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Ensure SmallVector::insert doesn't overwrite the last element in the range with the already-moved-from value

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This would cause the last element in a range to be in a moved-from state
after an insert at a non-end position, losing that value entirely in the
process.

Side note: move_backward is subtle. It copies [A, B) to C-1 and down.
(the fact that it decrements both the second and third iterators before
the first movement is the subtle part... kind of surprising, anyway)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210426 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Blaikie 2014-06-08 16:00:02 +00:00
parent 6e0ab2f54c
commit e570687bd8
2 changed files with 23 additions and 1 deletions
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2
include/llvm/ADT/SmallVector.h
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@ -488,9 +488,9 @@ public:
}
::new ((void*) this->end()) T(::std::move(this->back()));
this->setEnd(this->end()+1);
// Push everything else over.
this->move_backward(I, this->end()-1, this->end());
this->setEnd(this->end()+1);
// If we just moved the element we're inserting, be sure to update
// the reference.

22
unittests/ADT/SmallVectorTest.cpp
View File

@ -531,4 +531,26 @@ TEST(SmallVectorCustomTest, NoAssignTest) {
EXPECT_EQ(42, vec.pop_back_val().x);
}
struct MovedFrom {
bool hasValue;
MovedFrom() : hasValue(true) {
}
MovedFrom(MovedFrom&& m) : hasValue(m.hasValue) {
m.hasValue = false;
}
MovedFrom &operator=(MovedFrom&& m) {
hasValue = m.hasValue;
m.hasValue = false;
return *this;
}
};
TEST(SmallVectorTest, MidInsert) {
SmallVector<MovedFrom, 3> v;
v.push_back(MovedFrom());
v.insert(v.begin(), MovedFrom());
for (MovedFrom &m : v)
EXPECT_TRUE(m.hasValue);
}
}