[18 regression] Assertion `!T->isDependentType() && "should not see dependent types here"' failed.

[berolinux]

Test case extracted from qtwebengine 6.7.0-beta2:

$ clang++ -std=c++20 testcase.cpp
clang-18: /home/bero/abf/llvm/BUILD/llvm-project-release-18.x/build/tools/clang/include/clang/AST/TypeNodes.inc:36: TypeInfo clang::ASTContext::getTypeInfoImpl(const Type *) const: Assertion `!T->isDependentType() && "should not see dependent types here"' 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: /usr/bin/clang-18 -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name testcase.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/tmp -fcoverage-compilation-dir=/tmp -resource-dir /usr/lib64/clang/18 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-openmandriva-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/backward -internal-isystem /usr/lib64/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../x86_64-openmandriva-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++20 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=13.1.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/testcase-1cf133.o -x c++ testcase.cpp
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      testcase.cpp:6:6: Generating code for declaration 'construct_at'
 #0 0x00007f0d0238e916 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib64/libLLVM-18.so+0x458e916)
 #1 0x00007f0d0238d58a llvm::sys::RunSignalHandlers() (/usr/lib64/libLLVM-18.so+0x458d58a)
 #2 0x00007f0d0238e234 (/usr/lib64/libLLVM-18.so+0x458e234)
 #3 0x00007f0cfd855700 (/usr/lib64/libc.so.6+0x3d700)
 #4 0x00007f0cfd8a49cc (/usr/lib64/libc.so.6+0x8c9cc)
 #5 0x00007f0cfd855652 gsignal (/usr/lib64/libc.so.6+0x3d652)
 #6 0x00007f0cfd83e4ad abort (/usr/lib64/libc.so.6+0x264ad)
 #7 0x00007f0cfd83e3d5 (/usr/lib64/libc.so.6+0x263d5)
 #8 0x00007f0cfd84e042 (/usr/lib64/libc.so.6+0x36042)
 #9 0x00007f0d093767ce clang::ASTContext::getTypeInfoImpl(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x19767ce)
#10 0x00007f0d09376f31 clang::ASTContext::getTypeInfo(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x1976f31)
#11 0x00007f0d0a9e4f42 clang::CodeGen::CodeGenFunction::CreateIRTemp(clang::QualType, llvm::Twine const&) (/usr/lib64/libclang-cpp.so.18+0x2fe4f42)
#12 0x00007f0d0ac29ffe clang::CodeGen::CodeGenFunction::StartFunction(clang::GlobalDecl, clang::QualType, llvm::Function*, clang::CodeGen::CGFunctionInfo const&, clang::CodeGen::FunctionArgList const&, clang::SourceLocation, clang::SourceLocation) (/usr/lib64/libclang-cpp.so.18+0x3229ffe)
#13 0x00007f0d0ac2cc99 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/usr/lib64/libclang-cpp.so.18+0x322cc99)
#14 0x00007f0d0ac770fe clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32770fe)
#15 0x00007f0d0ac764ca clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32764ca)
#16 0x00007f0d0ac4483f clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324483f)
#17 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#18 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#19 0x00007f0d0ac417ab clang::CodeGen::CodeGenModule::Release() (/usr/lib64/libclang-cpp.so.18+0x32417ab)
#20 0x00007f0d0ad0b364 (/usr/lib64/libclang-cpp.so.18+0x330b364)
#21 0x00007f0d0ac18830 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/usr/lib64/libclang-cpp.so.18+0x3218830)
#22 0x00007f0d09245416 clang::ParseAST(clang::Sema&, bool, bool) (/usr/lib64/libclang-cpp.so.18+0x1845416)
#23 0x00007f0d0b77d34b clang::FrontendAction::Execute() (/usr/lib64/libclang-cpp.so.18+0x3d7d34b)
#24 0x00007f0d0b6e1799 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/usr/lib64/libclang-cpp.so.18+0x3ce1799)
#25 0x00007f0d0b7fc71a clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib64/libclang-cpp.so.18+0x3dfc71a)
#26 0x0000560e96d84096 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/usr/bin/clang-18+0x17096)
#27 0x0000560e96d7fd4f (/usr/bin/clang-18+0x12d4f)
#28 0x0000560e96d7e61b clang_main(int, char**, llvm::ToolContext const&) (/usr/bin/clang-18+0x1161b)
#29 0x0000560e96d8ef96 main (/usr/bin/clang-18+0x21f96)
#30 0x00007f0cfd83fc0a (/usr/lib64/libc.so.6+0x27c0a)
#31 0x00007f0cfd83fcc5 __libc_start_main (/usr/lib64/libc.so.6+0x27cc5)
#32 0x0000560e96d7bed1 _start (/usr/bin/clang-18+0xeed1)

