<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/147126>147126</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang]Assertion `Info.Ctx.hasSameUnqualifiedType(BaseIt->getType(), BaseType) && "base class initializers not in expected order` failed
        </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>
    Probably goes back to clang-6: https://godbolt.org/z/4hW6eTWxb

Generated by fuzzer.

Reduced Test:

```c++
template<int>
struct base
{
 union MyUnion {
          struct NonTrivial {
              NonTrivial() { /* Perform some operation */ }
          } member;
      } u;
  base() = default;
};

struct foo : base<1>, base<2>
{
  constexpr foo() : base<2>{}{}
  constexpr foo(int a) : base<2>{a}{}
};
```

It's interesting that if `constexpr foo()` or `constexpr foo(int a)` is commented out, the assertion won't be triggered until clang-14: https://godbolt.org/z/1G39fnYMv


Stack Dump:

```
clang++: /root/llvm-project/llvm/tools/clang/lib/AST/ExprConstant.cpp:6815: bool HandleConstructorCall(const clang::Expr*, const {anonymous}::LValue&, {anonymous}::CallRef, const clang::CXXConstructorDecl*, {anonymous}::EvalInfo&, clang::APValue&): Assertion `Info.Ctx.hasSameUnqualifiedType(BaseIt->getType(), BaseType) && "base class initializers not in expected order"' 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>:12:1: parsing struct/union/class body 'foo'
3.      <source>:15:36: parsing function body 'foo::foo'
 #0 0x0000000003f7e5c8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f7e5c8)
 #1 0x0000000003f7b9f4 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f7b9f4)
 #2 0x0000000003ec0318 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000784920e42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x0000784920e969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x0000784920e42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x0000784920e287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x0000784920e2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x0000784920e39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000007886402 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7886402)
#10 0x000000000788654f HandleConstructorCall(clang::Expr const*, (anonymous namespace)::LValue const&, llvm::ArrayRef<clang::Expr const*>, clang::CXXConstructorDecl const*, (anonymous namespace)::EvalInfo&, clang::APValue&) ExprConstant.cpp:0:0
#11 0x00000000078cd11a clang::Expr::isPotentialConstantExpr(clang::FunctionDecl const*, llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x78cd11a)
#12 0x0000000006a7a916 clang::Sema::CheckConstexprFunctionDefinition(clang::FunctionDecl const*, clang::Sema::CheckConstexprKind) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a7a916)
#13 0x00000000069ffaa3 clang::Sema::ActOnFinishFunctionBody(clang::Decl*, clang::Stmt*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69ffaa3)
#14 0x0000000006746c4f clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6746c4f)
#15 0x000000000664dcd0 clang::Parser::ParseLexedMethodDef(clang::Parser::LexedMethod&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x664dcd0)
