SmallVector::insert(iterator I, InTy From, InTy To) is broken

[llvmbot]

Bugzilla Link	3860
Resolution	FIXED
Resolved on	Nov 07, 2018 00:17
Version	2.5
OS	Windows NT
Reporter	LLVM Bugzilla Contributor

Extended Description

SmallVector insert triggers a debug validation failure with MSVC++, because it passes an invalid range to std::copy. Specifially,

// Copy the existing elements that get replaced.
std::copy(I, OldEnd-NumToInsert, I+NumToInsert);

in

template
iterator insert(iterator I, ItTy From, ItTy To)

passes an I > (OldEnd-NumToInsert) to std::copy, which would result in memory corruption at best.

Simple test case to trigger it.
const char * t = "Cannot load string";
// 01234567890123456789
const char * other = ">> \n";
// 012345
SmallVector<char, 16> test (t, t + 18);
SmallVector<char, 16>::iterator it = test.end ();
--it;

test.insert (it, other, other + 4);

Actually, any insert at begin () + N, with N 3..17 fails in that case, including at the end.

[lattner]

Fixed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20090316/075518.html

Plz verify, thanks!

[llvmbot]

Yep, works fine now. Thanks!