Some things from GCC 5

[bearophile via Digitalmars-d]

Some interesting changes in GCC 5.0:
https://gcc.gnu.org/gcc-5/changes.html

-----------------

A new command-line option -Wlogical-not-parentheses has been 
added for the C and C++ compilers, which warns about "logical 
not" used on the left hand side operand of a comparison.

bool not_equal(int x, int y) {
   return !x == y;  // warn here
}

return !(x == y);  // first fix-it, to negate comparison.

return (!x) == y;  // second fix-it, to silence warning.


Its usefulness:

> Close to 100% true positive.  That is hundreds of bugs found in 
> millions of
> lines of code.  For most cases, evaluating the comparison first 
> was the
> correct change.  For some others, the '!' was a typo and 
> removed.  A few
> cases involved macros.

If it's close to 100% positive then perhaps it's worth turning it 
into an error in D.

-----------------

There are now intrinsic functions to perform arithmetics with 
overflow guards, __builtin_add_overflow, __builtin_sub_overflow 
and __builtin_mul_overflow:


void *
calloc (size_t x, size_t y)
{
   size_t sz;
   if (__builtin_mul_overflow (x, y, &sz))
     return NULL;
   void *ret = malloc (sz);
   if (ret) memset (res, 0, sz);
   return ret;
}


They are the same in GCC and LLVM-Clang, so is it worth changing 
the API of core.checkedint to make is the same of those 
functions, for efficiency and GDC/LDC implementation simplicity?

-----------------

New warnings -Wsuggest-final-types and -Wsuggest-final-methods 
helps developers to annotate programs by final specifiers (or 
anonymous namespaces) in the cases where code generation 
improves. These warnings can be used at compile time, but they 
are more useful in combination with link-time optimization.

Some info:
https://gcc.gnu.org/ml/gcc-patches/2014-08/msg00119.html

For D this can become a "tip" from the compiler.

-----------------

C++ Dynamic Arrays, I miss them in D:
http://www.open-std.org/JTC1/sc22/WG21/docs/papers/2013/n3662.html

-----------------

Bye,
bearophile