[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Aaron Puchert]

https://bugs.kde.org/show_bug.cgi?id=385768

Aaron Puchert  changed:

   What|Removed |Added

 CC||aaronpuch...@alice-dsl.net
 Status|CONFIRMED   |RESOLVED
 Resolution|--- |FIXED

--- Comment #9 from Aaron Puchert  ---
The bug has been fixed, and the fix will be in Clang 11.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Rodrigo Fernandes]

https://bugs.kde.org/show_bug.cgi?id=385768

Rodrigo Fernandes  changed:

   What|Removed |Added

 CC||rfernan...@gmx.com

--- Comment #8 from Rodrigo Fernandes  ---
This bug renders KDevelop unusable for me, as most projects I deal with now a
days are C++17, and it would be unfeasable to manually add each of the
offending files to the filter. Is there any way to set the parser to c++17 mode
so the nullptr deref doesn't happen? Happy to dig submit patches to either
Kdevelop / Clang to help remediate this.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Kevin Funk]

https://bugs.kde.org/show_bug.cgi?id=385768

Kevin Funk  changed:

   What|Removed |Added

URL||https://bugs.llvm.org/show_
   ||bug.cgi?id=34960

--- Comment #7 from Kevin Funk  ---
Reported upstream, with the limited information at hand:
  https://bugs.llvm.org/show_bug.cgi?id=34960

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Craig Tenenbaum]

https://bugs.kde.org/show_bug.cgi?id=385768

--- Comment #6 from Craig Tenenbaum  ---
Yeah, I had been wondering why that is and frankly do not understand it, the
offending fragment of code appears to be:

  // Marking a DecompositionDecl as invalid implies all the child BindingDecl's
  // are invalid too.
  if (DecompositionDecl *DD = dyn_cast(this)) {
for (BindingDecl *Binding : DD->bindings()) {
  Binding->setInvalidDecl();
}
  }

in Decl::setInvalidDecl(bool):clang/lib/AST/DeclBase.cpp

The issue is, when not in C++17, the reference returned by `DD->bindings()`
seems to contain a nullptr, which is subsequently dereferenced with
`Binding->setInvalidDecl()`. The resulting segfault should kill just about
anything, right? What kind of insulation the clang driver must have is pretty
special. Unless they somehow avoid being on that codepath entirely or somehow
interfere with the erroneous initialization which must be occurring when
otherwise not in C++17 mode. It has been my experience, thus far, that even
invalid structured bindings do not result in this problem so long as the parser
is in C++17 mode. Why there's no guard-check in that loop or safe
initialization of that reference is as-yet unknown to me. I dunno if this would
be considered sufficient information, yet, to file a bug report upstream.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Kevin Funk]

https://bugs.kde.org/show_bug.cgi?id=385768

--- Comment #5 from Kevin Funk  ---
The surprising thing is that libclang crashes, while plain clang does not:

Note: MWE is:
% cat ~/test.cpp
#include "test.h"
% cat ~/test.h  
#pragma once

[Serializable]
public ref class NeptuneException : Exception
{
};


% KDEV_CLANG_DISPLAY_ARGS=1
~/devel/build/kf5/kdevelop/kdevplatform/util/duchainify/duchainify ~/test.cpp   
Added 1 files to the background parser
parsing with 4 threads
Invocation: clang -ferror-limit=100 -fspell-checking -Wdocumentation
-Wunused-parameter -Wunreachable-code -Wall -std=c++11 -nostdinc -nostdinc++
-xc++ -isystem/usr/include/c++/6 -isystem/usr/include/x86_64-linux-gnu/c++/6
-isystem/usr/include/c++/6/backward -isystem/usr/local/include
-isystem/home/kfunk/devel/build/llvm/lib/clang/5.0.1/include
-isystem/usr/include/x86_64-linux-gnu -isystem/usr/include -imacros
/tmp/duchainify.J20863 /home/kfunk/test.cpp
libclang: crash detected during parsing: {
  'source_filename' : '/home/kfunk/test.cpp'
  'command_line_args' : ['clang', '-ferror-limit=100', '-fspell-checking',
'-Wdocumentation', '-Wunused-parameter', '-Wunreachable-code', '-Wall',
'-std=c++11', '-nostdinc', '-nostdinc++', '-xc++',
'-isystem/usr/include/c++/6', '-isystem/usr/include/x86_64-linux-gnu/c++/6',
'-isystem/usr/include/c++/6/backward', '-isystem/usr/local/include',
'-isystem/home/kfunk/devel/build/llvm/lib/clang/5.0.1/include',
'-isystem/usr/include/x86_64-linux-gnu', '-isystem/usr/include', '-imacros',
'/tmp/duchainify.J20863'],
  'unsaved_files' : [],
  'options' : 781,
}
zsh: segmentation fault  KDEV_CLANG_DISPLAY_ARGS=1  ~/test.cpp

% clang -ferror-limit=100 -fspell-checking -Wdocumentation -Wunused-parameter
-Wunreachable-code -Wall -std=c++11 -nostdinc -nostdinc++ -xc++
-isystem/usr/include/c++/6 -isystem/usr/include/x86_64-linux-gnu/c++/6
-isystem/usr/include/c++/6/backward -isystem/usr/local/include
-isystem/home/kfunk/devel/build/llvm/lib/clang/5.0.1/include
-isystem/usr/include/x86_64-linux-gnu -isystem/usr/include -imacros
/tmp/duchainify.J20863 /home/kfunk/test.cpp
In file included from /home/kfunk/test.cpp:1:
/home/kfunk/test.h:3:1: warning: decomposition declarations are a C++17
extension [-Wc++17-extensions]
[Serializable]
^~
/home/kfunk/test.h:3:1: error: C++ requires a type specifier for all
declarations
/home/kfunk/test.h:3:1: error: decomposition declaration cannot be declared
with type 'int'; declared type must be 'auto' or reference to 'auto'
/home/kfunk/test.h:3:1: error: decomposition declaration '[Serializable]'
requires an initializer
/home/kfunk/test.h:3:15: error: expected ';' after top level declarator
[Serializable]
  ^
  ; 
1 warning and 4 errors generated.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Kevin Funk]

https://bugs.kde.org/show_bug.cgi?id=385768

--- Comment #4 from Kevin Funk  ---
Can reproduce. Offending file is NeptuneException.cpp in digikam.git.

Test run which crashes:
/kdevelop/kdevplatform/util/duchainify/duchainify
/home/kfunk/devel/src/kf5/digikam/utilities/mediaserver/upnpsdk/Platinum/Source/Extras/Managed/NeptuneException.cpp

Backtrace with a LLVM debug build (LLVM 5.0 branch):
#0  0x7fffc52a8f5b in clang::Decl::setInvalidDecl (this=0x0, Invalid=true)
at /home/kfunk/devel/src/llvm/tools/clang/lib/AST/DeclBase.cpp:112
#1  0x7fffc52a8fad in clang::Decl::setInvalidDecl (this=,
Invalid=) at
/home/kfunk/devel/src/llvm/tools/clang/lib/AST/DeclBase.cpp:129
#2  0x7fffbb7020aa in clang::ASTDeclReader::VisitDecl (this=0x7fffaa7fb0b0,
D=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:537
#3  0x7fffbb703da6 in clang::ASTDeclReader::VisitNamedDecl
(this=0x7fffaa7fb0b0, ND=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:609
#4  clang::ASTDeclReader::VisitValueDecl (this=0x7fffaa7fb0b0,
VD=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:746
#5  clang::ASTDeclReader::VisitDeclaratorDecl (this=0x7fffaa7fb0b0,
DD=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:759
#6  0x7fffbb70863b in clang::ASTDeclReader::VisitVarDeclImpl
(this=0x7fffaa7fb0b0, VD=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:1260
#7  0x7fffbb701db5 in clang::ASTDeclReader::VisitVarDecl
(this=0x7fffaa7fb0b0, VD=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:333
#8  clang::ASTDeclReader::VisitDecompositionDecl (this=0x7fffaa7fb0b0,
DD=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:1352
#9  clang::declvisitor::Base::Visit (this=0x7fffaa7fb0b0, D=0x7fff94029eb8) at
tools/clang/include/clang/AST/DeclNodes.inc:445
#10 0x7fffbb701332 in clang::ASTDeclReader::Visit (this=0x7fffaa7fb0b0,
D=0x7fff94029eb8) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:468
#11 0x7fffbb7276e1 in clang::ASTReader::ReadDeclRecord
(this=0x7fff9406b030, ID=19) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:3623
#12 0x7fffbb6c5d7d in clang::ASTReader::GetDecl (this=0x7fff9406b030,
ID=19) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReader.cpp:7102
#13 0x7fffbb727ccb in clang::ASTReader::PassInterestingDeclsToConsumer
(this=0x7fff9406b030) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReaderDecl.cpp:3674
#14 0x7fffbb6dbefc in non-virtual thunk to
clang::ASTReader::StartTranslationUnit(clang::ASTConsumer*) () at
/home/kfunk/devel/src/llvm/tools/clang/lib/Serialization/ASTReader.cpp:7356
#15 0x7fffbb821328 in clang::ParseAST (S=..., PrintStats=,
SkipFunctionBodies=) at
/home/kfunk/devel/src/llvm/tools/clang/lib/Parse/ParseAST.cpp:144

