<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/120081>120081</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang crash on x86_64-linux-gnu: Assertion `isa<T>(CanonicalType)' failed
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          bi6c
      </td>
    </tr>
</table>

<pre>
    Compiler Explorer: https://godbolt.org/z/qdx3o195o
```console
<source>:14:19: error: incompatible integer to pointer conversion passing 'int' to parameter of type 'volatile void *' [-Wint-conversion]
   14 |   __atomic_clear (__ATOMIC_RELEASE, __ATOMIC_RELEASE);
      | ^~~~~~~~~~~~~~~~
<built-in>:14:26: note: expanded from macro '__ATOMIC_RELEASE'
   14 | #define __ATOMIC_RELEASE 3
      | ^
clang: /root/llvm-project/clang/include/clang/AST/Type.h:8805: const T* clang::Type::castAs() const [with T = clang::PointerType]: Assertion `isa<T>(CanonicalType)' 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 -fno-verbose-asm -c --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics <source>
1.      <source>:18:1: current parser token 'int'
2.      <source>:8:1: LLVM IR generation of declaration 'tf'
3.      <source>:8:1: Generating code for declaration 'tf'
 #0 0x0000000003c56df8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3c56df8)
 #1 0x0000000003c54b04 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3c54b04)
 #2 0x0000000003ba2068 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x000078d6c8442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000078d6c84969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x000078d6c8442476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x000078d6c84287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000078d6c842871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x000078d6c8439e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000041e3763 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x41e3763)
#10 0x000000000437ec6a clang::CodeGen::CodeGenFunction::EmitBuiltinExpr(clang::GlobalDecl, unsigned int, clang::CallExpr const*, clang::CodeGen::ReturnValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x437ec6a)
#11 0x000000000446222e clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x446222e)
#12 0x00000000044b9ae4 (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprScalar.cpp:0:0
#13 0x00000000044ae16b clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#14 0x00000000044b3dac clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x44b3dac)
#15 0x000000000443c7fe clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x443c7fe)
#16 0x00000000044606d5 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x44606d5)
#17 0x0000000003fc23b5 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3fc23b5)
#18 0x0000000003fca024 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3fca024)
#19 0x0000000004032ff4 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4032ff4)
#20 0x0000000004045d38 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4045d38)
#21 0x00000000040adb4a clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x40adb4a)
