// Constants (static variables) can be used to match in patterns, but mutable // statics cannot. This ensures that there's some form of error if this is // attempted. static mut a: isize = 3; fn main() { // If they can't be matched against, then it's possible to capture the same // name as a variable, hence this should be an unreachable pattern situation // instead of spitting out a custom error about some identifier collisions // (we should allow shadowing) match 4 { a => {} //~ ERROR match bindings cannot shadow statics _ => {} } } struct NewBool(bool); enum Direction { North, East, South, West } const NEW_FALSE: NewBool = NewBool(false); struct Foo { bar: Option, baz: NewBool } static mut STATIC_MUT_FOO: Foo = Foo { bar: Some(Direction::West), baz: NEW_FALSE }; fn mutable_statics() { match (Foo { bar: Some(Direction::North), baz: NewBool(true) }) { Foo { bar: None, baz: NewBool(true) } => (), STATIC_MUT_FOO => (), //~^ ERROR match bindings cannot shadow statics Foo { bar: Some(Direction::South), .. } => (), Foo { bar: Some(EAST), .. } => (), Foo { bar: Some(Direction::North), baz: NewBool(true) } => (), Foo { bar: Some(EAST), baz: NewBool(false) } => () } }