clang 20: Sporadic crashes of clang-tidy check modernize-use-constraints

[pkl97]

clang-tidy check modernize-use-constraints crashes sporadically (approximately in 5% of the runs) when given this program to analyze:

#include <boost/filesystem/path.hpp>

int main(int argc, char** argv)
{
    return EXIT_FAILURE;
}

boost/filesystem/path.hpp was taken from the current version Boost 1.87.0.

Script to run clang-tidy in a loop:

for i in {0001..1000}
do
    echo "Iteration $i"
    clang-tidy --extra-arg=-I/usr/local/clang20el9/include/c++/v1 --checks=-*,modernize-use-constraints --header-filter=^/home/user/devel/PROJECTS/.* -p /home/user/devel /home/user/devel/PROJECTS/FileWriter/UnityBuild.cpp
done

A dump of the crash:
ClangTidyCrash.txt

The last commit included in my clang 20 build from branch master is 106c483 from 2025-01-19.

The crash does not occur in clang-tidy 19 with the same Boost header file.

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: None (pkl97)

clang-tidy check modernize-use-constraints crashes sporadically (approximately in 5% of the runs) when given this program to analyze: ```c++ #include <boost/filesystem/path.hpp>

int main(int argc, char** argv)
{
return EXIT_FAILURE;
}

boost/filesystem/path.hpp was taken from the current version Boost 1.87.0.

