After 4b163e343cf, Assertion failed: (result && "no existing substitution for template name"), function mangleExistingSubstitution

[DimitryAndric]

As reported in https://bugs.freebsd.org/278333, clang 18 asserts on the audio/noise-suppression-for-voice-lv2 port, with:

Assertion failed: (result && "no existing substitution for template name"), function mangleExistingSubstitution, file /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp, line 6697.
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -cc1 -triple x86_64-unknown-freebsd15.0 -emit-obj -disable-free -clear-ast-before-backend -main-file-name RnNoiseLadspaPlugin.cpp -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -fcoverage-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -sys-header-deps -D rnnoise_ladspa_EXPORTS -D JUCE_CUSTOM_VST3_SDK=1 -D JUCE_CUSTOM_VST3_SDK=1 -D NDEBUG -O3 -std=gnu++14 -fdeprecated-macro -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x c++ RnNoiseLadspaPlugin-f211a9.cpp
1.      <eof> parser at end of file
2.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:884:30: instantiating function definition 'ladspa::builder<RnNoiseMono>::_instantiate<RnNoiseMono>'
3.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: instantiating function definition 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t<RnNoiseMono, nullptr>'
4.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: LLVM IR generation of declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
5.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: Mangling declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
 #0 0x0000000005aa5a41 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:13
 #1 0x0000000005aa3a35 llvm::sys::RunSignalHandlers() /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:106:18
 #2 0x0000000005aa6042 SignalHandler(int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3
 #3 0x000000082adb3440 handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
 #4 0x000000082adb29fb thr_sighandler /usr/src/lib/libthr/thread/thr_sig.c:244:1
 #5 0x00000008289f62d3 ([vdso]+0x2d3)
 #6 0x000000082f96519a thr_kill /usr/obj/usr/src/amd64.amd64/lib/libsys/thr_kill.S:4:0
 #7 0x000000082d641714 _raise /usr/src/lib/libc/gen/raise.c:0:10
 #8 0x000000082d6f4cc9 abort /usr/src/lib/libc/stdlib/abort.c:67:17
 #9 0x000000082d625091 (/lib/libc.so.7+0x9c091)
#10 0x0000000002aae818 (/usr/bin/clang+0x2aae818)
#11 0x0000000002aa9e3f (anonymous namespace)::CXXNameMangler::mangleUnresolvedTypeOrSimpleId(clang::QualType, llvm::StringRef) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:7
#12 0x0000000002aa988f (anonymous namespace)::CXXNameMangler::mangleUnresolvedPrefix(clang::NestedNameSpecifier*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:9
#13 0x0000000002aaa0fe (anonymous namespace)::CXXNameMangler::mangleUnresolvedName(clang::NestedNameSpecifier*, clang::DeclarationName, clang::TemplateArgumentLoc const*, unsigned int, unsigned int) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:18
#14 0x0000000002aa6be3 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#15 0x0000000002aac304 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#16 0x0000000002aae8d1 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef<clang::TemplateArgument>) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5994:24
#17 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::QualType) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#18 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::NestedNameSpecifier*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:2164:5
#19 0x0000000002aa0ccf clang::DependentNameType::getIdentifier() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Type.h:5951:12
#20 0x0000000002aa0ccf (anonymous namespace)::CXXNameMangler::mangleType(clang::DependentNameType const*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:4296:23
#21 0x0000000002a9cf09 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#22 0x0000000002a9ced9 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#23 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArg((anonymous namespace)::CXXNameMangler::TemplateArgManglingInfo&, unsigned int, clang::TemplateArgument) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#24 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, clang::TemplateArgumentList const&) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5983:5
#25 0x0000000002aafbc8 (anonymous namespace)::CXXNameMangler::mangleNestedName(clang::GlobalDecl, clang::DeclContext const*, llvm::SmallVector<llvm::StringRef, 4u> const*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:1802:3
#26 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::getDepth() const /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:256:14
#27 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::pop((anonymous namespace)::CXXNameMangler::FunctionTypeDepthState) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:279:7
#28 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:855:23
#29 0x0000000002a9816e llvm::DenseMap<llvm::StringRef, unsigned int, llvm::DenseMapInfo<llvm::StringRef, void>, llvm::detail::DenseMapPair<llvm::StringRef, unsigned int>>::~DenseMap() /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMap.h:782:23
#30 0x0000000002a9816e (anonymous namespace)::CXXNameMangler::~CXXNameMangler() /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:218:7
#31 0x0000000002a9816e (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#32 0x00000000027a7b4a std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>::__is_long[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1773:29
#33 0x00000000027a7b4a std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>::size[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1177:12
#34 0x00000000027a7b4a std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>::empty[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1217:12
#35 0x00000000027a7b4a isUniqueInternalLinkageDecl(clang::GlobalDecl, clang::CodeGen::CodeGenModule&) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1774:35
#36 0x00000000027a7b4a getMangledNameImpl(clang::CodeGen::CodeGenModule&, clang::GlobalDecl, clang::NamedDecl const*, bool) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1851:23
#37 0x000000000279fa4a clang::Decl::getKind() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclBase.h:447:51
#38 0x000000000279fa4a clang::FunctionDecl::classof(clang::Decl const*) /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:3004:62
#39 0x000000000279fa4a llvm::isa_impl<clang::FunctionDecl, clang::NamedDecl, void>::doit(clang::NamedDecl const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:64:53
#40 0x000000000279fa4a llvm::isa_impl_cl<clang::FunctionDecl, clang::NamedDecl const*>::doit(clang::NamedDecl const*) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:110:12
#41 0x000000000279fa4a llvm::isa_impl_wrap<clang::FunctionDecl, clang::NamedDecl const*, clang::NamedDecl const*>::doit(clang::NamedDecl const* const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:137:12
#42 0x000000000279fa4a llvm::isa_impl_wrap<clang::FunctionDecl, clang::NamedDecl const* const, clang::NamedDecl const*>::doit(clang::NamedDecl const* const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:127:12
#43 0x000000000279fa4a llvm::CastIsPossible<clang::FunctionDecl, clang::NamedDecl const*, void>::isPossible(clang::NamedDecl const* const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:255:12
#44 0x000000000279fa4a llvm::CastInfo<clang::FunctionDecl, clang::NamedDecl const* const, void>::isPossible(clang::NamedDecl const* const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:509:12
#45 0x000000000279fa4a bool llvm::isa<clang::FunctionDecl, clang::NamedDecl const*>(clang::NamedDecl const* const&) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:549:10
#46 0x000000000279fa4a clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1972:3
#47 0x00000000027b5d39 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:3822:27
#48 0x0000000002ceff84 clang::CXXMethodDecl::getParent() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclCXX.h:2180:46
#49 0x0000000002ceff84 (anonymous namespace)::ItaniumCXXABI::EmitCXXConstructors(clang::CXXConstructorDecl const*) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp:1661:11
#50 0x000000000315d47c (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ModuleBuilder.cpp:189:73
#51 0x00000000031539b6 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:208:7
#52 0x0000000004620d7f clang::Sema::LocalEagerInstantiationScope::perform() /usr/src/contrib/llvm-project/clang/include/clang/Sema/Sema.h:10200:22
#53 0x0000000004620d7f clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:5207:23
#54 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#55 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#56 0x0000000004620da8 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:0:24
#57 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#58 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#59 0x0000000003c45b1f llvm::TimeTraceScope::~TimeTraceScope() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/TimeProfiler.h:155:9
#60 0x0000000003c45b1f clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1089:3
#61 0x0000000003c462ad clang::Sema::ActOnEndOfTranslationUnit() /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1130:9
#62 0x0000000003aeff75 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) /usr/src/contrib/llvm-project/clang/lib/Parse/Parser.cpp:0:13
#63 0x0000000003aea32e clang::ParseAST(clang::Sema&, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Parse/ParseAST.cpp:162:5
#64 0x000000000341cc7f clang::FrontendAction::Execute() /usr/src/contrib/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1073:10
#65 0x000000000334d28d llvm::Error::getPtr() const /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:276:42
#66 0x000000000334d28d llvm::Error::operator bool() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:239:16
#67 0x000000000334d28d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /usr/src/contrib/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1057:23
#68 0x00000000034e7c1c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /usr/src/contrib/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:272:25
#69 0x0000000002729621 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /usr/src/contrib/llvm-project/clang/tools/driver/cc1_main.cpp:294:15
#70 0x00000000027389ab ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:365:12
#71 0x0000000002737a97 clang_main(int, char**, llvm::ToolContext const&) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:405:12
#72 0x00000000027351ad main /usr/src/usr.bin/clang/clang/clang-driver.cpp:17:10
#73 0x000000082d6165ea __libc_start1 /usr/src/lib/libc/csu/libc_start1.c:157:2
Abort trap

