Ubuntu 20.04 LTS build error about cachelib

[sreenivasulureddysura]

Build error when building cachelib using the provided script build.sh:

./contrib/build.sh -d -j -T -v
Compiler versions:

• cmake: v3.22.2
• gcc/g++: v9.4.0

Error:

CacheLib/cachelib/../cachelib/datatype/FixedSizeArray.h:133:58: warning: returning reference to temporary [-Wreturn-local-addr]
  133 |   const T& getAt(uint32_t index) const { return elements_[index]; }
      |                                                 ~~~~~~~~~^
make[2]: *** [datatype/CMakeFiles/datatype-test-FixedSizeArrayTest.dir/build.make:76: datatype/CMakeFiles/datatype-test-FixedSizeArrayTest.dir/tests/FixedSizeArrayTest.cpp.o] Error 1
make[2]: Leaving directory '/CacheLib/build-cachelib'
make[1]: *** [CMakeFiles/Makefile2:3297: datatype/CMakeFiles/datatype-test-FixedSizeArrayTest.dir/all] Error 2

[sreenivasulureddysura]

@therealgymmy When I ran this command ./contrib/build.sh -d -j -T -v, I got the above mentioned issue. When I commented the below test cases issue is fixed. Causing file line is /cachelib/datatype/FixedSizeArray.h:133

const T& getAt(uint32_t index) const { return elements_[index]; }

Commented test cases.

cachelib/datatype/tests/FixedSizeArrayTest.cpp

//TYPED_TEST(FixedSizeArrayTest, Basic) { this->testBasic(); }
//TYPED_TEST(FixedSizeArrayTest, StdContainers) { this->testStdContainers(); }
//TYPED_TEST(FixedSizeArrayTest, StdAlgorithms) { this->testStdAlgorithms(); }
//TYPED_TEST(FixedSizeArrayTest, testFollyContainers) {
//  this->testFollyContainers();
//}

[therealgymmy]

@sreenivasulureddysura: do you still see this issue? We should have fixed this already.

[sreenivasulureddysura]

@therealgymmy your github action is failing in Ubuntu for the same issue I was mentioned above. Please take a look at it. Checking my previous comments for fixing the issue.

https://github.com/facebook/CacheLib/runs/7058670118?check_suite_focus=true#step:6:10590

[therealgymmy]

@sreenivasulureddysura: Yeah you're right. We have not yet landed the fix.

[therealgymmy]

@sreenivasulureddysura: can you verify if the fix has fixed. We have landed fix for FixedSizeArray on our end (removing the pack attribute).

[therealgymmy]

This particular issue should be fixed now but centos build is still broken. Will file a separate issue to track

[sreenivasulureddysura]

@therealgymmy Ubuntu issue is fixed. I was able to execute the command without any issues.
./contrib/build.sh -d -j -T -v