#16 0x000000000664d9bd clang::Parser::ParseLexedMethodDefs(clang::Parser::ParsingClass&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x664d9bd)
#17 0x00000000066a09d9 clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributes&, unsigned int, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66a09d9)
#18 0x00000000066a3790 clang::Parser::ParseClassSpecifier(clang::tok::TokenKind, clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66a3790)
#19 0x00000000066770f0 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66770f0)
#20 0x0000000006633114 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6633114)
#21 0x0000000006633b29 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6633b29)
#22 0x00000000066390e3 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66390e3)
#23 0x000000000663a55f clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x663a55f)
#24 0x000000000662e62a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x662e62a)
#25 0x00000000049360f8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x49360f8)
#26 0x0000000004c2fff5 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c2fff5)
#27 0x0000000004bacb9e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bacb9e)
#28 0x0000000004d22941 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4d22941)
#29 0x0000000000d908af cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd908af)
#30 0x0000000000d8748a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#31 0x000000000499cca9 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
#32 0x0000000003ec07b4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ec07b4)
#33 0x000000000499d2bf 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
#34 0x000000000495f28d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x495f28d)
#35 0x000000000496031e 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+++0x496031e)
#36 0x0000000004968eb5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4968eb5)
#37 0x0000000000d8cd5f clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd8cd5f)
#38 0x0000000000c422e4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc422e4)
#39 0x0000784920e29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#40 0x0000784920e29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#41 0x0000000000d86f35 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd86f35)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzkWl1v27i2_TXKC2FDomR9POTBdeLezm1vgyYz0_tkUNSWzROJ1JBU6vTXH5CSrA_baTKIBwc4QZraErm51tqbm1ukiFJsywGuncUHZ3FzRWq9E_L6W612not9_yoV2fP1nRQpSYtntBWgUEroI9IC0YLw7Sx0_CXaaV0px186eO3g9VZkqSj0XMitg9c_HbwOdn-G8PDnPnXcpeMuPwIHSTRkKH1Gef3zJ8h5c-cbZDWFDD2A0saeveiEbvNLHfzB_LpLDWVVEA2Ov2JcO_6t4y6VljXVKCUKTKfItEM1Z4KjL8-_2__bi4eftsv_Cf4g2RMjxVEL89PfdnDs4MQ0QpbqEt2BzIUskRIlIFEZWnYgbLRATnQzsuZEN6iEMgXp-P045mrdXbDw22H8G5RBTupCN3eNuebDgW0uBDIesN38lWekwKvuK26U6UhRwZWGfSVNt8Mgy1Hr6IMZpfl7qg_jGpHTHcmwZ4-1816D-5N2cKQQ4xokKM34Fukd0YjlyHj4GKETukjIUzc7KKYFU4iKsgRuokrU2oigd4CIUiCtS34I7uBIoxSQlmy7BQkZqrlmRRvJXvCaUPY--knO___LUxub7vJemwlxU5fVccQ67tIabwPXX5q4kUJoB6-L4qmcVVL8C2j31cFrLUShHLxuu60Lljp4vbx_cPD6dl_JlRGBcD2nlRkvjL2F9YQQBfofwrMCbAsTHEKuSGFi1grXsDQQ_aUxZEN01fjXRDThgj-XolbWc6bV5z9IUYODQ9PuZAtj_xvkvZ3BGKvv3wdIboAW7YgnLd0-keITz0U72sDO8q6HkRiqy4NLndA1feYrvZ_viLonJfzO_6pJwXIG2cNzZWbSB6Lgk545_u0WdHvNWMIrZG41VxJk7YfIwdgEtQGgTJQyzUjBfoJUiAuNGEewr4DaKJMZSAdjB0coJ6yAzCSxu8-3y_tbpOq0ZBoRlNZbJKESUpucOYkupnd1Oqei7P0_iQqmVA0mHhDhGWKcFnUGNrKpJGpnk7GWhILhU0mopKCgFGRIiVo2l01PopSgzOZcWXOkqGSVnh-iNztErzt33OROiq0kJSJyW5s5pdrIFZXBREVZsQLkDPZVIaQRoQnX2WG2qZmWNX908DplvI9mMwnQbJv9IDKfBWi2RTNh7JKqMtZrXdV6rtCsNCqg2WwfhzOiypl65prsHf_GpI0CzXIuZk8gU6HA3EezezSbbSmdmdlDd4Rxx795Ea9prDip1E5oNMupKIScZYxsuVCaUdWMYTUeXXb8VSuszayeUcvxVyByx79FFZEKJCIaAc-QyFHOCrMY4bZZ39Vfetj8McKaXiYPNnPFwWu7aDWqKYXMEowcHNmkFznu0j9lzWQBPxyay2tO7TQZGrBT6mAJOdh3kbt3ux8_j2BBY2SD0bZVz6r5cCcZ1zZaHpp4i_tGkvzYCKUlkLKdwGZVtrMqfqewcfAHd9_CM9O3Ae9NwKdJHpwCvyqA8Lr6yu_Zltt1vOa28slQIcwQl4BqwPRQ8QgqUNf3YrQyAfYNqHgC-dxga5K4bNY3A2zUZiW4hn2X_V37r7Hvt_ajOEiwCwFeYLcl1awh-zjchMGsYLzez7a8bm7QuRLz0EK2XXrAwdhgEiY5RZXeSSDZ5pEVxdus2_699cUUbhCFaKusBG-FHURhbzgcG8ZxlPuIpCYBv8ms7dibjY7MeumbDXppbzAeG_QTSMK3GbRdeoPJMMCiOA4DF793VLdmm0HN_HOngy6C_HwdMq5AmpqhqwpwfKgKECclqMpmmWRYi3Q9bIrpp_lSSvJs6hB_dXaIpi5-sT55C55X1ivoRMnWTVojnzeWj2aeR44KNfuJqTuhgZtypLPXVHFDVddtyj9i02t1X5Ki-AMM509lVZhlRGfNrYowOZbw3q4wnwW1TzUTondEGjQ3h9XRrkS3LfF3DzyrTR94o3QakogkXjhEdw8laR29A_q46p4deolyW90ZWq-S8BW2_5fx7ALcW3Y9d3_EPclzQvzT-JZUf-VrxpnadcQ-iOx5THlQmw-N6LKjbh4uLsGrQd7zCka8oiCkQT6JOAVy8LnjdK-JBlOovpbckaV7Kiq4TOi2RHqaixHNMMho5r4I7jPsIfsCeieyG_O0FZ9pPGh3ISoN2J5KOKWSpNkbqKjzXO6aKnZlSuDLkUnSrCcTjckQN8mSF8msvn__Yndz7iugLGddmoxfm0J_lV8VZEutJUtrDapdag6Fqy0PRz0OsX4BrawavVbxRCs_Sl6OYevIVieYLFtaPDYfHsQj8CaLvl4nw9oYPl6Kj0BkD-2-4Zmlm5pn5wHILvWdtdqN3Zblr_HgJXxj1O99k4x9E0Vu_rJvDAvS7FweyKvjNHoxkf--uF3iIxp6sT-zU4u2qXYYZXYLyNRzB6sXcIiV_OAQ7I4d4vueF_zSIV-HpconrkE2D66_zhBvbsH49rx_j_x1Ab2sIr1e3lSvFL-ciAcB_PWXFd5FVJtG2z-jWor7lIzxRLXEBf9F1W73TVAN1PtnlLqEFoZtr4U_0YIsFi9Xkg-i-gxPUDRL6FCErxX5q4Y7PXk0Mg0_SlFX9rnz9ph4X4R_EVldwKeyElLbSvVS64Cl2YswLqdDDCEmRyLYk4V4irth0y1-l6r_G0g94FFhHCR-6Obx6JFdZPAR-NJO7-4BGWitob3UHmm9L8wWSA9zVPQGFOd5vhjCXEuztPDsBM4LIWww9AhHlWyQEpomMBayGfOT3UigcFrL85QuEr8tzp7FqMYMMoyTwBtvjli8PZkncaoCPyJ7kRTU4uvRj6owN0vcmOSIUm9TEmMgPr19tSPHe1aja3iFngTLLkOiQXngMD4bcLM4CmKCOtlX3oPNC_FLm0vHhCZ7d8ZGW4oNdvcSlEn2BPJ4y2y85R8kCaUksZIMjHZHHxtpVbV322M_e1ri-EtKiiIl9HGT83FibwZuQ2flrURZEp5NZ_FJ7x120kRlRidGgIE4WjK-bZeLxrWHDpsN3e89r_mSEsXoRtnmrYSjxubCRkvCtOpuT8yRojBTQcjBfdNksJtjw6cR3HZxcFSQMs2Ig6NeKhx3xyO_ifSEM44ONaJ0eP5y6uiiufOt5vckh-J5pOXLfrvAIU2DuA94fxJcGU5HdcN_XXAYxecVkXruno-CYKzaIsdxdlY16zVytDJ2Uo5S96SjaTA6Anhd0-WonBkQe98qwdLuQ2lSzISu78FbRflNpOq8Ir-J1DzqnjkU-fVG__EG0osi9rv7F5fSitVLGU6kjCFdnIN9M_g8KhBOVAbnXPAPSnmBatXK04sXTdZwmnWPQl0l0oG3qWR5dGJ0boV-79rDIutxj6o_lwYYQ4AM4vceuDHdD5xMTnqTLHnjQbrtcjAYuFODELhoszF9NkoTqTcDWq8eAoLBEN7EyWHuL1Bj_P39ZIw3Qw_v-UsEUppVZdmEF8rbhwb7Zp6J_-YtKfSD6R2CPTPhlAHy_MBgrBWg2RPSAikAxAbFfDJ8o-4qu_azxE_IFVx70cILkyBaeFe7az9c-ItF4PlBHC-CNKFBFOMkSDIXIhrG0RW7xi5euJG7cBcL7HvzHPsJSaKcYteNaeQ5gQslYcXcxP5cyO2Vffvq2gsiD4dXBUmhUPZNWYxb5thZ3FzJa_vSVlpvlRO4BVNa9SY004V9vbbpsbj5z3p9LXRbr1zVsrj--6-ntRo9XeN_BwAA__-mgZtO">