[clang] "Assertion `ESD->getInstantiations() && "expansion statement not expanded?"' failed." with lambda

[efriedma-quic]

https://godbolt.org/z/MKWG5sz8c

void f() {
  struct S {};
  template for (const int &x : []{return S();}()) {
  }
}

clang++: /root/llvm-project/llvm/tools/clang/lib/CodeGen/CGDecl.cpp:149: void clang::CodeGen::CodeGenFunction::EmitDecl(const clang::Decl&, bool): Assertion `ESD->getInstantiations() && "expansion statement not expanded?"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++2c <source>
1.	<eof> parser at end of file
2.	<source>:1:6: LLVM IR generation of declaration 'f'
3.	<source>:1:6: Generating code for declaration 'f'
 #0 0x0000000004421578 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4421578)
 #1 0x000000000441e424 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x441e424)
 #2 0x000000000441ea5c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x441ea5c)
 #3 0x000000000435da38 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #4 0x0000738c16245330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
 #5 0x0000738c1629eb2c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9eb2c)
 #6 0x0000738c1624527e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
 #7 0x0000738c162288ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
 #8 0x0000738c1622881b (/lib/x86_64-linux-gnu/libc.so.6+0x2881b)
 #9 0x0000738c1623b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#10 0x0000000004e81cc2 clang::CodeGen::CodeGenFunction::EmitDecl(clang::Decl const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4e81cc2)
#11 0x0000000004aa139c clang::CodeGen::CodeGenFunction::EmitDeclStmt(clang::DeclStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4aa139c)
#12 0x0000000004abb1a7 clang::CodeGen::CodeGenFunction::EmitSimpleStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4abb1a7)
#13 0x0000000004ab2ae8 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ab2ae8)
#14 0x0000000004abad5b clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4abad5b)
#15 0x0000000004b23786 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b23786)
#16 0x0000000004b39024 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b39024)
#17 0x0000000004ba94aa clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba94aa)
#18 0x0000000004ba2854 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba2854)
#19 0x0000000004ba3043 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba3043)
#20 0x0000000004bb0719 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#21 0x0000000004f2e419 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#22 0x0000000004f1f4c4 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f1f4c4)
#23 0x0000000006d2d934 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d2d934)
#24 0x0000000004f2c288 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f2c288)
#25 0x0000000005259508 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5259508)
#26 0x00000000051e60cd clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x51e60cd)
#27 0x000000000532dc4d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x532dc4d)
#28 0x0000000000daf4dc cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdaf4dc)
#29 0x0000000000da60ea ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#30 0x0000000000da626d int llvm::function_ref<int (llvm::SmallVectorImpl<char const*>&)>::callback_fn<clang_main(int, char**, llvm::ToolContext const&)::'lambda'(llvm::SmallVectorImpl<char const*>&)>(long, llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#31 0x0000000004fa3749 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#32 0x000000000435de74 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x435de74)
#33 0x0000000004fa42b5 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#34 0x0000000004f5ca92 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f5ca92)
#35 0x0000000004f612c7 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+++0x4f612c7)
#36 0x0000000004f6b825 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f6b825)
#37 0x0000000000dab9ca clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdab9ca)
#38 0x0000000000cc5c5a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xcc5c5a)
#39 0x0000738c1622a1ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#40 0x0000738c1622a28b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#41 0x0000000000da5a95 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda5a95)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Compiler returned: 134

[llvmorg-github-actions]

@llvm/issue-subscribers-clang-frontend

Author: Eli Friedman (efriedma-quic)

Details

https://godbolt.org/z/MKWG5sz8c

void f() {
  struct S {};
  template for (const int &x : []{return S();}()) {
  }
}