This regressed with 4b163e3 ("Implement mangling rules for C++20 concepts and requires-expressions") by @zygoloid, cc @erichkeane @AaronBallman @rjmccall .

Minimized test case:

// clang -cc1 -triple x86_64-- -S -std=gnu++14 RnNoiseLadspaPlugin-min.cpp
template <bool> struct enable_if;
template <class _Tp> struct array {
  _Tp __elems_;
};
typedef void LADSPA_Handle;
typedef struct {
  LADSPA_Handle (*instantiate)(const int *, unsigned long);
} LADSPA_Descriptor;
template <typename> struct has_ctor_1_args {
  static constexpr bool value = 0;
};
template <class T, template <class> class HaveClass>
using en_if_doesnt_have = enable_if<HaveClass<T>::value>;
struct plugin_holder_t {
  template <class _Plugin,
            en_if_doesnt_have<_Plugin, has_ctor_1_args> * = nullptr>
  plugin_holder_t(_Plugin, long) {}
};
template <class> struct builder {
  template <class>
  static LADSPA_Handle _instantiate(const int *, unsigned long s) {
    plugin_holder_t(int(), s);
  }
  static constexpr LADSPA_Descriptor descriptor_for_ladspa{_instantiate<int>};
  static const LADSPA_Descriptor &get_ladspa_descriptor();
};
template <class... Args> struct collection {
  struct caller {
    const LADSPA_Descriptor &(&callback)();
  };
  array<caller> init_callers() {
    return {builder<Args>::get_ladspa_descriptor...};
  }
  array<caller> callers = init_callers();
};
void ladspa_descriptor() { collection<int> get_ladspa_descriptor; }

[llvmbot]

@llvm/issue-subscribers-c-14

Author: Dimitry Andric (DimitryAndric)

As reported in https://bugs.freebsd.org/278333, clang 18 asserts on the `audio/noise-suppression-for-voice-lv2` port, with:

