Clang crashes on variable template instantiated with a member of a template class

[oliora]

clang version 16.0.0 (https://github.com/llvm/llvm-project.git 08d094a)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/compiler-explorer/clang-16.0.0/bin

Log and the crash backtrace:

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-16.0.0/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-12.2.0 -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>
1.	<source>:55:67: current parser token ';'
2.	<source>:40:1: parsing struct/union/class body 'Builder'
 #0 0x000055ed179d48df llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x3ba18df)
 #1 0x000055ed179d290c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x3b9f90c)
 #2 0x000055ed17925518 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007fc08950c420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x000055ed1a94d2e9 clang::Sema::SubstituteExplicitTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo&, llvm::SmallVectorImpl<clang::DeducedTemplateArgument>&, llvm::SmallVectorImpl<clang::QualType>&, clang::QualType*, clang::sema::TemplateDeductionInfo&) (.constprop.0) SemaTemplateDeduction.cpp:0:0
 #5 0x000055ed1a94dd75 void llvm::function_ref<void ()>::callback_fn<clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, clang::QualType, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool)::'lambda'()>(long) SemaTemplateDeduction.cpp:0:0
 #6 0x000055ed1a041eb5 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x620eeb5)
 #7 0x000055ed1a98a059 clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, clang::QualType, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6b57059)
 #8 0x000055ed1a98a6cb clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6b576cb)
 #9 0x000055ed1a7a79aa clang::Sema::ResolveSingleFunctionTemplateSpecialization(clang::OverloadExpr*, bool, clang::DeclAccessPair*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x69749aa)
#10 0x000055ed1a98b52f ResolveOverloadForDeduction(clang::Sema&, clang::TemplateParameterList*, clang::Expr*, clang::QualType, bool) SemaTemplateDeduction.cpp:0:0
#11 0x000055ed1a98bcde DeduceTemplateArgumentsFromCallArgument(clang::Sema&, clang::TemplateParameterList*, unsigned int, clang::QualType, clang::Expr*, clang::sema::TemplateDeductionInfo&, llvm::SmallVectorImpl<clang::DeducedTemplateArgument>&, llvm::SmallVectorImpl<clang::Sema::OriginalCallArg>&, bool, unsigned int, unsigned int) SemaTemplateDeduction.cpp:0:0
#12 0x000055ed1a98ccad clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6b59cad)
#13 0x000055ed1a215087 clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x63e2087)
#14 0x000055ed1a22a93f clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x63f793f)
#15 0x000055ed1a253eed clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6420eed)
#16 0x000055ed19f47bc9 clang::Parser::ParseCXXClassMemberDeclaration(clang::AccessSpecifier, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo const&, clang::ParsingDeclRAIIObject*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6114bc9)
#17 0x000055ed19f48db4 clang::Parser::ParseCXXClassMemberDeclarationWithPragmas(clang::AccessSpecifier&, clang::ParsedAttributes&, clang::TypeSpecifierType, clang::Decl*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6115db4)
#18 0x000055ed19f49453 clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributes&, unsigned int, clang::Decl*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x6116453)
#19 0x000055ed19f4b7fe clang::Parser::ParseClassSpecifier(clang::tok::TokenKind, clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x61187fe)
#20 0x000055ed19f1c01e clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x60e901e)
#21 0x000055ed19ff42b7 clang::Parser::ParseSingleDeclarationAfterTemplate(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::ParsingDeclRAIIObject&, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x61c12b7)
#22 0x000055ed19ffcc5d clang::Parser::ParseTemplateDeclarationOrSpecialization(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x61c9c5d)
#23 0x000055ed19ffcf43 clang::Parser::ParseDeclarationStartingWithTemplate(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x61c9f43)
#24 0x000055ed19f28d0f clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x60f5d0f)
#25 0x000055ed19ef88a5 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x60c58a5)
#26 0x000055ed19efa72d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x60c772d)
#27 0x000055ed19ee9a8a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x60b6a8a)
#28 0x000055ed18cc4865 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x4e91865)
#29 0x000055ed185a0671 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x476d671)
#30 0x000055ed18524993 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x46f1993)
#31 0x000055ed18684b3b clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x4851b3b)
#32 0x000055ed151ad41c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x137a41c)
#33 0x000055ed151a8bdc ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#34 0x000055ed18385ce9 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 0x000055ed17925977 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x3af2977)
#36 0x000055ed18385f1c 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 0x000055ed1834e3fc clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x451b3fc)
#38 0x000055ed1834eded clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x451bded)
#39 0x000055ed1835923c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x452623c)
#40 0x000055ed151ab523 clang_main(int, char**) (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x1378523)
#41 0x00007fc088fba083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#42 0x000055ed151a4d1e _start (/opt/compiler-explorer/clang-16.0.0/bin/clang+++0x1371d1e)
clang-16: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