#22 0x00000000040a8dd5 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x40a8dd5)
#23 0x00000000040a91bb clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x40a91bb)
#24 0x00000000040b3983 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#25 0x00000000045e2b06 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#26 0x00000000045d3688 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x45d3688)
#27 0x00000000065ca1f4 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x65ca1f4)
#28 0x00000000045e0668 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x45e0668)
#29 0x0000000004899a89 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4899a89)
#30 0x000000000481c48e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x481c48e)
#31 0x00000000049862ce clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x49862ce)
#32 0x0000000000ce1c7f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xce1c7f)
#33 0x0000000000cd971a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#34 0x0000000004624ad9 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
#35 0x0000000003ba2514 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3ba2514)
#36 0x00000000046250cf 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
#37 0x00000000045ea3dd clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x45ea3dd)
#38 0x00000000045eb4cd 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+0x45eb4cd)
#39 0x00000000045f2a45 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x45f2a45)
#40 0x0000000000cdeac3 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xcdeac3)
#41 0x0000000000bac364 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbac364)
#42 0x000078d6c8429d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#43 0x000078d6c8429e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#44 0x0000000000cd91c5 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xcd91c5)
clang: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```
Code:
```c
#include <pthread.h>
#include <stdbool.h>

bool lock;
int counter;

void *
tf (void *arg)
{
  (void) arg;
  while (__atomic_test_and_set (&lock, __ATOMIC_ACQUIRE))
    ;
  ++counter;
  __atomic_clear (__ATOMIC_RELEASE, __ATOMIC_RELEASE);
  return (void *) 0;
}

int
main ()
{
  pthread_t thr;
  pthread_create (&thr, 0, tf, 0);
  tf ((void *) 0);
  pthread_join (thr, 0);
  return 0;
}
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzkWlFzmzoW_jXKi8YeEBjDQx4ISbq90zu322R7Hz1CEjY3ILGSSJN92N--IwkbhJ207vXd2ZnNtJkgpKPv-3R0dICDlaq3nLFrsLoBq9sr3OudkNdlnZCrUtDX60K0Xd0wCe9eukZIJkGUw53WnQJRDtA9QPdbQUvR6KWQW4Du_wXQ_T_pSyTCbCVAkIMkcP-I4Eo0zDRFhRK9JAxEdyDKw9j8yoxhJqWwM9SciLbDui4bBmuu2ZZJqAXshLmQkAj-zKSqBYed4cC3EKB1zTVAa9sPS9wy01NUUL92zNx-Fg3WdcPgs6gpBCg3ncHqZvF7zfViNAlWtyDIIYRhDMG6gBBuNliLtiYb0jAsIUDpZpM__vbrx2Lz5e7TXf5wB1ABj9syEN04UxBaU2B192__x-lR9nWjFzWfKIISIwQXmlllXjrMKaOwkqKFLSZSGErHU6496ABFlFU1Z0fgYDQHBoKcNJhvzXQA3UshNED3TfPcLjop_mDEXLoe6L7mpOkpm7TkD48A3T--dmy5A1GepsHKWDLLruEjQDncWwdRbrq5vwhWOlcApQBlQ2ewuvlW6