[cfe-dev] Bug Wrangling?

Jason Switzer jswitzer at gmail.com
Sun Jan 29 21:54:42 PST 2012

Hi, my name is Jason Switzer and I have been wanting to help out with LLVM
for some time. I decided to start by going through the bug database and
doing some wrangling (updating, verifying current behavior versus reported,
etc) as it seemed like the easiest way to learn the code base. So far, I've
found there are many low hanging fruit in the "quality-of-implementation"
bugs, and I've run into some bugs that are rather aged. For example, I
posted the following to bug 4665 (http://llvm.org/bugs/show_bug.cgi?id=4665

This bug appears to be no longer an issue. As of r148640, the following is
> produced:

> $ echo "int main() { unsigned int foo = -2; return foo; }" | clang
> -Wconversion -x c++ -

<stdin>:1:33: warning: implicit conversion changes signedness: 'int' to
> 'unsigned int' [-Wsign-conversion]

int main() { unsigned int foo = -2; return foo; }

                          ~~~   ^~

<stdin>:1:44: warning: implicit conversion changes signedness: 'unsigned
> int' to 'int' [-Wsign-conversion]

int main() { unsigned int foo = -2; return foo; }

                                    ~~~~~~ ^~~

2 warnings generated.

> The author of this bug was trying to use -Wall, which I'm not sure is
> valid for clang (it is for GCC, which reports this under -Wsign-compare).
> That being said, there is -Wconversion, which emits the
> "warn_impcast_integer_sign" warning (-Weverything turns on -Wconversion) at
> SemaChecking.cpp:3926.

> Given that it picked up both implicit casts and reported them as a warning
> when requested, this bug should probably be considered RESOLVED.

This bug was reported 2.5 years ago and hasn't seen a status change in 2
years. I don't feel right changing the status of this without someone else
at least seeing it and I'm afraid any email that bugzilla would send might
get overlooked by those that could do meaningful review.

So what's the current LLVM / Clang way of dealing with this? As a someone
who's just getting started with LLVM, I'd like to help, but I would hate to
pump a ton of time going through a bunch of bugs only to have my
help/feedback ignored. Should I double post my comments (llvm.org/bugs and
cfe-dev)? I'm guessing that if I have a patch to make, I should post it to
cfe-commits, but I am afraid that such small issues/changes might get lost
there as well.

-Jason "s1n" Switzer
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