[Bug testsuite/83303] [8 Regression] FAIL: g++.dg/opt/new1.C on arm-none-eabi (extra -Walloc-size-larger-than warning)

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83303

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-12-06
                 CC|                            |msebor at gcc dot gnu.org
          Component|middle-end                  |testsuite
     Ever confirmed|0                           |1

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
I can reproduce the warning with an arm-non-eabi cross-compiler.  Based on the
source code copied below the warning seems justified:

  template <typename T> void QScript::Buffer<T>::resize(int s) {
    if (m_capacity < s)   // s == 0 so m_capacity is negative
      reserve (s << 1);
  }

  template <typename T> void QScript::Buffer<T>::reserve(int x) {
    T *new_data = new T[m_capacity];   // m_capacity is negative
    ...
  }

  inline void QScriptObject::reset() { m_values.resize(0); }

Other compilers, and with -O2 also the arm-non-eabi cross-compiler, optimize
the test to a trap, further validating that a warning is justified (in fact,
I'd say not issuing one is suboptimal given that the emitted code will
unavoidably abort at runtime).

  QScript::Ecma::Boolean::newBoolean (struct Boolean * const this, struct
QScriptValueImpl * result, bool value)
  {
    int _4;

    <bb 2> [local count: 1073741825]:
    _4 ={v} MEM[(int *)0B + 4B];
    __builtin_trap ();
  }

Since the purpose of the test is to verify the absence of an ICE (pr39367),
whether or not it triggers any warnings doesn't seem important and pruning them
from its output should be appropriate.