Assertion failure when expanding packs in function parameters.

[mizvekov]

Repro: https://godbolt.org/z/ffrqoTzx1

template<typename ...T> struct D {
  template<typename... U> using B = int(int (*...p)(T, U));
  template<typename U1, typename U2> D(B<U1, U2>*);
};
using foo = D<float>::B<int>;

Crash:

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:1223: clang::TemplateArgument getPackSubstitutedTemplateArgument(clang::Sema&, clang::TemplateArgument): Assertion `S.ArgumentPackSubstitutionIndex < (int)Arg.pack_size()' 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 <source>
1.	<source>:5:23: current parser token 'B'
2.	<source>:1:32: instantiating class definition 'D<float>'
 #0 0x00005651c4c0994f PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x00005651c4c07674 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c07674)
 #2 0x00005651c4b458f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f8c6a6cd3c0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x143c0)
 #4 0x00007f8c6a19a03b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4303b)
 #5 0x00007f8c6a179859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f8c6a179729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f8c6a18b006 (/lib/x86_64-linux-gnu/libc.so.6+0x34006)
 #8 0x00005651c74ade3c getPackSubstitutedTemplateArgument(clang::Sema&, clang::TemplateArgument) (.isra.383) SemaTemplateInstantiate.cpp:0:0
 #9 0x00005651c74c8e65 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#10 0x00005651c74ce342 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
#11 0x00005651c74ce3de clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
#12 0x00005651c74df008 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformFunctionTypeParams(clang::SourceLocation, llvm::ArrayRef<clang::ParmVarDecl*>, clang::QualType const*, clang::FunctionType::ExtParameterInfo const*, llvm::SmallVectorImpl<clang::QualType>&, llvm::SmallVectorImpl<clang::ParmVarDecl*>*, clang::Sema::ExtParameterInfoBuilder&) SemaTemplateInstantiate.cpp:0:0
#13 0x00005651c74e2a94 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformFunctionProtoType(clang::TypeLocBuilder&, clang::FunctionProtoTypeLoc) SemaTemplateInstantiate.cpp:0:0
#14 0x00005651c74c8dbb clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#15 0x00005651c74cd422 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformParenType(clang::TypeLocBuilder&, clang::ParenTypeLoc) SemaTemplateInstantiate.cpp:0:0
#16 0x00005651c74c941b clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#17 0x00005651c74cd852 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformPointerType(clang::TypeLocBuilder&, clang::PointerTypeLoc) SemaTemplateInstantiate.cpp:0:0
#18 0x00005651c74c8f1b clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#19 0x00005651c74ce342 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
#20 0x00005651c74ce3de clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
#21 0x00005651c74dee36 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformFunctionTypeParams(clang::SourceLocation, llvm::ArrayRef<clang::ParmVarDecl*>, clang::QualType const*, clang::FunctionType::ExtParameterInfo const*, llvm::SmallVectorImpl<clang::QualType>&, llvm::SmallVectorImpl<clang::ParmVarDecl*>*, clang::Sema::ExtParameterInfoBuilder&) SemaTemplateInstantiate.cpp:0:0
#22 0x00005651c74e2a94 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformFunctionProtoType(clang::TypeLocBuilder&, clang::FunctionProtoTypeLoc) SemaTemplateInstantiate.cpp:0:0
#23 0x00005651c74c8dbb clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#24 0x00005651c74ce342 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
#25 0x00005651c74ce3de clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
#26 0x00005651c74d01f9 clang::Sema::SubstType(clang::QualType, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d01f9)
#27 0x00005651c73cd678 clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation, clang::TemplateArgumentListInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x63cd678)
#28 0x00005651c74d3b60 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformTemplateSpecializationType(clang::TypeLocBuilder&, clang::TemplateSpecializationTypeLoc, clang::TemplateName) SemaTemplateInstantiate.cpp:0:0
#29 0x00005651c74c9ab4 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#30 0x00005651c74cd852 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformPointerType(clang::TypeLocBuilder&, clang::PointerTypeLoc) SemaTemplateInstantiate.cpp:0:0
#31 0x00005651c74c8f1b clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#32 0x00005651c74ce342 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
#33 0x00005651c74d68b9 clang::Sema::SubstType(clang::TypeSourceInfo*, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName, bool) (.constprop.5263) SemaTemplateInstantiate.cpp:0:0
#34 0x00005651c74ddabc clang::Sema::SubstParmVarDecl(clang::ParmVarDecl*, clang::MultiLevelTemplateArgumentList const&, int, llvm::Optional<unsigned int>, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64ddabc)
#35 0x00005651c74de3fd (anonymous namespace)::TemplateInstantiator::TransformFunctionTypeParam(clang::ParmVarDecl*, int, llvm::Optional<unsigned int>, bool) SemaTemplateInstantiate.cpp:0:0
#36 0x00005651c74de5b6 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformFunctionTypeParams(clang::SourceLocation, llvm::ArrayRef<clang::ParmVarDecl*>, clang::QualType const*, clang::FunctionType::ExtParameterInfo const*, llvm::SmallVectorImpl<clang::QualType>&, llvm::SmallVectorImpl<clang::ParmVarDecl*>*, clang::Sema::ExtParameterInfoBuilder&) SemaTemplateInstantiate.cpp:0:0
