Bug: clang-format breaks function calls on user-defined-literals

[liss-h]

Currently clang-format removes spaces after user-defined-literals when calling functions on them.
This makes code not compile anymore.

Clang Format version: clang-format version 15.0.7 (Fedora 15.0.7-1.fc37)

Example:
Before Formatting:

$ cat test.cpp

#include <chrono>
using namespace std::chrono_literals;

int main() { auto x = 5s .count() == 5; }

$ clang++ test.cpp && echo $?
0

After Formatting:

$ clang-format test.cpp > testfmt.cpp

$ cat testfmt.cpp

#include <chrono>
using namespace std::chrono_literals;

int main() { auto x = 5s.count() == 5; }

$ clang++ testfmt.cpp

testfmt.cpp:4:24: error: invalid suffix 's.count' on integer constant
int main() { auto x = 5s.count() == 5; }
                       ^
1 error generated.

[llvmbot]

@llvm/issue-subscribers-clang-format

[rymiel]

I'm confused why s.count is attempted to be seen as an UDL if s.count isn't even a valid identifier. This looks like an issue of more than just clang-format

[liss-h]

Not entirely sure but at least cppreference.com says that it is normal that this doesn't compile.

https://en.cppreference.com/w/cpp/language/user_literal#Notes
"Otherwise, a single invalid preprocessing number token (e.g., 1.0_E+2.0 or 4s.count) is formed, which causes compilation to fail."

[rymiel]

Thank you for clarifying, it does appear something that should be preserved, then

[owenca]

https://reviews.llvm.org/D143546