docs/fuzzing.md: mention that afl-clang(++) may be needed for MacOS builds #17914

1. 
   Crypt-iQ commented at 1:21 am on January 13, 2020: contributor

   When fuzzing on my macOS Mojave laptop, I was unable to instrument the binaries with the command mentioned in the docs: ./configure --disable-ccache --disable-shared --enable-tests --enable-fuzz CC=${AFLPATH}/afl-gcc CXX=${AFLPATH}/afl-gcc++ This resulted in the following failure:

   0[-] On Apple systems, 'gcc' is usually just a wrapper for clang. Please use the
   1    'afl-clang' utility instead of 'afl-gcc'. If you really have GCC installed,
   2    set AFL_CC or AFL_CXX to specify the correct path to that compiler.
   3
   4[-] PROGRAM ABORT : AFL_CC or AFL_CXX required on MacOS X
   5         Location : edit_params(), afl-gcc.c:159
   

   When I replaced afl-gcc with afl-clang and afl-g++ with afl-clang++, the binaries were properly instrumented. I made an issue instead of a PR as I wasn’t sure whether others had run into this problem or if this was specific to my machine. If this is reproducible on other Macs, then this should be documented in fuzzing.md.

2. fanquake added the label Docs on Jan 13, 2020
3. MarcoFalke added the label macOS on Jan 13, 2020
4. MarcoFalke added the label good first issue on Jan 13, 2020
5. 
   MarcoFalke commented at 6:41 pm on January 13, 2020: member

   Looks like a good-first-issue for someone with macOS.

   Useful skills:

   Basic build system skills

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6. 
   MarcoFalke commented at 6:43 pm on January 13, 2020: member

   Similarly to afl, libFuzzer also needs some extra steps on macOS according to the second section of this comment: #17657 (comment)
7. MarcoFalke closed this on Jan 29, 2020

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8. DrahtBot locked this on Feb 15, 2022

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