clang++: /root/llvm-project/llvm/tools/clang/lib/CodeGen/CGDecl.cpp:149: void clang::CodeGen::CodeGenFunction::EmitDecl(const clang::Decl&, bool): Assertion `ESD->getInstantiations() && "expansion statement not expanded?"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++2c <source>
1.	<eof> parser at end of file
2.	<source>:1:6: LLVM IR generation of declaration 'f'
3.	<source>:1:6: Generating code for declaration 'f'
 #<!-- -->0 0x0000000004421578 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4421578)
 #<!-- -->1 0x000000000441e424 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x441e424)
 #<!-- -->2 0x000000000441ea5c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x441ea5c)
 #<!-- -->3 0x000000000435da38 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->4 0x0000738c16245330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
 #<!-- -->5 0x0000738c1629eb2c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9eb2c)
 #<!-- -->6 0x0000738c1624527e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
 #<!-- -->7 0x0000738c162288ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
 #<!-- -->8 0x0000738c1622881b (/lib/x86_64-linux-gnu/libc.so.6+0x2881b)
 #<!-- -->9 0x0000738c1623b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#<!-- -->10 0x0000000004e81cc2 clang::CodeGen::CodeGenFunction::EmitDecl(clang::Decl const&amp;, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4e81cc2)
#<!-- -->11 0x0000000004aa139c clang::CodeGen::CodeGenFunction::EmitDeclStmt(clang::DeclStmt const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4aa139c)
#<!-- -->12 0x0000000004abb1a7 clang::CodeGen::CodeGenFunction::EmitSimpleStmt(clang::Stmt const*, llvm::ArrayRef&lt;clang::Attr const*&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4abb1a7)
#<!-- -->13 0x0000000004ab2ae8 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef&lt;clang::Attr const*&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ab2ae8)
#<!-- -->14 0x0000000004abad5b clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&amp;, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4abad5b)
#<!-- -->15 0x0000000004b23786 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b23786)
#<!-- -->16 0x0000000004b39024 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b39024)
#<!-- -->17 0x0000000004ba94aa clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba94aa)
#<!-- -->18 0x0000000004ba2854 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba2854)
#<!-- -->19 0x0000000004ba3043 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ba3043)
#<!-- -->20 0x0000000004bb0719 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#<!-- -->21 0x0000000004f2e419 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#<!-- -->22 0x0000000004f1f4c4 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f1f4c4)
#<!-- -->23 0x0000000006d2d934 clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d2d934)
#<!-- -->24 0x0000000004f2c288 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f2c288)
#<!-- -->25 0x0000000005259508 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5259508)
#<!-- -->26 0x00000000051e60cd clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x51e60cd)
#<!-- -->27 0x000000000532dc4d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x532dc4d)
#<!-- -->28 0x0000000000daf4dc cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdaf4dc)
#<!-- -->29 0x0000000000da60ea ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;, llvm::IntrusiveRefCntPtr&lt;llvm::vfs::FileSystem&gt;) driver.cpp:0:0
#<!-- -->30 0x0000000000da626d int llvm::function_ref&lt;int (llvm::SmallVectorImpl&lt;char const*&gt;&amp;)&gt;::callback_fn&lt;clang_main(int, char**, llvm::ToolContext const&amp;)::'lambda'(llvm::SmallVectorImpl&lt;char const*&gt;&amp;)&gt;(long, llvm::SmallVectorImpl&lt;char const*&gt;&amp;) driver.cpp:0:0
#<!-- -->31 0x0000000004fa3749 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->32 0x000000000435de74 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x435de74)
#<!-- -->33 0x0000000004fa42b5 clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->34 0x0000000004f5ca92 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f5ca92)
#<!-- -->35 0x0000000004f612c7 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f612c7)
#<!-- -->36 0x0000000004f6b825 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f6b825)
#<!-- -->37 0x0000000000dab9ca clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdab9ca)
#<!-- -->38 0x0000000000cc5c5a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xcc5c5a)
#<!-- -->39 0x0000738c1622a1ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#<!-- -->40 0x0000738c1622a28b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#<!-- -->41 0x0000000000da5a95 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xda5a95)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Compiler returned: 134

[efriedma-quic]

CC @Sirraide

[Sirraide]

This seems like it’s fixed by #212319.

[efriedma-quic]

The crash here doesn't depend on the expansion being empty. For example, the following also crashes:

void f() {
  struct S {int x,y;};
  template for (const int &x : []{return S();}()) {
  }
}

Maybe some related refactoring fixes this, though.

[Sirraide]

The crash here doesn't depend on the expansion being empty. For example, the following also crashes:

void f() {
struct S {int x,y;};
template for (const int &x : []{return S();}()) {
}
}
Maybe some related refactoring fixes this, though.

That one also compiles; I don’t know what exactly fixed it though

[Sirraide]

Ah wait, nvm, the issue here was me not realising that this is a codegen crash, and I was testing with -fsyntax-only so of course it works...

[efriedma-quic]

If you want a variation that does crash with -fsyntax-only:

constexpr int f() {
  struct S {};
  template for (const int &x : []{return S();}()) {
  }
  return 0;
}
constexpr int i = f();