Script to run clang-tidy in a loop:
```Shell
for i in {0001..1000}
do
    echo "Iteration $i"
    clang-tidy --extra-arg=-I/usr/local/clang20el9/include/c++/v1 --checks=-*,modernize-use-constraints --header-filter=^/home/user/devel/PROJECTS/.* -p /home/user/devel /home/user/devel/PROJECTS/FileWriter/UnityBuild.cpp
done

A dump of the crash:
ClangTidyCrash.txt

The last commit included in my clang 20 build from branch master is 106c483 from 2025-01-19.

The crash does not occur in clang-tidy 19 with the same Boost header file.

[pkl97]

Btw. the operating system is Red Hat Enterprise Linux 9.5. clang 20 was compiled from the LLVM main branch in a two-step process, so finally clang 20 compiled itself.

[pkl97]

It turns out that a simpler Boost include file is sufficient to trigger the issue:

#include <boost/iterator/iterator_facade.hpp>

int main()
{
    return 0;
}

The preprocessed output has 30k lines of code and can be used to trigger the crash without the Boost dependency:

UnityBuild.cpp.gz

[pkl97]

Finally I can provide some information that should help tracking the problem down.

I built a debug version of clang 20 with assertions enabled and also reduced the test program that is required to reproduce the problem to 130 lines.

Now every time clang-tidy is run an assertion in TemplateBase.h, line 585 is triggered. The sporadic aspect of the problem is gone.

The clang-tidy backtrace:

clang-tidy: /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/TemplateBase.h:585: Expr *clang::TemplateArgumentLoc::getSourceExpression() const: Assertion `Argument.getKind() == TemplateArgument::Expression' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: clang-tidy --extra-arg=-I/usr/local/clang20el9/include/c++/v1 --checks=-*,modernize-use-constraints --header-filter=^/home/user/devel/.* -p /home/user/devel/ /home/user/devel/HelloWorld/main.cpp
1.      <eof> parser at end of file
2.      ASTMatcher: Processing 'modernize-use-constraints' against:
        FunctionTemplateDecl boost::iterators::detail::writable_postfix_increment_dereference_proxy::operator= : </home/user/devel/HelloWorld/main.cpp:115:9, line:123:9>
--- Bound Nodes Begin ---
    function - { CXXMethodDecl boost::iterators::detail::writable_postfix_increment_dereference_proxy::operator= : </home/user/devel/HelloWorld/main.cpp:116:9, line:123:9> }
    functionTemplate - { FunctionTemplateDecl boost::iterators::detail::writable_postfix_increment_dereference_proxy::operator= : </home/user/devel/HelloWorld/main.cpp:115:9, line:123:9> }
    return - { DependentNameTypeLoc : </home/user/devel/HelloWorld/main.cpp:116:9, line:119:12> }
--- Bound Nodes End ---
 #0 0x00007ffb07f99db9 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/build/devel/clang/20.0.0-20250119/llvm-project/llvm/lib/Support/Unix/Signals.inc:796:11
 #1 0x00007ffb07f9a26b PrintStackTraceSignalHandler(void*) /home/build/devel/clang/20.0.0-20250119/llvm-project/llvm/lib/Support/Unix/Signals.inc:872:1
 #2 0x00007ffb07f980df llvm::sys::RunSignalHandlers() /home/build/devel/clang/20.0.0-20250119/llvm-project/llvm/lib/Support/Signals.cpp:105:5
 #3 0x00007ffb07f9a7de SignalHandler(int) /home/build/devel/clang/20.0.0-20250119/llvm-project/llvm/lib/Support/Unix/Signals.inc:413:1
 #4 0x00007ffb0023e730 __restore_rt (/lib64/libc.so.6+0x3e730)
 #5 0x00007ffb0028ba6c __pthread_kill_implementation (/lib64/libc.so.6+0x8ba6c)
 #6 0x00007ffb0023e686 gsignal (/lib64/libc.so.6+0x3e686)
 #7 0x00007ffb00228833 abort (/lib64/libc.so.6+0x28833)
 #8 0x00007ffb0022875b _nl_load_domain.cold (/lib64/libc.so.6+0x2875b)
 #9 0x00007ffb002373c6 (/lib64/libc.so.6+0x373c6)
#10 0x0000561b1d60fb7f clang::TemplateArgumentLoc::getSourceExpression() const /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/TemplateBase.h:0:5
#11 0x0000561b1df8cc59 clang::tidy::modernize::handleReturnType(clang::FunctionDecl const*, clang::TypeLoc const&, clang::tidy::modernize::EnableIfData const&, clang::ASTContext&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp:351:23
#12 0x0000561b1df8c836 clang::tidy::modernize::UseConstraintsCheck::check(clang::ast_matchers::MatchFinder::MatchResult const&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/modernize/UseConstraintsCheck.cpp:476:12
#13 0x0000561b1d3b24ce clang::tidy::ClangTidyCheck::run(clang::ast_matchers::MatchFinder::MatchResult const&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/ClangTidyCheck.cpp:47:1
#14 0x00007ffb153d6e64 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::MatchVisitor::visitMatch(clang::ast_matchers::BoundNodes const&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1272:17
#15 0x00007ffb1546e836 clang::ast_matchers::internal::BoundNodesTreeBuilder::visitMatches(clang::ast_matchers::internal::BoundNodesTreeBuilder::Visitor*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchersInternal.cpp:106:20
#16 0x00007ffb153d6949 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::matchWithFilter(clang::DynTypedNode const&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1067:17
#17 0x00007ffb153d6562 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::matchDispatch(clang::Decl const*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1087:5
#18 0x00007ffb153d636d void clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::match<clang::Decl>(clang::Decl const&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:732:3
#19 0x00007ffb153d96a7 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1471:3
