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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Hi CFE-Devs,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">When I compile the following tiny test with ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">-std=c89</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’
(‘</span><span style="font-size:12.0pt;font-family:"Courier New"">clang –std=c89 –c xxx.c</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’):<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">foo(x) {<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New""> return;<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">I get the following error message:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">xxx.c:2:3: error: non-void function 'foo' should return a value [-Wreturn-type]<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New""> return;<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New""> ^<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">1 error generated.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">But for ANSI C89, this is legal, and it is a really common pattern to have a return with no value, even though the return type is implicitly ‘</span><span style="font-size:12.0pt;font-family:"Courier New"">int</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">’,
especially when K&R syntax is used:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><b><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Section 3.6.6.4. The return statement, Semantics, paragraph 3<o:p></o:p></span></b></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">If a return statement without an expression is executed, and the value of the function call is used by the caller, the behaviour is undefined. reaching
the </span><span style="font-size:12.0pt;font-family:"Courier New"">}</span><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"> that terminates a function is equivalent to executing a return statement without an expression.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Yet the following results in a warning and not an error:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">foo(x) {<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">I get the following perfectly reasonable warning:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">xxx.c:2:1: warning: control reaches end of non-void function [-Wreturn-type]<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">}<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">^<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:12.0pt;font-family:"Courier New"">1 warning generated.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">When compiling for ANSI C89, I think that the first example should also result in a warning and not an error.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"> MartinO<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Book Antiqua",serif"><o:p> </o:p></span></p>
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