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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - SFINAE leaks through requires expression requirement"
href="https://bugs.llvm.org/show_bug.cgi?id=44674">44674</a>
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<th>Summary</th>
<td>SFINAE leaks through requires expression requirement
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>10.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++2a
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>cjdb.ns@gmail.com
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>Created <span class=""><a href="attachment.cgi?id=23063" name="attach_23063" title="Initial preprocessed file">attachment 23063</a> <a href="attachment.cgi?id=23063&action=edit" title="Initial preprocessed file">[details]</a></span>
Initial preprocessed file
# Description
[iterator.concept.contiguous] depends on `std::to_address`, which (correctly)
fails in the "minimal" repro below. Unfortunately, the requirement seems to
leak an instantiation error, instead of SFINAEing out the overload and the
concept evaluating as false.
# LLVM configuration
```
cmake -GNinja ../llvm-project/llvm/
\
-DCMAKE_C_COMPILER=/usr/bin/clang-9
\
-DCMAKE_CXX_COMPILER=/usr/bin/clang++-9
\
-DCMAKE_BUILD_TYPE=Release
\
-DLLVM_TARGETS_TO_BUILD=X86
\
-DLLVM_ENABLE_PROJECTS='clang;clang-tools-extra;compiler-rt;libcxx;libcxxabi;lld'
\
-DLLVM_ENABLE_LLD=On
\
-DLLVM_ENABLE_LTO=Off
\
-DPYTHON_EXECUTABLE=/usr/bin/python3
\
-DLLVM_ENABLE_LIBCXX=On
\
-DLLVM_ENABLE_BINDINGS=Off
```
# Sample code built with
```
-std=c++2a -stdlib=libc++ -save-temps
```
# "Minimal" repo
```
#include <memory>
struct dummy {};
struct iterator {
using element_type = dummy;
int* operator->() const;
};
template<typename I>
concept passing = requires(I const& i) {
std::to_address(i);
};
static_assert(not passing<iterator>);
```</pre>
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