[clang++ ][crash-on-valid] crash on C-style array creation #112189
Labels
clang:codegen
IR generation bugs: mangling, exceptions, etc.
confirmed
Verified by a second party
crash-on-valid
regression:17
Regression in 17 release
Comments
github-actions
bot
added
the
clang
EugeneZelenko
added
clang:codegen
|
@llvm/issue-subscribers-clang-codegen Author: Tommaso Bonvicini (MuAlphaOmegaEpsilon)
The following C++ code crashes clang in versions 17, 18 and 19.
I think it's a regression from version 16, where it was compiling and running fine.
The issue has to do with the added template argument and the fact that 2 different template instantiations are performed: commenting either `foo<0>()` or `foo<1>()` will compile fine.
template<unsigned int EXTRA_SPACE>
void foo() { char buffer[sizeof("foo") + EXTRA_SPACE] {"foo"}; }
int main()
{
foo<0>();
foo<1>();
}GCC and MSVC compile and run fine. This is the output from the example on godbolt.org: |
|
If we change this to: https://godbolt.org/z/3ne4K13Wj foo<10>();
foo<1>();The diagnostic is intriguing: <source>:2:56: error: initializer-string for char array is too long, array size is 5 but initializer has size 14 (including the null terminating character)
2 | void foo() { char buffer[sizeof("foo") + EXTRA_SPACE] {"foo"}; }
| ^~~~~
<source>:6:5: note: in instantiation of function template specialization 'foo<1U>' requested here
6 | foo<1>();
| ^
1 error generated.
Compiler returned: 1 |
shafik
added
confirmed
|
@shafik yeah I know, I stumbled upon that first during my experiments, then I got the crash when trying to shrink those down for the bug report and decided to post the latter due to the added stack trace. If you change the EXTRA_SPACE you will see the diagnostic reported size change too! |
I've looked into this, seems the things are borked from the very inception (clang 3.8). Strangely, https://godbolt.org/z/hr6hvqz38 wants clang 6.0.0 to compile this (and barf on too long initializer), on my Windows desktop 3.8 is enough. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
The following C++ code crashes clang in versions 17, 18 and 19.
I think it's a regression from version 16, where it was compiling and running fine.
The issue has to do with the added template argument and the fact that 2 different template instantiations are performed: commenting either
foo<0>()orfoo<1>()will compile fine.GCC and MSVC compile and run fine.
This is the output from the example on godbolt.org:
The text was updated successfully, but these errors were encountered: