[Cling] Interpreter regression 6.24/06 -> 6.25/02

[greenc-FNAL]

• Checked for duplicates

Describe the bug

With 6.24/06 vanilla and v6-24-00-patches e9d29ae, the test runtime_cxxmodules_addr in the provided reproducer
passes regardless of the presence or absence of the feature runtime_cxxmodules. With 6.25/02—and master, per @pcanal—it fails with a segmentation violation trying to autoparse art::detail::are_cv_compatible<const int, const int*>.

Expected behavior

• runtime_cxxmodules_9583_good should pass in all cases.
• runtime_cxxmodules_9583_bad should pass when runtime_cxxmodules=OFF or Interpreter autoload lookup failure when runtime_cxxmodules=ON #9583 has been fixed.
• runtime_cxxmodules_addr should pass in all cases.

To Reproduce

• Ensure you are using ROOT 6.25/02 (or see below)
• Ensure you are using CMake >= 3.22.0
• Execute the provided runit script to configure, build, and execute the tests.

Setup

• SLF7
• CMAKE_CXX_STANDARD=17

Additional context

Preliminary investigation by @pcanal (to ensure that I hadn't messed up something basic in the configuration or XML) indicates that the problem was introduced by PR #7488 and not fixed by its partial reversion in 2d304cf. According to @pcanal, a reversion of both 2d304cf and 34590ae resolves this issue.

Reproducer: runtime_cxxmodules-reproducer.tar.gz

[hahnjo]

the problem was introduced by PR #7488 and not fixed by its partial reversion in 2d304cf

Small correction: Commit 2d304cf is not a reversion, but a cleanup of the infrastructure for the previous implementation; it happened in the same PR.

Reproducer: runtime_cxxmodules-reproducer.tar.gz

I have to say, this was quite hard to use and it took me some time to guess how things are supposed to work:

1. Don't install a released version of cetmodules, but use the one in third_party/ - I eventually found standalone/runit.
2. The cmake configuration failed even with CMake 3.22 or CMake master: $<EQUAL> parameter is not a valid integer. - I replaced it with STREQUAL (in third_party/cetmodules/Modules/BuildDictionary.cmake).
3. I have to specify CMAKE_CXX_STANDARD=17 manually for the reproducer project.

Anyway, I have it running now with runtime_cxxmodules_9583_good passing and runtime_cxxmodules_9583_bad crashing:

#5  0x00007ff9c7acc0f0 in clang::Stmt::getEndLoc() const () from /home/jhahnfel/ROOT/build/lib/libCling.so
#6  0x00007ff9c797c8c8 in clang::FunctionDecl::setBody(clang::Stmt*) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#7  0x00007ff9c5688477 in cling::AutoSynthesizer::Transform(clang::Decl*) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#8  0x00007ff9c56a3f17 in cling::DeclCollector::TransformDecl(clang::Decl*) const () from /home/jhahnfel/ROOT/build/lib/libCling.so
#9  0x00007ff9c56a409f in cling::DeclCollector::Transform(clang::DeclGroupRef&) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#10 0x00007ff9c56a4241 in cling::DeclCollector::HandleTopLevelDecl(clang::DeclGroupRef) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#11 0x00007ff9c5b21150 in clang::MultiplexConsumer::HandleTopLevelDecl(clang::DeclGroupRef) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#12 0x00007ff9c643e4b7 in clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#13 0x00007ff9c643da0f in clang::Sema::PerformPendingInstantiations(bool) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#14 0x00007ff9c5ecaefe in clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) [clone .part.1427] () from /home/jhahnfel/ROOT/build/lib/libCling.so
#15 0x00007ff9c5ecafdd in clang::Sema::ActOnEndOfTranslationUnit() () from /home/jhahnfel/ROOT/build/lib/libCling.so
#16 0x00007ff9c5d5279e in clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, bool) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#17 0x00007ff9c5668e00 in cling::IncrementalParser::ParseInternal(llvm::StringRef) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#18 0x00007ff9c5669d0c in cling::IncrementalParser::Compile(llvm::StringRef, cling::CompilationOptions const&) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#19 0x00007ff9c55e001a in cling::Interpreter::loadHeader(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cling::Transaction**) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#20 0x00007ff9c56b81d6 in cling::MetaSema::actOnLCommand(llvm::StringRef, cling::Transaction**) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#21 0x00007ff9c56b8319 in cling::MetaSema::actOnxCommand(llvm::StringRef, llvm::StringRef, cling::Value*) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#22 0x00007ff9c56c790f in cling::MetaParser::isXCommand(cling::MetaSema::ActionResult&, cling::Value*) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#23 0x00007ff9c56c7c14 in cling::MetaParser::isCommand(cling::MetaSema::ActionResult&, cling::Value*) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#24 0x00007ff9c56b2310 in cling::MetaProcessor::process(llvm::StringRef, cling::Interpreter::CompilationResult&, cling::Value*, bool) () from /home/jhahnfel/ROOT/build/lib/libCling.so
#25 0x00007ff9c54fa3ec in HandleInterpreterException(cling::MetaProcessor*, char const*, cling::Interpreter::CompilationResult&, cling::Value*) () from /home/jhahnfel/ROOT/build/lib/libCling.so

(would have been nice to get this stack trace with the original report)

[hahnjo]

What Cling is really crashing on is the definition of art::ensurePointer or more precisely any function definition with a try-catch block as body (which I just learned is valid C++...). The problem can be seen with

.rawInput
void f() try { } catch (...) { }

(on the ROOT prompt)

[vgvassilev]

What Cling is really crashing on is the definition of art::ensurePointer or more precisely any function definition with a try-catch block as body (which I just learned is valid C++...). The problem can be seen with

.rawInput
void f() try { } catch (...) { }

(on the ROOT prompt)

Yeah, that's a common pitfall, where the assumption that the function's body is a CompoundStmt is incorrect. I suspect the fix is trivial?

[hahnjo]

Well not entirely trivial, there's already code to handle this:

root/interpreter/cling/lib/Interpreter/AutoSynthesizer.cpp

Lines 108 to 109 in dd904f5

	else if (CXXTryStmt *TS = dyn_cast_or_null<CXXTryStmt>(Body))
	Body = m_AutoFixer->Fix(TS);

The problem is that apparently the SourceLocation is not properly set. I'm looking into it.

[hahnjo]

Or maybe I just completely broke that code path with said commit...