<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/163032>163032</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] -fsanitize=undefined causes Assertion `vlaSize && "no size for VLA!"' failed.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:codegen,
            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/x8s5GhbE8
```cpp
void foo(unsigned short i) {
  short a[i];
  auto bar = [&iv = a](short value) { iv[0] = 0; };
  bar(0);
}
```

Backtrace:
```console
clang++: /root/llvm-project/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp:2420: clang::CodeGen::CodeGenFunction::VlaSizePair clang::CodeGen::CodeGenFunction::getVLASize(const clang::VariableArrayType*): Assertion `vlaSize && "no size for VLA!"' 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++ -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 -fsanitize=undefined <source>
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      <source>:3:14: Generating code for declaration 'foo(unsigned short)::(anonymous class)::operator()'
 #0 0x00000000041e9638 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41e9638)
 #1 0x00000000041e6a64 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41e6a64)
 #2 0x000000000412b3b8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x000076bcc1642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000076bcc16969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x000076bcc1642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x000076bcc16287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000076bcc162871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x000076bcc1639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000004752e21 clang::CodeGen::CodeGenFunction::getVLASize(clang::VariableArrayType const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4752e21)
#10 0x000000000453cb7c getArrayIndexingBound(clang::CodeGen::CodeGenFunction&, clang::Expr const*, clang::QualType&, clang::LangOptionsBase::StrictFlexArraysLevelKind) (.constprop.0) CGExpr.cpp:0:0
#11 0x000000000453d2ed clang::CodeGen::CodeGenFunction::EmitArraySubscriptExpr(clang::ArraySubscriptExpr const*, bool)::'lambda'(bool)::operator()(bool) const CGExpr.cpp:0:0
#12 0x0000000004547478 clang::CodeGen::CodeGenFunction::EmitArraySubscriptExpr(clang::ArraySubscriptExpr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4547478)
#13 0x0000000004547ad3 clang::CodeGen::CodeGenFunction::EmitCheckedLValue(clang::Expr const*, clang::CodeGen::CodeGenFunction::TypeCheckKind) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4547ad3)
#14 0x0000000004559091 clang::CodeGen::CodeGenFunction::EmitBinaryOperatorLValue(clang::BinaryOperator const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4559091)
#15 0x000000000455f943 clang::CodeGen::CodeGenFunction::EmitLValueHelper(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x455f943)
#16 0x000000000455fd97 void llvm::function_ref<void ()>::callback_fn<clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t)::'lambda'()>(long) CGExpr.cpp:0:0
#17 0x00000000081aeb91 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x81aeb91)
#18 0x0000000004527e03 clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4527e03)