#37 0x00005651c74e214c clang::Sema::SubstFunctionDeclType(clang::TypeSourceInfo*, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName, clang::CXXRecordDecl*, clang::Qualifiers) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e214c)
#38 0x00005651c74fa791 clang::TemplateDeclInstantiator::SubstFunctionType(clang::FunctionDecl*, llvm::SmallVectorImpl<clang::ParmVarDecl*>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64fa791)
#39 0x00005651c7541172 clang::TemplateDeclInstantiator::VisitCXXMethodDecl(clang::CXXMethodDecl*, clang::TemplateParameterList*, llvm::Optional<clang::ASTTemplateArgumentListInfo const*>, clang::TemplateDeclInstantiator::RewriteKind) (.constprop.8050) SemaTemplateInstantiateDecl.cpp:0:0
#40 0x00005651c7542675 clang::TemplateDeclInstantiator::VisitFunctionTemplateDecl(clang::FunctionTemplateDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6542675)
#41 0x00005651c74d76fe clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*, clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d76fe)
#42 0x00005651c74efe42 clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation, clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64efe42)
#43 0x00005651c756637f void llvm::function_ref<void ()>::callback_fn<clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*)::'lambda'()>(long) SemaType.cpp:0:0
#44 0x00005651c6d9191f clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5d9191f)
#45 0x00005651c7570cfd clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6570cfd)
#46 0x00005651c7571115 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6571115)
#47 0x00005651c6dc508e clang::Sema::RequireCompleteDeclContext(clang::CXXScopeSpec&, clang::DeclContext*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5dc508e)
#48 0x00005651c73b7674 clang::Sema::LookupTemplateName(clang::LookupResult&, clang::Scope*, clang::CXXScopeSpec&, clang::QualType, bool, bool&, clang::Sema::RequiredTemplateKind, clang::Sema::AssumedTemplateKind*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x63b7674)
#49 0x00005651c73b89e6 clang::Sema::isTemplateName(clang::Scope*, clang::CXXScopeSpec&, bool, clang::UnqualifiedId const&, clang::OpaquePtr<clang::QualType>, bool, clang::OpaquePtr<clang::TemplateName>&, bool&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x63b89e6)
#50 0x00005651c6cefe88 clang::Parser::ParseOptionalCXXScopeSpecifier(clang::CXXScopeSpec&, clang::OpaquePtr<clang::QualType>, bool, bool, bool*, bool, clang::IdentifierInfo**, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cefe88)
#51 0x00005651c6c8f82c clang::Parser::TryAnnotateCXXScopeToken(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5c8f82c)
#52 0x00005651c6cb37a8 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cb37a8)
#53 0x00005651c6cb52f1 clang::Parser::ParseSpecifierQualifierList(clang::DeclSpec&, clang::AccessSpecifier, clang::Parser::DeclSpecContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cb52f1)
#54 0x00005651c6cb58b3 clang::Parser::ParseTypeName(clang::SourceRange*, clang::DeclaratorContext, clang::AccessSpecifier, clang::Decl**, clang::ParsedAttributes*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cb58b3)
#55 0x00005651c6cc8c12 clang::Parser::ParseAliasDeclarationAfterDeclarator(clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::Parser::UsingDeclarator&, clang::SourceLocation&, clang::AccessSpecifier, clang::ParsedAttributes&, clang::Decl**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cc8c12)
#56 0x00005651c6ccfa4c clang::Parser::ParseUsingDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ccfa4c)
#57 0x00005651c6cd0485 clang::Parser::ParseUsingDirectiveOrDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cd0485)
#58 0x00005651c6cbf678 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5cbf678)
#59 0x00005651c6c9649c clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5c9649c)
#60 0x00005651c6c97251 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5c97251)
#61 0x00005651c6c8cf7b clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5c8cf7b)
#62 0x00005651c5cd9970 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4cd9970)
#63 0x00005651c564e369 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x464e369)
#64 0x00005651c55e7eea clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45e7eea)
#65 0x00005651c571bdb3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x471bdb3)
#66 0x00005651c2452201 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x1452201)
#67 0x00005651c244b389 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#68 0x00005651c547b3d5 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#69 0x00005651c4b45ee3 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3b45ee3)
#70 0x00005651c547d766 clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x447d766)
#71 0x00005651c544c7f3 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x444c7f3)
#72 0x00005651c544d453 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+++0x444d453)
#73 0x00005651c5455abc clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4455abc)
#74 0x00005651c24504cc clang_main(int, char**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x14504cc)
#75 0x00007f8c6a17b0b3 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x240b3)
#76 0x00005651c244abfa _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x144abfa)
clang-15: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[mizvekov]

MR for fix: https://reviews.llvm.org/D128095

[mizvekov]

Fixed by b8a1b69

Note that the fix was implemented via https://reviews.llvm.org/D131802

Once https://reviews.llvm.org/D128095 is merged we will improve the diagnostics here to also include the mismatched outer parameter.