Description of problem:
I run cppcheck in a project that contains a file generated by flex which I want cppcheck to ignore. That's why I use the '-i' option. With the new version of cppcheck (2.15.0) issues in the ignored file are reported.

Version-Release number of selected component (if applicable):
2.15.0-1.fc40

How reproducible:
100% (in the project)

Steps to Reproduce:
1. git clone https://github.com/cfengine/core.git
2. cd core
3. ./autogen.sh
4. make
5. cppcheck --quiet -j4 --error-exitcode=1 ./ --suppressions-list=tests/static-check/cppcheck_suppressions.txt --check-level=exhaustive --include=config.h -I cf-serverd/ -I libpromises/ -I libcfnet/ -I libntech/libutils/ -i 3rdparty -i .github/codeql -i libntech/.lgtm -i tests -i libpromises/cf3lex.c

Actual results:
cf3lex.c:2370:2: warning: Possible null pointer dereference: b [nullPointer]

 ^
cf3lex.c:2263:18: note: Calling function 'yy_init_buffer', 1st argument '(yy_buffer_stack)?(yy_buffer_stack)[yy_buffer_stack_top]:NULL' value is 0

                 ^
cf3lex.c:2370:2: note: Null pointer dereference

 ^
cf3lex.c:2371:2: warning: Possible null pointer dereference: b [nullPointer]

 ^
cf3lex.c:2263:18: note: Calling function 'yy_init_buffer', 1st argument '(yy_buffer_stack)?(yy_buffer_stack)[yy_buffer_stack_top]:NULL' value is 0

                 ^
cf3lex.c:2371:2: note: Null pointer dereference

 ^


Expected results:
No issues found.

Additional info:
This works as expected with both 2.13.0-3.fc40 and 2.14.2-1.fc40. It is a regression in 2.15.0.

I tried things like './libpromises/cf3lex.c' or just 'cf3lex.c', but with no success. I also tried reproducing the issue in a simpler setup, but there it worked as expected:

[vpodzime@vp-desktop cppcheck_test]$ cppcheck ./
Checking strdup_null.c ...
strdup_null.c:5:5: error: Memory leak: copy [memleak]
    return 0;
    ^
strdup_null.c:4:25: error: Null pointer dereference [nullPointer]
    char *copy = strdup(NULL);
                        ^
1/2 files checked 18% done
Checking strtok_test.c ...
2/2 files checked 100% done
[vpodzime@vp-desktop cppcheck_test]$ cppcheck ./ -i strdup_null.c
Checking strtok_test.c ...