<source>:2:38: warning: defaulted comparison operators are a C++20 extension [-Wc++20-extensions]
    2 |   bool operator==(const A &) const = default;
      |                                      ^
<source>:5:18: warning: equality comparison result unused [-Wunused-comparison]
    5 | int main() { A() == A(); }
      |              ~~~~^~~~~~

clang++: /root/llvm-project/llvm/tools/clang/lib/CodeGen/CGExprCXX.cpp:327: clang::CodeGen::RValue clang::CodeGen::CodeGenFunction::EmitCXXMemberOrOperatorMemberCallExpr(const clang::CallExpr*, const clang::CXXMethodDecl*, clang::CodeGen::ReturnValueSlot, bool, clang::NestedNameSpecifier*, bool, const clang::Expr*, llvm::CallBase**): Assertion `MD->getParent()->mayInsertExtraPadding() && "unknown trivial member function"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -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 <source>
1.	<eof> parser at end of file
2.	<source>:5:5: LLVM IR generation of declaration 'main'
3.	<source>:5:5: Generating code for declaration 'main'
 #0 0x0000000003f9bf28 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f9bf28)
 #1 0x0000000003f99bb4 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f99bb4)
 #2 0x0000000003ede7e8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007636aee42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007636aee969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007636aee42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007636aee287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007636aee2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007636aee39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x000000000432d599 clang::CodeGen::CodeGenFunction::EmitCXXMemberOrOperatorMemberCallExpr(clang::CallExpr const*, clang::CXXMethodDecl const*, clang::CodeGen::ReturnValueSlot, bool, clang::NestedNameSpecifier*, bool, clang::Expr const*, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x432d599)
#10 0x000000000432dde3 clang::CodeGen::CodeGenFunction::EmitCXXOperatorMemberCallExpr(clang::CXXOperatorCallExpr const*, clang::CXXMethodDecl const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x432dde3)
#11 0x00000000043088a6 clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43088a6)
#12 0x000000000437b144 (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprScalar.cpp:0:0
#13 0x000000000436e230 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#14 0x000000000437c63a (anonymous namespace)::ScalarExprEmitter::VisitExprWithCleanups(clang::ExprWithCleanups*) CGExprScalar.cpp:0:0
#15 0x000000000436ee35 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#16 0x00000000043740ec clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43740ec)
#17 0x00000000042dedce clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42dedce)
#18 0x000000000430688d clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x430688d)
#19 0x000000000447cbc6 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x447cbc6)
#20 0x0000000004484b4c clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4484b4c)
#21 0x00000000044eacb6 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44eacb6)
#22 0x00000000044fe1cb clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44fe1cb)
#23 0x0000000004568225 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4568225)
#24 0x0000000004563394 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4563394)
#25 0x00000000045637ab clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45637ab)
#26 0x000000000456e473 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#27 0x000000000494b766 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#28 0x000000000493b394 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x493b394)
#29 0x00000000066335e4 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66335e4)
#30 0x00000000049478f8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x49478f8)
#31 0x0000000004c3f825 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c3f825)
#32 0x0000000004bbe4ee clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bbe4ee)
#33 0x0000000004d32309 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4d32309)
#34 0x0000000000daceaf cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdaceaf)
#35 0x0000000000da307a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#36 0x00000000049aebe9 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
#37 0x0000000003edec84 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3edec84)
#38 0x00000000049af1ff 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
#39 0x0000000004970fcd clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4970fcd)
#40 0x000000000497205e 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+++0x497205e)
#41 0x000000000497a345 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x497a345)
#42 0x0000000000da8e18 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda8e18)
#43 0x0000000000c2e464 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc2e464)
#44 0x00007636aee29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#45 0x00007636aee29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#46 0x0000000000da2b25 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda2b25)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134