http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51912
Bug #: 51912 Summary: [C++11] G++ accepts floating point case labels Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Keywords: accepts-invalid Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: ja...@gcc.gnu.org 5.19: A converted constant expression of type T is a literal constant expression, implicitly converted to type T, where the implicit conversion (if any) is permitted in a literal constant expression and the implicit conversion sequence contains only user-defined conversions, lvalue-to-rvalue conversions (4.1), integral promotions (4.5), and integral conversions (4.7) other than narrowing conversions (8.5.4). [ Note: such expressions may be used as case expressions (6.4.2), .... So a floating point literal is not a valid case expression, since converting it to the switch type would require a non-integral conversion. void f(int i) { switch (i) { case 1.0:; } }