FALSE NEGATIVE: `unreadVariable` misses a dead nested assignment

[Rodri]

Hi, I found a false negative in Cppcheck 2.21.0 and 2.22 dev when an assignment's expression value is returned but the value stored in the local variable is never read.

Affected tool

Cppcheck 2.21.0; also reproduced with Cppcheck 2.22 dev

Affected checker

Cppcheck unreadVariable

Minimal reproducer

int make_value();

int test() {
  int value;
  return value = make_value();
}

Reproduction command

cppcheck --version
cppcheck --enable=style --inconclusive --std=c++17 --checkers-report=checkers.txt --template='{file}:{line}:{column}: [{id}] {message}' cppcheck-unreadvariable-fn-nested-assignment.cpp

Current behavior

Cppcheck produces no unreadVariable diagnostic.

Expected behavior

Cppcheck should report line 5 because the assignment expression supplies the return value directly and the value stored in value is never read from the variable.

[CHR]

Thanks for reporting, example added here: https://trac.cppcheck.net/ticket/11222