<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/132344>132344</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] Crash with official test `CXX/special/class.inhctor/elsewhere.cpp` and virtual inheritance
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Rush10233
      </td>
    </tr>
</table>

<pre>
    Start from clang-6: [https://godbolt.org/z/rYhh565es](https://godbolt.org/z/rYhh565es)

Generated by fuzzer trying to change non-virtual inheritance to virtual ones.

Seed Program: https://github.com/llvm/llvm-project/blob/main/clang/test/CXX/special/class.inhctor/elsewhere.cpp

Stack Dump:

```
UNREACHABLE executed at /root/llvm-project/clang/lib/Sema/SemaDeclCXX.cpp:9229!
#0 0x00005ca81194cd3a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x254cd3a)
#1 0x00005ca81194a976 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x254a976)
#2 0x00005ca81194ad15 SignalHandler(int) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x254ad15)
#3 0x00007ef419642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x00007ef4196969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x00007ef419642476 raise (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x00007ef4196287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x00005ca8118ea06a (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x24ea06a)
#8 0x00005ca81291b211 clang::Sema::BuildUsingShadowDecl(clang::Scope*, clang::UsingDecl*, clang::NamedDecl*, clang::UsingShadowDecl*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x351b211)
#9 0x00005ca812c73896 clang::TemplateDeclInstantiator::VisitUsingDecl(clang::UsingDecl*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x3873896)
#10 0x00005ca812c52847 clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*, clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x3852847)
#11 0x00005ca812c63d7e clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation, clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x3863d7e)
#12 0x00005ca812c9e5da clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::TypeDiagnoser*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x389e5da)
#13 0x00005ca812c9e9a5 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::TypeDiagnoser&) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x389e9a5)
#14 0x00005ca812c9ec23 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, unsigned int) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x389ec23)
#15 0x00005ca81289550f clang::Sema::ActOnUninitializedDecl(clang::Decl*) [clone .part.2280] (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x349550f)
#16 0x00005ca8125e76e9 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31e76e9)
#17 0x00005ca8125f70c4 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31f70c4)
#18 0x00005ca8125d2100 clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31d2100)
