<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64088>64088</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] ICE with `dynamic_cast` and multiple inheritance: `Shouldn't query vtable linkage without key function`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang,
            c++,
            regression
      </td>
    </tr>

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

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

<pre>
    Starting with 9d525bf94b255df89587db955b5fa2d3c03c2c3e ("Optimize emission of `dynamic_cast` to final classes", @zygoloid) the following code triggers an assertion at `-O0 -g0`:

```c++
struct Foo {
    virtual void foo();
};
struct Bar {
    virtual void bar();
};
struct Baz final : Foo, Bar {
    void bar() override;
};

bool test(Foo *f) {
    return dynamic_cast<Baz*>(f);
}
```

```
clang++: /root/llvm-project/clang/lib/CodeGen/CGVTables.cpp:1060: llvm::GlobalValue::LinkageTypes clang::CodeGen::CodeGenModule::getVTableLinkage(const clang::CXXRecordDecl*): Assertion `(def || CodeGenOpts.OptimizationLevel > 0 || CodeGenOpts.getDebugInfo() != llvm::codegenoptions::NoDebugInfo) && "Shouldn't query vtable linkage without key function, " "optimizations, or debug info"' failed.
```
<details>
<summary>Full backtrace</summary>

```
0.      Program arguments: /opt/compiler-explorer/clang-assertions-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 -g0 <source>
1.      <eof> parser at end of file
2.      <source>:11:6: LLVM IR generation of declaration 'test'
3.      <source>:11:6: Generating code for declaration 'test'
 #0 0x000000000367ff18 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x367ff18)
 #1 0x000000000367dd9c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x367dd9c)
 #2 0x00000000035cb398 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f4275ecb420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f427598e00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f427596d859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f427596d729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f427597efd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00000000039f1d00 clang::CodeGen::CodeGenModule::getVTableLinkage(clang::CXXRecordDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x39f1d00)
 #9 0x0000000003acdff4 (anonymous namespace)::ItaniumCXXABI::shouldEmitExactDynamicCast(clang::QualType) ItaniumCXXABI.cpp:0:0
#10 0x0000000003d99f5f clang::CodeGen::CodeGenFunction::EmitDynamicCast(clang::CodeGen::Address, clang::CXXDynamicCastExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d99f5f)
#11 0x0000000003dc8c2b (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#12 0x0000000003dc355c clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#13 0x0000000003dc531b (anonymous namespace)::ScalarExprEmitter::Visit(clang::Expr*) CGExprScalar.cpp:0:0
#14 0x0000000003dc7d98 (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#15 0x0000000003dc38e7 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#16 0x0000000003dcb67c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3dcb67c)
#17 0x00000000039913c4 clang::CodeGen::CodeGenFunction::EmitReturnStmt(clang::ReturnStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x39913c4)
#18 0x000000000399888b clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x399888b)
#19 0x000000000399eb9c clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x399eb9c)
#20 0x00000000039fc686 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x39fc686)
#21 0x0000000003a0f8e8 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a0f8e8)
#22 0x0000000003a70fad clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a70fad)
#23 0x0000000003a6c185 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a6c185)
#24 0x0000000003a6c743 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a6c743)
#25 0x0000000003a758f3 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#26 0x00000000048d05a6 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#27 0x00000000048c2d48 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48c2d48)
#28 0x0000000005d7ae14 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5d7ae14)
#29 0x00000000048cd618 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48cd618)
#30 0x0000000004133f09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4133f09)
#31 0x00000000040b9c1e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40b9c1e)
#32 0x0000000004213e66 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4213e66)
#33 0x0000000000bc9242 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbc9242)
#34 0x0000000000bc1a2a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#35 0x0000000003f1adb9 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
#36 0x00000000035cb844 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x35cb844)
#37 0x0000000003f1b3af 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
#38 0x0000000003ee30a5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ee30a5)
#39 0x0000000003ee3b0d 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+++0x3ee3b0d)
#40 0x0000000003eeb63d clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3eeb63d)
#41 0x0000000000bc74f7 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbc74f7)
#42 0x0000000000ac1ff1 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xac1ff1)
#43 0x00007f427596f083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#44 0x0000000000bc150e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbc150e)
```

</details>

([Godbolt link](https://godbolt.org/z/jW6Ebh64j))

