[Clang] [Sema] Crash on constexpr by-value structured binding pack #170991
Description
Attempting to declare a constexpr structured binding pack that is not a reference crashes (https://godbolt.org/z/8bW78x454):
struct S { int x{}; };
template <typename = void>
void f() {
constexpr S s;
constexpr auto [...xs] = s;
}
template void f<void>();Assertion:
clang++: /root/llvm-project/llvm/tools/clang/lib/Sema/SemaDecl.cpp:16891:
clang::Decl* clang::Sema::ActOnFinishFunctionBody(clang::Decl*, clang::Stmt*, bool, bool):
Assertion `MaybeODRUseExprs.empty() && "Leftover expressions for odr-use checking"' failed.Stack trace:
0. Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++26 <source>
1. <source>:9:24: current parser token ';'
2. <source>:4:6: instantiating function definition 'f<void>'
#0 0x000000000429d868 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x429d868)
#1 0x000000000429ac94 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x429ac94)
#2 0x00000000041dfa68 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#3 0x0000775a08c42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x0000775a08c969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x0000775a08c42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x0000775a08c287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x0000775a08c2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#8 0x0000775a08c39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#9 0x0000000006d8a5b5 clang::Sema::ActOnFinishFunctionBody(clang::Decl*, clang::Stmt*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d8a5b5)
#10 0x00000000075b5d16 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75b5d16)
#11 0x00000000073c0c4a clang::Sema::ActOnExplicitInstantiation(clang::Scope*, clang::SourceLocation, clang::SourceLocation, clang::Declarator&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x73c0c4a)
#12 0x00000000069d70ad clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69d70ad)
#13 0x00000000069e477a clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69e477a)
#14 0x0000000006ab4ec8 clang::Parser::ParseDeclarationAfterTemplate(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo&, clang::ParsingDeclRAIIObject&, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ab4ec8)
#15 0x0000000006ab5a1c clang::Parser::ParseExplicitInstantiation(clang::DeclaratorContext, clang::SourceLocation, clang::SourceLocation, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ab5a1c)
#16 0x0000000006ac2898 clang::Parser::ParseDeclarationStartingWithTemplate(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac2898)
#17 0x00000000069edb00 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69edb00)
#18 0x00000000069aa51c clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69aa51c)
#19 0x00000000069ab405 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69ab405)
#20 0x000000000698c46a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x698c46a)
#21 0x0000000004be4698 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4be4698)
#22 0x0000000004ed9e05 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ed9e05)
#23 0x0000000004e5a06e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4e5a06e)
#24 0x0000000004fd2e7d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fd2e7d)
#25 0x0000000000dcc160 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdcc160)
#26 0x0000000000dc2bda ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#27 0x0000000000dc2d5d int llvm::function_ref<int (llvm::SmallVectorImpl<char const*>&)>::callback_fn<clang_main(int, char**, llvm::ToolContext const&)::'lambda'(llvm::SmallVectorImpl<char const*>&)>(long, llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#28 0x0000000004c57089 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#29 0x00000000041dff04 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41dff04)
#30 0x0000000004c5769f clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#31 0x0000000004c17e92 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c17e92)
#32 0x0000000004c18e3e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c18e3e)
#33 0x0000000004c20275 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c20275)
#34 0x0000000000dc8581 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdc8581)
#35 0x0000000000c73f44 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc73f44)
#36 0x0000775a08c29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#37 0x0000775a08c29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#38 0x0000000000dc2675 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdc2675)