Extend examples for [dcl.spec.auto.general]

Signed-off-by: Mauro Russo <[email protected]>

source/declarations.tex

@@ -1836,6 +1836,15 @@
 auto g() { return 0.0; }        // OK, \tcode{g} returns \tcode{double}
 auto (*fp)() -> auto = f;       // OK
 auto h();                       // OK, \tcode{h}'s return type will be deduced when it is defined
+auto j() -> auto;               // OK, deduction of \tcode{j}'s return type postponed at the definition
+auto (*jp)() -> auto = j;       // error, cannot use \tcode{j}'s before deducing its return type
+auto (*kp)() -> auto;           // error, not a function declaration; needs an initializer
+constexpr auto l =
+  [](auto (*fp)() -> auto)      // OK, \tcode{l}'s parameter \tcode{fp} is a function pointer,
+  { return fp; };               // whose return type will be deduced when \tcode{l} is invoked
+int foo();
+static_assert(l(foo) == foo);   // OK
+
 \end{codeblock}
 \end{example}
 The \keyword{auto} \grammarterm{type-specifier}