tree f2e85b5cbf295eb13d69dc66f47805230c83ec76
parent ab14ae2ab16088b6a7f69eac6e152c3e9f9ea01b
author Richard Smith <richard-llvm@metafoo.co.uk> 1328083820 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> 1328083820 +0000

constexpr: check for overflow in pointer subtraction.

This is a mess. According to the C++11 standard, pointer subtraction only has
undefined behavior if the difference of the array indices does not fit into a
ptrdiff_t.

However, common implementations effectively perform a char* subtraction first,
and then divide the result by the element size, which can cause overflows in
some cases. Those cases are not considered to be undefined behavior by this
change; perhaps they should be.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149490 91177308-0d34-0410-b5e6-96231b3b80d8