<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/151531>151531</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] UNREACHABLE executed at /root/llvm-project/llvm/tools/clang/lib/Sema/SemaExpr.cpp:14597!
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:frontend,
            crash
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          k-arrows
      </td>
    </tr>
</table>

<pre>
    Reproducer:
https://godbolt.org/z/eM7n4GT1h
```cpp
struct w { int n; };

template<const w* X>
void f() {
  static_assert(X->n == 42);
}

template<w X>
void g() {
  f<&X>();
}

int main() {
 constexpr w X = {42};
 g<X>();
}
```

Backtrace:
```console
Unknown/unexpected decl type
UNREACHABLE executed at /root/llvm-project/llvm/tools/clang/lib/Sema/SemaExpr.cpp:14597!
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 --std=c++20 <source>
1.      <eof> parser at end of file
2.      <source>:9:6: instantiating function definition 'g<w{42}>'
3.      <source>:4:6: instantiating function definition 'f<&<template param w{42}>>'
 #0 0x0000000003fdb0d8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fdb0d8)
 #1 0x0000000003fd8504 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fd8504)
 #2 0x0000000003f1ccf8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00006ffc0b842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00006ffc0b8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00006ffc0b842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00006ffc0b8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x0000000003f284ba (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f284ba)
 #8 0x0000000006bb755b clang::Sema::CheckAddressOfOperand(clang::ActionResult<clang::Expr*, true>&, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6bb755b)
 #9 0x0000000006bd3a53 clang::Sema::CreateBuiltinUnaryOp(clang::SourceLocation, clang::UnaryOperatorKind, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6bd3a53)
#10 0x000000000703ba11 clang::Sema::BuildExpressionFromDeclTemplateArgument(clang::TemplateArgument const&, clang::QualType, clang::SourceLocation, clang::NamedDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x703ba11)
#11 0x00000000071c6a66 (anonymous namespace)::TemplateInstantiator::transformNonTypeTemplateParmRef(clang::Decl*, clang::NonTypeTemplateParmDecl const*, clang::SourceLocation, clang::TemplateArgument, clang::UnsignedOrNone, bool) SemaTemplateInstantiate.cpp:0:0
#12 0x00000000071ea895 (anonymous namespace)::TemplateInstantiator::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#13 0x00000000071b6719 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#14 0x00000000071e8e80 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformMemberExpr(clang::MemberExpr*) SemaTemplateInstantiate.cpp:0:0
#15 0x00000000071b6893 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#16 0x00000000071b66c6 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#17 0x00000000071dfac8 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformBinaryOperator(clang::BinaryOperator*) SemaTemplateInstantiate.cpp:0:0
#18 0x00000000071b63da clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#19 0x00000000071f4a42 clang::Sema::SubstExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71f4a42)
#20 0x000000000720cf7e clang::TemplateDeclInstantiator::VisitStaticAssertDecl(clang::StaticAssertDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x720cf7e)
