https://bugs.llvm.org/show_bug.cgi?id=41845
Bug ID: 41845
Summary: Crash when expanding an empty fold expression
Product: clang
Version: trunk
Hardware: Macintosh
OS: MacOS X
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected]
Created attachment 21932
--> https://bugs.llvm.org/attachment.cgi?id=21932&action=edit
Crash Log
See https://godbolt.org/z/QJQ4A7.
#include <tuple>
#include <type_traits>
#include <utility>
template <typename... DstArgs>
struct ArgsPackChecker
{
template <typename... SrcArgs>
using EnableIf = std::enable_if_t<
(std::is_convertible_v<SrcArgs, DstArgs> && ...)>;
};
template <typename DstArgsTuple,
typename IndexSeq =
std::make_index_sequence<std::tuple_size_v<DstArgsTuple>>>
struct ArgsChecker;
template <typename DstArgsTuple, int... Is>
struct ArgsChecker<DstArgsTuple, std::index_sequence<Is...>>
{
template <typename... SrcArgs>
using EnableIf =
typename ArgsPackChecker<std::tuple_element_t<Is,
DstArgsTuple>...>::template EnableIf<SrcArgs...>;
};
template <typename... Args,
typename = typename ArgsChecker<std::tuple<>>::template
EnableIf<Args...>>
void f(Args&&... args)
{
}
This builds without an error with GCC 9.1, but crashes with clang trunk. The
attached crash backtrace was generated using Xcode 10.2.1 using the following
command:
$ clang -std=c++17 test.cpp
clang: error: unable to execute command: Segmentation fault: 11
clang: error: clang frontend command failed due to signal (use -v to see
invocation)
Apple LLVM version 10.0.1 (clang-1001.0.46.4)
Target: x86_64-apple-darwin18.5.0
Thread model: posix
InstalledDir:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
clang: note: diagnostic msg: PLEASE submit a bug report to
http://developer.apple.com/bugreporter/ and include the crash backtrace,
preprocessed source, and associated run script.
clang: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg:
/var/folders/v1/0ffrrhw11394l1p_rl193z340000gn/T/test-87fcfd.cpp
clang: note: diagnostic msg:
/var/folders/v1/0ffrrhw11394l1p_rl193z340000gn/T/test-87fcfd.sh
clang: note: diagnostic msg: Crash backtrace is located in
clang: note: diagnostic msg:
/Users/ryan/Library/Logs/DiagnosticReports/clang_<YYYY-MM-DD-HHMMSS>_<hostname>.crash
clang: note: diagnostic msg: (choose the .crash file that corresponds to your
crash)
clang: note: diagnostic msg:
********************
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