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<p class="MsoNormal" style="margin-left:.5in">Is this right? GCC and the current patch coincide on the handling of `\ `. The only deviation is in the `#` case, no?<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><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">Sorry, you are correct, GCC was getting "\ " right but "\#" wrong. Clang was doing both wrong.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">So, for Nico's example, "\ " would be converted to "\\\ " by gcc, but not by Clang, and that's being fixed by the patch.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">But GCC would emit "\#" as "\\#" which GNU make would interpret as "\" followed by a comment, and if that failed, try to interpret it as "\\" followed by a
comment, neither of which would look for the correct file. The patch causes Clang to emit this as "\\\#" which lets GNU make find the right file.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Regarding ninja, I don't think ninja can directly read Make-style dependency files? Its syntax naively looks different enough that I'm not really sure that's
relevant here.<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"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></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""> Sean Silva [mailto:chisophugis@gmail.com]
<br>
<b>Sent:</b> Friday, May 08, 2015 6:40 PM<br>
<b>To:</b> Robinson, Paul<br>
<b>Cc:</b> Nico Weber; reviews+D9208+public+0ac91376ffbd3e34@reviews.llvm.org; cfe-commits@cs.uiuc.edu<br>
<b>Subject:</b> Re: [PATCH] Fix dependency file escaping<o:p></o:p></span></p>
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<p class="MsoNormal">On Fri, May 8, 2015 at 5:57 PM, Robinson, Paul <<a href="mailto:Paul_Robinson@playstation.sony.com" target="_blank">Paul_Robinson@playstation.sony.com</a>> wrote:<o:p></o:p></p>
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If a program (say, ninja) tries to be compatible with gnu make's depfile parsing, it would previously convert "\ " to a space from what I understand. Now it's going to get "\\\ " and think that that's "\ ".<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="14d363012a24af9b__MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span></a><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">You're mixing things up. #include "\ " would be converted by gcc to "\\ " (because it escapes the
space but not the backslash) which would be de-escaped by GNU Make as "\" followed by a space delimiter.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Now Clang will give it "\\\ " which will be handled as "\ " which is correct.</span><o:p></o:p></p>
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<p class="MsoNormal">Is this right? GCC and the current patch coincide on the handling of `\ `. The only deviation is in the `#` case, no?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- Sean Silva<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">(Remember that the string you hand to #include is NOT a normal C string; it has no escaping in it.)</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><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"">
<a href="mailto:cfe-commits-bounces@cs.uiuc.edu" target="_blank">cfe-commits-bounces@cs.uiuc.edu</a> [mailto:<a href="mailto:cfe-commits-bounces@cs.uiuc.edu" target="_blank">cfe-commits-bounces@cs.uiuc.edu</a>]
<b>On Behalf Of </b>Nico Weber<br>
<b>Sent:</b> Friday, May 08, 2015 4:36 PM<br>
<b>To:</b> <a href="mailto:reviews%2BD9208%2Bpublic%2B0ac91376ffbd3e34@reviews.llvm.org" target="_blank">
reviews+D9208+public+0ac91376ffbd3e34@reviews.llvm.org</a><br>
<b>Cc:</b> <a href="mailto:cfe-commits@cs.uiuc.edu" target="_blank">cfe-commits@cs.uiuc.edu</a><br>
<b>Subject:</b> Re: [PATCH] Fix dependency file escaping</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">On Fri, May 8, 2015 at 4:01 PM, Paul Robinson <<a href="mailto:Paul_Robinson@playstation.sony.com" target="_blank">Paul_Robinson@playstation.sony.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">In
<a href="http://reviews.llvm.org/D9208#169446" target="_blank">http://reviews.llvm.org/D9208#169446</a>, @thakis wrote:<br>
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> Does gcc intend to fix this soon? Isn't being compatible with gcc important<br>
> than the other things?<br>
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<br>
If gcc emitted an incorrect relocation, would you argue that it's important to be compatible with gcc? Even if you could not point to any linker that handled that buggy relocation in a reasonable way?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">'course not, but that's not the case here. If a program (say, ninja) tries to be compatible with gnu make's depfile parsing, it would previously convert "\ " to a space from what
I understand. Now it's going to get "\\\ " and think that that's "\ ". So this is breaking backwards compat of clang with itself.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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