Test case

struct BasicPersistent;
template <typename> BasicPersistent &&__declval(int);
template <typename _Tp> auto declval() -> decltype(__declval<_Tp>(0));
template <typename _Tp> _Tp forward;
template <typename _Tp, typename... _Args>
auto construct_at(_Tp *, _Args...) -> decltype(new _Tp(declval<_Args>()...)) {return 0;}
template <typename> struct allocator;
template <typename> struct allocator_traits;
template <typename _Tp> struct allocator_traits<allocator<_Tp>> {
  using pointer = _Tp *;
  template <typename _Up, typename... _Args>
  static void construct(_Up __p, _Args...) {
    construct_at(__p, forward<_Args>...);
  }
};
struct __alloc_traits : allocator_traits<allocator<BasicPersistent>> {
} push_back___x;
__alloc_traits::pointer _M_impl_0;
template <typename... _Args> void emplace_back(_Args...) {
  __alloc_traits::construct(_M_impl_0, forward<_Args>...);
}
struct SourceLocation {
  static SourceLocation Current(const char * = __builtin_FUNCTION());
};
struct BasicPersistent {
  BasicPersistent(BasicPersistent &&,
                  SourceLocation = SourceLocation::Current());
};
void CFXJSE_EngineAddObjectToUpArray() { emplace_back(push_back___x); }

testcase.cpp.txt

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: Bernhard Rosenkraenzer (berolinux)

Test case extracted from qtwebengine 6.7.0-beta2:

$ clang++ -std=c++20 testcase.cpp
clang-18: /home/bero/abf/llvm/BUILD/llvm-project-release-18.x/build/tools/clang/include/clang/AST/TypeNodes.inc:36: TypeInfo clang::ASTContext::getTypeInfoImpl(const Type *) const: Assertion `!T->isDependentType() && "should not see dependent types here"' 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: /usr/bin/clang-18 -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name testcase.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/tmp -fcoverage-compilation-dir=/tmp -resource-dir /usr/lib64/clang/18 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-openmandriva-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/backward -internal-isystem /usr/lib64/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../x86_64-openmandriva-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++20 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=13.1.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/testcase-1cf133.o -x c++ testcase.cpp
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      testcase.cpp:6:6: Generating code for declaration 'construct_at'
 #<!-- -->0 0x00007f0d0238e916 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/usr/lib64/libLLVM-18.so+0x458e916)
 #<!-- -->1 0x00007f0d0238d58a llvm::sys::RunSignalHandlers() (/usr/lib64/libLLVM-18.so+0x458d58a)
 #<!-- -->2 0x00007f0d0238e234 (/usr/lib64/libLLVM-18.so+0x458e234)
 #<!-- -->3 0x00007f0cfd855700 (/usr/lib64/libc.so.6+0x3d700)
 #<!-- -->4 0x00007f0cfd8a49cc (/usr/lib64/libc.so.6+0x8c9cc)
 #<!-- -->5 0x00007f0cfd855652 gsignal (/usr/lib64/libc.so.6+0x3d652)
 #<!-- -->6 0x00007f0cfd83e4ad abort (/usr/lib64/libc.so.6+0x264ad)
 #<!-- -->7 0x00007f0cfd83e3d5 (/usr/lib64/libc.so.6+0x263d5)
 #<!-- -->8 0x00007f0cfd84e042 (/usr/lib64/libc.so.6+0x36042)
 #<!-- -->9 0x00007f0d093767ce clang::ASTContext::getTypeInfoImpl(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x19767ce)
#<!-- -->10 0x00007f0d09376f31 clang::ASTContext::getTypeInfo(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x1976f31)
#<!-- -->11 0x00007f0d0a9e4f42 clang::CodeGen::CodeGenFunction::CreateIRTemp(clang::QualType, llvm::Twine const&amp;) (/usr/lib64/libclang-cpp.so.18+0x2fe4f42)
#<!-- -->12 0x00007f0d0ac29ffe clang::CodeGen::CodeGenFunction::StartFunction(clang::GlobalDecl, clang::QualType, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;, clang::CodeGen::FunctionArgList const&amp;, clang::SourceLocation, clang::SourceLocation) (/usr/lib64/libclang-cpp.so.18+0x3229ffe)
#<!-- -->13 0x00007f0d0ac2cc99 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;) (/usr/lib64/libclang-cpp.so.18+0x322cc99)
#<!-- -->14 0x00007f0d0ac770fe clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32770fe)
#<!-- -->15 0x00007f0d0ac764ca clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32764ca)
#<!-- -->16 0x00007f0d0ac4483f clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324483f)
#<!-- -->17 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#<!-- -->18 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#<!-- -->19 0x00007f0d0ac417ab clang::CodeGen::CodeGenModule::Release() (/usr/lib64/libclang-cpp.so.18+0x32417ab)
#<!-- -->20 0x00007f0d0ad0b364 (/usr/lib64/libclang-cpp.so.18+0x330b364)
#<!-- -->21 0x00007f0d0ac18830 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&amp;) (/usr/lib64/libclang-cpp.so.18+0x3218830)
#<!-- -->22 0x00007f0d09245416 clang::ParseAST(clang::Sema&amp;, bool, bool) (/usr/lib64/libclang-cpp.so.18+0x1845416)
#<!-- -->23 0x00007f0d0b77d34b clang::FrontendAction::Execute() (/usr/lib64/libclang-cpp.so.18+0x3d7d34b)
#<!-- -->24 0x00007f0d0b6e1799 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/usr/lib64/libclang-cpp.so.18+0x3ce1799)
#<!-- -->25 0x00007f0d0b7fc71a clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib64/libclang-cpp.so.18+0x3dfc71a)
#<!-- -->26 0x0000560e96d84096 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/usr/bin/clang-18+0x17096)
#<!-- -->27 0x0000560e96d7fd4f (/usr/bin/clang-18+0x12d4f)
#<!-- -->28 0x0000560e96d7e61b clang_main(int, char**, llvm::ToolContext const&amp;) (/usr/bin/clang-18+0x1161b)
#<!-- -->29 0x0000560e96d8ef96 main (/usr/bin/clang-18+0x21f96)
#<!-- -->30 0x00007f0cfd83fc0a (/usr/lib64/libc.so.6+0x27c0a)
#<!-- -->31 0x00007f0cfd83fcc5 __libc_start_main (/usr/lib64/libc.so.6+0x27cc5)
#<!-- -->32 0x0000560e96d7bed1 _start (/usr/bin/clang-18+0xeed1)

