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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Not to be super snarky, but is there some reason why Chrome project preferences must be encoded into Clang compiler features?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This is really a stylistic choice in how you want to manage your project. There's no end to the potential who-wins argument, whether it should be '#pragma
dammit' or the '—dammit' command line option. We have one way in place, and you have other tactics available to enforce a different choice.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></a></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> cfe-dev [mailto:cfe-dev-bounces@lists.llvm.org]
<b>On Behalf Of </b>James Y Knight via cfe-dev<br>
<b>Sent:</b> Thursday, January 24, 2019 12:00 PM<br>
<b>To:</b> Nico Weber<br>
<b>Cc:</b> cfe-dev<br>
<b>Subject:</b> Re: [cfe-dev] Does `#pragma GCC diagnostic warning` intentionally win over -Werror?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Perhaps a lint rule triggering on "#pragma GCC diagnostic warning", saying "We don't allow warnings, please use `#pragma GCC diagnostic error` (or ignored)" would solve the problem sufficiently.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Separately, I note that "#pragma GCC diagnostic error" allows errors to bypass -Wfatal-errors. That certainly seems to serve no useful purpose and could be removed.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Jan 24, 2019 at 11:20 AM Nico Weber <<a href="mailto:thakis@chromium.org" target="_blank">thakis@chromium.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">On Thu, Jan 24, 2019 at 11:12 AM James Y Knight <<a href="mailto:jyknight@google.com" target="_blank">jyknight@google.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">I don't think we should have such a flag. The explicit intent of '#pragma gcc diagnostic warning' is to allow downgrading an error to a warning, while still allowing it to be emitted.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Perhaps a new value for pragma diagnostic which emits an upgradeable warning would be reasonable.<o:p></o:p></p>
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<p class="MsoNormal">The use case here is that we don't allow non-error diagnostics in chrome. Some subproject used `#pragma GCC diagnostic warning` because they wanted to configure warning flags in cc files instead of in build files for some reason. They didn't
expect this to trigger a warning instead of an error. A new pragma would meet that use case, but I don't want source code to be able to opt out of -Werror. In my experience, once it's known that such an option exist, someone will use it. So we do need some
kind of "_all_ warnings are errors" toggle.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Jan 24, 2019 at 9:56 AM Nico Weber via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Re "intentional?", it matches gcc which explicitly documents on <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html" target="_blank">https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html</a> that the pragma wins over
-Werror.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Does anyone know if there's a flag that says "I want all warnings to be errors, not just most of them"?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If there isn't one yet, what would be a good UI for that?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Wed, Jan 23, 2019 at 11:11 PM Nico Weber <<a href="mailto:thakis@chromium.org" target="_blank">thakis@chromium.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Consider:<o:p></o:p></p>
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<p class="MsoNormal">$ cat test.cc<o:p></o:p></p>
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<p class="MsoNormal">#pragma GCC diagnostic warning "-Wsign-compare"<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">bool f(int a, unsigned b) {<o:p></o:p></p>
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<p class="MsoNormal"> return a != b;<o:p></o:p></p>
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<p class="MsoNormal">}<o:p></o:p></p>
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<p class="MsoNormal">$ out/gn/bin/clang -c test.cc -Werror<o:p></o:p></p>
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<p class="MsoNormal">test.cc:4:12: warning: comparison of integers of different signs: 'int' and 'unsigned int' [-Wsign-compare]<o:p></o:p></p>
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<p class="MsoNormal"> return a != b;<o:p></o:p></p>
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<p class="MsoNormal"> ~ ^ ~<o:p></o:p></p>
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<p class="MsoNormal">1 warning generated.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I found it surprising that this is emitted as a warning, not as an error. If this is intentional, is there some other way to say "I want my compiler warnings to always be errors"?<o:p></o:p></p>
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<p class="MsoNormal"><br>
Thanks,<o:p></o:p></p>
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<p class="MsoNormal">Nico<o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
cfe-dev mailing list<br>
<a href="mailto:cfe-dev@lists.llvm.org" target="_blank">cfe-dev@lists.llvm.org</a><br>
<a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev" target="_blank">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><o:p></o:p></p>
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