Assertion failed: (result && "no existing substitution for template name"), function mangleExistingSubstitution, file /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp, line 6697.
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -cc1 -triple x86_64-unknown-freebsd15.0 -emit-obj -disable-free -clear-ast-before-backend -main-file-name RnNoiseLadspaPlugin.cpp -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -fcoverage-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -sys-header-deps -D rnnoise_ladspa_EXPORTS -D JUCE_CUSTOM_VST3_SDK=1 -D JUCE_CUSTOM_VST3_SDK=1 -D NDEBUG -O3 -std=gnu++14 -fdeprecated-macro -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x c++ RnNoiseLadspaPlugin-f211a9.cpp
1.      <eof> parser at end of file
2.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:884:30: instantiating function definition 'ladspa::builder<RnNoiseMono>::_instantiate<RnNoiseMono>'
3.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: instantiating function definition 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t<RnNoiseMono, nullptr>'
4.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: LLVM IR generation of declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
5.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: Mangling declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
 #<!-- -->0 0x0000000005aa5a41 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:13
 #<!-- -->1 0x0000000005aa3a35 llvm::sys::RunSignalHandlers() /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:106:18
 #<!-- -->2 0x0000000005aa6042 SignalHandler(int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3
 #<!-- -->3 0x000000082adb3440 handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
 #<!-- -->4 0x000000082adb29fb thr_sighandler /usr/src/lib/libthr/thread/thr_sig.c:244:1
 #<!-- -->5 0x00000008289f62d3 ([vdso]+0x2d3)
 #<!-- -->6 0x000000082f96519a thr_kill /usr/obj/usr/src/amd64.amd64/lib/libsys/thr_kill.S:4:0
 #<!-- -->7 0x000000082d641714 _raise /usr/src/lib/libc/gen/raise.c:0:10
 #<!-- -->8 0x000000082d6f4cc9 abort /usr/src/lib/libc/stdlib/abort.c:67:17
 #<!-- -->9 0x000000082d625091 (/lib/libc.so.7+0x9c091)
#<!-- -->10 0x0000000002aae818 (/usr/bin/clang+0x2aae818)
#<!-- -->11 0x0000000002aa9e3f (anonymous namespace)::CXXNameMangler::mangleUnresolvedTypeOrSimpleId(clang::QualType, llvm::StringRef) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:7
#<!-- -->12 0x0000000002aa988f (anonymous namespace)::CXXNameMangler::mangleUnresolvedPrefix(clang::NestedNameSpecifier*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:9
#<!-- -->13 0x0000000002aaa0fe (anonymous namespace)::CXXNameMangler::mangleUnresolvedName(clang::NestedNameSpecifier*, clang::DeclarationName, clang::TemplateArgumentLoc const*, unsigned int, unsigned int) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:18
#<!-- -->14 0x0000000002aa6be3 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->15 0x0000000002aac304 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->16 0x0000000002aae8d1 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef&lt;clang::TemplateArgument&gt;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5994:24
#<!-- -->17 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::QualType) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->18 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::NestedNameSpecifier*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:2164:5
#<!-- -->19 0x0000000002aa0ccf clang::DependentNameType::getIdentifier() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Type.h:5951:12
#<!-- -->20 0x0000000002aa0ccf (anonymous namespace)::CXXNameMangler::mangleType(clang::DependentNameType const*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:4296:23
#<!-- -->21 0x0000000002a9cf09 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->22 0x0000000002a9ced9 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->23 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArg((anonymous namespace)::CXXNameMangler::TemplateArgManglingInfo&amp;, unsigned int, clang::TemplateArgument) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->24 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, clang::TemplateArgumentList const&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5983:5
#<!-- -->25 0x0000000002aafbc8 (anonymous namespace)::CXXNameMangler::mangleNestedName(clang::GlobalDecl, clang::DeclContext const*, llvm::SmallVector&lt;llvm::StringRef, 4u&gt; const*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:1802:3
#<!-- -->26 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::getDepth() const /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:256:14
#<!-- -->27 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::pop((anonymous namespace)::CXXNameMangler::FunctionTypeDepthState) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:279:7
#<!-- -->28 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:855:23
#<!-- -->29 0x0000000002a9816e llvm::DenseMap&lt;llvm::StringRef, unsigned int, llvm::DenseMapInfo&lt;llvm::StringRef, void&gt;, llvm::detail::DenseMapPair&lt;llvm::StringRef, unsigned int&gt;&gt;::~DenseMap() /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMap.h:782:23
#<!-- -->30 0x0000000002a9816e (anonymous namespace)::CXXNameMangler::~CXXNameMangler() /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:218:7
#<!-- -->31 0x0000000002a9816e (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->32 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::__is_long[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1773:29
#<!-- -->33 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::size[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1177:12
#<!-- -->34 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::empty[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1217:12
#<!-- -->35 0x00000000027a7b4a isUniqueInternalLinkageDecl(clang::GlobalDecl, clang::CodeGen::CodeGenModule&amp;) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1774:35
#<!-- -->36 0x00000000027a7b4a getMangledNameImpl(clang::CodeGen::CodeGenModule&amp;, clang::GlobalDecl, clang::NamedDecl const*, bool) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1851:23
#<!-- -->37 0x000000000279fa4a clang::Decl::getKind() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclBase.h:447:51
#<!-- -->38 0x000000000279fa4a clang::FunctionDecl::classof(clang::Decl const*) /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:3004:62
#<!-- -->39 0x000000000279fa4a llvm::isa_impl&lt;clang::FunctionDecl, clang::NamedDecl, void&gt;::doit(clang::NamedDecl const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:64:53
#<!-- -->40 0x000000000279fa4a llvm::isa_impl_cl&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const*) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:110:12
#<!-- -->41 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const*, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:137:12
#<!-- -->42 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const* const, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:127:12
#<!-- -->43 0x000000000279fa4a llvm::CastIsPossible&lt;clang::FunctionDecl, clang::NamedDecl const*, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:255:12
#<!-- -->44 0x000000000279fa4a llvm::CastInfo&lt;clang::FunctionDecl, clang::NamedDecl const* const, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:509:12
#<!-- -->45 0x000000000279fa4a bool llvm::isa&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:549:10
#<!-- -->46 0x000000000279fa4a clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1972:3
#<!-- -->47 0x00000000027b5d39 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:3822:27
#<!-- -->48 0x0000000002ceff84 clang::CXXMethodDecl::getParent() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclCXX.h:2180:46
#<!-- -->49 0x0000000002ceff84 (anonymous namespace)::ItaniumCXXABI::EmitCXXConstructors(clang::CXXConstructorDecl const*) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp:1661:11
#<!-- -->50 0x000000000315d47c (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ModuleBuilder.cpp:189:73
#<!-- -->51 0x00000000031539b6 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:208:7
#<!-- -->52 0x0000000004620d7f clang::Sema::LocalEagerInstantiationScope::perform() /usr/src/contrib/llvm-project/clang/include/clang/Sema/Sema.h:10200:22
#<!-- -->53 0x0000000004620d7f clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:5207:23
#<!-- -->54 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->55 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->56 0x0000000004620da8 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:0:24
#<!-- -->57 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->58 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->59 0x0000000003c45b1f llvm::TimeTraceScope::~TimeTraceScope() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/TimeProfiler.h:155:9
#<!-- -->60 0x0000000003c45b1f clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1089:3
#<!-- -->61 0x0000000003c462ad clang::Sema::ActOnEndOfTranslationUnit() /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1130:9
#<!-- -->62 0x0000000003aeff75 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) /usr/src/contrib/llvm-project/clang/lib/Parse/Parser.cpp:0:13
#<!-- -->63 0x0000000003aea32e clang::ParseAST(clang::Sema&amp;, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Parse/ParseAST.cpp:162:5
#<!-- -->64 0x000000000341cc7f clang::FrontendAction::Execute() /usr/src/contrib/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1073:10
#<!-- -->65 0x000000000334d28d llvm::Error::getPtr() const /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:276:42
#<!-- -->66 0x000000000334d28d llvm::Error::operator bool() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:239:16
#<!-- -->67 0x000000000334d28d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) /usr/src/contrib/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1057:23
#<!-- -->68 0x00000000034e7c1c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /usr/src/contrib/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:272:25
#<!-- -->69 0x0000000002729621 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) /usr/src/contrib/llvm-project/clang/tools/driver/cc1_main.cpp:294:15
#<!-- -->70 0x00000000027389ab ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:365:12
#<!-- -->71 0x0000000002737a97 clang_main(int, char**, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:405:12
#<!-- -->72 0x00000000027351ad main /usr/src/usr.bin/clang/clang/clang-driver.cpp:17:10
#<!-- -->73 0x000000082d6165ea __libc_start1 /usr/src/lib/libc/csu/libc_start1.c:157:2
Abort trap

This regressed with 4b163e3 ("Implement mangling rules for C++20 concepts and requires-expressions") by @zygoloid, cc @erichkeane @AaronBallman @rjmccall .

Minimized test case:

// clang -cc1 -triple x86_64-- -S -std=gnu++14 RnNoiseLadspaPlugin-min.cpp
template <bool> struct enable_if;
template <class _Tp> struct array {
  _Tp __elems_;
};
typedef void LADSPA_Handle;
typedef struct {
  LADSPA_Handle (*instantiate)(const int *, unsigned long);
} LADSPA_Descriptor;
template <typename> struct has_ctor_1_args {
  static constexpr bool value = 0;
};
template <class T, template <class> class HaveClass>
using en_if_doesnt_have = enable_if<HaveClass<T>::value>;
struct plugin_holder_t {
  template <class _Plugin,
            en_if_doesnt_have<_Plugin, has_ctor_1_args> * = nullptr>
  plugin_holder_t(_Plugin, long) {}
};
template <class> struct builder {
  template <class>
  static LADSPA_Handle _instantiate(const int *, unsigned long s) {
    plugin_holder_t(int(), s);
  }
  static constexpr LADSPA_Descriptor descriptor_for_ladspa{_instantiate<int>};
  static const LADSPA_Descriptor &get_ladspa_descriptor();
};
template <class... Args> struct collection {
  struct caller {
    const LADSPA_Descriptor &(&callback)();
  };
  array<caller> init_callers() {
    return {builder<Args>::get_ladspa_descriptor...};
  }
  array<caller> callers = init_callers();
};
void ladspa_descriptor() { collection<int> get_ladspa_descriptor; }

[llvmbot]

@llvm/issue-subscribers-c-20

Author: Dimitry Andric (DimitryAndric)

As reported in https://bugs.freebsd.org/278333, clang 18 asserts on the `audio/noise-suppression-for-voice-lv2` port, with:

