<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Mar 22, 2016 at 11:35 PM, Chris Lattner via swift-evolution <span dir="ltr"><<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Hello Swift community,<br>
<br>
The review of "Adding initializers to Int and UInt to convert from UnsafePointer and UnsafeMutablePointer" begins now and runs through March 25th. The proposal is available here:<br>
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<a href="https://github.com/apple/swift-evolution/blob/master/proposals/0016-initializers-for-converting-unsafe-pointers-to-ints.md" rel="noreferrer" target="_blank">https://github.com/apple/swift-evolution/blob/master/proposals/0016-initializers-for-converting-unsafe-pointers-to-ints.md</a><br>
<br>
Reviews are an important part of the Swift evolution process. All reviews should be sent to the swift-evolution mailing list at:<br>
<a href="https://lists.swift.org/mailman/listinfo/swift-evolution" rel="noreferrer" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br>
or, if you would like to keep your feedback private, directly to the review manager.<br>
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What goes into a review?<br>
<br>
The goal of the review process is to improve the proposal under review through constructive criticism and, eventually, determine the direction of Swift. When writing your review, here are some questions you might want to answer in your review:<br>
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* What is your evaluation of the proposal?<br></blockquote><div>-1. While it is tempting to have the full power of converting pointers to ints, it's a recipe for security issues as already mentioned.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
* Does this proposal fit well with the feel and direction of Swift?<br></blockquote><div>No. Swift feels safer than doing raw pointer arithmetic.</div><div>I'm for the alternative mentioned in the proposal (comments inline):</div><div><br></div><div><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">...The next alternative was to add functions to </span><code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:rgb(51,51,51)">Unsafe[Mutable]Pointer</code><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"> which covered the identified pointer arithmetic cases. This alternative was rejected because it either would have required us to imagine every use-case of pointer arithmetic [...] or it would have required adding a full suite of arithmetic and bitwise operators to </span><code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:rgb(51,51,51)">Unsafe[Mutable]Pointer</code><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">. </span></div><div>I think the full suite is worth eliminating potential raw pointer arithmetic bugs.<span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><br></span></div><div><br></div><div><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Because some of these operations are defined only on signed integers, and others on unsigned, it would have required splitting </span><code style="font-family:Consolas,'Liberation Mono',Menlo,Courier,monospace;font-size:14px;padding:0.2em 0px;margin:0px;background-color:rgba(0,0,0,0.0392157);border-top-left-radius:3px;border-top-right-radius:3px;border-bottom-right-radius:3px;border-bottom-left-radius:3px;color:rgb(51,51,51)">Unsafe[Mutable]Pointer</code><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"> into signed and unsigned variants, which would have complicated things for users who did not need to do pointer arithmetic.</span></div><div>What operations are defined only on signed/unsigned ints?<span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><br></span></div><div><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px"><br></span></div><div><span style="color:rgb(51,51,51);font-family:'Helvetica Neue',Helvetica,'Segoe UI',Arial,freesans,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px">Additionally, the implementations of these operations would have probably converted the pointers to integers, perform a single operation, and then convert them back. When chaining operations, this would create a lot of unnecessary conversions.</span><br></div><div>Isn't that for the optimizer to optimize?<br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> * How much effort did you put into your review? A glance, a quick reading, or an in-depth study?<br></blockquote><div>A quick reading. </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<br>
More information about the Swift evolution process is available at<br>
<br>
<a href="https://github.com/apple/swift-evolution/blob/master/process.md" rel="noreferrer" target="_blank">https://github.com/apple/swift-evolution/blob/master/process.md</a><br>
<br>
Thank you,<br>
<br>
-Chris Lattner<br>
Review Manager<br>
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