<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/101304>101304</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Clang][C23] Assertion failure with invalid `constexpr` declaration with incomplete struct
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          MitalAshok
      </td>
    </tr>
</table>

<pre>
    https://godbolt.org/z/q4P5javej

```c++
constexpr struct X x = { 0 };
```

```
test.c:1:20: error: constexpr variable cannot have non-literal type 'const struct X'
    1 | constexpr struct X x = { 0 };
      |                    ^
clang: /llvm/llvm-project/llvm/include/llvm/Support/Casting.h:578: decltype(auto) llvm::cast(From *) [To = clang::CXXRecordDecl, From = clang::RecordDecl]: Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' 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: /cmake-build-debug/bin/clang -cc1 -std=c23 test.c
1. test.c:1:22: current parser token '='
 #0 0x00005625b90db92d llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /llvm/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:11
 #1 0x00005625b90dbe1b PrintStackTraceSignalHandler(void*) /llvm/llvm-project/llvm/lib/Support/Unix/Signals.inc:798:1
 #2 0x00005625b90d9e86 llvm::sys::RunSignalHandlers() /llvm/llvm-project/llvm/lib/Support/Signals.cpp:105:5
 #3 0x00005625b90dc5d5 SignalHandler(int) /llvm/llvm-project/llvm/lib/Support/Unix/Signals.inc:413:1
 #4 0x00007f52fc6a1520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #5 0x00007f52fc6f59fc __pthread_kill_implementation ./nptl/./nptl/pthread_kill.c:44:76
 #6 0x00007f52fc6f59fc __pthread_kill_internal ./nptl/./nptl/pthread_kill.c:78:10
 #7 0x00007f52fc6f59fc pthread_kill ./nptl/./nptl/pthread_kill.c:89:10
 #8 0x00007f52fc6a1476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #9 0x00007f52fc6877f3 abort ./stdlib/./stdlib/abort.c:81:7
#10 0x00007f52fc68771b _nl_load_domain ./intl/./intl/loadmsgcat.c:1177:9
#11 0x00007f52fc698e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#12 0x00005625b94a5078 decltype(auto) llvm::cast<clang::CXXRecordDecl, clang::RecordDecl>(clang::RecordDecl*) /llvm/llvm-project/llvm/include/llvm/Support/Casting.h:579:10
#13 0x00005625bf61a6d7 clang::Sema::RequireLiteralType(clang::SourceLocation, clang::QualType, clang::Sema::TypeDiagnoser&) /llvm/llvm-project/clang/lib/Sema/SemaType.cpp:9270:29
#14 0x00005625bf61b0ac clang::Sema::RequireLiteralType(clang::SourceLocation, clang::QualType, unsigned int) /llvm/llvm-project/clang/lib/Sema/SemaType.cpp:9345:10
#15 0x00005625be1b99a7 clang::Sema::CheckVariableDeclarationType(clang::VarDecl*) /llvm/llvm-project/clang/lib/Sema/SemaDecl.cpp:8759:7
#16 0x00005625be1b6d15 clang::Sema::CheckVariableDeclaration(clang::VarDecl*, clang::LookupResult&) /llvm/llvm-project/clang/lib/Sema/SemaDecl.cpp:8809:7
#17 0x00005625be1b3fc4 clang::Sema::ActOnVariableDeclarator(clang::Scope*, clang::Declarator&, clang::DeclContext*, clang::TypeSourceInfo*, clang::LookupResult&, llvm::MutableArrayRef<clang::TemplateParameterList*>, bool&, llvm::ArrayRef<clang::BindingDecl*>) /llvm/llvm-project/clang/lib/Sema/SemaDecl.cpp:7964:24
