[Bug middle-end/54299] New: Array parameter does not allow for iterator syntax

[drepper.fsp at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299

             Bug #: 54299
           Summary: Array parameter does not allow for iterator syntax
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: drepper....@gmail.com


Compile the following code:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int aa[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

int f(int arr[10])
{
  int s = 0;
  for (auto i : arr)
    s += i;
  return s;
}

int main()
{
  return f(aa);
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This fails with

u.cc: In function ‘int f(int*)’:
u.cc:18:17: error: ‘begin’ was not declared in this scope
u.cc:18:17: error: ‘end’ was not declared in this scope
u.cc:18:17: error: unable to deduce ‘auto’ from ‘<expression error>’



This indicates that the problem is that the parameter is seen as 'int *'
instead of as 'int [10]'.  According to Andrew another problem caused by the
too-early decay of arguments to pointers (bug 24666).

Changing the code as follows makes it compile:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int aa[1][10] = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };

int f(int arr[1][10])
{
  int s = 0;
  for (auto i : arr[0])
    s += i;
  return s;
}

int main()
{
  return f(aa);
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~