#20 0x00007ffb15437bf6 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDeclContextHelper(clang::DeclContext*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1543:7
#21 0x00007ffb153e112f clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseCXXRecordDecl(clang::CXXRecordDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:2059:1
#22 0x00007ffb153da0b7 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:414:1
#23 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#24 0x00007ffb153e2cf3 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseClassTemplateDecl(clang::ClassTemplateDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1946:1
#25 0x00007ffb153da2b2 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:524:1
#26 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#27 0x00007ffb15437bf6 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDeclContextHelper(clang::DeclContext*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1543:7
#28 0x00007ffb153dd409 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseNamespaceDecl(clang::NamespaceDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1679:1
#29 0x00007ffb153d9b62 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:170:1
#30 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#31 0x00007ffb15437bf6 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDeclContextHelper(clang::DeclContext*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1543:7
#32 0x00007ffb153dd409 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseNamespaceDecl(clang::NamespaceDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1679:1
#33 0x00007ffb153d9b62 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:170:1
#34 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#35 0x00007ffb15437bf6 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDeclContextHelper(clang::DeclContext*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1543:7
#36 0x00007ffb153dd409 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseNamespaceDecl(clang::NamespaceDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1679:1
#37 0x00007ffb153d9b62 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:170:1
#38 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#39 0x00007ffb15437bf6 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDeclContextHelper(clang::DeclContext*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1543:7
#40 0x00007ffb153da7a1 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseTranslationUnitDecl(clang::TranslationUnitDecl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:1643:1
#41 0x00007ffb153d982f clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/buildgit-main-debug-binaries-bootstrap/tools/clang/include/clang/AST/DeclNodes.inc:24:1
#42 0x00007ffb153d96b6 clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl(clang::Decl*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1472:48
#43 0x00007ffb153567e2 clang::RecursiveASTVisitor<clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor>::TraverseAST(clang::ASTContext&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/include/clang/AST/RecursiveASTVisitor.h:190:5
#44 0x00007ffb15356579 clang::ast_matchers::MatchFinder::matchAST(clang::ASTContext&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1700:11
#45 0x00007ffb153d930e clang::ast_matchers::internal::(anonymous namespace)::MatchASTConsumer::HandleTranslationUnit(clang::ASTContext&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/ASTMatchers/ASTMatchFinder.cpp:1564:3
#46 0x00007ffb18b55fdc clang::MultiplexConsumer::HandleTranslationUnit(clang::ASTContext&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Frontend/MultiplexConsumer.cpp:338:23
#47 0x00007ffb140eb432 clang::ParseAST(clang::Sema&, bool, bool) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Parse/ParseAST.cpp:184:13
#48 0x00007ffb18b14257 clang::ASTFrontendAction::ExecuteAction() /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1188:1
#49 0x00007ffb18b13b39 clang::FrontendAction::Execute() /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1076:7
#50 0x00007ffb18a2829f clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1056:33
#51 0x00007ffb191545e1 clang::tooling::FrontendActionFactory::runInvocation(std::__1::shared_ptr<clang::CompilerInvocation>, clang::FileManager*, std::__1::shared_ptr<clang::PCHContainerOperations>, clang::DiagnosticConsumer*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Tooling/Tooling.cpp:467:33
#52 0x0000561b1d2fb3ad clang::tidy::runClangTidy(clang::tidy::ClangTidyContext&, clang::tooling::CompilationDatabase const&, llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>, llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem>, bool, bool, llvm::StringRef)::ActionFactory::runInvocation(std::__1::shared_ptr<clang::CompilerInvocation>, clang::FileManager*, std::__1::shared_ptr<clang::PCHContainerOperations>, clang::DiagnosticConsumer*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/ClangTidy.cpp:581:37
#53 0x00007ffb19154398 clang::tooling::ToolInvocation::runInvocation(char const*, clang::driver::Compilation*, std::__1::shared_ptr<clang::CompilerInvocation>, std::__1::shared_ptr<clang::PCHContainerOperations>) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Tooling/Tooling.cpp:441:18
#54 0x00007ffb191531f1 clang::tooling::ToolInvocation::run() /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Tooling/Tooling.cpp:426:10
