[Bug middle-end/99676] New: missing detail in warning for passing smaller array to bigger argument

[Bug middle-end/99676] New: missing detail in warning for passing smaller array to bigger argument

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99676

            Bug ID: 99676
           Summary: missing detail in warning for passing smaller array to
                    bigger argument
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

The warning(s) below are confusing:
1) each mentions the argument type is 'int *' when it actually uses 'int[4]' to
trigger, and
2) it doesn't point to the declaration of the object or subobject whose size it
uses.
In cases like pr99673 the missing details make the warning harder than
necessary to understand and decide if it's a false positive.

$ cat x.c && gcc -O -S -Wall x.c
struct A { int a[2], b[2]; };

void f (int[4], int[4]);

void g (int *p, int *q)
{
  f (p, q);
}

void h (struct A *p)
{
  g (p->a, p->b);
}
In function ‘g’,
    inlined from ‘h’ at x.c:12:3:
x.c:7:3: warning: ‘f’ accessing 16 bytes in a region of size 8
[-Wstringop-overflow=]
    7 |   f (p, q);
      |   ^~~~~~~~
x.c: In function ‘h’:
x.c:7:3: note: referencing argument 1 of type ‘int *’
In function ‘g’,
    inlined from ‘h’ at x.c:12:3:
x.c:7:3: warning: ‘f’ accessing 16 bytes in a region of size 8
[-Wstringop-overflow=]
x.c: In function ‘h’:
x.c:7:3: note: referencing argument 2 of type ‘int *’
x.c:3:6: note: in a call to function ‘f’
    3 | void f (int[4], int[4]);
      |      ^

[Bug middle-end/99676] missing detail in warning for passing smaller array to bigger argument

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99676

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Blocks|                            |88443

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The warning should also not be -Wstringop-overflow or -Wstringop-overread
(which are meant to be about accesses by functions declared in <string.h> and
maybe also direct string accesses by pointers) but probably -Warray-bounds.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88443
[Bug 88443] [meta-bug] bogus/missing -Wstringop-overflow warnings