  } // namespace fizzy
  