<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/75933>75933</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            __underlying_type compiler crash
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          ordinary-github-user
      </td>
    </tr>
</table>

<pre>
    https://godbolt.org/z/fKf4K8zcr

`-std=c++26`

```c++
template<auto Value>struct Constant{};

template<class T>
void asdf()noexcept
{
        []<T flag>(Constant<flag>)
        {
                static_cast<__underlying_type(decltype(flag))>(flag);
        }(Constant<T::a>{});
}

enum class E{a};

int main()
{
        asdf<E>();
}
```

```
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-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++26 <source>
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      <source>:6:2: Generating code for declaration 'asdf()::(anonymous class)::operator()'
 #0 0x0000000003527418 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3527418)
 #1 0x0000000003525564 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3525564)
 #2 0x0000000003472a38 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007fe524642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00000000037cafb2 clang::CodeGen::CGDebugInfo::getOrCreateType(clang::QualType, llvm::DIFile*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x37cafb2)
 #5 0x00000000037cb268 clang::CodeGen::CGDebugInfo::EmitExplicitCastType(clang::QualType) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x37cb268)
 #6 0x0000000003c4c5fc (anonymous namespace)::ScalarExprEmitter::VisitExplicitCastExpr(clang::ExplicitCastExpr*) CGExprScalar.cpp:0:0
 #7 0x0000000003c41379 (anonymous namespace)::ScalarExprEmitter::Visit(clang::Expr*) CGExprScalar.cpp:0:0
 #8 0x0000000003c43633 clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3c43633)
 #9 0x0000000003be78be clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3be78be)
#10 0x0000000003c019cb clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3c019cb)
#11 0x000000000382c22e clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x382c22e)
#12 0x0000000003832149 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3832149)
#13 0x000000000389b419 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x389b419)
#14 0x00000000038f62db clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x38f62db)
#15 0x00000000038f2043 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x38f2043)
#16 0x00000000038fbcf2 clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x38fbcf2)
#17 0x00000000038fbd0a clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x38fbd0a)
#18 0x00000000038fe473 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x38fe473)
#19 0x0000000003d5b50a (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#20 0x0000000003d5a224 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3d5a224)
#21 0x0000000005b978b9 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5b978b9)
#22 0x0000000003d59875 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3d59875)
#23 0x0000000003fde3c1 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fde3c1)
#24 0x0000000003f5b93b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3f5b93b)
#25 0x00000000040bd4d3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x40bd4d3)
#26 0x0000000000c10dd6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc10dd6)
#27 0x0000000000c0982d ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#28 0x0000000003da0629 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 0x0000000003472e63 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3472e63)
#30 0x0000000003da0849 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 0x0000000003d68ec7 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3d68ec7)