Test case

struct BasicPersistent;
template <typename> BasicPersistent &&__declval(int);
template <typename _Tp> auto declval() -> decltype(__declval<_Tp>(0));
template <typename _Tp> _Tp forward;
template <typename _Tp, typename... _Args>
auto construct_at(_Tp *, _Args...) -> decltype(new _Tp(declval<_Args>()...)) {return 0;}
template <typename> struct allocator;
template <typename> struct allocator_traits;
template <typename _Tp> struct allocator_traits<allocator<_Tp>> {
  using pointer = _Tp *;
  template <typename _Up, typename... _Args>
  static void construct(_Up __p, _Args...) {
    construct_at(__p, forward<_Args>...);
  }
};
struct __alloc_traits : allocator_traits<allocator<BasicPersistent>> {
} push_back___x;
__alloc_traits::pointer _M_impl_0;
template <typename... _Args> void emplace_back(_Args...) {
  __alloc_traits::construct(_M_impl_0, forward<_Args>...);
}
struct SourceLocation {
  static SourceLocation Current(const char * = __builtin_FUNCTION());
};
struct BasicPersistent {
  BasicPersistent(BasicPersistent &&,
                  SourceLocation = SourceLocation::Current());
};
void CFXJSE_EngineAddObjectToUpArray() { emplace_back(push_back___x); }

testcase.cpp.txt

[berolinux]

Slightly further reduced test case:

struct a;
template <typename> a &&b(int);
template <typename c> auto d() -> decltype(b<c>(0));
template <typename c> c e;
template <typename c, typename... f>
auto g(c *, f...) -> decltype(new c(d<f>()...)) {}
template <typename> struct h;
template <typename c> struct h<h<c>> {
  using i = c *;
  template <typename j, typename... f> static void k(j p1, f...) {
    g(p1, e<f>...);
  }
};
struct l : h<h<a>> {
} m;
l::i n;
template <typename... f> void o(f...) { l::k(n, e<f>...); }
struct p {
  static p r(const char * = __builtin_FUNCTION());
};
struct a {
  a(a &&, p = p::r());
};
void q() { o(0); }

[tbaederr]

The type is:

DecltypeType 0x5210000a5d80 'decltype(new struct a(d<int>()))' sugar dependent
|-CXXNewExpr 0x5210000a5d38 'struct a *' Function 0x5210000a4630 'operator new' 'void *(unsigned long)'
| `-CXXConstructExpr 0x5210000a5cf8 'struct a' 'void (a &&, p)'
|   |-CallExpr 0x5210000a4448 'a':'struct a' xvalue
|   | `-ImplicitCastExpr 0x5210000a4428 'auto (*)(void) -> decltype(b<int>(0))' <FunctionToPointerDecay>
|   |   `-DeclRefExpr 0x5210000a4350 'auto (void) -> decltype(b<int>(0))' lvalue Function 0x5210000a4240 'd' 'auto (void) -> decltype(b<int>(0))' (FunctionTemplate 0x521000074060 'd') non_odr_use_unevaluated
|   `-CXXDefaultArgExpr 0x5210000a5cc8 'p':'struct p' has rewritten init
|     `-CallExpr 0x5210000a5c40 'p':'struct p'
`-PointerType 0x5210000a32d0 'struct a *'
  `-SubstTemplateTypeParmType 0x5210000a3290 'struct a' sugar typename depth 0 index 0 c
    |-FunctionTemplate 0x521000097e10 'g'
    `-RecordType 0x5210000737a0 'struct a'
      `-CXXRecord 0x5210000a0ba0 'a'

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Bernhard Rosenkraenzer (berolinux)

Test case extracted from qtwebengine 6.7.0-beta2:

