<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/67356>67356</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Assertion failure with constrained parameter referring to previous parameter
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    The following valid C++ code

```cpp
template<typename, typename>
concept c = true;

template<typename T>
void a(T x, c<decltype(x)> auto) {
}

void b() {
        a(0, 0);
}
```

causes clang to crash with

```console
clang++: /root/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5590: void {anonymous}::CXXNameMangler::mangleFunctionParam(const clang::ParmVarDecl*): Assertion `parmDepth < FunctionTypeDepth.getDepth()' 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 -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 -w <source>
1.      <eof> parser at end of file
2.      <source>:8:6: LLVM IR generation of declaration 'b'
3.      <source>:8:6: Generating code for declaration 'b'
4.      <source>:5:6: Mangling declaration 'a'
 #0 0x00000000036f5d28 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36f5d28)
 #1 0x00000000036f39ec llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36f39ec)
 #2 0x000000000363c578 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007fe4f43d1420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007fe4f3e9400b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007fe4f3e73859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007fe4f3e73729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007fe4f3e84fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00000000070e640c (anonymous namespace)::CXXNameMangler::mangleFunctionParam(clang::ParmVarDecl const*) ItaniumMangle.cpp:0:0
 #9 0x00000000070e2e43 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) ItaniumMangle.cpp:0:0
#10 0x00000000070d5213 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) ItaniumMangle.cpp:0:0
#11 0x00000000070f11e0 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) ItaniumMangle.cpp:0:0
#12 0x00000000070f0033 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef<clang::TemplateArgument>) ItaniumMangle.cpp:0:0
#13 0x00000000070f1766 (anonymous namespace)::CXXNameMangler::mangleTemplateName(clang::TemplateDecl const*, llvm::ArrayRef<clang::TemplateArgument>) ItaniumMangle.cpp:0:0
#14 0x00000000070ef071 (anonymous namespace)::CXXNameMangler::mangleTypeConstraint(clang::ConceptDecl const*, llvm::ArrayRef<clang::TemplateArgument>) ItaniumMangle.cpp:0:0
#15 0x00000000070ef31b (anonymous namespace)::CXXNameMangler::mangleTypeConstraint(clang::TypeConstraint const*) ItaniumMangle.cpp:0:0
#16 0x00000000070ee6b8 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, clang::TemplateArgumentList const&) ItaniumMangle.cpp:0:0
#17 0x00000000070d15de (anonymous namespace)::CXXNameMangler::mangleNameWithAbiTags(clang::GlobalDecl, llvm::SmallVector<llvm::StringRef, 4u> const*) ItaniumMangle.cpp:0:0