Minimal code:

#include <string_view>
#include <array>

template <const std::string_view&... Strs>
struct Join {
    static constexpr auto impl() noexcept {
        // Logic does not matter
        std::array<char, (Strs.size() + ... + 0)> arr{};
        return arr;
    }
    static constexpr auto arr = impl();
    static constexpr std::string_view value{ arr.data(), arr.size() - 1 };
};

template <const std::string_view&... Strs>
constexpr std::string_view JoinStringViews = details::Join<Strs...>::value;

static constexpr std::string_view LengthValue = "12345678";

enum class Version { v1, v2 };

template <Version V>
class Builder {
public:
    static constexpr std::string_view Equal = "=";
    
    // Crash is happening for this line
    // No crash without passing a template member `Equal`
    static constexpr auto Val = JoinStringViews<Equal, LengthValue>;

    // Note that the following line compiles just fine
    // static constexpr auto Val = Join<Equal, LengthValue>::value;
};

[EugeneZelenko]

Crashes in main: https://godbolt.org/z/azsqEKf6a

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[shafik]

Greatly simplified: https://godbolt.org/z/1srzd9EzY

Removed all includes:

struct A{};
template <const A&... Strs>
constexpr A JoinStringViews = details::Join<Strs...>;

template <int V>
class Builder {
public:
    static constexpr A Equal{} ;
    
    // Crash is happening for this line
    // No crash without passing a template member `Equal`
    static constexpr auto Val = JoinStringViews<Equal>;

    // Note that the following line compiles just fine
    // static constexpr auto Val = Join<Equal, LengthValue>::value;
};

Note assertions build gives a different backtrace:

Assertion:

clang++: /root/llvm-project/llvm/include/llvm/Support/Casting.h:578:
decltype(auto) llvm::cast(From*) [with To = clang::FunctionTemplateDecl; From = clang::NamedDecl]:
Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

Backtrace:

