| Issue |
137846
|
| Summary |
Clang 21 accepts invalid # 0 preprocessor lines leading to undefined behavior at compile time
|
| Labels |
clang
|
| Assignees |
|
| Reporter |
mariete1223
|
## Summary
Clang 21 accepts invalid standalone # 0 preprocessor lines in C source files without emitting an error or a warning. When compiled, the program exhibits undefined behavior (e.g., prints unlimited spaces or crashes), despite the code being syntactically invalid.
## Program
```
uint32_t square(uint32_t x)
# 0
# 0
```
## To reproduce Quickly
https://gcc.godbolt.org/z/c1daT34v6
It gets:
[Truncated]
Compiler returned: 143
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