#18 0x00000000070d22a7 (anonymous namespace)::CXXNameMangler::mangleName(clang::GlobalDecl) ItaniumMangle.cpp:0:0
#19 0x00000000070e7cf8 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) ItaniumMangle.cpp:0:0
#20 0x00000000070e8fb7 (anonymous namespace)::CXXNameMangler::mangle(clang::GlobalDecl) ItaniumMangle.cpp:0:0
#21 0x00000000070eb8be (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&) ItaniumMangle.cpp:0:0
#22 0x000000000710f183 clang::MangleContext::mangleName(clang::GlobalDecl, llvm::raw_ostream&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x710f183)
#23 0x0000000003ab9043 getMangledNameImpl(clang::CodeGen::CodeGenModule&, clang::GlobalDecl, clang::NamedDecl const*, bool) CodeGenModule.cpp:0:0
#24 0x0000000003abc02d clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abc02d)
#25 0x0000000003aea963 clang::CodeGen::CodeGenModule::GetAddrOfFunction(clang::GlobalDecl, llvm::Type*, bool, bool, clang::CodeGen::ForDefinition_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3aea963)
#26 0x0000000003de0ecc EmitFunctionDeclPointer(clang::CodeGen::CodeGenModule&, clang::GlobalDecl) CGExpr.cpp:0:0
#27 0x0000000003def38a EmitDirectCallee(clang::CodeGen::CodeGenFunction&, clang::GlobalDecl) CGExpr.cpp:0:0
#28 0x0000000003e0b156 clang::CodeGen::CodeGenFunction::EmitCallee(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e0b156)
#29 0x0000000003e0b0f7 clang::CodeGen::CodeGenFunction::EmitCallee(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e0b0f7)
#30 0x0000000003e0b832 clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e0b832)
#31 0x0000000003e53309 (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprScalar.cpp:0:0
#32 0x0000000003e4a1c9 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#33 0x0000000003e500ac clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e500ac)
#34 0x0000000003de8466 clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3de8466)
#35 0x0000000003e0939b clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e0939b)
#36 0x0000000003a12a92 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a12a92)
#37 0x0000000003a18f2c clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a18f2c)
#38 0x0000000003a76946 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a76946)
#39 0x0000000003a89ada clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a89ada)
#40 0x0000000003aeae33 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3aeae33)
#41 0x0000000003ae5f25 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ae5f25)
#42 0x0000000003ae64eb clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ae64eb)
#43 0x0000000003aef963 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#44 0x0000000004960176 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#45 0x0000000004950d88 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4950d88)