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 <source>
1.	<source>:12:55: current parser token ';'
2.	<source>:6:1: parsing struct/union/class body 'Builder'
 #0 0x00000000036b1be8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36b1be8)
 #1 0x00000000036af8ac llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36af8ac)
 #2 0x00000000035f91c8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f78d54d7420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f78d4f9a00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f78d4f79859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f78d4f79729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f78d4f8afd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00000000066e7766 clang::Sema::ResolveSingleFunctionTemplateSpecialization(clang::OverloadExpr*, bool, clang::DeclAccessPair*, clang::TemplateSpecCandidateSet*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x66e7766)
 #9 0x00000000068bf05d ResolveOverloadForDeduction(clang::Sema&, clang::TemplateParameterList*, clang::Expr*, clang::QualType, bool, clang::TemplateSpecCandidateSet*) SemaTemplateDeduction.cpp:0:0
#10 0x00000000068bf5ce DeduceTemplateArgumentsFromCallArgument(clang::Sema&, clang::TemplateParameterList*, unsigned int, clang::QualType, clang::Expr*, clang::sema::TemplateDeductionInfo&, llvm::SmallVectorImpl<clang::DeducedTemplateArgument>&, llvm::SmallVectorImpl<clang::Sema::OriginalCallArg>&, bool, unsigned int, unsigned int, clang::TemplateSpecCandidateSet*) SemaTemplateDeduction.cpp:0:0
#11 0x00000000068cfcc4 clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::TemplateSpecCandidateSet*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x68cfcc4)
#12 0x0000000006141400 clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6141400)
#13 0x0000000006141c37 clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6141c37)
#14 0x0000000006171fc2 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6171fc2)
#15 0x0000000005e67374 clang::Parser::ParseCXXClassMemberDeclaration(clang::AccessSpecifier, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo const&, clang::ParsingDeclRAIIObject*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e67374)
#16 0x0000000005e68225 clang::Parser::ParseCXXClassMemberDeclarationWithPragmas(clang::AccessSpecifier&, clang::ParsedAttributes&, clang::TypeSpecifierType, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e68225)
#17 0x0000000005e69b2a clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributes&, unsigned int, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e69b2a)
#18 0x0000000005e6bc00 clang::Parser::ParseClassSpecifier(clang::tok::TokenKind, clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e6bc00)
#19 0x0000000005e45380 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e45380)
#20 0x0000000005f07ab2 clang::Parser::ParseSingleDeclarationAfterTemplate(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::ParsingDeclRAIIObject&, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f07ab2)
#21 0x0000000005f0de38 clang::Parser::ParseTemplateDeclarationOrSpecialization(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (.part.0) ParseTemplate.cpp:0:0
#22 0x0000000005f0e0f3 clang::Parser::ParseDeclarationStartingWithTemplate(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f0e0f3)
#23 0x0000000005e4bf0b clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e4bf0b)
#24 0x0000000005e16d34 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e16d34)
#25 0x0000000005e17c1d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e17c1d)
#26 0x0000000005e0bf7a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e0bf7a)
#27 0x0000000004916af8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4916af8)
#28 0x0000000004178979 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4178979)
#29 0x00000000040fb40e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40fb40e)
#30 0x0000000004258fc6 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4258fc6)
#31 0x0000000000bd2107 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd2107)
#32 0x0000000000bca7ba ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#33 0x0000000003f5d009 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
#34 0x00000000035f9674 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x35f9674)
#35 0x0000000003f5d5ff 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
#36 0x0000000003f25ee5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f25ee5)
#37 0x0000000003f2694d 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+++0x3f2694d)
#38 0x0000000003f2e815 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f2e815)
#39 0x0000000000bd039c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd039c)
#40 0x0000000000accef1 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xaccef1)
#41 0x00007f78d4f7b083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#42 0x0000000000bca29e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbca29e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

[shafik]

Looks similar to: #60615

[oliora]

If it's the same issue as #60615 (looks similar for me) then it probably should be tagged with crash-on-valid too.

Also not sure whether the reduced code is equivalent because the backtrace is different. (see next comment)

PS thank you for rapid reaction

[oliora]

Simplified code of @shafik is correct simplification. Even if I reintroduce the class template back it still crashes in clang::Sema::ResolveSingleFunctionTemplateSpecialization with the same backtrace.

https://godbolt.org/z/x4n9TvEaf

struct A{};

template <const A&... Strs>
struct Join {
    static constexpr unsigned value = sizeof...(Strs);
};

template <const A&... Strs>
constexpr auto JoinStringViews = Join<Strs...>::value;

template <int V>
class Builder {
public:
    static constexpr A Equal{} ;
    
    // Crash is happening for this line
    // No crash without passing a template member `Equal`
    static constexpr auto Val = JoinStringViews<Equal>;

    // Note that the following line compiles just fine
    // static constexpr auto Val = Join<Equal>::value;
};

[LYP951018]

Is anyone working on this issue? I’m new to clang and looking into this issue. It seems that when deducing the type for Val, clang thinks JoinStringViews<Equal> is an overload set and casts the expr into FunctionTemplates which causes the crash.
Interestingly, I changed the type of the template parameter from const A&... Strs to A... Strs and the code compiled fine.