Assertion failed: (result && "no existing substitution for template name"), function mangleExistingSubstitution, file /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp, line 6697.
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -cc1 -triple x86_64-unknown-freebsd15.0 -emit-obj -disable-free -clear-ast-before-backend -main-file-name RnNoiseLadspaPlugin.cpp -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -fcoverage-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -sys-header-deps -D rnnoise_ladspa_EXPORTS -D JUCE_CUSTOM_VST3_SDK=1 -D JUCE_CUSTOM_VST3_SDK=1 -D NDEBUG -O3 -std=gnu++14 -fdeprecated-macro -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x c++ RnNoiseLadspaPlugin-f211a9.cpp
1.      <eof> parser at end of file
2.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:884:30: instantiating function definition 'ladspa::builder<RnNoiseMono>::_instantiate<RnNoiseMono>'
3.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: instantiating function definition 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t<RnNoiseMono, nullptr>'
4.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: LLVM IR generation of declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
5.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: Mangling declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
 #<!-- -->0 0x0000000005aa5a41 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:13
 #<!-- -->1 0x0000000005aa3a35 llvm::sys::RunSignalHandlers() /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:106:18
 #<!-- -->2 0x0000000005aa6042 SignalHandler(int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3
 #<!-- -->3 0x000000082adb3440 handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
 #<!-- -->4 0x000000082adb29fb thr_sighandler /usr/src/lib/libthr/thread/thr_sig.c:244:1
 #<!-- -->5 0x00000008289f62d3 ([vdso]+0x2d3)
 #<!-- -->6 0x000000082f96519a thr_kill /usr/obj/usr/src/amd64.amd64/lib/libsys/thr_kill.S:4:0
 #<!-- -->7 0x000000082d641714 _raise /usr/src/lib/libc/gen/raise.c:0:10
 #<!-- -->8 0x000000082d6f4cc9 abort /usr/src/lib/libc/stdlib/abort.c:67:17
 #<!-- -->9 0x000000082d625091 (/lib/libc.so.7+0x9c091)
#<!-- -->10 0x0000000002aae818 (/usr/bin/clang+0x2aae818)
#<!-- -->11 0x0000000002aa9e3f (anonymous namespace)::CXXNameMangler::mangleUnresolvedTypeOrSimpleId(clang::QualType, llvm::StringRef) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:7
#<!-- -->12 0x0000000002aa988f (anonymous namespace)::CXXNameMangler::mangleUnresolvedPrefix(clang::NestedNameSpecifier*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:9
#<!-- -->13 0x0000000002aaa0fe (anonymous namespace)::CXXNameMangler::mangleUnresolvedName(clang::NestedNameSpecifier*, clang::DeclarationName, clang::TemplateArgumentLoc const*, unsigned int, unsigned int) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:18
#<!-- -->14 0x0000000002aa6be3 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->15 0x0000000002aac304 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->16 0x0000000002aae8d1 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef&lt;clang::TemplateArgument&gt;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5994:24
#<!-- -->17 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::QualType) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->18 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::NestedNameSpecifier*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:2164:5
#<!-- -->19 0x0000000002aa0ccf clang::DependentNameType::getIdentifier() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Type.h:5951:12
#<!-- -->20 0x0000000002aa0ccf (anonymous namespace)::CXXNameMangler::mangleType(clang::DependentNameType const*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:4296:23
#<!-- -->21 0x0000000002a9cf09 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->22 0x0000000002a9ced9 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->23 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArg((anonymous namespace)::CXXNameMangler::TemplateArgManglingInfo&amp;, unsigned int, clang::TemplateArgument) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->24 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, clang::TemplateArgumentList const&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5983:5
#<!-- -->25 0x0000000002aafbc8 (anonymous namespace)::CXXNameMangler::mangleNestedName(clang::GlobalDecl, clang::DeclContext const*, llvm::SmallVector&lt;llvm::StringRef, 4u&gt; const*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:1802:3
#<!-- -->26 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::getDepth() const /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:256:14
#<!-- -->27 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::pop((anonymous namespace)::CXXNameMangler::FunctionTypeDepthState) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:279:7
#<!-- -->28 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:855:23
#<!-- -->29 0x0000000002a9816e llvm::DenseMap&lt;llvm::StringRef, unsigned int, llvm::DenseMapInfo&lt;llvm::StringRef, void&gt;, llvm::detail::DenseMapPair&lt;llvm::StringRef, unsigned int&gt;&gt;::~DenseMap() /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMap.h:782:23
#<!-- -->30 0x0000000002a9816e (anonymous namespace)::CXXNameMangler::~CXXNameMangler() /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:218:7
#<!-- -->31 0x0000000002a9816e (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->32 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::__is_long[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1773:29
#<!-- -->33 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::size[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1177:12
#<!-- -->34 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::empty[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1217:12
#<!-- -->35 0x00000000027a7b4a isUniqueInternalLinkageDecl(clang::GlobalDecl, clang::CodeGen::CodeGenModule&amp;) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1774:35
#<!-- -->36 0x00000000027a7b4a getMangledNameImpl(clang::CodeGen::CodeGenModule&amp;, clang::GlobalDecl, clang::NamedDecl const*, bool) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1851:23
#<!-- -->37 0x000000000279fa4a clang::Decl::getKind() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclBase.h:447:51
#<!-- -->38 0x000000000279fa4a clang::FunctionDecl::classof(clang::Decl const*) /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:3004:62
#<!-- -->39 0x000000000279fa4a llvm::isa_impl&lt;clang::FunctionDecl, clang::NamedDecl, void&gt;::doit(clang::NamedDecl const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:64:53
#<!-- -->40 0x000000000279fa4a llvm::isa_impl_cl&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const*) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:110:12
#<!-- -->41 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const*, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:137:12
#<!-- -->42 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const* const, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:127:12
#<!-- -->43 0x000000000279fa4a llvm::CastIsPossible&lt;clang::FunctionDecl, clang::NamedDecl const*, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:255:12
#<!-- -->44 0x000000000279fa4a llvm::CastInfo&lt;clang::FunctionDecl, clang::NamedDecl const* const, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:509:12
#<!-- -->45 0x000000000279fa4a bool llvm::isa&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:549:10
#<!-- -->46 0x000000000279fa4a clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1972:3
#<!-- -->47 0x00000000027b5d39 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:3822:27
#<!-- -->48 0x0000000002ceff84 clang::CXXMethodDecl::getParent() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclCXX.h:2180:46
#<!-- -->49 0x0000000002ceff84 (anonymous namespace)::ItaniumCXXABI::EmitCXXConstructors(clang::CXXConstructorDecl const*) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp:1661:11
#<!-- -->50 0x000000000315d47c (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ModuleBuilder.cpp:189:73
#<!-- -->51 0x00000000031539b6 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:208:7
#<!-- -->52 0x0000000004620d7f clang::Sema::LocalEagerInstantiationScope::perform() /usr/src/contrib/llvm-project/clang/include/clang/Sema/Sema.h:10200:22
#<!-- -->53 0x0000000004620d7f clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:5207:23
#<!-- -->54 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->55 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->56 0x0000000004620da8 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:0:24
#<!-- -->57 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->58 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->59 0x0000000003c45b1f llvm::TimeTraceScope::~TimeTraceScope() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/TimeProfiler.h:155:9
#<!-- -->60 0x0000000003c45b1f clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1089:3
#<!-- -->61 0x0000000003c462ad clang::Sema::ActOnEndOfTranslationUnit() /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1130:9
#<!-- -->62 0x0000000003aeff75 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) /usr/src/contrib/llvm-project/clang/lib/Parse/Parser.cpp:0:13
#<!-- -->63 0x0000000003aea32e clang::ParseAST(clang::Sema&amp;, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Parse/ParseAST.cpp:162:5
#<!-- -->64 0x000000000341cc7f clang::FrontendAction::Execute() /usr/src/contrib/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1073:10
#<!-- -->65 0x000000000334d28d llvm::Error::getPtr() const /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:276:42
#<!-- -->66 0x000000000334d28d llvm::Error::operator bool() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:239:16
#<!-- -->67 0x000000000334d28d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) /usr/src/contrib/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1057:23
#<!-- -->68 0x00000000034e7c1c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /usr/src/contrib/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:272:25
#<!-- -->69 0x0000000002729621 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) /usr/src/contrib/llvm-project/clang/tools/driver/cc1_main.cpp:294:15
#<!-- -->70 0x00000000027389ab ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:365:12
#<!-- -->71 0x0000000002737a97 clang_main(int, char**, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:405:12
#<!-- -->72 0x00000000027351ad main /usr/src/usr.bin/clang/clang/clang-driver.cpp:17:10
#<!-- -->73 0x000000082d6165ea __libc_start1 /usr/src/lib/libc/csu/libc_start1.c:157:2
Abort trap