#21 0x0000000007270ca4 void llvm::function_ref<void ()>::callback_fn<clang::Sema::SubstDecl(clang::Decl*, clang::DeclContext*, clang::MultiLevelTemplateArgumentList const&)::'lambda'()>(long) SemaTemplateInstantiateDecl.cpp:0:0
#22 0x0000000007f4fe61 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7f4fe61)
#23 0x000000000720e7da clang::Sema::SubstDecl(clang::Decl*, clang::DeclContext*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x720e7da)
#24 0x00000000071afcdd clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformDeclStmt(clang::DeclStmt*) SemaTemplateInstantiate.cpp:0:0
#25 0x00000000071fa52e clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*, bool) SemaTemplateInstantiate.cpp:0:0
#26 0x0000000007203be4 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7203be4)
#27 0x0000000007263eb0 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7263eb0)
#28 0x0000000007261b76 clang::Sema::PerformPendingInstantiations(bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7261b76)
#29 0x00000000072641b3 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x72641b3)
#30 0x0000000007261b76 clang::Sema::PerformPendingInstantiations(bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7261b76)
#31 0x00000000068372f2 clang::Sema::ActOnEndOfTranslationUnitFragment(clang::TUFragmentKind) (.part.0) Sema.cpp:0:0
#32 0x0000000006837672 clang::Sema::ActOnEndOfTranslationUnit() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6837672)
#33 0x0000000006694340 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6694340)
#34 0x0000000006685fda clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6685fda)
#35 0x0000000004987388 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4987388)
#36 0x0000000004c7aa05 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c7aa05)
#37 0x0000000004bf780e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bf780e)
#38 0x0000000004d6e731 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4d6e731)
#39 0x0000000000daa41f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdaa41f)
#40 0x0000000000da106a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#41 0x00000000049eeaa9 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
#42 0x0000000003f1d194 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f1d194)
#43 0x00000000049ef0bf 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
#44 0x00000000049b16ed clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x49b16ed)
#45 0x00000000049b277e 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+++0x49b277e)
#46 0x00000000049ba7b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x49ba7b5)
#47 0x0000000000da68cf clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda68cf)
#48 0x0000000000c5b7d4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc5b7d4)
#49 0x00006ffc0b829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#50 0x00006ffc0b829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#51 0x0000000000da0b15 