Executor: Check validity of action outputs in compatible mode

This ensures that any entries that the standard remote execution
protocol accepts but are invalid in justbuild, i.e., upwards
symlinks, are rejected.

For this purpose, do not fail in the action response instances,
just perform the check there, as all required information is
available, and set a flag that the executor can check as needed.

1 files changed, 4 insertions, 0 deletions

diff --git a/test/buildtool/execution_engine/executor/executor.test.cpp b/test/buildtool/execution_engine/executor/executor.test.cpp
index 93dd10b6..cba6c977 100644
--- a/test/buildtool/execution_engine/executor/executor.test.cpp
+++ b/test/buildtool/execution_engine/executor/executor.test.cpp
@@ -139,6 +139,10 @@ class TestResponse : public IExecutionResponse {
         static const DirSymlinks kEmptySymlinks{};
         return gsl::not_null<DirSymlinks const*>(&kEmptySymlinks);
     }
+    [[nodiscard]] auto HasUpwardsSymlinks() noexcept
+        -> expected<bool, std::string> final {
+        return false;
+    }
 
   private:
     TestApiConfig config_{};