Created attachment 110085 [details]
proposed patch to fix the problem

I get the crash running the command below:
clazy-standalone -checks=level2 -p build/bear/compile_commands.json build/bear/DatabaseManager/DatabaseManager_autogen/mocs_compilation.cpp
There are a lot of files that include other files. If necessary, if you tell me how to track everything down, I could try to gather them up and to find the command line options.
I have Fedora 27 x86_64. I installed clang-5.0.0-1.fc27.x86_64, llvm-5.0.0-5.fc27.x86_64, and the corresponding libraries and development packages. I cloned clazy from git and built it from source linked to Fedora's clang and llvm.
I have the traceback below, and looking at the code where it crashed and other similar sections of code, it looked like the problem was that after checking for !qt2.getTypePtrOrNull(), it also needed to check for qt2->isIncompleteType(). I put in debug code to show that when it got an incomplete type, m_astContext.getTypeSize(qt2) crashed.

Program received signal SIGSEGV, Segmentation fault.
clang::ASTContext::getASTRecordLayout (this=this@entry=0x8763c0, D=<optimized out>, D@entry=0x2f7c5e0)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/AST/RecordLayoutBuilder.cpp:2964
2964        if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
(gdb) bt
#0  clang::ASTContext::getASTRecordLayout (this=this@entry=0x8763c0, D=<optimized out>, D@entry=0x2f7c5e0)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/AST/RecordLayoutBuilder.cpp:2964
#1  0x00007ffff50a362a in clang::ASTContext::getTypeInfoImpl (this=this@entry=0x8763c0, T=0x2f7c6e0) at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/AST/ASTContext.cpp:1872
#2  0x00007ffff509b325 in clang::ASTContext::getTypeInfo (this=0x8763c0, T=<optimized out>) at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/AST/ASTContext.cpp:1612
#3  0x00007ffff761d0de in clang::ASTContext::getTypeInfo (this=0x8763c0, T=...) at /usr/include/clang/AST/ASTContext.h:1918
#4  0x00007ffff761d103 in clang::ASTContext::getTypeSize (this=0x8763c0, T=...) at /usr/include/clang/AST/ASTContext.h:1924
#5  0x00007ffff763e077 in InefficientQListBase::VisitDecl (this=0x885320, decl=0x2f7c9a8) at /u/u3/gnu/clazy/src/checks/inefficientqlistbase.cpp:99
#6  0x00007ffff76691a0 in ClazyASTConsumer::VisitDecl (this=0x860850, decl=0x2f7c9a8) at /u/u3/gnu/clazy/src/Clazy.cpp:104
#7  0x00007ffff769c762 in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/RecursiveASTVisitor.h:483
#8  0x00007ffff76a6b4a in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromNamedDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:95
#9  0x00007ffff76aae5a in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromValueDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:355
#10 0x00007ffff76aaf42 in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromDeclaratorDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:365
#11 0x00007ffff768ec52 in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromVarDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:441
#12 0x00007ffff768efa6 in clang::RecursiveASTVisitor<ClazyASTConsumer>::WalkUpFromParmVarDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:463
#13 0x00007ffff7683ee6 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseParmVarDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/RecursiveASTVisitor.h:2026
#14 0x00007ffff767a82c in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDecl (this=0x860850, D=0x2f7c9a8) at /usr/include/clang/AST/DeclNodes.inc:463
#15 0x00007ffff769e33a in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseFunctionProtoTypeLoc (this=0x860850, TL=...)
    at /usr/include/clang/AST/RecursiveASTVisitor.h:1214
#16 0x00007ffff768a7c5 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseTypeLoc (this=0x860850, TL=...) at /usr/include/clang/AST/TypeNodes.def:79
#17 0x00007ffff768e5b6 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseFunctionHelper (this=0x860850, D=0x2f7ce60) at /usr/include/clang/AST/RecursiveASTVisitor.h:1937
#18 0x00007ffff7683364 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseCXXConstructorDecl (this=0x860850, D=0x2f7ce60)
    at /usr/include/clang/AST/RecursiveASTVisitor.h:1982
#19 0x00007ffff767a661 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDecl (this=0x860850, D=0x2f7ce60) at /usr/include/clang/AST/DeclNodes.inc:403
#20 0x00007ffff768a351 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDeclContextHelper (this=0x860850, DC=0x2f7b2d8)
    at /usr/include/clang/AST/RecursiveASTVisitor.h:1350
#21 0x00007ffff7681788 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseCXXRecordDecl (this=0x860850, D=0x2f7b2a0) at /usr/include/clang/AST/RecursiveASTVisitor.h:1787
#22 0x00007ffff767a265 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDecl (this=0x860850, D=0x2f7b2a0) at /usr/include/clang/AST/DeclNodes.inc:251
#23 0x00007ffff768a351 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDeclContextHelper (this=0x860850, DC=0x87be90)
    at /usr/include/clang/AST/RecursiveASTVisitor.h:1350
#24 0x00007ffff7685093 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseTranslationUnitDecl (this=0x860850, D=0x87be70)
    at /usr/include/clang/AST/RecursiveASTVisitor.h:1442
#25 0x00007ffff767aa90 in clang::RecursiveASTVisitor<ClazyASTConsumer>::TraverseDecl (this=0x860850, D=0x87be70) at /usr/include/clang/AST/DeclNodes.inc:553
#26 0x00007ffff76694ad in ClazyASTConsumer::HandleTranslationUnit (this=0x860850, ctx=...) at /u/u3/gnu/clazy/src/Clazy.cpp:153
#27 0x00007ffff6fe18d8 in clang::MultiplexConsumer::HandleTranslationUnit (this=<optimized out>, Ctx=...)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/Frontend/MultiplexConsumer.cpp:305
#28 0x00007ffff4a81ce9 in clang::ParseAST (S=..., PrintStats=<optimized out>, SkipFunctionBodies=<optimized out>)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/Parse/ParseAST.cpp:159
#29 0x00007ffff6fb3256 in clang::FrontendAction::Execute (this=this@entry=0x861120) at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/Frontend/FrontendAction.cpp:902
#30 0x00007ffff6f715ba in clang::CompilerInstance::ExecuteAction (this=this@entry=0x7fffffffa730, Act=...)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/Frontend/CompilerInstance.cpp:980
#31 0x00007ffff34b4a00 in clang::tooling::FrontendActionFactory::runInvocation (this=0x79d2a0, Invocation=..., Files=0x72f670, PCHContainerOps=..., DiagConsumer=0x0)
    at /usr/src/debug/clang-5.0.0-1.fc27.x86_64/lib/Tooling/Tooling.cpp:321