#19 0x00005ca8125d27f9 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*, clang::AccessSpecifier) [clone .part.167] (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31d27f9)
#20 0x00005ca8125d83fa clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31d83fa)
#21 0x00005ca8125d90eb clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31d90eb)
#22 0x00005ca8125cda72 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x31cda72)
#23 0x00005ca8123d97e8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x2fd97e8)
#24 0x00005ca811f1d366 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x2b1d366)
#25 0x00005ca811ee4eae clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x2ae4eae)
#26 0x00005ca811fba51a clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0x2bba51a)
#27 0x00005ca81013e430 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0xd3e430)
#28 0x00005ca8100b8d8e main (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0xcb8d8e)
#29 0x00007ef419629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#30 0x00007ef419629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#31 0x00005ca81013a3ea _start (/opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0+0xd3a3ea)
Stack dump:
0.      Program arguments: /opt/compiler-explorer/clang-assertions-6.0.0/bin/clang-6.0 -cc1 -triple x86_64-unknown-linux-gnu -S -disable-free -main-file-name example.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debug-info-kind=limited -dwarf-version=4 -debugger-tuning=gdb -coverage-notes-file /app/output.gcno -resource-dir /opt/compiler-explorer/clang-assertions-6.0.0/lib/clang/6.0.0 -internal-isystem /opt/compiler-explorer/gcc-7.3.0/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0 -internal-isystem /opt/compiler-explorer/gcc-7.3.0/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/x86_64-linux-gnu -internal-isystem /opt/compiler-explorer/gcc-7.3.0/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/backward -internal-isystem /usr/local/include -internal-isystem /opt/compiler-explorer/clang-assertions-6.0.0/lib/clang/6.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir /app -ferror-limit 19 -fmessage-length 0 -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -mllvm --x86-asm-syntax=intel -o /app/output.s -x c++ <source> 
1.      <source>:45:11: current parser token ';'
2.      <source>:42:29: instantiating class definition 'E<bool>'
clang-6.0: error: unable to execute command: Aborted (core dumped)
clang-6.0: error: clang frontend command failed due to signal (use -v to see invocation)
Compiler returned: 254
