<div dir="ltr">clang generally also understands __null (for the same reasons GCC does - to provide better diagnostics when using NULL in non-pointer contexts). See, for example, this warning (not an error): <a href="https://godbolt.org/z/KvdW7a">https://godbolt.org/z/KvdW7a</a><br><br>Can't say I know much about the NDK or what version of clang it has, what flags you might be passing, or why else it might be having trouble with __null, unfortunately.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Nov 4, 2019 at 9:15 AM pendyala syam via cfe-users <<a href="mailto:cfe-users@lists.llvm.org">cfe-users@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">I have a .cpp file which has usage of <strong style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">NULL</strong> at several places. When I try to compile this cpp file for Android/x86 platform using clang++ on Windows machine + standalone tool chain, I am running into "expected expression" error at the places where <strong style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">NULL</strong> is used. I find the definition of <strong style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">NULL</strong> in stddef.h of clang headers provided by Android NDK as below.</p><pre style="margin-top:0px;margin-bottom:1em;padding:12px 8px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;background-color:rgb(239,240,241);border-radius:3px;color:rgb(57,51,24)"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;box-sizing:inherit;white-space:inherit"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#if defined(__need_NULL)</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#undef</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)"> NULL
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#ifdef</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)"> __cplusplus
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#  if !defined(__MINGW32__) && !defined(_MSC_VER)</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#    define NULL __null</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#  else</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#    define NULL 0</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#  endif</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#else</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#  define NULL ((void*)0)</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(48,51,54)">
</span><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;color:rgb(133,140,147)">#endif</span></code></pre><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">As far as I know, <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;background-color:rgb(239,240,241);white-space:pre-wrap">__null</code> is specific to GNU compiler. In my case both _MSC_VER and <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;background-color:rgb(239,240,241);white-space:pre-wrap">__MINGW32__</code> are undefined because I am compiling for Android platform using clang++ and standalone tool chain. So it is hitting into <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;background-color:rgb(239,240,241);white-space:pre-wrap">define NULL __null</code>. Since clang++ has no clue of what <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;background-color:rgb(239,240,241);white-space:pre-wrap">__null</code> is, it is resulting into "expected expression" error.</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">My question is, why is clang using macros(like <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;font-size:13px;vertical-align:baseline;box-sizing:inherit;background-color:rgb(239,240,241);white-space:pre-wrap">__null</code>) provided by GNU compiler? Or am I missing something here?</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(36,39,41)">Could somebody please help me understand. Thanks</p></div>
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