[cfe-dev] Asserts in Clang crashes my Kdevelop

[Lucas Tanure]

Hi,

Well, I just jumped in kdevelop, just because I need a good editor to
develop linux kernel. I don't understand the code of kdevelop and clang.
My "test case" is import the top makefile from linux tree and wait to clang
to parse. Just that. It crashes a few minutes latter in a thread from clang
parser.

I know that this asserts are important, but I get this tip to disable
asserts from kdevelop community. I think that would take a few days for me
to understand what's happening.
I really would like to understand and fix this issue. If someone is willing
to help me and mentor would be great.

I compiled all llvm, clang, kdevelop and kdev-clang plugin in my Arch Linux
Desktop. My goal is to have a good editor for linux kernel, with the same
features that I had with vim+cscope.

Thanks



--
Lucas Tanure
+55 (19) 988176559

On Wed, Jan 28, 2015 at 12:10 AM, Richard Smith <richard at metafoo.co.uk>
wrote:

> On Mon, Jan 26, 2015 at 11:46 PM, Olivier J. G. <olivier.jg at gmail.com>
> wrote:
>
>> void Lexer::lexVerbatimBlockFirstLine(Token &T) {
>>> again:
>>>   assert(BufferPtr < CommentEnd);
>>>
>>> So, failing that assertion is equivalent to memory OOB access.
>>>
>>> Barring an enormous push to stabilize Clang and make it less crashy, you
>>> have two options:
>>> 1. Try to recover from assertion failures and segfaults with
>>> CrashRecoveryContext
>>> 2. Rig up a separate process to run clang in from kdevelop
>>>
>>> A separate process will be more stable but far more effort.
>>>
>>> You'd think compilers wouldn't crash very often, but take a look at the
>>> list of crashers found by AFL:
>>> http://llvm.org/bugs/buglist.cgi?quicksearch=fuzz&list_id=66187
>>> While these are all bugs we'd like fixed, it's not clear how soon that
>>> will happen. Until then, KDevelop and IDEs in general will need to cope
>>> with compiler crashes somehow.
>>>
>>>
>> While it seems like this assertion failure would lead to a crash, I
>> should note that I haven't run into any crashes during AST traversal when
>> clang is in release mode. OTOH, clang compiled in debug mode will fairly
>> regularly come up with assertions during AST traversal.
>>
>> For the initial parsing we see plenty of crashes and asserts in both
>> debug and release, but libclang already runs those in a
>> CrashRecoveryContext, so it's not usually an issue (unless you're trying to
>> run KDevelop in gdb...).
>>
>> In short, KDevelop/kdev-clang runs smoothly with release-build clang and
>> is not really usable when clang is built w/ assertions.
>>
>
> Nonetheless, if you can provide us with testcases for the crashes, we'd
> appreciate them.
>
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>
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