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    <p>To be honest, with your samples I see little wrong.</p> <p>However, there are a number of cases where the compiler seems to accept 'violations' of the standard conversion rules...:</p> <h3>Initializer lists (§ 8.5.4)</h3> <p>However I spotted this one in the standard: </p> <p>For initialzer lists, the following is not allowed (§ 8.5.4, under <strong>3.</strong>)</p> <pre><code>int ai[] = { 1, 2.0 }; // error narrowing </code></pre> <p>Under <strong>6.</strong> it goes on to give a general list of examples:</p> <blockquote> <p><em>[ Note: As indicated above, such conversions are not allowed at the top level in list-initializations.—end note ]</em></p> </blockquote> <pre><code>int x = 999; // x is not a constant expression const int y = 999; const int z = 99; char c1 = x; // OK, though it might narrow (in this case, it does narrow) char c2{x}; // error: might narrow char c3{y}; // error: narrows (assuming char is 8 bits) char c4{z}; // OK: no narrowing needed unsigned char uc1 = {5}; // OK: no narrowing needed unsigned char uc2 = {-1}; // error: narrows unsigned int ui1 = {-1}; // error: narrows signed int si1 = { (unsigned int)-1 }; // error: narrows int ii = {2.0}; // error: narrows float f1 { x }; // error: might narrow float f2 { 7 }; // OK: 7 can be exactly represented as a float int f(int); int a[] = { 2, f(2), f(2.0) }; // OK: the double-to-int conversion is not at the top level </code></pre> <p>Interestingly, g++ 4.6.1 with <code>--std=c++0x -Wall -pedantic</code> catches <strong>only one</strong> of these violations:</p> <pre><code> char c3{y}; // warning: overflow in implicit constant conversion [-Woverflow] </code></pre> <hr> <h3>Outside initializer lists...</h3> <p>I don't think the truncation of a float to an int is considered <code>narrowing</code>. </p> <p>It is just a well-defined conversion, much like</p> <pre><code>int i = 31; i /= 4; // well defined loss of precision... i /= 4.0; // equally well-defined conversion from floating point to int </code></pre>
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    1. COThanks! Okay, so if this code `int f = {42.7};` also doesn't give an error, then would you agree there's a problem? BTW: no error on g++ 4.6.2.
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    2. CO@tdistler: AFAICT yes, that shoud not compile. (no error? I assume you mean no error message :))
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    3. COYeah "no error message" :)
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