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Craig Tenenbaum]

https://bugs.kde.org/show_bug.cgi?id=385768

--- Comment #3 from Craig Tenenbaum  ---
I can reproduce on KDevelop master and a Clang-6 checkout only a few hours old,
the files that trigger it seem to be the "Managed" C++ files under
'digikam/utilities/mediaserver/upnpsdk/Platinum/Source/Extras/Managed/', and
while I'm not entirely sure why Clang is trying to parse anything in there as a
structured binding, it doesn't surprise me that fake, MS C++ masquerading as
real C++ should cause issues. It accidentally confirms that the nullptr deref
in Clang is a real bug in the parser, however, so I'll start trying to figure
it out.

WORKAROUND: for the moment, so long as you don't have a burning desire or need
to edit these files in KDevelop, you can add the entire directory to the
project's exclude filters. While one could edit KDevelop's project file with a
text editor and then launch KDevelop afterward, I was lazy and so temporarily
disabled KDevelop's background parsing, added the directory to the filter from
inside KDevelop, and then re-enabled background parsing. That ended the
segfaulting for me.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Craig Tenenbaum]

https://bugs.kde.org/show_bug.cgi?id=385768

Craig Tenenbaum  changed:

   What|Removed |Added

 CC||zarathustra.zoroaster@gmail
   ||.com

--- Comment #2 from Craig Tenenbaum  ---
Odd, I've seen this exact bug before and it pertains to the use of C++17
structured bindings. Looking at the backtrace itself, you can even see calls
into the structured binding machinery at #7 with the call to
`clang::ASTDeclReader::VisitDecompositionDecl(clang::DecompositionDecl*)`;
"decomposition declaration" was just a prior name for this feature.
Specifically, the cause of the segfault is an attempt to dereference a nullptr,
which results from some data-structure (involved in the parsing of structured
bindings), somewhere, not being initialized properly when the parser isn't in
C++17 mode. I never narrowed the specific cause because fixes to CMake support
obviated the issue for me, but I could look back into it if requested.

That said, I'm not sure what's causing this specific failure; some cursory
investigation into digikam's sources uncovers nothing in CMake instructing the
use of C++17 features at compile-time, and moreover, trying some grep patterns
which should match a structured binding declaration come up empty, so either
something is going very wrong the parser, or is it possible you have some local
changes to the code using structured bindings, or additional projects open?

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Kevin Funk]

https://bugs.kde.org/show_bug.cgi?id=385768

Kevin Funk  changed:

   What|Removed |Added

 Status|UNCONFIRMED |CONFIRMED
 Ever confirmed|0   |1

--- Comment #1 from Kevin Funk  ---
If you could isolate on which file(s) this is happening on, that'd be great.
Then we can report a ticket upstream at the LLVM project.

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Johannes Hirte]

https://bugs.kde.org/show_bug.cgi?id=385768

Johannes Hirte  changed:

   What|Removed |Added

   Platform|Other   |Gentoo Packages

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[kdevelop] [Bug 385768] segfault on parsing project: in clang::Decl::setInvalidDecl(bool) () from /usr/lib64/llvm/5/lib64/../lib64/libclangAST.so.5

[Johannes Hirte]

https://bugs.kde.org/show_bug.cgi?id=385768

Johannes Hirte  changed:

   What|Removed |Added

Version|unspecified |git master

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