[Bug tree-optimization/39974] New: [4.5 regression] Bogus "array subscript is below array bounds" warning in compiler generated code

[reichelt at gcc dot gnu dot org]

The following code snippet produces a bogus warning when compiled with
"-O2 -Wall" on trunk:

bug.cc: In function 'void
_Z41__static_initialization_and_destruction_0ii.clone.0()':
bug.cc:3: warning: array subscript is below array bounds
bug.cc:3: warning: array subscript is below array bounds
bug.cc:3: warning: array subscript is below array bounds

Maybe the warning indicates a code generation bug.

Interestingly, the second array must contain at least 42 elements ;-)

==================================================================
#include<string>

std::string x[2][3] = { { "", "", "" }, { "", "", "" } };

struct A
{
  A(int);
};

struct B
{
  A a1, a2, a3, a4, a5, a6;
};

B b[42] =
{
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 },
  { 0, 0, 0, 0, 0, 0 }
};
==================================================================


-- 
           Summary: [4.5 regression] Bogus "array subscript is below array
                    bounds" warning in compiler generated code
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: reichelt at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39974