This was reduced from a larger program where this commit caused the emission of the derived type's vtable even though the key function was not defined in that TU. This caused a linker error, as some of the non-`inline` virtual functions were defined in a different shared object and had hidden visibility.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzkWl9z3CgS_zT4hRqXBv1_8MN47PF5K3vZi33ZvE0hQBoSBHOAHE8-_RVIYwt57LWznq2tu1TsshA0v193090CsDG8kYydgfQcpBcnuLMbpc_OmbZYYHlxUim6O7uxWFsuG_id2w0saYrSqi6TCqUprYsyLXJalWlapTVGNCZRTBCJGQSoAAh93Fre8h8MspYbw5WEqoYgi-hO4paTNcHGgiyCVsGaSywgEdgYZgBCAC0hSKIfu0YJxSlAJbQbBmslhPru8BBFGbSaNw3TBmIJ3Uht3STYuklmHyM4ayKQRSBegOgCRPvfWdT_JwCdu_--1VjdEQtXSkGQD20QQnjHte2wgHeKU1gr5ZmVIB66gPzi4e9BxDnWL4iosH6NiB-DRkC8cJicOp7KDeRBdce05pQdFNz_rpQS0DJjASo8U7So3dBArGa20xIGRoqX5_gHQAsQXwJU1FP4oV4PKrt_JALLZlB7vIAArbRSFqCVEHftbKvVV0bc49BvJXgF0GqpKLti0v119fkWV4KZU7Ldgngxj7x5oRvuzBwvroSqsPiMRcf6hg9cfsMNu91tmYG9XN--Fzp--FXRTgzjGmb7uQYBABVESWMDGV--fGJEaXrBiHDqcXpZwMWDKzriqKCshiBfgnwJh4k-bq05HZYHdj0_sDvmrH0Jo0NdG2YvWNU117IePBACNAfxxYi5WxENk2rr5Jm-7Z9qNMyNyQDKIEDoZqM6QSVAuYX_6ZjewTvryELRs_XrXXUWfmM7WHeSOKF-USLkftQIu3HtSkPqpoLcz4UAymGNuWD09LB7xEvKLObCOJ_aN5mubbHegfhy1QkBK0y-WY0JA_ESoNXj2xdcLDoFUfmbVo3GLcS66VomrRm8TW29d6l2ywXTM3a_FUozvfe42UMQMTOrO_kNoFXF5aNDOseFs4Z-x7qeJXDWwJlbRSu83Trpnd129tTAWevMAmez-yKbYdPOzE5afA_iCy4tE3B2A2ezhpCZVUqQDeYSxBcvwnOdjcRbs1EWzmqihNIzynEjlbGcGDirpZoRjc0mbG4i6PSqOu20OChu7nQE4iVTtXO5LdaGaRc3maQuRtdcsL4nGno-CogX8zmIF5nT6IcPn3-F159gwyTT3hfcaMqIwMOjczAfb_JeXvyivKtBzj6-196rnpcGAYojGN1H-39xltf1vBitCrMblsJvmkt7YzH5dus9ChWPnTT-vlbGaoZbv0SWkEvbL5jinbwGoPPofoDnwsQD_vkEP6UlOYR_KRiW3fajvOGNxAKgopM-g1MolJvlGGgdmAAtCtCmpIrLAi6d27lAeMf0rof3DyypcJMWgyaDPkslLbu3QxCP_M_DFPEwRV4nKE8ZqRIUwfVaM2OVZmttB559brgvsnWWzASX3f2skV3_Yms3mmF6atRp5LnMkwRFAZMkmKYsWBRVUGNu2CvkEyc585KTOIqqQHIaSs5okZYQV-pVyEeSESrSMpCcTSXnD1Z_tcwchTLzUGbOapq9TWYc1zQLZBaBl5T1nEbRn829z2Rd6JNyn3vffQH0yANqZUANE1rXiZsXSyV3reoMlLhlZutDTNkDvrZY8q5dfvmyOL8elrXPv5ctt5f3mNiLvthaYl-ajbj-q8PClS6OXSDm6dpxsSQMhrQs67T-I8Wv9tndNzpIz6IJhi8o1cz45B8aZzT88n6rj2qhnuKDhZwOwoBKSUFQ9UcWuiFYYO3QOv6W6b75Mzfc7nlMVPHQ6nktr9xDL-awadAEVpymZKy4G9taP5_S59i4isdY2r_ClK63ypUOui_B3sgFLUcJpS-N-1L-kWRIzmF5NbF4QiyN539K3yGUN-k4mUDJaVn8DUyfTk1fsPx_wvTZhFiV5eTt4eYR9VPTj4LHErrP16MEEQ88CCJ5mMHKeUyStzP75D-le5WOmT227_llR0lfHnbAa5KZy6Ioqp-w2BNGYy6L0OsWWuPdJ1aDeDkasLB2ZNz48jj8Hb2Afznhz6ryJzx2qdqt6iR1rH_vP5RviNpO65RRr5Gd9368fHbeRdP4pXoj1FG-QnraY72gaFKxkazI3q6Xfcu5orsX_eMYpZqDHHAKCwEc1QUr3sZp-B5l7mXIp99m6rd9xs7-ML5fBc_OdrXveC1rddQg0PMOFBOWIjiPakzfUp47U_cK2LO4YDWXvCf-GjWNd-mO4w89q4B2WKjgjMyL9Odo_w3pejYB3WRKN0_in6P7PMmjEMmTOCCSTtw1Leo3E7lVW7_F2sMe03ncunVcTrdY29PIlz9jSQfrHxTUP0lBoxRnf1SjDWJdXFH6ut2KvrnfMHkZ5pVW3dZlUlTCHtZ5xwVlh6szlIfoCKJJEP_OMfnGJF0qabp2X_e-Fcc723-AGdg_qFlSmmM2D2qx37A2bHFzO8k4rMWTfHuk-nGAFGAuJ7qn2fxQ7lmME-g9I51lQ9N-k_-9teuAjJGG-6fJPI7rqBwjXWklLZP0ANQjgewxBCCDVJ5EVUnmDE5KLTfttTQWS8IOa_R5VkdJvQPOgEiQehM0j1kW1FkD5Ec-d4rgp_Cf8D1KVhnwBQSCJBpVpEQJgoTM1y12MorDdf8GT4r9JQzb0NIfZx6HR48yoJFMaMwxwnCv_OX81keKEZmbFgvxmZGHmH2AUxYmfSdj2OgOCjyq-d0zITsOU109x7Qq-3PeR7n707i19rr1b_dHysN3PcFCVJh8W9cy_Orq5x58aDlfqrbFkk4X9UEbPmxJ9AeM2OlgpB-ruWx8z8vBwA8D1mtyf-8PeUC8qLDhZG1890GLQWfXsLYac2v2ryfisBBuTSg9eu-6jLYIvBP1OvdDAMoFbiuKAcofVYWK_cHJL6o6bI9setxRJMnIFIcONYYv_E7e4JqJXaDOl013hGqqRxx4fj5xsSrGwRbx_52LTMq-Z30h3DphLI5w-qzivO3wk4y512YQzCcDXYdgu-B1XRdBsTPi9q4O1dMOHKqc6qWK6Fv18ouqzPNK-UVVH7gJ91BeCs0PfrDF3LmAP4J8vR4HZ_lrtFlFwUdqEk20WWXxs9q8GP0dFA4HKobnrPAXavP9w1uvnkB_80liz5N62GvfVyh7_D6sLJ5sVz6Xtt-9JnHIAuhBbRhhMq_rOXSg33vuXnQwdzw5Wa6jIobrteCVi8RY2_UIyGvPmpOoCL7kkydVVxox2Mt_f_064Y-zH7yc5m8VPbmGNMAtQHp-pWilhPW3okB6AVCxsXbrb2SgFUCrpn9_qnQD0OoHQKuvv2eX1SZLvoLROXv_-3bDDfyODdSMdoRRWGvVQgwF1g3TcDvcWfq-YZpB6zoT1bbcQoI7w6i_ADm-SemeKXNrj0Lrz4hzs7_Gxe6YhHajumbj-42vcXkMUllIWc0lo5C7rtjC23-fQg9ymBB73kxDprXyORgbaFTL9rNLJWcgi7gUXDKQRQ9XHfdTGfjdkRlNhCHldc00kxaaDdaMQlV9ZcRCFzU2mMINp5RJeMcNr7jgdnd6Qs9iWsYlPmFn86yMUIKyIjvZnM1RnsxJUaRlVeakZgiXcYpTFCGMUF0nJ_wMRSiOcpSgOJ2j7DSqMoRLVleYoKjCNUgi1mIuTl0AcGY84cZ07CxLoqI4EbhiwvgbsggNHoYAWrqnva8Nz5o1mnnTuKb04kSf-TuNVdcYkESCG2seJ7HcCn_ztheaXsDr5WV_x_bA_VinmbYTlm8Fg1xumOb7r1zX_efu8mXRSafF2cSfud101SlR7XAn8-nVTK8fA9DKq-i_AQAA__8hZ36E">