#19 0x000000000455800b clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x455800b)
#20 0x00000000046d7f87 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46d7f87)
#21 0x00000000046e021c clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46e021c)
#22 0x000000000474879e clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x474879e)
#23 0x000000000475a7c4 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x475a7c4)
#24 0x00000000047c73d0 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47c73d0)
#25 0x00000000047c2284 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47c2284)
#26 0x00000000047cf12c clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47cf12c)
#27 0x00000000047d17d3 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47d17d3)
#28 0x0000000004b31ebe (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#29 0x0000000004b2dec5 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b2dec5)
#30 0x00000000068c62bc clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x68c62bc)
#31 0x0000000004b2e6a8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b2e6a8)
#32 0x0000000004e1a3a5 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4e1a3a5)
#33 0x0000000004d9bade clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4d9bade)
#34 0x0000000004f116bd clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f116bd)
#35 0x0000000000dbfa50 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdbfa50)
#36 0x0000000000db65ba ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#37 0x0000000000db673d int llvm::function_ref<int (llvm::SmallVectorImpl<char const*>&)>::callback_fn<clang_main(int, char**, llvm::ToolContext const&)::'lambda'(llvm::SmallVectorImpl<char const*>&)>(long, llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#38 0x0000000004b97839 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
#39 0x000000000412b854 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x412b854)
#40 0x0000000004b97e4f 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
#41 0x0000000004b59162 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b59162)
#42 0x0000000004b5a10e 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+++0x4b5a10e)
#43 0x0000000004b61845 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b61845)
#44 0x0000000000dbbf79 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdbbf79)
#45 0x0000000000c6bf74 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc6bf74)
#46 0x000076bcc1629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#47 0x000076bcc1629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#48 0x0000000000db6055 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdb6055)
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/eJzkWl9z27aX_TTwC0YeEvz_4AdattK0bpuNstlHDUheSlhTAAcAFbmffgcAZYqMnFiu1e3ML-PMSPhzcc7FwcUFBKoUW3OAGxTdoujuinZ6I-TN44xKKb6pq0JUTzefoZWi6kqQKMiRl2-0bpX5SBaILNaiKkSjr4VcI7L4C5HFPlXRh01xnyIvR7Hn_sq2RV6-E6zCtRCIpB23Q1dYbYTUmCGSYZTcIi_HfRFF0S1D0R0KXCnttMAFlRgFd9gAJjHb2S_UtCKp67ajTQe9Ncx2KLr1UHRn23kouMUoebZYUIlI6iGSuRJTdYTZfPbyW1o-aklLcOwHRoIr0QDy8rKhfI3IrfkLcozIQgqhEVk0zW47a6X4XygPXxFZaCEahcii77ZoWIHIYi4q-AB8-LToeKmZ4NfGdUFOQuIZ665XkKMgP3Q5_nLo5Qq_NnTJ_oJPlMnzOq5Bf33ITV9EUsNUH_f_SiWjRQO5lPTpy1MLiOTWiTnOlQJp7GAUezs3PEYkRiTGiBAusDIltZD460OOiI8IQSTBNWUNVNfIyz893OfLe6y6Yss0prjo1lhCa6ZWCzwRH9ObrrguxXZw78TpTKkOjLsx5RVmvGy6CrDeAC4lVRtcPE8vmeNWGq2XoJQRpuikKzY9qVKiZFRDhWXHsSola7XBu9S0fMRVt22dQLxr5GWfpFhLusVUrrstcK16YYjWYCrFtmUNyBns20ZIkAc1zOjBfWqmZccfEVkUjA9iMRrDszWeCWONtq2x2em209cKz7aGO57N9mk8o2o7U09c0z0K7hjX0OBZzcVsB7IQCkw9ni3xbLYuy5mRZLmhjKPg7ocoTWPFaas2QuNZXYpGyFnF6JoLpVmp3BjWs5NiRTnTRk_BXccrqJlZ-yiY914O7pGX-8Z1KJiDqFFwj1sqFUhMNQZeYVHjmtn1RqyHQc7Md_zw8PV3_PEzXgMHSa2EvTzoLQ3WgzxAQe6HZiI-9E35GpeicmqsoGyo648RSU4FKSdxK76UcsGftqJTZl0o9VwlWmNZmLhiykhiAg0igYe9vXf4F_qQxUGKrWJtN_Wk3IdPknFtJfXFiTIdGkn6bSWUlkC3dkXNMePaRjoz2LtoC5Fbb9_DM_gdeH8CPqZxeAr8vAHKu_ZPvmRrTptjBzbCDHEJqAbMAJWMoZIiKFI8N3r8DKXYgXxy2H6hvGrMiGnvw1GbueAa9roPvZ797-wHvf0kLsrSj0MSEa8n5eL4Po1XcThrGO_2szXvXEV5rcR17CCbLgPgcGwwi7O6xK3eSKDV6pE1zXnWbf_BejSFGyYxXivrgnNhh0k8GI7Hhkma1AGmhYnSZ5m1HQezyXdm_eJsg34xGEzHBoMMsvg8g7bLYDAbCSyJCBD_7-ytP9hVsd143d767gvHIXe8zBIfB6goKIukxGvQFs1HXsGe8fWt6Hg1Rv1Dvi5KHbW-37fyiNao7r862rhkYtrrgfL1n62ldUsVuMKllqzUiwb2FqJ6gB00vzGDz3rr2g7TStFee3aBfzCDT5a0Ye5PmFcEqvNm9H7LnJ-WXeESAzPU2E_f14_8UAjRHO0vSUO3RUXN_kHSUd10gznUOmsvsxwHxihMwiT9_2L57mJ2dAYxB1OytArOJzvfQPkI1cNXd6JIX6njnxs3KrfGj-T63v6gVTD4Ixz7I8q87MygZfxxyziVT3_2AjzllnGLi8YvR2KgGE0o1ln4hil3pH6BpgX5xhn_jYtv_A_B_-iaZnWR9MyRG6jHU-pVlmB71B5ytLqnupJQo2Bua_sQYpNjFOQlbRpzGlrVHAXzN7ruvZx2MhD2aEl6yCZfjHbJsUtSn0IxFrzNsO_3G9opw-KQDbo0u-P_w_Rm2dU1Kxn06fiyden4sRF7uHgQpTt1kPmr_f3-oug5DqJIx6IgCXhvXg__3pVgaQ2ks8lKSD2vOJ_0xzUXEqrvd7cJ80usbIP4mQ8ZJ2VxldRpcj6fpd7qiXL1Vo-mcBCu3cE_W9Ee7-taHzG_iIJ7egP5cV4Wg0f88g2buNi2Jms1lM2yFp1elqKFaRY7tDrwjIeM5WWN5-u1XSLLRlxE4Y724JRxGpeEaZLB-U45lNyK6umHyrjAucNCHggFk_MUTcrwPEL9bQ6YyjGZD40oaHMHZTPW-HA--XHu9uHQ8COvxZEsLnEaM7wHr4wTtqRMgsr7mVd-F1XXwDDJjv2Bwh3UjDPH-jU-cuV9-L-MEiyrgXM04UxI-lMlnOb8b-Rq2Axc4wnX2ic_jW1TrndQg5RQubTiApANqAFyMoZc-cnPz1THkD9DA-bwfiG0Fs-Adpz-FIEPBeDRvS2nW1AuqctGoN3h5eO2bVyxSw6_SMpVYzO9_-Zssp_myy_9lWEfHxzx2441FZzIT8k4USlIBWV07MxbWj4Cr-aCq257SEzfAuS9_eygPvt5fK8dp2VMipGQP1GpIF9-mewysKWTDfZCVwM9pAGwP_E8xPTUPUh-vGPuoew09EWX0a8DMsAc7_Pg04COBLKQZpp5dQLnhRA6DAPC8cZdZQWtJpmIG_MjV5ryEk778mVKl9GvwzmwGG-0te_HRTW-sLR4BzK75-PeNH8ckb3MNuLwDehHW6ZXFTWNPFyW_mpLjYH0dFq_oZNcfo7HZWRurw8uQ8KhHDjEEw5xVFB8cPvc_2LjwhGT5ZY2zVcon2P0CULxeH83NvqwOEruhxYfuZadYjv4DPWc609aomA-VO_q_heuBWtg-aQ0bPtDUCXZ7lSED5IprSSoMOP65TsCU_kWpj-8wTkowf7K5ebZTmv-Gg-dvoV5G8DDpc3xqK_t_7KXJ9t8lqRB9p5XX27gfo3P_bnYbimvpuH25DJTujrc2JvRaTNS1FJLxte25X2_Bp87rFblfu_77ktBFStXyjbvHTRqbApWWlKm1aF6Yo42jYlZQh7VmyZHN_L58w8Ir7t3-1UUJyYjm_72mkbHPxOf-oW1Tw07vqQ1NE8jX_7TV2g94ufIFHpTcUFY4_9kcdif1VoqtftF7aQKwkmCFWV-TF70mp01-l0Kc3DlaI-ddDQNRtH8dU3zUd55ROx90zlLe5ASmTiF-h6c65RfRaFe9sivonhg6qX97ftI-6yAljLpdp9znNjL5B9xpXHW4Mpx3lnEfhpGL8G-O_o8yuROpHAvTcE_6MoLHCusewbnhZOspKiTDL9DovD-SaJBNuAeJ7plXNRJiA3i9x7YmR4Gnr5zyarszPc-tstgcPrCJYPQw6uV6bNSmkq9OqL16iEgPBoinaaeXhRhZ_z958kYd0Mf1wU5BinNrtK_WMV1f7rDZa9_9-ITf2N6g2HPtHuK5wehwdgpwLMd1gIrAMyOTl1mpMNpC0vQneRglp_pefw896q6CaosyOgV3PhJ7JEgI6F3tbnxyjhJCgJRGpOwyIKo8jwoo4AkBEhIiyt2QzwS-Z5PvIB4oXft1yQhXkTiqoIiqAMUerClrLk2y-JayPWVfWR648eBF5CrhhbQKPukmpBDEDDk1sDta9e5KTfJkPkW3V3JG_tmtejWCoVew5RWg2nNdGPfZztL0d1LbylL2ilQf_cB7lUnm5u3P7LtXbC7If8XAAD__xdDMtQ">