#32 0x0000000003d6987d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3d6987d)
#33 0x0000000003d735cc clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3d735cc)
#34 0x0000000000c0e1b1 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc0e1b1)
#35 0x0000000000b07f11 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb07f11)
#36 0x00007fe524629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#37 0x00007fe524629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#38 0x0000000000c0902e _start (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc0902e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzkWl1z3CgW_TXyC6UuCX0_-KGtdmc9k6nJxt7sYxcCJGuDQAXI055fv4VQ20JuO3ZWuzVVm3ISN7rAOedeuBdaSKm24ZReesmVl-wu0KDvhbwUkrQcyUe_afX9UPmDovKiEuTx8l7rXnnR1oN7D-4bQSrB9EbIxoP7Pz24r3-t41_zP7H0gp0XbKd_08BXmnjRDnvwyoNXMPXSYGFhfyYD26pp1zOkqReVaNACfENsoF50rbQcsAal4Eojrr3syst2XnQ1H3HWFzOkFLjzomv76EG0BCBFag_mHiy4oEdMez31zp6GKawoXlTegZqhxgwA86dZo_KpsXjuMu8eFEoj3eIDRsrYHw4DJ1Syx5Y3B_3YUw_mhGI2_ToOBwvzM850-hzNhsx2LoQ744toi0wPK8O8Q7abS0L50AErhjFGL0VruQYdarkV5qUgo2hReW3xnZ_q5Mmz7rUfv3y-3t5eAzVUXasBAtXQAEl7ITXQAixCbIzADRadB_eMPZz-83sp_kWx9uC-VWqgyoN7gDgBLcdsIBToewqwROoeVAh_1xJh6sES9JL2UmCqFCVAiUHaZtMTKSVwizQlQA4cKCzbXm8s5FuN8HdAhq43yMamYOMFxRcpGok6gGQzdJRrAxx4cC96gwyLrm8ZlT499kxIKk0bQ7zxtRz4dw_uKyO2bbORD_yG_IFk7cfAb4AvzGCo782Qg-4HvVHA74wAwPePeeoj1fnqkWt09KJdyzVlwL8Fvt9g7GshGL43_ox2b2IyxoqjXt0LDfwaCyakT1rUcKF0ixXway78UU23ebGqgReVk6anxRYalbyopKL2omvQI6moBEgDygkQNahbRq0lHPWk0jdN4PPnb7-Bm6-goZxKpFvBrVU0jfc8TbRNvWgLjfCfJmPeACwIBbWQwCwwZEcAHsye171dOR7MERf8sRODsovj6ZHozWBCTuYwswiAB6MABMfg9CdKYBaHORijc-ypHpX95YtsuR5j584GYP5sJNEfB6G0pKjzYGqCsOXagwUY5_v5CPLgVXCcMD2tYgM6XIBOkjQ-B7pkFPGh_53ftg1HzIP5wMc0QQATZpbVIBoEDkToQIwziKIclCbuvlIsHqh8tJj-hjhhZqZ80syxKQXX9Kg3uDerNRj_Pk0RTVNkNU1gnMYwgcHEh7WVB_fHPD2ksc9aPhz9hg_2Ad4osUlH4GMXB3bswM4wqisILF-rqCD0E-XTh087Wg3NDa-FbWio_l2WkiJN72wmmHX9-4CYbS1nvtrd7M26gdvVnGFBO6ySBasKpvn7WV13rb4-9qzFrS6R0m9RW42DgehwSB0OOMZJjYGz5jnqqOrHxTmt-1uMGJLXx14aDppK2_ytVS4jY-Eyevl0dFD5yXyww54PymwBM4yy4j-B-QLW-6HkCyhRGkWve91-2A8cj1v0k-efwb2EArCpX0ZAJaiEYKsFgEXrBEDh0Klollf043S2_PEdXF4bdts0Y-l6y4RenbOl9FyuwSh0sxMOwgJXH-d803AhKfkh77V8N8J0eLgJK4cYwp_w3a3uFuvBtDiOe95Yt1Kix6-0tseGU4et1jPGY8W_DmnLySHtpsA8gmFcfJx0KbpeDJwYqv9s9b0Y9C0Wyx14bnXilz5H6Hsjei0xRq6OGJErRlHF4QfFmEpCah665D8xUSG2o5i5IfDU_-1FXX46GZqcN1NvLTVGso4abpmR1ykkP1zXvwkyMPocGJb1CfqO1i1vLdv3aGPb7Tl8xbVvqThckwVXGMQ_TEPnuf5lOBoKDsd0wbHC9Rtl43mOO1pTKSmxh5S1oBokDtRsCZUE6C8ClQTIgZovoNI4-1DkfKWMIkXXRWlAOCjduoQkVRKgH1V8E1h7Kr3pemab7WHoTiKu2HjO_QdfVoDb27vpUDRtUZbw1dAyQs8UguYoFiwQIgjjuY5XCH-nnJSCq6E7VZ8_g2UViS2-ucTQKR-SqsjyykkeX5BUdHt7tygOaIcWWXDNem3C4QCFC6WLPEvOROx2nuOPFA-aTk0rhqqd3YHnJuGa0AiHc3h7adzJyRl8ayKzEzvI3IRYJ1URLRKinetmvC_F9Lx2r1NZMT4tOAe9k-LioCIxcTaqCecziQeB0UvML0iul7QmUA5qJ2kFOAwISQHG4WG6OD5fS9-jRQFdArcNluBBtGRF8Baagz1zsQdFDgk4yVyGd-M6nzG47RBj3yh-2m7PEEnd6sGMMW1vTk1IZPvw2k7rZiyCghQWoxqzceupYjvIUdDx6eke89qaYMRYhfD3Q83d44ude4qWMixF1yFOlgv1rOPGC157GWpmR0aDmT5atrwZLa8nrz51OBzw8RiG9kOFVIsPajSfVHSMTcNBS9RqdXq8GA4xZqJfyNlzYzK7RBgjx2o-Xe1mDHUVQR7MnqWC-ekS8xdRnfdHsbyFpGk0c8W5u8apdBj4Laope3TkfNt1a20wFuY83Be31AQFuXuU_L-LC6P0pkdSb4K3AmBxU07SnOLsVeFGh6EXqe-kprNXLzoaA-fc_T7TrVOfzLitkP5Hrk4ULaqTtMgz8lExfhGVel2JX0T1uVXuDcRbm_CT83vUGr-P3wG8X7wpQv57EhqFHAndCopkUYLxa3B3s9-dCuBM6n9N-v-hhGuVnaMmjmjxIlnTsJrKzlOpcQI97hrbF3d5r6XiVYqLEY6D1ynngirI6jAcv01fZUI7njNh6n6TBQtSfPCbrLGLM2a2HJPGATgcTLeD0kjqw4zRu2ehsTtLvqzDAkiBHX8l75gRn6acP462gEpp0sXWBhOop5of4CnKa9QySsAfrb4H9Nhq-11yGI2RMygK_AegBVCUgnZWk0-TncpxIKkeJKdmnZnOizchLshlRIqoQBf0MswCWBRxVGQX95ekqGCV1DTKo6yCKEmrhMACk6QI4iyl4UV7CQMYhTAswigpkmyDcUIrHCUkqtKqyEIvDmiHWrYxS2EjZHMxviFxmSVFFF0wVFGmTi_8yMvxZYpqaJQXB6xVWj13061m9PLFWyvg5Bb7fsXFINnyvaAPvLQxovp3AAAA__-SLvPS">