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copied!<p>[<em>Note: Originally, this was not meant to be a self-answered question; I just happened to find the answer myself while I was describing my attempts to investigate, and I thought it would have been nice to share it.</em>]</p> <p>According to Annex C (2.14.5) of the C++11 Standard:</p> <blockquote> <p>The type of a string literal is changed from “array of char” to “<strong>array of const char</strong>.” [....]</p> </blockquote> <p>Moreover, Paragraph 7.1.6.2/4 specifies (about the result of <code>decltype</code>):</p> <blockquote> <p>The type denoted by <code>decltype(e)</code> is defined as follows:</p> <p>— if <code>e</code> is an unparenthesized id-expression or an unparenthesized class member access (5.2.5), <code>decltype(e)</code> is the type of the entity named by <code>e</code>. If there is no such entity, or if <code>e</code> names a set of overloaded functions, the program is ill-formed;</p> <p>— otherwise, if <code>e</code> is an xvalue, <code>decltype(e)</code> is <code>T&&</code>, where <code>T</code> is the type of <code>e</code>;</p> <p>— <strong>otherwise, if <code>e</code> is an lvalue, <code>decltype(e)</code> is <code>T&</code>, where <code>T</code> is the type of <code>e</code></strong>;</p> <p>— otherwise, <code>decltype(e)</code> is the type of <code>e</code>.</p> </blockquote> <p>Since <strong><a href="https://stackoverflow.com/questions/15036281/c11-value-category-of-string-literal/15036305#15036305">string literals are lvalues</a></strong>, according to the above Paragraph and the Paragraph from Annex C, the result of <code>decltype("Hello")</code> is an <strong><em>lvalue reference to</em></strong> an array of size 6 of constant narrow characters:</p> <pre><code>#include <type_traits> int main() { // This will NOT fire static_assert( std::is_same<decltype("Hello"), char const (&)[6]>::value, "Error!" ); } </code></pre> <p>Finally, even though the <code>hello</code> variable <em>is</em> also an lvalue, the second compile-time assertion from the question's text does not fire, because <code>hello</code> is an <em>unparenthesized id-expression</em>, which makes it fall into the first item of the above list from Paragraph 7.1.6.2/4. Therefore, the result of <code>decltype(hello)</code> is the type of the entity named by <code>hello</code>, which is <code>char const[6]</code>.</p>

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