From the commit diff which introduced support in gcc 4.9, the only difference is that gcc now accepts binary literals as a language feature of C++1y, and doesn't warn that they're a gcc extension if C++1y support is specified. There is no change to the actual implementation.
Previously:
warning : binary constants are a GCC extension
Now, unless -std=c++1y
is specified:
warning : binary constants are a C..1y feature or GCC extension
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