[LLVMbugs] [Bug 12659] New: clangs fails to warn integer overflow in expression

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12659

             Bug #: 12659
           Summary: clangs fails to warn integer overflow in expression
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Frontend
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: weimingz at codeaurora.org
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Created attachment 8451
  --> http://llvm.org/bugs/attachment.cgi?id=8451
test case

clang version 3.1 (branches/release_31 154941)

For the following code, Clang accepts it without warning:
#include <limits.h>
int foo(int i)
{
  switch (i)
  {
    case INT_MAX + 2:  /* error - constant is too large */
      return 1;

    case (INT_MAX*4)/4:  /* error - constant is too large */
      return 2;

    default:
      return 0;
  }
  return 0;
}

with "-std=c99 -pedantic", no warnings either.

GCC will warn:
constant_ov.c: In function 'foo':
constant_ov.c:6: warning: integer overflow in expression
constant_ov.c:9: warning: integer overflow in expression

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