This regressed with 4b163e3 ("Implement mangling rules for C++20 concepts and requires-expressions") by @zygoloid, cc @erichkeane @AaronBallman @rjmccall .

Minimized test case:

// clang -cc1 -triple x86_64-- -S -std=gnu++14 RnNoiseLadspaPlugin-min.cpp
template <bool> struct enable_if;
template <class _Tp> struct array {
  _Tp __elems_;
};
typedef void LADSPA_Handle;
typedef struct {
  LADSPA_Handle (*instantiate)(const int *, unsigned long);
} LADSPA_Descriptor;
template <typename> struct has_ctor_1_args {
  static constexpr bool value = 0;
};
template <class T, template <class> class HaveClass>
using en_if_doesnt_have = enable_if<HaveClass<T>::value>;
struct plugin_holder_t {
  template <class _Plugin,
            en_if_doesnt_have<_Plugin, has_ctor_1_args> * = nullptr>
  plugin_holder_t(_Plugin, long) {}
};
template <class> struct builder {
  template <class>
  static LADSPA_Handle _instantiate(const int *, unsigned long s) {
    plugin_holder_t(int(), s);
  }
  static constexpr LADSPA_Descriptor descriptor_for_ladspa{_instantiate<int>};
  static const LADSPA_Descriptor &get_ladspa_descriptor();
};
template <class... Args> struct collection {
  struct caller {
    const LADSPA_Descriptor &(&callback)();
  };
  array<caller> init_callers() {
    return {builder<Args>::get_ladspa_descriptor...};
  }
  array<caller> callers = init_callers();
};
void ladspa_descriptor() { collection<int> get_ladspa_descriptor; }

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Dimitry Andric (DimitryAndric)

As reported in https://bugs.freebsd.org/278333, clang 18 asserts on the `audio/noise-suppression-for-voice-lv2` port, with:

Assertion failed: (result && "no existing substitution for template name"), function mangleExistingSubstitution, file /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp, line 6697.
PLEASE submit a bug report to https://bugs.freebsd.org/submit/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -cc1 -triple x86_64-unknown-freebsd15.0 -emit-obj -disable-free -clear-ast-before-backend -main-file-name RnNoiseLadspaPlugin.cpp -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -fcoverage-compilation-dir=/wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/.build -sys-header-deps -D rnnoise_ladspa_EXPORTS -D JUCE_CUSTOM_VST3_SDK=1 -D JUCE_CUSTOM_VST3_SDK=1 -D NDEBUG -O3 -std=gnu++14 -fdeprecated-macro -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -x c++ RnNoiseLadspaPlugin-f211a9.cpp
1.      <eof> parser at end of file
2.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:884:30: instantiating function definition 'ladspa::builder<RnNoiseMono>::_instantiate<RnNoiseMono>'
3.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: instantiating function definition 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t<RnNoiseMono, nullptr>'
4.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: LLVM IR generation of declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
5.      /wrkdirs/share/dim/ports/audio/noise-suppression-for-voice-lv2/work/noise-suppression-for-voice-1.03/src/ladspa_plugin/ladspa++.h:823:9: Mangling declaration 'ladspa::plugin_holder_t<RnNoiseMono>::plugin_holder_t'
 #<!-- -->0 0x0000000005aa5a41 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:723:13
 #<!-- -->1 0x0000000005aa3a35 llvm::sys::RunSignalHandlers() /usr/src/contrib/llvm-project/llvm/lib/Support/Signals.cpp:106:18
 #<!-- -->2 0x0000000005aa6042 SignalHandler(int) /usr/src/contrib/llvm-project/llvm/lib/Support/Unix/Signals.inc:0:3
 #<!-- -->3 0x000000082adb3440 handle_signal /usr/src/lib/libthr/thread/thr_sig.c:0:3
 #<!-- -->4 0x000000082adb29fb thr_sighandler /usr/src/lib/libthr/thread/thr_sig.c:244:1
 #<!-- -->5 0x00000008289f62d3 ([vdso]+0x2d3)
 #<!-- -->6 0x000000082f96519a thr_kill /usr/obj/usr/src/amd64.amd64/lib/libsys/thr_kill.S:4:0
 #<!-- -->7 0x000000082d641714 _raise /usr/src/lib/libc/gen/raise.c:0:10
 #<!-- -->8 0x000000082d6f4cc9 abort /usr/src/lib/libc/stdlib/abort.c:67:17
 #<!-- -->9 0x000000082d625091 (/lib/libc.so.7+0x9c091)
#<!-- -->10 0x0000000002aae818 (/usr/bin/clang+0x2aae818)
#<!-- -->11 0x0000000002aa9e3f (anonymous namespace)::CXXNameMangler::mangleUnresolvedTypeOrSimpleId(clang::QualType, llvm::StringRef) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:7
#<!-- -->12 0x0000000002aa988f (anonymous namespace)::CXXNameMangler::mangleUnresolvedPrefix(clang::NestedNameSpecifier*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:9
#<!-- -->13 0x0000000002aaa0fe (anonymous namespace)::CXXNameMangler::mangleUnresolvedName(clang::NestedNameSpecifier*, clang::DeclarationName, clang::TemplateArgumentLoc const*, unsigned int, unsigned int) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:18
#<!-- -->14 0x0000000002aa6be3 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->15 0x0000000002aac304 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->16 0x0000000002aae8d1 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef&lt;clang::TemplateArgument&gt;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5994:24
#<!-- -->17 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::QualType) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->18 0x0000000002ab44d6 (anonymous namespace)::CXXNameMangler::manglePrefix(clang::NestedNameSpecifier*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:2164:5
#<!-- -->19 0x0000000002aa0ccf clang::DependentNameType::getIdentifier() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Type.h:5951:12
#<!-- -->20 0x0000000002aa0ccf (anonymous namespace)::CXXNameMangler::mangleType(clang::DependentNameType const*) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:4296:23
#<!-- -->21 0x0000000002a9cf09 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->22 0x0000000002a9ced9 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) /usr/obj/usr/src/amd64.amd64/lib/clang/libclang/clang/AST/TypeNodes.inc:0:1
#<!-- -->23 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArg((anonymous namespace)::CXXNameMangler::TemplateArgManglingInfo&amp;, unsigned int, clang::TemplateArgument) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:5
#<!-- -->24 0x0000000002ab1402 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, clang::TemplateArgumentList const&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:5983:5
#<!-- -->25 0x0000000002aafbc8 (anonymous namespace)::CXXNameMangler::mangleNestedName(clang::GlobalDecl, clang::DeclContext const*, llvm::SmallVector&lt;llvm::StringRef, 4u&gt; const*, bool) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:1802:3
#<!-- -->26 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::getDepth() const /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:256:14
#<!-- -->27 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::FunctionTypeDepthState::pop((anonymous namespace)::CXXNameMangler::FunctionTypeDepthState) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:279:7
#<!-- -->28 0x0000000002a9b157 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:855:23
#<!-- -->29 0x0000000002a9816e llvm::DenseMap&lt;llvm::StringRef, unsigned int, llvm::DenseMapInfo&lt;llvm::StringRef, void&gt;, llvm::detail::DenseMapPair&lt;llvm::StringRef, unsigned int&gt;&gt;::~DenseMap() /usr/src/contrib/llvm-project/llvm/include/llvm/ADT/DenseMap.h:782:23
#<!-- -->30 0x0000000002a9816e (anonymous namespace)::CXXNameMangler::~CXXNameMangler() /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:218:7
#<!-- -->31 0x0000000002a9816e (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&amp;) /usr/src/contrib/llvm-project/clang/lib/AST/ItaniumMangle.cpp:0:0
#<!-- -->32 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::__is_long[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1773:29
#<!-- -->33 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::size[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1177:12
#<!-- -->34 0x00000000027a7b4a std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt;&gt;::empty[abi:sn180100]() const /usr/obj/usr/src/amd64.amd64/tmp/usr/include/c++/v1/string:1217:12
#<!-- -->35 0x00000000027a7b4a isUniqueInternalLinkageDecl(clang::GlobalDecl, clang::CodeGen::CodeGenModule&amp;) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1774:35
#<!-- -->36 0x00000000027a7b4a getMangledNameImpl(clang::CodeGen::CodeGenModule&amp;, clang::GlobalDecl, clang::NamedDecl const*, bool) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1851:23
#<!-- -->37 0x000000000279fa4a clang::Decl::getKind() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclBase.h:447:51
#<!-- -->38 0x000000000279fa4a clang::FunctionDecl::classof(clang::Decl const*) /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:3004:62
#<!-- -->39 0x000000000279fa4a llvm::isa_impl&lt;clang::FunctionDecl, clang::NamedDecl, void&gt;::doit(clang::NamedDecl const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:64:53
#<!-- -->40 0x000000000279fa4a llvm::isa_impl_cl&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const*) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:110:12
#<!-- -->41 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const*, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:137:12
#<!-- -->42 0x000000000279fa4a llvm::isa_impl_wrap&lt;clang::FunctionDecl, clang::NamedDecl const* const, clang::NamedDecl const*&gt;::doit(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:127:12
#<!-- -->43 0x000000000279fa4a llvm::CastIsPossible&lt;clang::FunctionDecl, clang::NamedDecl const*, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:255:12
#<!-- -->44 0x000000000279fa4a llvm::CastInfo&lt;clang::FunctionDecl, clang::NamedDecl const* const, void&gt;::isPossible(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:509:12
#<!-- -->45 0x000000000279fa4a bool llvm::isa&lt;clang::FunctionDecl, clang::NamedDecl const*&gt;(clang::NamedDecl const* const&amp;) /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Casting.h:549:10
#<!-- -->46 0x000000000279fa4a clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:1972:3
#<!-- -->47 0x00000000027b5d39 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenModule.cpp:3822:27
#<!-- -->48 0x0000000002ceff84 clang::CXXMethodDecl::getParent() const /usr/src/contrib/llvm-project/clang/include/clang/AST/DeclCXX.h:2180:46
#<!-- -->49 0x0000000002ceff84 (anonymous namespace)::ItaniumCXXABI::EmitCXXConstructors(clang::CXXConstructorDecl const*) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ItaniumCXXABI.cpp:1661:11
#<!-- -->50 0x000000000315d47c (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/ModuleBuilder.cpp:189:73
#<!-- -->51 0x00000000031539b6 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) /usr/src/contrib/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:208:7
#<!-- -->52 0x0000000004620d7f clang::Sema::LocalEagerInstantiationScope::perform() /usr/src/contrib/llvm-project/clang/include/clang/Sema/Sema.h:10200:22
#<!-- -->53 0x0000000004620d7f clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:5207:23
#<!-- -->54 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->55 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->56 0x0000000004620da8 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:0:24
#<!-- -->57 0x0000000004623b52 clang::FunctionDecl::isDefined() const /usr/src/contrib/llvm-project/clang/include/clang/AST/Decl.h:2222:12
#<!-- -->58 0x0000000004623b52 clang::Sema::PerformPendingInstantiations(bool) /usr/src/contrib/llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6446:23
#<!-- -->59 0x0000000003c45b1f llvm::TimeTraceScope::~TimeTraceScope() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/TimeProfiler.h:155:9
#<!-- -->60 0x0000000003c45b1f clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1089:3
#<!-- -->61 0x0000000003c462ad clang::Sema::ActOnEndOfTranslationUnit() /usr/src/contrib/llvm-project/clang/lib/Sema/Sema.cpp:1130:9
#<!-- -->62 0x0000000003aeff75 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) /usr/src/contrib/llvm-project/clang/lib/Parse/Parser.cpp:0:13
#<!-- -->63 0x0000000003aea32e clang::ParseAST(clang::Sema&amp;, bool, bool) /usr/src/contrib/llvm-project/clang/lib/Parse/ParseAST.cpp:162:5
#<!-- -->64 0x000000000341cc7f clang::FrontendAction::Execute() /usr/src/contrib/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1073:10
#<!-- -->65 0x000000000334d28d llvm::Error::getPtr() const /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:276:42
#<!-- -->66 0x000000000334d28d llvm::Error::operator bool() /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:239:16
#<!-- -->67 0x000000000334d28d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) /usr/src/contrib/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1057:23
#<!-- -->68 0x00000000034e7c1c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /usr/src/contrib/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:272:25
#<!-- -->69 0x0000000002729621 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) /usr/src/contrib/llvm-project/clang/tools/driver/cc1_main.cpp:294:15
#<!-- -->70 0x00000000027389ab ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:365:12
#<!-- -->71 0x0000000002737a97 clang_main(int, char**, llvm::ToolContext const&amp;) /usr/src/contrib/llvm-project/clang/tools/driver/driver.cpp:405:12
#<!-- -->72 0x00000000027351ad main /usr/src/usr.bin/clang/clang/clang-driver.cpp:17:10
#<!-- -->73 0x000000082d6165ea __libc_start1 /usr/src/lib/libc/csu/libc_start1.c:157:2
Abort trap