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzMWl1z4ygW_TXkhcIlIUu2HvKgOPFM1_bO9CY9u71PKQRXNtMSaAAlTv_6LZAdWYo709mKd6cqlSh83HvOAS4XJGat3CiAS5ReofT6gnVuq83lbWe3cUST5KLU4unyzjHjcGV0g3nN1IZkKCkwSq-2zrUWJQWia0TXGy1KXbuZNhtE198QXZt_b7dploJF6TWiyx9vTnMUFSgqfgIFhjkQuHzCVfftGxjszJNUG-w05lumNoCVVuRBGtexGku1BSMdUxx8i0OxVmBnvck7AIE_Gb0xrPE0JqCk23bljOsG0XVdPxz-kNbo34E7RNdlrUtE1w2TCtF1EATRtQPrK1dfviC6ti1wyeq-2tqZVFvutEF0DbWFxy0YmPG23QNyjH_F113TehShCGXR_icqfvvl9qZY_VxcfbzBsAPeeTWYw14vrd1LfAdEtfQw76Bh-z_XwOvVly_Bc1LklOaIxt4bTSIc7aIoilLOlnGcz7lIGA70kwIlhX2y_cMnI5ULgD8bxgHR5dDIsMd7bZ0B1iCaIZpjRJeIrnUbUOmmlTUYAru21gbMASlh1oJxUitLslk0i7zEg7S-DNGraEfTgGo_NWgSTyCzfJGdgnzbqTu5Uaz-mSlRg7EB1fuD8_6fwdEpOBGneAQD0aVU7ixARJw-A0n2QBZQzeM8m9OURnuP_fzYLbP7bE5qqbod2aiur-Azq2dZsBi6PNubj-3lWV5x3LqtASbuv8q6fpvx0P_ZeDoFO19k2DBp4a2Q50djkY2t0uWiSjArtXFvsxo6PltdjEZ4CSzK2DsP5TwYffa4PPZI87ikcdzH436ih5Uenq46WYvfrFSbuy0T-tEvfESXx225bgHRAtHVsYnQp289rfqFNSBOV73wVLz7tE7SQPdZi3ykBV8kyzw7hvQZmrZmDjyeD8o6ppxkPgKH2n9KK90R1-V3JXhvGsuAdIhh0ZhHSpfzxekxHVjAyu8pk_HUneHwUXPmQUzGZ_Xlyy1wbb4zfH9S_feudvIjPEB9ELUwm64B5T5K6zDXym982aTXoe1dvxPKbwHY36QSvmGpdX0GcYN8g7jxWNwsEQv4MXFPo3-L5N-3clrl_4teQZFBLzrWK4dUsNN63cIfnTSw0k1bg4PPTy18aNppjHlNoH90rPbdJsWDC195LdlGaeupnWMtBoID_WRKP2fpD9M_I_X3T6U89ZwNSUI8n1LnNDk39U6Fo4fA50iDPENOh906TkcMl3maRtVphgV3v6rflFTShYV42PWOSR7vD-kVr7UCPGuZcTNKlxFKr9-ZzTzgHdhkIzYpLDLIj9l8YsZPneHZA2YmDElROTCH_7UplCicM7LsHNiXLPtGL-P7Cw_iEME-qEp_b1c47rXW5tYf3z4o6c6yvuMgyyDaYixatYj4_E9F-8norh3L4uv2OYKP1i9ZDrqttHKwc9OVPlki073gf6tS0GFQaZxlpoLGUfSnKv1q1p3i_e5WfVAOjGL1S9XGE2aYdv-SbhtYnp4xr4pdcA7Whm2zkp7_uwsUJBgEyqcCLaofXnsjnUKEmWYV7yXTdE6dkmkcueJs8f6BKw7yDMfiaCLeMqnYq-Ld7PrJdCTi2QR7_5nj6Q3k4wn5PILyVfKfdRsS75cb0K8t-6ODT86gZDWJPCFi3UKFkpuz5A5xwD2wGmeNKRdsQV-wKu4-T9KEcC2VDcntuZLcOAAa4I6zvETkC1iOMnct4CdQRVilfdFNf-u2LzrH7VEVYAwgR_lYXMUiyUbH27XxG4sSJ1CeBV8ZEAz4RtlUDDAHBmMRe4_9uYrDaR2_T-gc14csoBw4ZGONS5bGo1C0RztQeXjesJevUT1DJKFlQDdgH6UyUZzAPIkw5_F9fyl9dClbGMOeQjRY8S0zh8SsCNFhhcdldIUftBTnoCACxoHBKM2IonIploA9-vd1y4PhwW0-uQvMRf7G69DQZbhejaYGYR7h-3vf5946Ztz9EakfdgHzIxfxZLBZAgz3xt97jLzp3nH_UkI8v5SIZijK929NMNtfANnwGug9_GPCeYyJM7KtAe8V6tRXpR_VoBQmd5gIaVlZA6kMACZeXVLJGohiDWDYMX8wnfG2xaQxUO_XLGm0gBpbx5zkmDT9hfW-tNVW7jBpni23BGrZYFI1zG0JGKO092Qb8gCm1Nb7DYvGdNxpQ1gtmQWLSdOpR6kEcd6OxaTqLBCf5xHm1yEmjpkNOMLbzpMk2RwT8chMRbiuu0YR6Q9PREDZbcIz-SqVQMl1LRvpQBxaP4CxIfBfz_etN2CI65T0Yel6I0pMuH4AwzZAlHZgg0Z-rFjb-hHrXNu52YZ7ZgZsOJEQIc1_OZz9zD68eQqlmMj9QYBI-2QdNK_b3nBOFrPkyNyG89PL5dBsNnv5SypedwK8E0Svwk_f_q-G54SpvyDEkvGvj8yI09A662H4RVYPdt7K4i2T6qQXCGcE_hLYQOwVpU_0frsLTCoBrQHOHAjSMG50KPLruOfch6H9CmM-PFVgjDYkLG0c5z7cgLV-xdagNm6LI0wqXf7OiemUkw34lc05JhXf7QjsOLRBL2_p-B_RXx06yS2xW_1IdKjy_XStDTmqx6TxqQImxEcjH-Dsk3Jsh5JrT73GRL-IGRaTHd5PFIySVR87UHKDUVTEfps4LkRJMU9RUsSx3yt4Zwwoh9tw0sFOfwW_Ny5QcuV_RwU91Z-ipKC57y-f7-ml2uDwbh2L55O0t3SDklU4SPj8xlsctrikwEFx_9ApH6Gx04dX6pjrpmE-1ha4KLXxwdYnetpA2AVB9PviaXOhFFf7JPZgC1dM1iCw6IInG17_equd30EeQhkAlkeZpXdxyCixAdcZBQETTefH3wVciMtE5EnOLuAyXsxpmizSOL3YXka8WgigfJGwMipjFieZiFORs6QUJWXLC3lJI5pGCY2jLI7TdJYsGBN5lAGt4rKiJZpH0DBZz_zMmGmzuZDWdnAZJzSZzy9qVkJtw_cilO7XJkXp9YW5DN8hlN3GonlUS-vsYMJJV4ePTPoe6TVeGWa3-FG6LdZVJblkNXZgHUZZ9LaPKLIIe7FPfAFy0Zn68s3fdwS6FtH1nvHDJf1PAAAA__9Fu_os">