#46 0x0000000005e58a84 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e58a84)
#47 0x000000000495d028 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x495d028)
#48 0x00000000041c3a49 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41c3a49)
#49 0x000000000414479e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x414479e)
#50 0x00000000042a2cce clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42a2cce)
#51 0x0000000000bdc3c6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbdc3c6)
#52 0x0000000000bd3c8a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#53 0x0000000003fa24e9 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
#54 0x000000000363ca24 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x363ca24)
#55 0x0000000003fa2adf 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
#56 0x0000000003f6ae25 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f6ae25)
#57 0x0000000003f6b88d 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+++0x3f6b88d)
#58 0x0000000003f737b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f737b5)
#59 0x0000000000bd986c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd986c)
#60 0x0000000000ad49a1 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xad49a1)
#61 0x00007fe4f3e75083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#62 0x0000000000bd376e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd376e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```

See it live: https://godbolt.org/z/5rev7119d

This worked as of trunk a week or two ago.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzkW11zo7qW_TXkReUUSHw-5MFxOj19qs-9PZ1Uz31zCWnjMA2IkkQ-5tdPSYCNiJPYSdw1U_fWPefEILbWWtpbe0sIqlS5aQAuvOjSi67OaKfvhLzg9L7kSosGznLBny5u7wAVoqrEQ9ls0D2tSo5WHr708CVigoPnX3n-cvh37Pf_Z23bX9FQtxXV4JGVfmqhoTV4eIW2f5MvfTsmGgatRgx55App2YFHLqem9xhCt9vH70XJEfVweosejX3mkRUHVpmmHk4fPZx55AuinRYezpCXjLaTq2kn1kzu4dRt5GfGtG8M-9bSs6dH3lNjjHYKFGIVbTZIC8QkVXfoodR3-yUTjRLVIKd9qBfZI0vk4WsphPbwdVXd14tWiv8GZn4O7a6rMvfw9fLm1sPX3zRtyq7-mzabCs7NSJBlFGW-MWQJesklbUTzVItOGQpk6ZHl6l__-getoX9K9tdq--O6a5guRfODSlp7ODVAdU-rb_aDyvoXlVfAKg8vrUBLtFQKpHkMebHfUllfQavvkEdWaDR4-9SCvXq-AW3_6JX3cIIKWlbAz3s1fnz_srz5glSX16VGFOXdBklohdRG1zutW2WQ4GsPX29Kfdfl50zUg1rPRSuV6kB5-BrRhqOyYVXHAek7GIYop-y3lpRZT20ltFIwUAo4UqKT_WXzJFVKsJJq4Eh2DVJMlq0eIN9oyn4j3tVG_f6Sf-752Q8pNpLWiMpNV0Oj1TC8orXDKeq2rEAu4LGthAQ5DvGCjnKqhZZd89vD13nZ7DzAhuNiwx-oLBYhWmzQQhi7tG2N9U63nT5XaFEbLdBi8ZjGC6rqhXpqNH30yFXZaKjQ4gYtFhvGFlqIit3RsvHI1avwTGPV0FbdCY0WBROVkAte0k0jlC6ZQouiEQsrrHtZae6RK9ZDxz5aPBjnGBQe4zowmnlkBaIw8dtSqUAiqhE0HIkCFeUYMXhouTNAlqlHlrER-Pv3X3-jbz_RBhqQ1HqlKJCZIOjw08NJ7uGkt0Ves_V1sNFs7PSHCiFfthTusRSNlmysGTuzx-n2ceRh4iP_0R__R-Ii4jhF1rFt8KknNUShLBtt3e62991010jSh7VQWoIJ4Nj4b9loO8eZgPsU5_Pwpf84wDMxvMUfzPCTDNg-_KsKaNO1_2xuyk1DKw-nXWMTFEeVML2cAq0B46DFLlrCoiRFK-