[BUG] Segmentation fault from trying to print std::string as %d

[Source61]

Describe the bug

Doesn't happen on its own, but with 2 preceding arguments it segfaults.
Haven't tested anything else, like how many arguments are required to cause segfault, etc.

Code to reproduce the behaviour:

from libcpp.string cimport string

cdef:
        string s = b"abc"

print("addCost %f -> this.cost: %f (this.ip: %d)" % (7, 77, s))

Expected behaviour

No response

OS

Linux (Ubuntu 22.04.3 LTS WSL)

Python version

3.10.12

Cython version

3.0.4

Additional context

No response

[matusvalo]

Issue is caused by string s formatted as integer using %d. Changing line to:

print("addCost %f -> this.cost: %f (this.ip: %s)" % (7, 77, s))

Fixes the issue. But still we should error out in better way than segfault...

[matusvalo]

OK this is minimal reproducer:

s= 'asdf'
"%d" % (s,)

Compiling it and importing will cause segfault.

When brackets are not used:

s= 'asdf'
"%d" % s

the compiling and running an example will end up with an exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "nogil.pyx", line 2, in init nogil
    "%d" % s
TypeError: %d format: a number is required, not str

[scoder]

Thanks for investigating. There was a missing failure check which made it continue the formatting with a NULL pointer.