Is the test for parallel std::is_partitioned compatible with EXHAUSTIVE?

[mikekazakov]

Hi STL devs!

There's a chance that the test at STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp doesn't like the EXHAUSTIVE testing. When this macro is turned on, the iteration at :105 with testSize=3 ends up with a container {1, 0, 0} which is partitioned, but the assert expects it to be not partitioned:

It's reproducible:

git clone https://github.com/microsoft/STL.git
sed -i -e 's/is_partitioned(par,/is_partitioned(/g' STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp
sed -i -e 's/using namespace std::execution;//g' STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp
sed -i -e 's/#include <execution>;//g' STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp
clang++ -std=c++17 STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp -ISTL/tests/std/include -o test && ./test && echo OK
clang++ -std=c++17 STL/tests/std/tests/P0024R2_parallel_algorithms_is_partitioned/test.cpp -ISTL/tests/std/include -o test -DEXHAUSTIVE && ./test && echo OK
> OK
> Assertion failed: (!is_partitioned( c.begin(), c.end(), read_char_as_bool)), function test_case_is_partitioned_parallel, file test.cpp, line 105.

Pardon the sed hackery - found this under macOS where the test fails even with the traditional serial implementation from libc++.

[CaseyCarter]

We don't normally run this test with EXHAUSTIVE defined, but it would be nice if doing so worked correctly. This case, for example, needs testSize >= 4 but isn't guarded appropriately. (The next case is fine with testSize == 3). There are also some redundant std::-qualifications in here that need cleaning up.

I'll submit a tiny PR with a fix / cleanup if the EXHAUSTIVE run I'm validating locally ever completes.

EDIT: I suppose the proper answer here is "No, this test is not compatible with EXHAUSTIVE, but there's no particular reason it shouldn't be."

[CaseyCarter]

Submitted #3174. The EXHAUSTIVE test run took only 15728.15s to complete on my 3950X - I wonder why we don't run this all the time? ;)

[mikekazakov]

Thank you a lot! Indeed Azure won't be very happy with running this test occasionally :)
And overall thanks for the great test suite, regarding both coverage and portability - kudos!