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issue 15645 - Prevent unsafe usage of Tuple.slice #5342

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dlang-bot merged 1 commit into from
May 17, 2017
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issue 15645 - Prevent unsafe usage of Tuple.slice #5342

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13 changes: 11 additions & 2 deletions std/typecons.d
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Original file line number Diff line number Diff line change
Expand Up @@ -970,7 +970,7 @@ template Tuple(Specs...)
}

/**
* Takes a slice of this `Tuple`.
* Takes a slice by-reference of this `Tuple`.
*
* Params:
* from = A `size_t` designating the starting position of the slice.
Expand All @@ -982,9 +982,14 @@ template Tuple(Specs...)
* the original.
*/
@property
ref Tuple!(sliceSpecs!(from, to)) slice(size_t from, size_t to)() @trusted
ref inout(Tuple!(sliceSpecs!(from, to))) slice(size_t from, size_t to)() inout @trusted
if (from <= to && to <= Types.length)
{
static assert(
(typeof(this).alignof % typeof(return).alignof == 0) &&
(expand[from].offsetof % typeof(return).alignof == 0),
"Slicing by reference is impossible because of an alignment mistmatch. (See Phobos issue #15645.)");

return *cast(typeof(return)*) &(field[from]);
}

Expand All @@ -997,6 +1002,10 @@ template Tuple(Specs...)
auto s = a.slice!(1, 3);
static assert(is(typeof(s) == Tuple!(string, float)));
assert(s[0] == "abc" && s[1] == 4.5);

// Phobos issue #15645
Tuple!(int, short, bool, double) b;
static assert(!__traits(compiles, b.slice!(2, 4)));
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@JackStouffer JackStouffer May 17, 2017

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I don't know much about this code, but isn't the 4 out of bounds? Or are the arguments 1-indexed?

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@tsbockman tsbockman May 17, 2017

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From the docs:

to = A size_t designating the ending position (exclusive) of the slice.

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@JackStouffer JackStouffer May 17, 2017

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Ah, thanks

}

/**
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