Annex C (informative) Compatibility [diff]

C.5 C++ and ISO C++ 2011 [diff.cpp11]

C.5.2 [lex]: lexical conventions [diff.cpp11.lex]

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Affected subclause: [lex.ppnumber]
Change: pp-number can contain one or more single quotes.

Rationale: Necessary to enable single quotes as digit separators.

Effect on original feature: Valid C++ 2011 code may fail to compile or may change meaning in this revision of C++.
For example, the following code is valid both in C++ 2011 and in this revision of C++, but the macro invocation produces different outcomes because the single quotes delimit a character-literal in C++ 2011, whereas they are digit separators in this revision of C++.
[Example 1: #define M(x, ...) __VA_ARGS__ int x[2] = { M(1'2,3'4, 5) }; // int x[2] = { 5 };      --- C++ 2011 // int x[2] = { 3'4, 5 }; --- this revision of C++ — end example]