False positive: [knownConditionTrueFalse] increment in loop condition, valueflow

[Andreas Grob]

#include <iostream>

int main() {
    int a = 0;
    while (++a < 5) {
    }
    if (a == 1) {}
    std::cout << a << '\n';
}

output:

$ ./a.out 
5

cppcheck: commit 62702a6
built with: make MATCHCOMPILER=yes FILESDIR=/usr/share/cppcheck HAVE_RULES=yes

$ cppcheck --enable=all main.cpp 
Checking main.cpp ...
main.cpp:7:11: style: Condition 'a==1' is always true [knownConditionTrueFalse]
    if (a == 1) {}
          ^
main.cpp:4:13: note: Assignment 'a=0', assigned value is 0
    int a = 0;
            ^
main.cpp:5:14: note: a is incremented', new value is 1
    while (++a < 5) {
             ^
main.cpp:7:11: note: Condition 'a==1' is always true
    if (a == 1) {}
          ^

[Daniel Marjamäki]

Thanks! I can reproduce. I created ticket https://trac.cppcheck.net/ticket/9808

[Andreas Grob]

Fixed for me in 48a6852.