<div dir="ltr">Hi Saleem,<div><br></div><div>About the technical aspects. The feature to be able to add extra information to library functions would be really helpful in the Clang Static Analyzer. APINotes might be a way forward to achieve that.</div><div><br></div><div>We'd like to add the following to functions<br></div><div><ul><li>Argument constraints</li><ul><li>Not null</li><li>Range, e.g. isalpha(int x) x must be in [0,255].</li><li>Buffer size, e.g. fread(x1, x2, x3) x1 is a buffer with a size denoted by x2 * x3</li></ul><li>Taint rules</li><ul><li>propagation <br> <font face="monospace">int x; // x is tainted<br> int y;<br> myPropagator(x, &y); // y is tainted</font></li><li>filter<br> <font face="monospace">int x; // x is tainted<br> isOutOfRange(&x); // x is not tainted anymore</font><br></li><li>sink<br> <font face="monospace">int x; // x is tainted<br> myNamespace::mySink(x); // It will warn</font><br></li></ul><li>Error return rules, e.g. the return value of <a href="https://wiki.sei.cmu.edu/confluence/display/c/ERR33-C.+Detect+and+handle+standard+library+errors">mktime() should always be checked against -1.</a> (<a href="https://reviews.llvm.org/D72705">D72705</a>)</li><li>Indicate which functions we should consider with <a href="https://www.youtube.com/watch?v=IM1DYZ-xn-k">statistical checkers</a> (WIP, not upstreamed yet).</li></ul></div><div>Note to taint analysis: we might want to tag global variables as sources. E.g. std::cin.</div><div><br></div><div>I think that we could extend the APINote implementation that you have in the referenced commit, but with a CSA specific attribute:</div><div><font face="monospace">def CSANotes : InheritableAttr {<br> let Spellings = [GNU<"csa">];<br> let Args = [StringArgument<"FreeFormatOrSomeYamlMaybe">];<br> let Subjects = SubjectList<[Tag, Function, Var],<br> ErrorDiag>;<br>}<br></font>The string argument could be parsed specifically to the CSA developers' needs in a CSA specific implementation file. IMHO it would be a flexible solution because we could avoid adding many CSA specific attributes to Attrs.td and it would allow us to make experiments.</div><div><br></div><div>My concerns about the referenced APINotes implementation:</div><div><ul><li>Specifically with the `'Name' key`. How could we match in C++</li><ul><li>overloaded functions</li><li>member functions</li><li>functions in namespaces</li><li>function templates</li><li>member functions of class templates (e.g. std::vector::begin)</li></ul><li>Do we have a mechanism to test/indicate if a note is not applied but it should have been?</li></ul></div><div><br></div><div>Adding CSA guys who might want to comment.<br></div><div><div><a class="gmail_plusreply" id="plusReplyChip-0" href="mailto:noqnoqneo@gmail.com" tabindex="-1">+Artem Dergachev</a> <br></div><div><a class="gmail_plusreply" id="plusReplyChip-2" href="mailto:xazax.hun@gmail.com" tabindex="-1">+Gábor Horváth</a> <br></div></div><div><br></div><div>Thanks,</div><div>Gabor</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Sep 28, 2020 at 11:10 PM Saleem Abdulrasool via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr">Hi!<div><br></div><div>I'd like to revive the effort around merging APINotes support into the <a href="http://llvm.org/" target="_blank">llvm.org</a> repository. This was previously discussed at <a href="http://lists.llvm.org/pipermail/cfe-dev/2017-May/053860.html" target="_blank">http://lists.llvm.org/pipermail/cfe-dev/2017-May/053860.html</a> nearly 3 years ago. The overall consensus seemed neutral to slightly positive. Now that the Swift specific attributes have been merged, the APINotes seem like a good next step towards converging the fork.</div><div><br></div><div>I've put up <a href="https://reviews.llvm.org/D88446" target="_blank">https://reviews.llvm.org/D88446</a> to add initial documentation on the feature before trying to add the actual implementation with the goal of gathering commits on the technical aspects of the feature.</div><div><br></div><div>Thanks.</div><font color="#888888"><div></div></font><div><br></div>-- <br><div dir="ltr">Saleem Abdulrasool<br>compnerd (at) compnerd (dot) org</div></div></div>
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