Lifetime of temporaries

A temporary object is destroyed when the full-expression that lexically contains the rvalue whose evaluation created that temporary object is completely evaluated. Let me demonstrate with ASCII art:

____________________   full-expression ranges from 'b' to last ')'
bar( foo().c_str() );
     ^^^^^          ^
       |            |
     birth       funeral

$12.2/3- "Temporary objects are destroyed as the last step in evaluating the full-expression (1.9) that (lexically) contains the point where they were created. This is true even if that evaluation ends in throwing an exception."

The lifetime of the temporary returned by foo() extends until the end of the full expression where it is created i.e. until the end of the function call 'bar'.

EDIT 2:

$1.9/12- "A full-expression is an expression that is not a subexpression of another expression. If a language construct is defined to produce an implicit call of a function, a use of the language construct is considered to be an expression for the purposes of this definition."