[GSoC][Static Analyzer] Some questions and request for a small patch to work on

[David Malcolm]

On Wed, 2023-02-22 at 15:11 +0100, Shengyu Huang wrote:
> Hi Dave,
> 
> 
> > But a better place to look would probably be in our bugzilla; see
> > the
> > links on the wiki page:
> >  https://gcc.gnu.org/wiki/StaticAnalyzer 
> > The "open bugs" list currently has 41 "RFE" bugs ("request for
> > enhancement" i.e. ideas for new features), some of which might make
> > suitable GSoC ideas, and/or be of interest to you (ideally both!)
> > 
> > Also, the GSoC wiki page has some project ideas:
> >  https://gcc.gnu.org/wiki/SummerOfCode#Selected_Project_Ideas
> > 
> 
> Yeah I was also searching for interesting ideas on the bugzilla, and
> I will communicate to you once I have any more concrete ideas.
> > 
> > If you haven't seen it yet, you might find my guide to GCC for new
> > contributors helpful:
> >  https://gcc-newbies-guide.readthedocs.io/en/latest/index.html
> > 
> 
> Just started reading it. Thanks for sharing!
> 
> > IIRC I saw you post a few days ago about trying to build gcc on
> > your M2
> > laptop; did you manage this?  Building GCC trunk from a git
> > checkout,
> > and hacking in a "hello world" warning would be a great place to
> > start.
> > See the guide above for some hints on how to make this process
> > quicker,
> > and let me know if you need help if you run into difficulties. 
> > Given
> > that the analyzer is about emitting warnings, rather than
> > generating
> > code, it may be that although we don't yet fully support your
> > hardware,
> > we *might* already support it enough to allow for hacking on the
> > analyzer, perhaps with some judicious choices of "configure"
> > options.
> 
> I just finished building it today on my laptop (Thanks Iain!). The
> GCC-12 branch did not work (I got `configure: error: C preprocessor
> "/lib/cpp" fails sanity check`) but the development branch works for
> me (haven’t encountered the potential pitfalls mentioned yet after
> testing it with some simple programs). Besides, I have also set up
> everything on both my university server and the compile farm machine,
> so I can test my work on these two machines as well.
> 
> What do you mean by a “hello world” warning? You meant to write some
> simple code like
> 
> ```
> #include <stdio.h>
> int main ()
> {
>   int a;
>   printf ("hello world\n");
>   return a;
> }
> ```
> 
> and to get the warning “warning: use of uninitialized value ‘a’ [CWE-
> 457] [-Wanalyzer-use-of-uninitialized-value]”? 

Sorry, I was unclear; I was referring to this part of my guide:
https://gcc-newbies-guide.readthedocs.io/en/latest/getting-started.html#hello-world-from-the-compiler

i.e. try writing a new warning that simply emits something like:

test.c:2:1: warning: hello world, I'm compiling 'main'
    2 | int main ()
      |     ^~~~

for each function that it sees.

That way you can easily see that you've modified the compiler, that
your code is running inside it.

Dave