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Sort of related, last night I managed to make Clang crash by feeding it a certain C++ program: https://i.imgur.com/r5MC2aK.png https://i.imgur.com/r5MC2aK.png

Sort of related, last night I managed to make Clang crash by feeding it a certain C++ program: https://i.imgur.com/r5MC2aK.png https://i.imgur.com/r5MC2aK.png It was very surprising that there was a way to get Clang to segfault. Should I report it somewhere? The code is basically doing a recursive template expansion with some C++20 concept constraints. So it's not quite as simple as "And. And...", but it's similar in that certain input text causes a crash. I just have no idea whether to report it, or where.

tylerhou 5y ago
Clang segfaulting is somewhat common. It usually doesn't happen, but sometimes when I write some cursed template metaprogramming code it crashes and I'm not surprised. In your case, especially because you are using C++20 concepts, that is a newer feature and you probably hit some less-tested codepath.
mtoner23 5y ago
Definitely report it, it'll be fun to see what happens. https://llvm.org/docs/HowToSubmitABug.html https://llvm.org/docs/HowToSubmitABug.html
- sillysaurusx 5y ago
  Thank you for the link! Maybe that should've been obvious to me, but it really wasn't -- I had no clue where to start. The segfault just said "Please attach these files to the bug report" with no more info. Really appreciated. In that case I'll spend some time to clean up the repro case and submit it. Thanks again.
  - D-Coder 5y ago
    > The segfault just said "Please attach these files to the bug report" with no more info. The message should include the URL. Sounds like a bug that should be reported.
mshockwave 5y ago
> Should I report it somewhere? Please do. You can open an issue (Bugzilla has been deprecated) on LLVM's github repo: https://github.com/llvm/llvm-project https://github.com/llvm/llvm-project
hoten 5y ago
You should report it to their GitHub repro: https://github.com/llvm/llvm-project https://github.com/llvm/llvm-project
nopakos 5y ago
By chance, I was just reading that typing "x = 4.725" on Atari ST Basic crashed the computer. Still not fixed 35 years later :) [https://en.wikipedia.org/wiki/Atari_ST_BASIC#Bugs https://en.wikipedia.org/wiki/Atari_ST_BASIC#Bugs]
dzaima 5y ago
Note that it might be worth trying the latest clang version first. The latest proper version is 14.0.0 from Mar 25, which is only a month old compared to the 7 months of 13.0.0, but if it's something that's condensable to a single file, you could test it on https://godbolt.org/z/hv41441jK https://godbolt.org/z/hv41441jK, which has daily builds.

tylerhou 5y ago

Clang segfaulting is somewhat common. It usually doesn't happen, but sometimes when I write some cursed template metaprogramming code it crashes and I'm not surprised. In your case, especially because you are using C++20 concepts, that is a newer feature and you probably hit some less-tested codepath.

mtoner23 5y ago

Definitely report it, it'll be fun to see what happens. https://llvm.org/docs/HowToSubmitABug.html https://llvm.org/docs/HowToSubmitABug.html

sillysaurusx 5y ago
Thank you for the link! Maybe that should've been obvious to me, but it really wasn't -- I had no clue where to start. The segfault just said "Please attach these files to the bug report" with no more info. Really appreciated. In that case I'll spend some time to clean up the repro case and submit it. Thanks again.
- D-Coder 5y ago
  > The segfault just said "Please attach these files to the bug report" with no more info. The message should include the URL. Sounds like a bug that should be reported.

mshockwave 5y ago

> Should I report it somewhere? Please do. You can open an issue (Bugzilla has been deprecated) on LLVM's github repo: https://github.com/llvm/llvm-project https://github.com/llvm/llvm-project

hoten 5y ago

You should report it to their GitHub repro: https://github.com/llvm/llvm-project https://github.com/llvm/llvm-project

nopakos 5y ago

By chance, I was just reading that typing "x = 4.725" on Atari ST Basic crashed the computer. Still not fixed 35 years later :) [https://en.wikipedia.org/wiki/Atari_ST_BASIC#Bugs https://en.wikipedia.org/wiki/Atari_ST_BASIC#Bugs]

dzaima 5y ago

Note that it might be worth trying the latest clang version first. The latest proper version is 14.0.0 from Mar 25, which is only a month old compared to the 7 months of 13.0.0, but if it's something that's condensable to a single file, you could test it on https://godbolt.org/z/hv41441jK https://godbolt.org/z/hv41441jK, which has daily builds.