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<p class="MsoNormal">I support this proposal. I very much dislike the current function parameter formatting (in function declarations/definitions). It just adds a bunch of whitespace without improvement in readability.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In practice there are already various mixtures of formatting being used. For example:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> bool tailDuplicate(bool IsSimple,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> MachineBasicBlock *TailBB,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> MachineBasicBlock *ForcedLayoutPred,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> SmallVectorImpl<MachineBasicBlock *> &TDBBs,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> SmallVectorImpl<MachineInstr *> &Copies,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> SmallVectorImpl<MachineBasicBlock *> *CandidatePtr);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> void appendCopies(MachineBasicBlock *MBB,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> SmallVectorImpl<std::pair<Register, RegSubRegPair>> &CopyInfos,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> SmallVectorImpl<MachineInstr *> &Copies);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> void removeDeadBlock(<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> MachineBasicBlock *MBB,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas"> function_ref<void(MachineBasicBlock *)> *RemovalCallback = nullptr);</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">These are 3 adjacent declarations in the same file (llvm/include/llvm/CodeGen/TailDuplicator.h).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I don’t think that the alternative format would make call sites immune to renaming, since it can still cause fewer or more function arguments to fit in a given line of code. I still think it’s a worthwhile change in style.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Consolas">-- </span>
<span style="font-size:9.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Consolas">Krzysztof Parzyszek
<a href="mailto:kparzysz@quicinc.com"><span style="color:#0563C1">kparzysz@quicinc.com</span></a> AI tools development<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <llvm-dev-bounces@lists.llvm.org> <b>On Behalf Of
</b>Nikita Popov via llvm-dev<br>
<b>Sent:</b> Thursday, December 3, 2020 3:01 PM<br>
<b>To:</b> llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> [EXT] [llvm-dev] Change coding style for argument alignment?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">LLVM currently uses a coding style where arguments and parameters need to be aligned to the opening parenthesis "(".<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> someFunctionCall(Arg1, Arg2,<o:p></o:p></p>
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<p class="MsoNormal"> Arg3, Arg4);<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">This style guideline is unfortunate for a couple of reasons:<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. If a function is renamed, it is necessary to also reindent the arguments at all call-sites. For functions with many or complex arguments, this may require significant reflow.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">2. It causes significant right-ward drift. Especially for declarations, it's somewhat common for code ending up like this...<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> Foo SomeClassName::someMethodName(Bar &Arg1,<br>
Bar &Arg2,<br>
Bar &Arg3,<br>
Bar &Arg4) {<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">... because there is just enough space to fit each argument individually, but still a need to break each one out on a separate line. Closure arguments are another common case of very awkward formatting.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">3. There are some arcane rules about when this is not the preferred style and you're supposed to indent arguments on the following line instead.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Is there any chance that the style could be changed towards indenting (but not aligning) the following line instead?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> someFunctionCall(<o:p></o:p></p>
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<p class="MsoNormal"> Arg1, Arg2, Arg3, Arg4);<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">This is unaffected by renames, does not cause rightward drift and results in very predictable formatting.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Based on past discussions, LLVM seems to be open to improving coding style for the better, so I thought I'd give this a shot, as this is a continuous source of friction for me.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Regards,<o:p></o:p></p>
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<p class="MsoNormal">Nikita<o:p></o:p></p>
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