#55 0x00007ffb19155f6d clang::tooling::ClangTool::run(clang::tooling::ToolAction*) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang/lib/Tooling/Tooling.cpp:625:23
#56 0x0000561b1d2f5c49 clang::tidy::runClangTidy(clang::tidy::ClangTidyContext&, clang::tooling::CompilationDatabase const&, llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>, llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem>, bool, bool, llvm::StringRef) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/ClangTidy.cpp:602:8
#57 0x0000561b1d2c05f1 clang::tidy::clangTidyMain(int, char const**) /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp:714:7
#58 0x0000561b1d2beb72 main /home/build/devel/clang/20.0.0-20250119/llvm-project/clang-tools-extra/clang-tidy/tool/ClangTidyToolMain.cpp:20:3
#59 0x00007ffb002295d0 __libc_start_call_main (/lib64/libc.so.6+0x295d0)
#60 0x00007ffb00229680 __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x29680)
#61 0x0000561b1d2bea85 _start (/usr/local/clang20el9-20.0.0-20250119-debug-bootstrap/bin/clang-tidy+0xbfea85)

The program that triggers the error:

namespace boost::mpl {
    template< bool C_ > struct bool_;

    typedef bool_<true> true_;
    typedef bool_<false> false_;

    struct integral_c_tag { static const int value = 0; };
    template <class I, I val> struct integral_c;
}

namespace boost {

   template <class T, T val>
   struct integral_constant
   {
      typedef mpl::integral_c_tag tag;
      typedef T value_type;
      typedef integral_constant<T, val> type;
      static const T value = val;

      operator const mpl::integral_c<T, val>& ()const
      {
         static const char data[sizeof(long)] = { 0 };
         static const void* pdata = data;
         return *(reinterpret_cast<const mpl::integral_c<T, val>*>(pdata));
      }
      constexpr operator T()const { return val; }
   };

   template <class T, T val>
   T const integral_constant<T, val>::value;

   template <bool val>
   struct integral_constant<bool, val>
   {
      typedef mpl::integral_c_tag tag;
      typedef bool value_type;
      typedef integral_constant<bool, val> type;
      static const bool value = val;

      operator const mpl::bool_<val>& ()const
      {
         static const char data[sizeof(long)] = { 0 };
         static const void* pdata = data;
         return *(reinterpret_cast<const mpl::bool_<val>*>(pdata));
      }
      constexpr operator bool()const { return val; }
   };

   template <bool val>
   bool const integral_constant<bool, val>::value;

   typedef integral_constant<bool, true> true_type;
   typedef integral_constant<bool, false> false_type;
} // namespace boost

namespace boost::iterators {

    template <class Iterator>
    struct iterator_value
    {
    };

    template<bool>
    struct enabled
    {
      template<typename T>
      struct base
      {
        typedef T type;
      };
    };

    template<>
    struct enabled<false>
    {
      template<typename T>
      struct base
      {
      };
    };

    template <class Cond, class Return>
    struct enable_if
      : enabled<(Cond::value)>::template base<Return>
    {
    };

  template <class I, class V, class TC, class R, class D> class iterator_facade;

  namespace detail
  {

    template <class Iterator>
    class writable_postfix_increment_dereference_proxy;

    template <class T>
    struct is_not_writable_postfix_increment_dereference_proxy :
        public boost::true_type
    {};

    template <class Iterator>
    struct is_not_writable_postfix_increment_dereference_proxy<writable_postfix_increment_dereference_proxy<Iterator>> :
        public boost::false_type
    {};

    template <class Iterator>
    class writable_postfix_increment_dereference_proxy
    {
     public:
        explicit writable_postfix_increment_dereference_proxy(Iterator const& x)
          : stored_iterator(x)
        {}

        template <class T>
        typename iterators::enable_if< // <--- this line triggers the bug
            is_not_writable_postfix_increment_dereference_proxy< T >,
            writable_postfix_increment_dereference_proxy const&
        >::type operator=(T&& x) const
        {
            *this->stored_iterator = static_cast< T&& >(x);
            return *this;
        }
     private:
        Iterator stored_iterator;
    };

  }
} // namespace boost::iterators

int main()
{
    return 0;
}

[pkl97]

Btw. this issue could be related to #123163 where also check modernize-use-constraints is mentioned to trigger a crash.

[chrchr-github]

No crash here for some reason: https://godbolt.org/z/shx9xsx8c

[pkl97]

@chrchr-github: It seems Compiler Explorer does not use the assertion build when running clang-tidy, just for the compilation itself.

When using arguments "-version -checks=modernize-use-constraints" in the clang-tidy window Compiler Explorer emits

LLVM (http://llvm.org/):
  LLVM version 20.0.0git
  Optimized build.

However an optimized build with assertions enabled creates this output:

LLVM (http://llvm.org/):
  LLVM version 20.0.0git
  Optimized build with assertions.

And without assertions enabled the crash only occurs sporadically. With the 130 line example the probability is so low, I couldn't trigger it even if performing more than 10000 clang-tidy runs.

[chrchr-github]

@chrchr-github: It seems Compiler Explorer does not use the assertion build when running clang-tidy, just for the compilation itself.

Yeah, that's unfortunate. Good catch.