[Bug c++/51311] New: bogus array bounds warning

[bruck.michael at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51311

             Bug #: 51311
           Summary: bogus array bounds warning
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: bruck.mich...@googlemail.com


command line:
arm-elf-g++ -Wall -Werror -O3 -std=gnu++0x -c foo.cpp

error:
foo.cpp: In function 'void bar()':
foo.cpp:23:44: error: array subscript is above array bounds
[-Werror=array-bounds]


The error is triggered by case 0x02, which in reality is not encountered with
in_data.


foo.cpp:


#include <string.h>

char in_data[] = {0x01, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00};

void bar()
{
    size_t in_length = sizeof(in_data) / sizeof(in_data[0]);

    size_t pos = 0;

    while (pos < in_length)
    {
    size_t next = pos;

    auto fill = [&](size_t data_len) -> bool
    {
        next = pos + 1 + data_len;

        if (next > in_length)
        return false;

        memset(in_data + pos + 1, 0, data_len);

        return true;
    };

    switch (in_data[pos])
    {
    case 0x01:
        if (!fill(4))
        return;
        break;

    case 0x02:
        if (!fill(16))
        return;
        break;
    }

    pos = next;
    }
}