<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div class="gmail_quote"><div>Hi,</div><div><br></div><div>That may be a really nice check indeed.</div><div>I think that a good way to proceed would be to start a review on Phabricator (<a href="https://reviews.llvm.org/">https://reviews.llvm.org/</a>).</div><div><br></div><div>From what I've seen there are some things that you could achieve through AST matchers instead of checking conditions when already having a candidate match.</div><div><br></div><div>For instance, instead of:</div><div><div>Finder->addMatcher( </div><div> cxxMethodDecl(eachOf(unless(returns(voidType())), (isConst()))) </div><div> .bind("noDiscardCandidate"), </div><div> this); </div></div><div>and then if (MatchedDecl->hasUnusedResultAttr()) </div><div><br></div><div>you can just add unless(hasAttr(clang::attr::WarnUnusedResult)) inside eachOf.</div><div><br></div><div>And for the hint insertion location, these 3 should always be fine for you even in the case of trailing return type:</div><div>* "getBeginLoc()"<br></div><div>* "getInnerLocStart()"<br></div><div>* "getOuterLocStart()"<br></div><div>See slightly modified Stephen's example at: <a href="http://ec2-52-14-16-249.us-east-2.compute.amazonaws.com:10240/z/8GsU8c">http://ec2-52-14-16-249.us-east-2.compute.amazonaws.com:10240/z/8GsU8c</a>.</div><div><br></div><div>Best regards,</div><div>Marek</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">---------- Forwarded message ----------<br>From: MyDeveloper Day via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>><br>To: <br>Cc: <a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a><br>Bcc: <br>Date: Thu, 6 Dec 2018 20:13:07 +0000<br>Subject: Re: [cfe-dev] [clang-tidy] Adding a new use nodiscard checker (help needed)<br><div dir="ltr"><div dir="ltr"><div dir="ltr">Thanks for the pointers.. this led me to look a little deeper at some of the other checkers</div><div dir="ltr"><br></div><div>looks like ConstReturnTypeCheck uses getInnerLocStart() to locate the return type</div><div dir="ltr"><br></div><div>Substituting this in seems to find the correct location, but I suspect this doesn't work well for the training return type</div><div><br></div><div dir="ltr"><div dir="ltr">auto retLoc = MatchedDecl->getInnerLocStart();</div><div dir="ltr"><br></div><div dir="ltr"> // This function could be marked [[nodiscard]]</div><div dir="ltr"> diag(retLoc, "function %0 should be marked [[nodiscard]]")</div><div dir="ltr"> << MatchedDecl << FixItHint::CreateInsertion(retLoc, "[[nodiscard]] ");</div><div dir="ltr"><br></div><div dir="ltr"><br></div><div dir="ltr">---------------------------------------------------------------</div><div><br></div><div><div>test.cxx:18:5: warning: function 'empty' should be marked [[nodiscard]] [modernize-use-nodiscard]</div><div> bool empty() const</div><div> ^</div><div> [[nodiscard]]</div><div>test.cxx:22:5: warning: function 'empty' should be marked [[nodiscard]] [modernize-use-nodiscard]</div><div> bool empty(int val) const</div><div> ^</div><div> [[nodiscard]]</div><div>test.cxx:50:5: warning: function 'empty' should be marked [[nodiscard]] [modernize-use-nodiscard]<br></div><div> const bool empty() const</div><div> ^</div><div> [[nodiscard]]</div><div>test.cxx:55:5: warning: function 'empty' should be marked [[nodiscard]] [modernize-use-nodiscard]</div><div> inline const bool empty() const</div><div> ^</div><div> [[nodiscard]]</div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Dec 6, 2018 at 7:19 PM Stephen Kelly via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">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">On 06/12/2018 19:08, MyDeveloper Day via cfe-dev wrote:<br>
> I'm currently using (following a series of trail and errors) to find the <br>
> location just before the return type<br>
<br>
Here are the locations you can get for FunctionDecls:<br>
<br>
<a href="http://ec2-52-14-16-249.us-east-2.compute.amazonaws.com:10240/z/oiG2nf" rel="noreferrer" target="_blank">http://ec2-52-14-16-249.us-east-2.compute.amazonaws.com:10240/z/oiG2nf</a><br>
<br>
See also if you have not already:<br>
<br>
<br>
<a href="https://steveire.wordpress.com/2018/11/11/future-developments-in-clang-query/" rel="noreferrer" target="_blank">https://steveire.wordpress.com/2018/11/11/future-developments-in-clang-query/</a><br>
<br>
If there isn't a location in that output for what you need, then you are <br>
going to have to check the tokens yourself. Many existing clang tidy <br>
checks do things like this due to lack of location for a particular need.<br>
<br>
Thanks,<br>
<br>
Stephen.<br></blockquote></div>
</blockquote></div></div></div></div></div></div></div>