<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi!<div class=""><br class=""></div><div class="">There is strange behaviour of nullable const pointer.</div><div class=""><br class=""></div><div class="">Lets say I have function f.</div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(186, 45, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">int</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> f(</span><span style="font-variant-ligatures: no-common-ligatures" class="">int</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">* </span><span style="font-variant-ligatures: no-common-ligatures" class="">_Nonnull</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> i) {</span></div><div style="margin: 0px; font-size: 11px; 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="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> *i;</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-family: Helvetica; font-size: 12px;" class="">And code like this:</span></div><div style="margin: 0px; line-height: normal;" class=""><div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">int</span><span style="font-variant-ligatures: no-common-ligatures" class=""> main() {</span></div><div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal; color: rgb(186, 45, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">int</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">* </span><span style="font-variant-ligatures: no-common-ligatures" class="">_Nullable</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> p = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">;</span></div><div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> f(p);</span></div><div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><span style="font-family: Helvetica; font-size: 12px;" class="">produces error as expected, if I pass -Wnullable-to-nonnull-conversion</span></span></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><font face="Menlo" color="#001e57" class="">$ clang t.c -Werror -Wnullable-to-nonnull-conversion<br class="">t.c:7:12: error: implicit conversion from nullable pointer 'int * _Nullable' to non-nullable pointer type 'int * _Nonnull' [-Werror,-Wnullable-to-nonnull-conversion]<br class=""> return f(p);<br class=""> ^<br class="">1 error generated.</font></span></div><div style="margin: 0px; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">But, if I change code like so</span></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">int</span><span style="font-variant-ligatures: no-common-ligatures" class=""> main() {</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(186, 45, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">int</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">* </span><span style="font-variant-ligatures: no-common-ligatures" class="">_Nullable</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class=""><b class="">const</b></span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> p = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">0</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">;</span></div><div style="margin: 0px; font-size: 11px; 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="">return</span><span style="font-variant-ligatures: no-common-ligatures" class=""> f(p);</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div style="margin: 0px; line-height: normal;" class="">compiler does not produces any errors.</div><div style="margin: 0px; line-height: normal;" class=""><br class=""></div><div style="margin: 0px; line-height: normal;" class="">It looks very strange.</div></span></div></div></body></html>