O9P4GJe5BPPbz_oA038yROByWdNivRaHjUw-Tr23-2XZChi6SAsAgJD0Lso_VagtJCwlrqgWc_pz-m8ToOF1XZdI-LTdP1N1p9J4HycyXOfcslCEPsO0zCaTcEstD3cyRpqeAA-8xYjq3lkPh-7liOXMsJSaMM0VwchHxiGeM0yhzL8dxysh31g20m2LWZuDbTsODxcTYJKXjs2EynXpL4EIc-Mza3aRWZ-kS1Ng6zoxPs3tSKbN7tEyzal-NnbpbNMGIIyfsxfnlsJShVisYFaK5PkK3QNmhtXKxQLkR1AGIzUfguYh7h4AOIb_vSb4L1Pzta9VcPghO4cIogAP8DcIb6dSk3LqrJDVsRHCkanqH0ffIR0XZg1H6Y_xgq-N0MvpSSPv2EwiOr12iRLwcyInPdkzj-OKMe9z5Gs-A6JbVwFpOFnwQf8_CVwS2pDbYpuVW_nvqD3KI5NxLkp-Hm3jtmXjQ44xlOiPP0TwTMKyJ_L9WWRnwgjWQ2WQYRh_fTMJf_q9R3y7y8pXMmXyuR06pf3k096KamVfULmBbSI6vJdS3LZmNcC69Q2JnC_cgxmuVXjjFNPkbuZUYHAZon04QVH3CaMeF_aZjgZbP5GDg8y5uQFvkH1PogmFnWhDzN3_RLx-xQO3-r22oKawB8mGfO1zsHIXczaeAXQUqmUevAO9y_Xsf1yUuaAfa2WDW8nHxKaJ75IUEb0D0fbtBbsWf5g8NXaJwffwveGf-IZ9OZy3Zyw5jmz1LQWNw4VvcPSTiDznzM0WEo7SWX5Wue_dlLyx6rMw6RSwZoFpNjyHwFveRc_rMYp4_DfK6veCfK7_77UufXQl5BUTal6WV9ko2Cnr6jj5OYCQcfGENf6lKPfA23H6JstF13f4KzZmj11Sxg9jtfMsNTkJRaPFelBKZXtKoA3gayG633Q3HyIQE_D6L4LdfZ9tuv0-pyL-LZ-u3zB7oH6wx0NmfjF8n_HzZ-kUzZzPbnwM9Tgt_HxqCf-dNw1Zk_X7L9E3Qnm1-06uCmEieJ2p6dQ9_d3oOIED97K9_fMFpRaYgZ6nqsP36V6gghxojpje2Nm9luHoQ0YNlUvxtda9urkJdUgUdWdlfa3KKcr9txslkdz8iZg-2gGNR2A3ik6lI0WA4mRmaq-z5lxzvdDvUbmzpjyv50f7LAHX8KZ7NuGsbvmOqWzdMBtF4yu9xsJmF0Ovo9O4d-NJtNMpLlx9P_tmmEBP6mBKeYIQxih5Kb12mAafaOCbIPj3nAHLW3sdR6Qr7f2Pj0usbSc_gnM_5pgd8RqytRt6JruGFtVuqi0zdMzLc4p60mOwpvl3yuy59CF0Pb0cUtamgSZ-E7In28cin406v-cQJOFrLDyS1taJpRTo_jNLxeBHPzsAJ_V2C-Oqmtvo4NvzWFcLabPl0Yy3sqTOjPFz9Ajlr8mKHuBditBsYVymEy9de3mfg0axogzpomDGa0owJH76P9f5GuYePQxTO6cQhvZq_9dP_oWt3idIjM9kygOHKtbojcivY73MMAe0pnd1LGcDlvqdTn_mFbIqFTH4VZ7AfJ229HerNmXhFyt7HWv8N-HeZXKbrWbuVmqId12ZUVh_11aRi56CKfp-lUt0vKfkPDV6JRXT3W_cfi-OTxH2A64-_ULBFEKU3D2ZEnBfa4lZNxoKazfHui0nGA5GBOZtpzH6d7fHY5TaCPwDoNy3E76TTqGiAOUifzhwEjNHSWZddSNBoavgfqiUD2GByQmQsyDJMM0KzUMt1-a5SmDYP9ir7M6iSpd8A5JRI5qTfEFDPmEBkg7_jcC0afw3_G9yRZZcDnEHCSqJ9zRliMGAvWNTU20v11_x2dFfsr5F7DK3sc8jQ8epQODTyjQVhK0Sj-Kri1M0W69_VaP2fv4RTP9nqFqIYXFE6Bx2V5_8KUHbmprqA4hKw_J7qzWww111pabftTpH1QjzsajFZVTtnvddG4q66-78GHVsFK1DVt-Dyo947hdjNGtKZ3Wr3wmtFgsAO8fWC9Zo-PQdD_yKkq2VrZ5oOKTmNzYa0lLbUab8_M0aoyMWHfc473TZPJ5oh1ol5z-4iHk4rWObeH-bZS4XQ8y_aXyPePRzg_gUZxOBmKfefMhv2_rrmhBVRPjpyvD90pDtVZxI7nR3MXo7xA_84uMiv7XvQFd-ukiCm4ywdHODt29FnGHNV0JvPZg6aBs11wWNOlU-xMuH2qQ_W0HYdKZrrkacqP1eUvkauXRflL5LNTGS-cfBim5q0ftLQ0LjCcfjtUx8FZ_oiaRixHTXcjpkhIkr_oZVeTv53CYU_F8NIo_EE1P3966-Vx9MtmiT1L42GDb6xQRvx2Wlk-2658KW1_ek1ikE2hx05t6FMeZjRABvRn992bdvoOZod9Iz8laL2uytzMxFTq9QTIocd_Q989_RA_q7qSGFBv__P1Nca3vU9vkyUCKU1yWA4fBBXDagCxwXv7L17s90EIHkvdf10QkNDA7BSgxT3SAikAVE5K9KGzsTpH0r4FBBM_5uFXvk-6MZY0qsp7s3aZf0YjeC4qfS7kxsPX_-Ph60jCfRIEGZ_auL0rFXoQ8jdwRBUSBbISIYoeAH4jIZF-EIhuxPkZvyA8Ixk9g4sgzqI4jnGCz-4uoiIkOIUi8amfUVwUYZHjrKBpgMM4YflZeYF9TPwMR0GKQxKchxGl3A95EKWhT3zfC32oaVmdm4gyiM_sFz4XcUKi-KyiOVTKfuSGcQMPyN70MPaiqzN5Yb8NyruN8kK_KpVWOyu61BVc7D5kMiPUSeiHiI0HEIGjlkpag7bqFyBNEWGGqpVwX4pO7e6fdbK6eP_3SpbQ_wYAAP__tDAGkA">