#18 0x00005625be1a9a92 clang::Sema::HandleDeclarator(clang::Scope*, clang::Declarator&, llvm::MutableArrayRef<clang::TemplateParameterList*>) /llvm/llvm-project/clang/lib/Sema/SemaDecl.cpp:6405:9
#19 0x00005625be1a8cd0 clang::Sema::ActOnDeclarator(clang::Scope*, clang::Declarator&) /llvm/llvm-project/clang/lib/Sema/SemaDecl.cpp:6046:15
#20 0x00005625bdca55cc clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) /llvm/llvm-project/clang/lib/Parse/ParseDecl.cpp:2754:14
#21 0x00005625bdca42fb clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) /llvm/llvm-project/clang/lib/Parse/ParseDecl.cpp:2559:9
#22 0x00005625bdbf612c clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) /llvm/llvm-project/clang/lib/Parse/Parser.cpp:1249:10
#23 0x00005625bdbf560e clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) /llvm/llvm-project/clang/lib/Parse/Parser.cpp:1271:12
#24 0x00005625bdbf4e99 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) /llvm/llvm-project/clang/lib/Parse/Parser.cpp:1074:14
#25 0x00005625bdbf2cbc clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) /llvm/llvm-project/clang/lib/Parse/Parser.cpp:763:12
#26 0x00005625bdbf2360 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) /llvm/llvm-project/clang/lib/Parse/Parser.cpp:608:8
#27 0x00005625bdbed771 clang::ParseAST(clang::Sema&, bool, bool) /llvm/llvm-project/clang/lib/Parse/ParseAST.cpp:170:15
#28 0x00005625ba6403f1 clang::ASTFrontendAction::ExecuteAction() /llvm/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1194:1
#29 0x00005625ba63fe0c clang::FrontendAction::Execute() /llvm/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1082:7
#30 0x00005625ba55a556 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /llvm/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1061:23
#31 0x00005625ba81df3e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /llvm/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:280:8
#32 0x00005625b71dcb29 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /llvm/llvm-project/clang/tools/driver/cc1_main.cpp:285:13
#33 0x00005625b71cf472 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) /llvm/llvm-project/clang/tools/driver/driver.cpp:215:5
#34 0x00005625b71ce1db clang_main(int, char**, llvm::ToolContext const&) /llvm/llvm-project/clang/tools/driver/driver.cpp:256:5
#35 0x00005625b72038d5 main /cmake-build-debug/tools/clang/tools/driver/clang-driver.cpp:17:3
#36 0x00007f52fc688d90 __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:58:16
#37 0x00007f52fc688e40 call_init ./csu/../csu/libc-start.c:128:20
#38 0x00007f52fc688e40 __libc_start_main ./csu/../csu/libc-start.c:379:5
#39 0x00005625b71cdc65 _start (/cmake-build-debug/clang+0x5bd2c65)
```

It also complains about a "non-literal type", which shouldn't be checked outside of C++
