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.error { color:#AA0000; }</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="bloop_markdown"><p>Why do you cast against an existential in first place?</p>
<p>This solves the given example:</p>
<pre><code class="swift">protocol Something {}
protocol IntContainer {
var ints: [Int] { get set }
}
func processSomething(_ state: Something) {
if let intContainer = state as? IntContainer {
print(intContainer.ints)
}
}
struct MySomething: Something, IntContainer {
var ints: [Int] = []
}
let mySomething = MySomething()
processSomething(mySomething)
</code></pre>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <br> <div id="bloop_sign_1491230830869369856" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 3. April 2017 um 16:31:02, Rudolf Adamkovič via swift-users (<a href="mailto:swift-users@swift.org">swift-users@swift.org</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div></div><div>
<title></title>
<div class="">I'm getting an `EXC_BAD_ACCESS` here:</div>
<div class=""><br class=""></div>
<div class="">
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">protocol</span> <span style="font-variant-ligatures: no-common-ligatures" class="">Something
{}</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; min-height: 15px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">protocol</span> <span style="font-variant-ligatures: no-common-ligatures" class="">IntContainer
{</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span> <span style="font-variant-ligatures: no-common-ligatures" class="">ints:
[</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Int</span><span style="font-variant-ligatures: no-common-ligatures" class="">] {</span>
<span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">get</span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">set</span> <span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; min-height: 15px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span> <span style="font-variant-ligatures: no-common-ligatures" class="">processSomething(</span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">_</span> <span style="font-variant-ligatures: no-common-ligatures" class="">state:</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Something</span><span style="font-variant-ligatures: no-common-ligatures" class="">)
{</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">if</span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span> <span style="font-variant-ligatures: no-common-ligatures" class="">intContainer
= state</span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures" class="">?</span>
<span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Something</span> <span style="font-variant-ligatures: no-common-ligatures" class="">&</span>
<span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">IntContainer</span> <span style="font-variant-ligatures: no-common-ligatures" class="">{</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(intContainer.</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">ints</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; min-height: 15px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; color: rgb(79, 129, 135);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">struct</span> <span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">MySomething:</span> <span style="font-variant-ligatures: no-common-ligatures" class="">Something</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">,</span> <span style="font-variant-ligatures: no-common-ligatures" class="">IntContainer</span> <span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">{</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">var</span> <span style="font-variant-ligatures: no-common-ligatures" class="">ints:
[</span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Int</span><span style="font-variant-ligatures: no-common-ligatures" class="">] =
[]</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; min-height: 15px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span> <span style="font-variant-ligatures: no-common-ligatures" class="">mySomething
=</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">MySomething</span><span style="font-variant-ligatures: no-common-ligatures" class="">()</span></div>
<div style="margin: 0px; font-size: 13px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">processSomething</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">mySomething</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">)</span> <span style="font-variant-ligatures: no-common-ligatures" class="">//
EXC_BAD_ACCESS here</span></div>
</div>
<div class=""><br class=""></div>
<div class="">The execution stops here:</div>
<div class=""><br class=""></div>
<div class=""><font face="Menlo" size="2" class="">libswiftCore.dylib`_swift_release_dealloc:</font></div>
<div class=""><font face="Menlo" size="2" class="">
0x11be163e0 <+0>: movq (%rdi), %rax</font></div>
<div class=""><font face="Menlo" size="2" class="">->
0x11be163e3 <+3>: jmpq *-0x10(%rax)</font></div>
<div class=""><font face="Menlo" size="2" class="">
0x11be163e6 <+6>: nopw %cs:(%rax,%rax)</font></div>
<div class=""><br class=""></div>
<div class="">Any ideas why this is?</div>
<div class=""><br class=""></div>
<div class="">P.S. Related StackOverflow question with no good
answer:</div>
<div class=""><a href="http://stackoverflow.com/questions/35199077/exc-bad-access-using-protocol-composition" class="">http://stackoverflow.com/questions/35199077/exc-bad-access-using-protocol-composition</a></div>
<div class=""><br class=""></div>
<div class="">R+</div>
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