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error: no template named '__vector_base' in namespace 'std' #1867

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yurivict opened this issue Sep 26, 2022 · 2 comments
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error: no template named '__vector_base' in namespace 'std' #1867

yurivict opened this issue Sep 26, 2022 · 2 comments

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@yurivict
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In file included from /disk-samsung/freebsd-ports/devel/folly/work/folly-2022.09.26.00/folly/memory/test/UninitializedMemoryHacksTest.cpp:17:
/disk-samsung/freebsd-ports/devel/folly/work/folly-2022.09.26.00/folly/memory/UninitializedMemoryHacks.h:302:23: error: no template named '__vector_base' in namespace 'std'
    using Base = std::__vector_base<T, std::allocator<T>>;
                 ~~~~~^

Where is std::__vector_base specified?
https://en.cppreference.com/ doesn't have any information about it.

Version: 2022.09.26.00
FreeBSD 13.1
@yurivict yurivict mentioned this issue Sep 26, 2022
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@Orvid
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Orvid commented Oct 10, 2022

It used to be defined in <vector> when using libc++, but it looks like newer versions of libc++ don't have it, so that bit of code will need to be reworked in order to build against the newer libc++ :(

@yfeldblum yfeldblum mentioned this issue Jan 11, 2023
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yfeldblum added a commit to yfeldblum/folly that referenced this issue Jan 11, 2023
@yfeldblum @facebook-github-bot
revise std::vector uninit-mem hacks under libc++
1e0ce7a 
Summary:
The `std::__vector_base` class in libc++ is removed in libc++ 15 (llvm/llvm-project@b82da8b). So the two current implementations of the hacks - the implementation for libc++ 14 and the implementation for earlier libc++ - both fail.

Even with libc++ 14, which retains `std::__vector_base`, Xcode 14 fails to compile the hacks:

```
In file included from folly/memory/test/UninitializedMemoryHacksODR.cpp:17:
folly/memory/UninitializedMemoryHacks.h:461:1: error: conversion from 'std::__vector_base<char, std::allocator<char>>::pointer std::__vector_base<char, std::allocator<char>>::*' to 'char *std::vector<char>::*' is not allowed in a converted constant expression
FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT(char)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
folly/memory/UninitializedMemoryHacks.h:327:7: note: expanded from macro 'FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT'
      &std::vector<TYPE>::__end_,                                    \
      ^~~~~~~~~~~~~~~~~~~~~~~~~~
...
```

Since libc++ is unlikely to change the internal layout of `std::vector` on a cadence which is too frequent for folly, we can use a layout struct rather than a template instance for the hacks and have it work for a range of versions of libc++ and Xcode.

Closes: facebook#1867.

Differential Revision: D42459219

fbshipit-source-id: cce2a1e4b8ba5791061cbe9f313cb33bee058fa3
@yfeldblum
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@yurivict Would you be able to test #1912?

yfeldblum added a commit to yfeldblum/folly that referenced this issue Jan 14, 2023
@yfeldblum @facebook-github-bot
revise std::vector uninit-mem hacks under libc++ (facebook#1912)
a147f52 
Summary:
Pull Request resolved: facebook#1912
Closes: facebook#1867

The `std::__vector_base` class in libc++ is removed in libc++ 15 (llvm/llvm-project@b82da8b). So the two current implementations of the hacks - the implementation for libc++ 14 and the implementation for earlier libc++ - both fail.

Even with libc++ 14, which retains `std::__vector_base`, Xcode 14 fails to compile the hacks:

```
In file included from folly/memory/test/UninitializedMemoryHacksODR.cpp:17:
folly/memory/UninitializedMemoryHacks.h:461:1: error: conversion from 'std::__vector_base<char, std::allocator<char>>::pointer std::__vector_base<char, std::allocator<char>>::*' to 'char *std::vector<char>::*' is not allowed in a converted constant expression
FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT(char)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
folly/memory/UninitializedMemoryHacks.h:327:7: note: expanded from macro 'FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT'
      &std::vector<TYPE>::__end_,                                    \
      ^~~~~~~~~~~~~~~~~~~~~~~~~~
...
```

Since libc++ is unlikely to change the internal layout of `std::vector` on a cadence which is too frequent for folly - any material change would be an ABI break -, we can use a layout struct rather than a template instance for the hacks and have it work for a range of versions of libc++ and Xcode.

Reviewed By: simpkins, swolchok

Differential Revision: D42459219

fbshipit-source-id: 379b86055601e5cc166a4d3364ab8d10be86f001
facebook-github-bot pushed a commit to facebook/hhvm that referenced this issue Jan 14, 2023
@yfeldblum @facebook-github-bot
revise std::vector uninit-mem hacks under libc++ (#1912)
4b346fa 
Summary:
X-link: facebook/folly#1912
Closes: facebook/folly#1867

The `std::__vector_base` class in libc++ is removed in libc++ 15 (llvm/llvm-project@b82da8b). So the two current implementations of the hacks - the implementation for libc++ 14 and the implementation for earlier libc++ - both fail.

Even with libc++ 14, which retains `std::__vector_base`, Xcode 14 fails to compile the hacks:

```
In file included from folly/memory/test/UninitializedMemoryHacksODR.cpp:17:
folly/memory/UninitializedMemoryHacks.h:461:1: error: conversion from 'std::__vector_base<char, std::allocator<char>>::pointer std::__vector_base<char, std::allocator<char>>::*' to 'char *std::vector<char>::*' is not allowed in a converted constant expression
FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT(char)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
folly/memory/UninitializedMemoryHacks.h:327:7: note: expanded from macro 'FOLLY_DECLARE_VECTOR_RESIZE_WITHOUT_INIT'
      &std::vector<TYPE>::__end_,                                    \
      ^~~~~~~~~~~~~~~~~~~~~~~~~~
...
```

Since libc++ is unlikely to change the internal layout of `std::vector` on a cadence which is too frequent for folly - any material change would be an ABI break -, we can use a layout struct rather than a template instance for the hacks and have it work for a range of versions of libc++ and Xcode.

Reviewed By: simpkins, swolchok

Differential Revision: D42459219

fbshipit-source-id: e23ef383869681b5c81e4301114020b9089c7461
@carlocab carlocab mentioned this issue Jun 15, 2023
Merged
carlocab added a commit to carlocab/homebrew-core that referenced this issue Jun 15, 2023
@carlocab
clickhouse-odbc: revision bump (icu4c 73.2)
418a10a 
Also:

- deprecate, because it vendors an ancient version of folly that no
  longer works with newer versions of libc++. See facebook/folly#1867.
- remove Ventura bottles, because they will fail to build.
@tarunparmar tarunparmar mentioned this issue Feb 9, 2024
Closed
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revise std::vector uninit-mem hacks under libc++ yfeldblum/folly
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@yfeldblum @yurivict @Orvid