Transformations that hide multiplications can end up with an pair of
parentheses that is no longer needed.  E.g. with a rule like this:

  @@
  expression E;
  @@
  - E * 2
  + double(E)

... we might get a patch like this:

  -	x = (a + b) * 2;
  +	x = double((a + b));

Add a pair of parentheses to the preimage side of such rules.
Coccinelle will generate patches that remove them if they are present,
and it will still match expressions that lack them.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Similar to COPY_ARRAY (introduced in 60566cbb), add a safe and
convenient helper for moving potentially overlapping ranges of array
entries.  It infers the element size, multiplies automatically and
safely to get the size in bytes, does a basic type safety check by
comparing element sizes and unlike memmove(3) it supports NULL
pointers iff 0 elements are to be moved.

Also add a semantic patch to demonstrate the helper's intended usage.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add a semantic patch for using ALLOC_ARRAY to allocate arrays and apply
the transformation on the current source tree.  The macro checks for
multiplication overflow and infers the element size automatically; the
result is shorter and safer code.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add a semantic patch for converting certain calls of memcpy(3) to
COPY_ARRAY() and apply that transformation to the code base.  The result
is
 shorter and safer code.  For now only consider calls where source and
destination have the same type, or in other words: easy cases.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>