fuzz: remove legacy setup for running fuzzers outside oss-fuzz We don't need this anymore. Differential Revision: https://phab.mercurial-scm.org/D7567

tests: finally fix up test-fuzz-targets.t It's been failing on my workstation for a while, since I have a new enough LLVM that I had the fuzzer goo, but not so new that I actually had FuzzedDataProvider. This is a better solution all around in my opinion. I _believe_ this should let us run these tests on most systems, even those using GCC instead of clang. That said, my one attempt to test this on my macOS laptop failed miserably, and I don't feel like doing more work on this right now. Differential Revision: https://phab.mercurial-scm.org/D7566

fuzz: make standalone_fuzz_target_runner call LLVMFuzzerInitialize Otherwise some of our fuzzers crash when they try and use Python. Differential Revision: https://phab.mercurial-scm.org/D7565

fuzz: use a more standard approach to allow local builds of fuzzers This is taken from the (improved since we started fuzzing) guide on ideal integrations. Rather than have our own wonky targets for building outside the fuzzer universe, we have a driver program we carry along and use when we're not using LibFuzzer. This will let us jettison a fair amount of goo. contrib/fuzz/standalone_fuzz_target_runner.cc is https://github.com/google/oss-fuzz/ file projects/example/my-api-repo/standalone from git revision c4579d9358a73ea5dbcc99cb985de1f2bf76dcf7, reformatted with out clang-format settings and a no-check-code comment added. It allows running a single test input through a fuzzer, rather than performing ongoing fuzzing as libfuzzer would. contrib/fuzz/FuzzedDataProvider.h is https://github.com/llvm/llvm-project/ file /compiler-rt/include/fuzzer/FuzzedDataProvider.h from git revision a44ef027ebca1598892ea9b104d6189aeb3bc2f0, reformatted with our clang-format settings and a no-check-code comment added. We can discard this if we instead want to add an hghave check for a new enough llvm that includes FuzzedDataProvder.h in the fuzzer headers. Differential Revision: https://phab.mercurial-scm.org/D7564

fuzz: use a variable to allow specifying python-config to use Eventually we should probably default this to just `python-config` and have the oss-fuzz build.sh script specify the sanpy python-config, but for now this lets us make progress. Differential Revision: https://phab.mercurial-scm.org/D7563

fuzz: suppress deprecated-register warnings in our compile These come from the Python.h headers still using the `register` keyword and our use of C++17. I think this will go away when we're using Python 3 for our fuzzing, but that can come later. Differential Revision: https://phab.mercurial-scm.org/D7562

fuzz: follow modern guidelines and use LIB_FUZZING_ENGINE This will make our lives easier in an upcoming change, but it's also how we're supposed to set things up anyway. Differential Revision: https://phab.mercurial-scm.org/D7561

fuzz: always define LLVMFuzzerInitialize() even if we don't need it This will make it easier to test our fuzzers outside oss-fuzz. Differential Revision: https://phab.mercurial-scm.org/D7560

fuzz: remove debug prints from revlog_corpus.py Differential Revision: https://phab.mercurial-scm.org/D7559

fuzz: fix an unused result on getcwd() in pyutil clang was rightly complaining about this, so let's just fix it. Differential Revision: https://phab.mercurial-scm.org/D7558