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzUWt9v4yoW_mvoC2qE8e-HPrhJs1tprm532h3dtwgDSbgl4Au4t92_fgV2EttNO-l0ZqUdVRPHmMP3fedwOOAQa8VGcX4F0muQLi5I67baXP0mHJGV3erHi1qzl6utc40FcQXwEuDlRrNaSzfTZgPw8j8AL_9K7tI_yRP_E6AFQFX_f4a6Pwrwtf8Ld6lW1vHnxkDrTEsd_AM-QxAvIMivIYIgX4D4emLgpNXuq-PWzSiIqwjEFUYgriA3Rht_cRzqiRhBaskhJUppB7fkiUOl1aUUjhsioXtpOAQ4D10OyADOu1EghDCCIJ_DD8CH4Z_vdOIfSG96PSRRG48W4KWUT7v-47Ix-k9O3fGuUFS2jB9v3LdNo41_Yk6sE2oz24K4SvPCW2OcSk8K4IK0TgNcwtAtrkBcUWIdwMXS6B0EuPKNIL1-0IHIHhCIq_kff3zlVBu24FQCPIddj_FDgyfShR-6spYbJ7SCIEPCEhDPHzSIbwAuvhEZBsMZwBkEGAck8fzhpWv3jcRs2h1XDuo1FIrqXUOc8L7r6EQAY4BzuCZCcjbrRLz7clPd30Db1jvhIIF1u4GGe3Wg03ASvcJt23pG9e5NxYW1LbcALyFRDPbCQ7flkBpit7Am9NEZQrnXpDG8MZpyazmDVremu-17Ems1FcRxBk2roKVGNK6HfO8IfYSs3TUeWbiFZvDO6I0hu4MIto8MuiOP_LJuhWSXjNetn3i1UL7FewJeUhrBS-sYiBcUx7CfFsFsNIPjWYLD5GiN8So3xFhuoNOPXPkZAOLFMewBjhFEzwghlGY4rUvE6hKzQSjZF9td3BmhXCD10ClTHB8y5O-Vts5wsguun0OhXBcI78e8FPUo0P-txLO_ITaKSDsTynPKceyZRUfM0RQzj2o4AdjZ-CdRTHIDcPGkBdvPhZ-CqiyC3gdQeAKq5EV2SsivrRphs_28-CiqPRza-AiLUOqTwxFOPIFDU5bCqSg_001JFI8FSXoE-TrFa5qRKMUIBrK9weciW2XJpRSqfb7cqLZroDOrZxnA1-g5wSlGAJdHm-nY5jot1xSuVo3bGk7Y6lFIuRK7RnI_uUhIUjOAl6pxEuDl4HLYI8ycJPFOzY5DZecMpRw3ishzBwm5O0LHQfJTgwy7nWu5KCeWi6n6SZ7BjQ0uC0a7S282fHuxjDc-JzbaBu8aIiwPtn3SqAbKlGPTRZ6vY0hqn42DKcc6_46-hPYOqk9SfQbykxm9MhfVcKXkSmrCVkzviOi8KNRBhv7SP7GzG0r67BflHmp5tB2NbZcFL7OPxWBc8jI7xKC3OZ7oCUlRXpyxHsfz91be0wtuWDRPN52Xys4uKobh40mO0sc6i0jG8iHIe74je0x_tcLwL12l9dBpMHwyLJlfNA3TccL1X-2-y_y0dd-4EGSjtPUZK3uXdGfhkK-8ke7DW-kTZYlzX0UOHZpMuNaI0F_MtVWhLmffXSjPohQn6cR96ZASj-qyJG-4b77l9PFbXz_7yCImgH9N7hsx50Tem4h95x5xkaflOAlkE8AZi9KPAX4b7MgLX7R-bJuv3LbS_XA8DakUaEIln1CJ1zQ5TaWi7nc1paLNJKao9p6Y8hg-np1om2vl-LN73dE7tovTW7XWZwg0H2Sy31rnsVbGkJevfD1Oag9810ji-B0xZMcdN1-EDQB8GpvDWmv5yuBpS9dCMaE2ew_6_p90U15mfoHHydFPxdhPpCQlPu2nrmD6rIN-hoqfVCFLQpk4yH3lRISCMvROsH5Og8-iR0nm81x6gI9HuxdGSZrSUeq-C7ufwfUgYVRrx80RYaVY5ZwRdev83rA4c669GoHtHeinV3ee8H6vpTZfidrwWyXcx5JrsLL_HAiF89QHe3QMdhxNhErwuv6uUP8wum3GUvi2fmbeN5yezj2dVocM9Jr5SOmPKfr6-emiOw3CX6x1Gpay45TCo_qQ-YICfz8mfzfLVlFPYMHXt_224rX0Zyj33SfedV9FKbfWt4m18BXXjwlk9ttSnEwqSxxP5EkzxM-dsiOVhBKv1_1fItI0on66SHkUPo4iJROREl6W74p089yFzJsF0a8S5pPUUT7NVOmEOqb1-9PnQTdf-BOXXbUw5Px7Q_5q-Z0z4xX2kNrC2ntzIqMcFr3fNGslv935PdO9I45_bB07yTnP4om3synlOEPvUl4KY93_G-8MFb5ePtLOx7Q5y_PoFe3q_mFSaoTaIDtWlPvPH0NX3T_sYzFsDIfVxahCJFmC4vUIYHX_sDR-lVOsClmpu33zzGnreH_rO6d7Y2h7c4PLzsweY1Qmx1M2j7EcY4zXHI2myzsAfzI0VODRRmh8tEzSlKRpNnr9oHeNkNzcKuuIovy0em9z-VBIDuBPxz0QyMLxeXxkMKqaSBGxdTxaq3qsR4NPhyqkeI_ohxLnHvlDiPLlm2PuC5ICjabZ-GA6jxitcQkpjVY7ItToHH-4IdkSsy9e9xu48T08h-ecqe-5OK2lBXjJjHjyS-Zyj-AAO5xhDMSPx7jpOskx3LOfR50cA_T3OyLlN06dNre7Rp4kMdmIeRt9mTqo1H-ETXex5xINDuM9lWRChUesr773TgjnQJ3EQdHqfwM0zcZAR4tvjlFcsBSGA9g3XlLt7b_tZt9wORo1ykFcDRw9OWkvClYiuFpJUdOVdcS4FSVSrg7nwNS2r4-t-4PxU526I85w9J4dR82no_IEwdDHF5bTgbpLb_0yWO_Om3HRvZU-GC1OGR1ROcXipPE4nMkOfFNOgojRLIWd1f5I-5SDesdco-e0Zphm6fEs-9Tr91sHibR-3-q3XEJZSGrdOkggwHj6Rj28qp3Dv7eCbqHd6lYyBXDuYM0h3XL6yBnUrbOCcajXcN79TuCCXcWsjEtywa-iHOMkisu8vNhe1UlUF0m9TghFRVLEUZ4glJI1znNOE84vxBVGOEF5HKEiKuNyFmVRnecoj1lW5gkqQIL4jgg587Nhps3mIrzqvYpQFKPkQpKaSxt-C4FxLwwG6eLCXIXpU7cbCxIkhXX2aMIJJ8MPKOahR7rwlzgG6WLwKnxNhGwNh38Lt4VCPREpGAQZOvyeAGQovCToi_P9g0Fn7nj_c4OL1sjprzE-8D675_l0hf8bAAD__8TgXn4">