[clang][modules] RecordLayoutBuilder.cpp crash: Cannot get layout of forward declarations

[rupprecht]

This is a failure that bisects to #147835 , but I don't have a repro yet. Working on that now.

assertion failed at clang/lib/AST/RecordLayoutBuilder.cpp:3380 in const ASTRecordLayout &clang::ASTContext::getASTRecordLayout(const RecordDecl *) const: D && "Cannot get layout of forward declarations!"
*** Check failure stack trace: ***
    @     0x557b3889784f  clang::ASTContext::getASTRecordLayout()
    @     0x557b3823cd68  clang::ASTContext::getTypeInfoImpl()
    @     0x557b3823e25c  clang::ASTContext::getTypeInfo()
    @     0x557b3823d855  clang::ASTContext::getPreferredTypeAlign()
    @     0x557b3823bf01  clang::ASTContext::getDeclAlign()
    @     0x557b366c6a06  clang::CodeGen::CodeGenFunction::EmitAutoVarAlloca()
    @     0x557b366c165c  clang::CodeGen::CodeGenFunction::EmitVarDecl()
    @     0x557b366c1120  clang::CodeGen::CodeGenFunction::EmitDecl()
    @     0x557b36760580  clang::CodeGen::CodeGenFunction::EmitDeclStmt()
    @     0x557b36754d50  clang::CodeGen::CodeGenFunction::EmitSimpleStmt()
    @     0x557b3675403e  clang::CodeGen::CodeGenFunction::EmitStmt()
    @     0x557b36761891  clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope()
    @     0x557b368c47d5  clang::CodeGen::CodeGenFunction::GenerateCode()
    @     0x557b368ef9f6  clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition()
    @     0x557b368e6bc8  clang::CodeGen::CodeGenModule::EmitGlobalDefinition()
    @     0x557b368d7786  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
...
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d41ae  clang::CodeGen::CodeGenModule::Release()
    @     0x557b36a1e14e  (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit()

[llvmbot]

@llvm/issue-subscribers-clang-modules

Author: Jordan Rupprecht (rupprecht)

This is a failure that bisects to #147835 , but I don't have a repro yet. Working on that now.

assertion failed at clang/lib/AST/RecordLayoutBuilder.cpp:3380 in const ASTRecordLayout &clang::ASTContext::getASTRecordLayout(const RecordDecl *) const: D && "Cannot get layout of forward declarations!"
*** Check failure stack trace: ***
    @     0x557b3889784f  clang::ASTContext::getASTRecordLayout()
    @     0x557b3823cd68  clang::ASTContext::getTypeInfoImpl()
    @     0x557b3823e25c  clang::ASTContext::getTypeInfo()
    @     0x557b3823d855  clang::ASTContext::getPreferredTypeAlign()
    @     0x557b3823bf01  clang::ASTContext::getDeclAlign()
    @     0x557b366c6a06  clang::CodeGen::CodeGenFunction::EmitAutoVarAlloca()
    @     0x557b366c165c  clang::CodeGen::CodeGenFunction::EmitVarDecl()
    @     0x557b366c1120  clang::CodeGen::CodeGenFunction::EmitDecl()
    @     0x557b36760580  clang::CodeGen::CodeGenFunction::EmitDeclStmt()
    @     0x557b36754d50  clang::CodeGen::CodeGenFunction::EmitSimpleStmt()
    @     0x557b3675403e  clang::CodeGen::CodeGenFunction::EmitStmt()
    @     0x557b36761891  clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope()
    @     0x557b368c47d5  clang::CodeGen::CodeGenFunction::GenerateCode()
    @     0x557b368ef9f6  clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition()
    @     0x557b368e6bc8  clang::CodeGen::CodeGenModule::EmitGlobalDefinition()
    @     0x557b368d7786  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
...
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @     0x557b368d41ae  clang::CodeGen::CodeGenModule::Release()
    @     0x557b36a1e14e  (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit()

[shafik]

CC @mizvekov

[rupprecht]

cvise reduction: repro.tar.gz. To repro, unpack it and run CLANG=<path to bad clang> make

I turned off warnings while reducing (as is usually recommended) but this left it with field has incomplete type in the reduced form, and attempting to fix that error makes the crash go away. So this might be enough to figure out what the issue is, although it may not be representative of the full unreduced crash. I'll see if I can get a cleaner repro, but cvise took 10 hours to reduce it down from 100M/7000 files to this, so unlikely I'll have anything more today.

[mizvekov]

Thanks for trying. The repro is not super helpful because it does crash on main before #147835 anyway.

If you get a chance to run that reduction again, can you please try to make your interestingness test check that it compiles cleanly with clang built from the commit previous to #147835?

Thanks.

[rupprecht]

Still running cvise. It ran all weekend and is still at ~33M / 3.8k files, after starting from ~105M / ~7k files.

[mizvekov]

Thanks. Yeah we are in dire need of better tooling for reducing modules based projects.

[mizvekov]

@rupprecht Can you check if #155375 fixes your issue?

[rupprecht]

@rupprecht Can you check if #155375 fixes your issue?

AFAICT, it doesn't help these crashes.