x18hCC6nY767FbfDl7dGuu5Ukxq4wYgCWqFQVQ8Gg1RWmAueE1wY3ujzKx1heuG0SUI8s9OA9WXba0hhmW_hZJ1QmrjPTP_rvWuL5dEtIMcx6rUSvVMAXQPMadw0AbqHYNEYrWDJSZPWmLCjJt0knVSEKYUo3DYCKiwI7FSgtRYMwplz6Eisu60wfugMXmCtG87AyvIgyUIss9SbCVuIZbbvmVcq2HlRGdXati5C7bfucNaLfBeNLXQsudPAN2XNd_fhost_YZltYjhYgsXxs3ucdcZu73uer1UcFFxsXhmshSKLbBq4YLAxWJLyEIL0ZAdNo58-y4S01lx3Kmd0HBREdEIuaA13nKhdE2GOax6XrMXO4I8NDrM40lqflnf66VkXJtooGz8eGJ8jBMgyNGJ4YfRnz59_RV-_AK3jDOJrZOJClJGGjxcArTWlbMUvWfpw2CBbyERlMFKyLfsmB0bwOAl2P9EZJXQKoXW8ewuUK9q2A6y5tp6xqPzrXTsJPG3jVBaMtwClBj_sqQzaHfan3QRgG6ClwGY2VoOdjiDHZdBfAp20TDM--43_lBvOW4ASntuTyEKG2GMXxakgTGCRB7IEqMgSWFh3OwLI-KZyVeH6m-Y08bMlQ66eX0KwTV70UvSmf0Y2P_OfjTYX6c0IWkcoxUKBjpNXQJ0_5ImmyReNDXvXxZb3rsbZKnEMrGQ7ZARcOwbzJKsIrDTO8kw3TzVTXOedTt-tL6aw43XCdwqK8G5sON1MhpOfMMoXVcRxKUJsGeZtQNHs-sjs2F5tsGwHA2mvsEoY1lynkE7ZDSYTR0sDlm0TqLL-fNg0E1n9pwXK-JozUiCp0dmISj7wLh3cd9zYqZxjXdtrW9M-lHzu5fOePxk-IdGlLi5ZaQxIeSwT-2eKLx5cNOY4e4It7lV8SaOL0z3kn_FTc8eGnHZsDRoMCrkhaU4ThBC7HyF9vx8ef4c62ISHY2lG6yYtZFfVhHHeVQE-YqUGWaxmc5kTK-t6BXkuGWqs2dK5vA9ENxgabgaNbR9DgBR_rVWZ2iTweKDaXLGZtHTIIt8ZJiFSTnV80G32k4ppBUrKpSm7hamdDM8HRhlz6bjrYZdJAPZnuN7nj4_g-XHWMUzvSOKyfkeOEL2cRz5XylEc2EHspBHB1r5hCKyrn5iS-X89QfYvGU23269rfQXsLa8RtbJLJAECV2dz_rjlgvJ6HeZXzYAGKwjk7WXBFUEReVPMHEbYL4lvMUbd1QuJX79wioQFZMBudYTzua57ZK5nyM20k5ntHGA4p84CUTbiZ5TQ_b3Wu9Erx-IMM-YXvSb9NozTEY__VG_vqwchvAoh5-pBBGqqp-QY99yI-jru95wSYd2YA9UkJ8FBfGKRul5VIZHNGZuvpcCjR59GP9-nCo-7Dt-5JWYuMJF9bCMRz38nCfAtIy_mxX-KmjfsHFhHe89-FtW1bx2fH9EHdd-OEcvy9byGdmiGduUfj8wn2b7v8XS8BhZRjOWWViWP8fybW6XxW8Qjvj9LCgooyyNzsX_KLpP7JkNaKcsXMt-CZYdlnoZ2Nxsauk4OUN-LrNiqAyS72WPg00TMIT82HaNa3bvDN7H-EGKvjPnIMqgw2SevSg7kTciP-FY0ShJvah2g8kT47QQXPXtPiM_F8TlFtwBHBfcyzKSFcGhf758xlIx-9bYOzVYi2dH5cVTuwHMCDWdOUGQJKfOj3x69r0w0ms2NLnX1xfU0kIYAfpndZplOM2mAO-l4JpxegLhxbG52Q_Y_NeVcRqSOJ09DbjZPnKlMSfstH5vk7n0YekQjvj9wzJLE0Q8_APSkcazIPgY9RHNSx8IDtmI2zv2AsJCsq4gIeGmxWZoejr53uFZxl1Avw0V9vvYpeE7fCP6yEdPs3WI4V7qIny0e37C4aHFTfOVkUPEPUEl8U9nY2N4U-vlXVTWz6cCbuQfUQmKMc3cx8LRaDUkRBtp9Rw-Jdqtun9ZQHDTlJg8bSruP-64iQd3KcJCtC3mdL5bT67b4T2H6Mzs2AgwEUfLmm9tz7thUQ8DNhvy8hKG7qLEqiYbZbsPEnqdTcNGS1xrtb89M4ebxri_kJP7psvk1UN--JTnhgC0bnBbUgzQepQKpfu3_b-I8sRirOZv6lfh9HPCqffxw3u2nj_gijWvnpbvr9tFH7Qc1tHVk5lbrQJSwf9nt5ilaKfXfz07k3FE6Zuq2fXCR2ffXkovUM8Gmg7eE_qPdc29JGVC7GIZgCE8OtE8RSljcrYcv4hSva3FL6L8VCv_bcV78few9h2uzbIffxR4V77BQf5iEY1Mo4h-GrWqEI5XbwG-nfztpQAnzv63xP8vinjR7NMKc5AtDmZnNcNkeHTb5xp72DZw5Edv_946iS-XXVhMI2IvpwtKTKIkhgbr5aZ0Rscp0ezTZEazM7_82iGjwWhukMUB3GzMmI3SWOrNhNAPT8HiyRTxPAkLyQo645dcG2PWTXooMDpUermak2pI-SEZPNyV6kBbB8Reau0KJ8LIfqjqFYOLZ6gFVIzBepKQmzkOJWvSfnBjZoOZkdNiNNuN2keRaYmak2VfvwOiYvjQvty5chP_ptLUBK7DzSA3l7AR5MnVfdXc4O7tNynbAIL8UHsW5LoyZPYNWG6HhVm7mrHhntkn5t5QSfZtVzfMVaANNWmaKb3BnG4UG1YtsRCmFWl58fd_fPxiK9Lcl2oI4d4iQDcA3Xg4L1Dx5sSfEjREgkGH9a1Tw8SNIB_9eMp_X-Sgod4dcO0biWRYs4GuuY8KGJhfuhr-PCBxMh8BGTvsbf4hHIzR3JyND3_vNlf0OqJZlOErdh2uozhareM0u9pdM5ylFV5HlKXZOg4ZJbSKKcVVRhkKs_CqvkYBikMUJmG0SoNsmZZlwFKKI4ppRNYMxAFrcd0sTSxdCrm9sqVm1yEKgjS8anDJGmWLNxEadhwCq9sreW0r1Mp-q0AcNLXSajSha92wa7fxXH2a4PAodPxkdd1VL5vrny-gG4g9X6P_BAAA__-nMw35">