Compile error in debug mode about sparsepp HOT 11 CLOSED

I did some more digging. The problem is the -D_GLIBCXX_DEBUG flag, that is, the checked STL version. When removing this, compilation works. But I'd prefer to keep it.

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It would be useful to know what's on line 86 of /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/debug/array.
Even more useful would be the output of the preprocessor (add -save-temps to your flags and look for a .ii file).

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Line 86 is already printed in the detail listing of my post ;-)

Here is a bit more context. The problematic line is in the swap function of std::array. It seems to be the noexcept specification that is causing trouble:

void
swap(array& __other)
noexcept(noexcept(swap(std::declval<_Tp&>(), std::declval<_Tp&>())))
{ std::swap_ranges(begin(), end(), __other.begin()); }

I also got the preprocessor .ii file: chunkify.ii.zip. Unpacked, it is 4MB, because of all the headers. Let me know if you want me to prepare something more light-weight instead.

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What is the definition of your sparsepp map or set?

from sparsepp.

I'm using

spp::sparse_hash_map< typename HashFunction::DigestType, size_t >

where HashFunction::DigestType is

using DigestType = std::array< uint32_t, 5 >;

Interesting! Because of the abstraction of DigestType, I didn't see the connection between my hash key type and the array that is causing the compile error. Is this an issue with the STL implementation, after all? Or am I using sparsepp wrongly?

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I don't think the issue is in your code. I think it may be an issue with the checked STL, but not 100% sure. Does the issue occur if you use std::unordered_map instead of spp::sparse_hash_map?

from sparsepp.

No, using a std::unordered_map compiles fine with the same debug settings.

By the way, if it helps, the only operations that I am doing with the map are:

// Init a map from hashes to chunk IDs.
using ChunkHashMap = spp::sparse_hash_map< typename HashFunction::DigestType, size_t >;
ChunkHashMap hash_to_chunk;

// Check if a hash is in there. If so, use the chunk ID. If not, add it.
auto const hash_it = hash_to_chunk.find( hash_digest );
if( hash_it != hash_to_chunk.end() ) {
    auto const chunk_id = hash_it->second;
    // ...
} else {
    // ...
    hash_to_chunk[ hash_digest ] = chunk_count;
}

(some variable declarations left out for simplicity)

The line that is causing the compile error is the last one, where a new element is added.

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I think that the checked STL the code you quoted should have a std:: before the swap() call in the noexcept clause, otherwise it tries to call itsef swap(array& __other) which takes a single __other argument

void
swap(array& __other)
noexcept(noexcept(std::swap(std::declval<_Tp&>(), std::declval<_Tp&>())))
{ std::swap_ranges(begin(), end(), __other.begin()); }```

from sparsepp.

Yep, that works. With the added std::, my code compiles. I just sent a bug report to the libc++ mailing list, let's see what they say about this.

Thanks! I guess, we can close this issue then.

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Short update:

It seems there were two problems involved. One with Clang (http://lists.llvm.org/pipermail/cfe-dev/2018-May/058005.html), and one with the libstdc++ (GCC) STL implementation (http://lists.llvm.org/pipermail/cfe-dev/2018-May/058017.html) - the added std however seems not to be the correct solution. The problem was however solved in libstdc++ a while ago, so I probably just need to update, and find out why Clang uses the GCC STL implementation in my setup...

Anyway, the problem is not due to sparsepp, so all good here ;-)

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@lczech thanks a lot for the update!

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