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llvm_unreachable when processing comment & line continuation #62054

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rupprecht opened this issue Apr 11, 2023 · 7 comments
Closed

llvm_unreachable when processing comment & line continuation #62054

rupprecht opened this issue Apr 11, 2023 · 7 comments
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clang:diagnostics New/improved warning or error message in Clang, but not in clang-tidy or static analyzer clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party crash Prefer [crash-on-valid] or [crash-on-invalid]

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@rupprecht
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rupprecht commented Apr 11, 2023 •
edited by VoltrexKeyva
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Crash when processing an "almost trailing comment" line:

https://godbolt.org/z/ehPM8f1ob

/*<*\
/

->

<source>:1:5: warning: escaped newline between */ characters at block comment end [-Wcomment]
/*<*\
    ^
if this is an almost Doxygen comment, it should be ordinary
UNREACHABLE executed at /root/llvm-project/clang/lib/Sema/Sema.cpp:2405!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics <source>
1.	<unknown> parser at unknown location
 #0 0x0000562be67b783f llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c6283f)
 #1 0x0000562be67b557c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c6057c)
 #2 0x0000562be67028c8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f668966b420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f668913800b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f6689117859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x0000562be670dbae (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3bb8bae)
 #7 0x0000562be900ed4e clang::Sema::ActOnComment(clang::SourceRange) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64b9d4e)
 #8 0x0000562be8eaf494 (anonymous namespace)::ActionCommentHandler::HandleComment(clang::Preprocessor&, clang::SourceRange) Parser.cpp:0:0
 #9 0x0000562bea9ba487 clang::Preprocessor::HandleComment(clang::Token&, clang::SourceRange) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7e65487)
@rupprecht rupprecht added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" crash Prefer [crash-on-valid] or [crash-on-invalid] labels Apr 11, 2023
@llvmbot
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llvmbot commented Apr 11, 2023

@llvm/issue-subscribers-clang-frontend

@EugeneZelenko EugeneZelenko removed the clang Clang issues not falling into any other category label Apr 11, 2023
@shafik
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shafik commented Apr 11, 2023

Confirmed

@shafik shafik added the confirmed Verified by a second party label Apr 11, 2023
@shafik
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shafik commented Apr 11, 2023

CC @cor3ntin I think you recently modified the code around this crash maybe you have an idea what is going on.

@cor3ntin
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@shafik I think this is prexisting

RawComment::getCommentKind() classify the comment as invalid because it does not end with */ and ActOnComment does not account for that.

I'm playing with seeking backward through the splice to find the *, but I'm wondering if we should just remove the
unreachable, or the check that produced the invalid comment

@rupprecht
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Sorry, I forgot to mention this isn't reporting a recent regression. I just found this recently in an LLDB fuzzing report (which uses Clang libraries for expression evaluation).

The oldest clang+asserts binary I have on hand is from 2019 (r374907 / 84423bd) and the issue reproduces there.

@shafik
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shafik commented Apr 11, 2023

That is good to know, we don't mind bug found via fuzzing as long as they are curated to avoid a lot of noise and the volume is not too high.

@cor3ntin
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Fix here https://reviews.llvm.org/D148029

@EugeneZelenko EugeneZelenko added the clang:diagnostics New/improved warning or error message in Clang, but not in clang-tidy or static analyzer label Apr 12, 2023
flemairen6 pushed a commit to Xilinx/llvm-project that referenced this issue May 10, 2023
@cor3ntin
[Clang] Fix crash caused by line splicing in doc comment
a6b6626 
Because the comment parser does not support slices,
we emit a warning for comments that do contain
a splice within their delimiter, and do not add them as
documentation comment.

Fixes llvm#62054

Reviewed By: shafik, aaron.ballman

Differential Revision: https://reviews.llvm.org/D148029
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clang:diagnostics New/improved warning or error message in Clang, but not in clang-tidy or static analyzer clang:frontend Language frontend issues, e.g. anything involving "Sema" confirmed Verified by a second party crash Prefer [crash-on-valid] or [crash-on-invalid]
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@rupprecht @cor3ntin @shafik @EugeneZelenko @llvmbot