$ clang++ -std=c++20 testcase.cpp
clang-18: /home/bero/abf/llvm/BUILD/llvm-project-release-18.x/build/tools/clang/include/clang/AST/TypeNodes.inc:36: TypeInfo clang::ASTContext::getTypeInfoImpl(const Type *) const: Assertion `!T->isDependentType() && "should not see dependent types here"' 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: /usr/bin/clang-18 -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name testcase.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/tmp -fcoverage-compilation-dir=/tmp -resource-dir /usr/lib64/clang/18 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/x86_64-openmandriva-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../include/c++/13.2.1/backward -internal-isystem /usr/lib64/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-openmandriva-linux-gnu/13.2.1/../../../../x86_64-openmandriva-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++20 -fdeprecated-macro -ferror-limit 19 -fgnuc-version=13.1.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/testcase-1cf133.o -x c++ testcase.cpp
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      testcase.cpp:6:6: Generating code for declaration 'construct_at'
 #<!-- -->0 0x00007f0d0238e916 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/usr/lib64/libLLVM-18.so+0x458e916)
 #<!-- -->1 0x00007f0d0238d58a llvm::sys::RunSignalHandlers() (/usr/lib64/libLLVM-18.so+0x458d58a)
 #<!-- -->2 0x00007f0d0238e234 (/usr/lib64/libLLVM-18.so+0x458e234)
 #<!-- -->3 0x00007f0cfd855700 (/usr/lib64/libc.so.6+0x3d700)
 #<!-- -->4 0x00007f0cfd8a49cc (/usr/lib64/libc.so.6+0x8c9cc)
 #<!-- -->5 0x00007f0cfd855652 gsignal (/usr/lib64/libc.so.6+0x3d652)
 #<!-- -->6 0x00007f0cfd83e4ad abort (/usr/lib64/libc.so.6+0x264ad)
 #<!-- -->7 0x00007f0cfd83e3d5 (/usr/lib64/libc.so.6+0x263d5)
 #<!-- -->8 0x00007f0cfd84e042 (/usr/lib64/libc.so.6+0x36042)
 #<!-- -->9 0x00007f0d093767ce clang::ASTContext::getTypeInfoImpl(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x19767ce)
#<!-- -->10 0x00007f0d09376f31 clang::ASTContext::getTypeInfo(clang::Type const*) const (/usr/lib64/libclang-cpp.so.18+0x1976f31)
#<!-- -->11 0x00007f0d0a9e4f42 clang::CodeGen::CodeGenFunction::CreateIRTemp(clang::QualType, llvm::Twine const&amp;) (/usr/lib64/libclang-cpp.so.18+0x2fe4f42)
#<!-- -->12 0x00007f0d0ac29ffe clang::CodeGen::CodeGenFunction::StartFunction(clang::GlobalDecl, clang::QualType, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;, clang::CodeGen::FunctionArgList const&amp;, clang::SourceLocation, clang::SourceLocation) (/usr/lib64/libclang-cpp.so.18+0x3229ffe)
#<!-- -->13 0x00007f0d0ac2cc99 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;) (/usr/lib64/libclang-cpp.so.18+0x322cc99)
#<!-- -->14 0x00007f0d0ac770fe clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32770fe)
#<!-- -->15 0x00007f0d0ac764ca clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/usr/lib64/libclang-cpp.so.18+0x32764ca)
#<!-- -->16 0x00007f0d0ac4483f clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324483f)
#<!-- -->17 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#<!-- -->18 0x00007f0d0ac4486b clang::CodeGen::CodeGenModule::EmitDeferred() (/usr/lib64/libclang-cpp.so.18+0x324486b)
#<!-- -->19 0x00007f0d0ac417ab clang::CodeGen::CodeGenModule::Release() (/usr/lib64/libclang-cpp.so.18+0x32417ab)
#<!-- -->20 0x00007f0d0ad0b364 (/usr/lib64/libclang-cpp.so.18+0x330b364)
#<!-- -->21 0x00007f0d0ac18830 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&amp;) (/usr/lib64/libclang-cpp.so.18+0x3218830)
#<!-- -->22 0x00007f0d09245416 clang::ParseAST(clang::Sema&amp;, bool, bool) (/usr/lib64/libclang-cpp.so.18+0x1845416)
#<!-- -->23 0x00007f0d0b77d34b clang::FrontendAction::Execute() (/usr/lib64/libclang-cpp.so.18+0x3d7d34b)
#<!-- -->24 0x00007f0d0b6e1799 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/usr/lib64/libclang-cpp.so.18+0x3ce1799)
#<!-- -->25 0x00007f0d0b7fc71a clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib64/libclang-cpp.so.18+0x3dfc71a)
#<!-- -->26 0x0000560e96d84096 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/usr/bin/clang-18+0x17096)
#<!-- -->27 0x0000560e96d7fd4f (/usr/bin/clang-18+0x12d4f)
#<!-- -->28 0x0000560e96d7e61b clang_main(int, char**, llvm::ToolContext const&amp;) (/usr/bin/clang-18+0x1161b)
#<!-- -->29 0x0000560e96d8ef96 main (/usr/bin/clang-18+0x21f96)
#<!-- -->30 0x00007f0cfd83fc0a (/usr/lib64/libc.so.6+0x27c0a)
#<!-- -->31 0x00007f0cfd83fcc5 __libc_start_main (/usr/lib64/libc.so.6+0x27cc5)
#<!-- -->32 0x0000560e96d7bed1 _start (/usr/bin/clang-18+0xeed1)