This regressed with 4b163e3 ("Implement mangling rules for C++20 concepts and requires-expressions") by @zygoloid, cc @erichkeane @AaronBallman @rjmccall .

Minimized test case:

// clang -cc1 -triple x86_64-- -S -std=gnu++14 RnNoiseLadspaPlugin-min.cpp
template <bool> struct enable_if;
template <class _Tp> struct array {
  _Tp __elems_;
};
typedef void LADSPA_Handle;
typedef struct {
  LADSPA_Handle (*instantiate)(const int *, unsigned long);
} LADSPA_Descriptor;
template <typename> struct has_ctor_1_args {
  static constexpr bool value = 0;
};
template <class T, template <class> class HaveClass>
using en_if_doesnt_have = enable_if<HaveClass<T>::value>;
struct plugin_holder_t {
  template <class _Plugin,
            en_if_doesnt_have<_Plugin, has_ctor_1_args> * = nullptr>
  plugin_holder_t(_Plugin, long) {}
};
template <class> struct builder {
  template <class>
  static LADSPA_Handle _instantiate(const int *, unsigned long s) {
    plugin_holder_t(int(), s);
  }
  static constexpr LADSPA_Descriptor descriptor_for_ladspa{_instantiate<int>};
  static const LADSPA_Descriptor &get_ladspa_descriptor();
};
template <class... Args> struct collection {
  struct caller {
    const LADSPA_Descriptor &(&callback)();
  };
  array<caller> init_callers() {
    return {builder<Args>::get_ladspa_descriptor...};
  }
  array<caller> callers = init_callers();
};
void ladspa_descriptor() { collection<int> get_ladspa_descriptor; }

[DimitryAndric]

If there's no movement on this issue, can we revert 4b163e3 for now?

[cor3ntin]

@zygoloid

[zygoloid]

If there's no movement on this issue, can we revert 4b163e3 for now?

I don't think that would be a good idea -- it would introduce a lot of ABI churn to revert and then later reapply an ABI change we've already shipped.

Can you work around this with -fclang-abi-compat=17?

[DimitryAndric]

-fclang-abi-compat=17 makes both the reduced and the original full test case work, so I guess for the FreeBSD port that is a good enough workaround. But it would be nice to have the assertion fixed at some point. :)

[zygoloid]

If someone wants to take a look, here's a further reduced testcase:

template<bool> struct A;

template<typename> struct B {
  static constexpr bool value = 0;
};

template<class T, template <class> class TT>
  using C = A<TT<T>::value>;

template<class T, C<T, B>* = nullptr> void f() {}

template void f<int>();

[zygoloid]

A clue:

template<bool> struct A;

template<typename> struct B {
  static constexpr bool value = false;
};

template<
#if BAD
    class T,
#endif
    template <class> class TT>
  using C = A<TT<int>::value>;

template<template<class> class TT,
         C<
#if BAD
           int,
#endif
           TT>* = nullptr> void f() {}

template void f<B>();

... crashes with #define BAD but not without. This probably suggests some confusion between the template parameters of C and the template parameters of one of the other involved templates in mangling, likely because expansion of the alias template has muddled together template parameter references into different templates.

[zyn0217]

Seems to have been fixed somewhere in trunk https://gcc.godbolt.org/z/KWvhen5TW

@mizvekov related to any of your patches?

[DimitryAndric]

It looks like llvmorg-20-init-01320-g7f78f99 fixed this. Would be a good candidate to merge to the 19.x branch, unless the revisions before that are prerequisites?