error: unable to find numeric literal operator ‘operator"" f’

[Henrik Mannerström]

In his blog, Herb Sutter says it's "Modern C++ style" to use "auto x =
42f;".  When compiling the program below with gcc 4.8.1, I get an error.

int main() {
  auto a = 42f;
  return a;
}

$ g++ -std=gnu++1y -Wall -Wextra -pedantic test.cc
test.cc: In function ‘int main()’:
test.cc:2:12: error: unable to find numeric literal operator ‘operator"" f’
   auto a = 42f;

Am I missing something?
BR,
Henrik Mannerström

http://herbsutter.com/2013/08/12/gotw-94-solution-aaa-style-almost-always-auto/