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda0b15)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzkWl1346rV_jXkhuUsCX1f5EJx4vPxzkzyJpnTc-eFELJpJFABJU5_fRdItozspJNpPO20XT1rHAGb53nY7L1BwkqxFaf0AkSXILo6w51eC3nxOMNSimd1Vojy5eKOtlKUHaESBDnw8rXWrTI_0QKgxUqUhaj1uZArgBZ_B2hBPyc8_OXBXwMvB7HX_5-0LfBypWVHNHyGILmEjGvIQXAJQXIFgkvT28s1bdoaawqCORFcafgMUA7_BME18PInwUpYAZQClBkTwMshVBprRpZYKSo1QOmfMxBccwiCKxBcwRABlA3Wk6uDOZ4d06uJ6QoEc4Bi28W2TAwZBg1m3B1mcdNNK-Ez_NPgMA0h2rGEKxDMX7G5lau3f4nJo5aY0F74UUzBlagp8PKv_JGLZw7QouN001KiaQlLSmqoX1rb4cvddT7_Nb_8dA3phpLOdMAaArSQQmiAFnX91MxaKf5KyfZPgBZaiFoBtCA15mZha1YAtLinDR7-ud608tysapD7YZQlAPnAy28_Xef311B1RcM0xLDoVlDSVkgNtYATz2F63RXnRDTjtBMwTKmOGhgQ8xIyTuqupFCvKSQSqzUsdgKhOWylcVRClaIlVKKT_WMzEislCMOGu-w4VESyVp8DL7_XmDzCsmvaXmLvHHjZrRQriRuI5aprKNcGshFMtAYTEU3LaipndNPWQlK5VWnWuyATXM207PgjQIvCOMdWxEuALuFsVT5jWc1COFvBmTB2cdsa651uO32u4KwxKsDZbJPGM6yamXrhGm9AcMW4pjWcVVzMnqgshKKmHc7u4Wy2ImRmFo2sjUMGV2_iNZ0Vx61aCw1nFRG1kLOS4RUXSjOi-jmsxu7jmdIlCK5ITwZ5EATzQWq7jXyjHwjmVFQguIYtlopK42-Ul1BUsGLWbdHQbRwa5BkI8tgozbjSmGuGNeMrWHWcGE1hSSvGmf0JUGL20PO4r64BSoCXB0fshu-yO2x5EMy3UcKQwA10JtvOBwEKPOhtvO3_gqosvDKF1p2DHAS5elH9j1vJuLb-9tB7bDp2kvh5KZSWFDdmcjQ3wdGGFBMiPsTxALr0NgM8E3V68P4EfBp54THw85pi3rU3_J6tOK4BSjtuU0cJa2GmOAVUA2aEilyoPiFVCufGRe8oEU9UvvTYfsW8rM2M6aCh02cuuKYbPUQuz_7X2w8G-3FVEa9IQxQZ97ak-uC3SeNlHM5qxrvNbMW7voGcK3EeW8h2yAg4dA1mcVYR2Oq1pLhcPrK6fp91O360Hk3hhkkMV8pK8F7YYRKPhmPXMEqTKoC4MCH8XWbtwNFs4i4fSsMCf7zPWLPjpOn-pHFRJFFUwH6UdWubz3oHX1PymJelpErdVDctlZiXAKV7nXMbL-6o6mptypOxxeRCgHKzb7XsbNzpd_H-VDYkfRIEGysn2DADvZF85pIvAxwFr5CXFGt62bFaM_6VY_ly07rcp-gdasMIKrEW8v-Y0c1p35OnEKI-CXfLruduwpoTlBMvKLDvH-duWJcGIVWKCb6QormipH4Yon8-1ACuHNPWvuY7XPT_73D9YAqxt33BafyCG1oaCFayD5dqEGOUykkBiU9iHMdmUswFf2lEpyDHDVWtzVmZy_-3XUoVsm_REnNVCdl8Edww3_a8xbK5o5Ur446lK8DhSNNxq_G0-5tiHi7jxHP7JHYjvwhO9x3UOMghSzrJG0Y_5OpHcZpF36_fw1Y_Q_mOVv3emYq2a8jfhzVwsRZx4meOXJLSHQJbCX0HjesJk0MK34U9nOic0tQ7OfbPtCmoPGSw__ydPKLpGqRZ8LOsQTzFHpP4Z8GeuNjLCpP05Ngv2X5udFlM297JJ52uRVDin2UtMhd7FeIQHU_P912h9BuzOuH8c1dr9ok-0YP0_Ymp_ST98Vm157DLqsgtQJBHqoQeS0wmmh9mgT-YYuasqBnJLYQ-UzoV2UHrSaqFHvnIy60WUOIRHEJ7eTaeGrdH66Wk5jhtW7d3XYNDEVzXBSaPy4q7pfRk5Q95H68ZzNPhaPevuEXfH6Ckxk1RYnPI3-FG6fak-4qfGwyHvo7c-qAKKxq7pajG5PF6s8adMqJtj6_9vUDH_8L0-r6rKkYYHe4P7vuN-3Z9_q3LcQKf6TmOPhNM9gJN3Ej1713zE2wZQ3CkPylccEXK8uSB2ohzrxt9KGT_9H0BG02KlgpHiJ6cw1w0reh4ecjDbcm_q3BH8cQtg4KGb7jlIYq92f9TPM9wGD3PLXlQHNDCO85wT6nFEC6udvei77gKGAfvdmy_MNN_T0De0hvJpxPyfpHEx8nfUmnc7ZbykvHVKIWZFaD09MANtBF4NgEe-sUr9zb_Fatm6O3IB95PumruTXqcBgmqXilpc6Jv-DUvbyob6WoL-StneiHx6shd09ft8_5qzVI5b7HU59424B1GN_e63OCJk_fi2b7W_OC7uh7LqJxTHsRxFgahE6Vu7Uukvd8PorXx9bBQuGnx3zp6q6VbVJqOv0jRtXemAjp2ObsT47Mou5r-1rRC2gKcniZUDzRHEUJXhDSq3BrJEs_vHya72r6PjX_ARh0gjYCdiiDM0iRIneP0XJT0F8r7S_Ptoc2-fx4encS5BiAjTCfJhyTB2Iuc0CdNBcnLIzhPhLDHMCJ0knRYVEnqUTipdcycfYTrvwU41PJ1Sifx3wHnyMLJtmEZ0yTw3XcAFu9I5mmXiqaFnUP2JKfaAd-I3km5Xolx6FeQEH85fN0xHqZyKfGLDSNzssZyvJQ2YWUO3Wdobo_GpyHRo9xxCL0JB9-LMdzKPvcfbFzYY3Lf4Lr-gxIt5G9NWx8lFLsnSWNjOHE5dWwp2ROVh0ko9N0gQSnG2UfeFvQTD64z9-eiaTAvp7v46OrZDxnMM9Ga2bERYE8cLRlfDemiX9rdgOWSbDa-3_9RYMXIUtnug4ROZ_NgqSVmWm2bJ-ZwXZutIOReu-myV4ZZ9-kF_6YLit9FcWQxpi_QSz_bf9d_7DV533LX8Xtc0frF0fJHXysMiEeHDybOVXlFBf-XnWNSGB73gtBVrfBjWr6qml01fJAZt1I6oXsy0HR47bXoG11zp5zZI_axVYKlPbrSpJgpUOLe1n6LKL-LQr2uyO-imBz_9wPrYSzeeUCLmVl8dvDu8k0RBzf5IVIasUYp44mUOCmi12Bf7f12CoQjlcFrS_ADpTxBtWrlGcVLJjk8TskQ0raVyBa8DSX5EAj-eYb-8NrDIBtxO9WfR6IiKUP7ZexHT9ybHifOJh8rZWX2zo-27JCdwcibGqShB5dLM2apNJZ6uUfrm6ege0e9yJ8sslf4EeyNf_w6GeP91PttQQ6plPZtU-9esBoODZAM_l9hVtMSPjO9hnTDjDuVFPpBaDB2isLZE9QCKkoh2yvmzUzbIh5KqjvJqdl-ZuT-J8xn5UVQZkGGz-iFn0RBlgRpkp2tLygpKCpCSpIkQF5YlH5JEK2CrEqSssDojF0gD0VeEvh-GCVRdp6lIfEjXBUxTjKPRCD0aINZfW62xbmQqzP7GfGFH_lR4J_VuKC1sl-8I7QNAlv6ACGA5qbBVEPmr-jqTF7Yz5KLbqVA6NVMaTXa1kzX9vv53lR0BX_kJ9dnnawvvv-z6kGSpwv0jwAAAP__f_Lc8A">