Test case

struct BasicPersistent;
template <typename> BasicPersistent &&__declval(int);
template <typename _Tp> auto declval() -> decltype(__declval<_Tp>(0));
template <typename _Tp> _Tp forward;
template <typename _Tp, typename... _Args>
auto construct_at(_Tp *, _Args...) -> decltype(new _Tp(declval<_Args>()...)) {return 0;}
template <typename> struct allocator;
template <typename> struct allocator_traits;
template <typename _Tp> struct allocator_traits<allocator<_Tp>> {
  using pointer = _Tp *;
  template <typename _Up, typename... _Args>
  static void construct(_Up __p, _Args...) {
    construct_at(__p, forward<_Args>...);
  }
};
struct __alloc_traits : allocator_traits<allocator<BasicPersistent>> {
} push_back___x;
__alloc_traits::pointer _M_impl_0;
template <typename... _Args> void emplace_back(_Args...) {
  __alloc_traits::construct(_M_impl_0, forward<_Args>...);
}
struct SourceLocation {
  static SourceLocation Current(const char * = __builtin_FUNCTION());
};
struct BasicPersistent {
  BasicPersistent(BasicPersistent &&,
                  SourceLocation = SourceLocation::Current());
};
void CFXJSE_EngineAddObjectToUpArray() { emplace_back(push_back___x); }

testcase.cpp.txt

[shafik]

CC @erichkeane any ideas on what might have caused the regression?

[erichkeane]

CC @erichkeane any ideas on what might have caused the regression?

Nothing comes to mind, but something wacky is going on with the pointee of the PointerType.

[berolinux]

FWIW this is triggered by libstdc++'s implementation of std::construct_at in some contexts (so far I've only seen it triggered by building v8 with clang using libstdc++).

Patching libstdc++ to use libc++'s implementation of std::construct_at while otherwise leaving libstdc++ untouched works around the problem.

libstdc++'s std::construct_at that does trigger the problem:

  template<typename _Tp, typename... _Args>
    constexpr auto
    construct_at(_Tp* __location, _Args&&... __args)
    noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...)))
    -> decltype(::new((void*)0) _Tp(std::declval<_Args>()...))
    { return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); }

libc++'s std::construct_at that does NOT trigger the problem (slightly adapted to work inside libstdc++):

  template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
    return ::new (const_cast<void*>(static_cast<const volatile void*>(__location))) _Tp(std::forward<_Args>(__args)...);                 
  }

A variant of libstdc++'s std::construct_at that also does NOT trigger the problem:

  template<typename _Tp, typename... _Args>
    constexpr _Tp*
    construct_at(_Tp* __location, _Args&&... __args)
    noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...)))
    { return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); }