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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/cleanup-rvalue-scopes.rs | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/src/test/ui/cleanup-rvalue-scopes.rs b/src/test/ui/cleanup-rvalue-scopes.rs new file mode 100644 index 000000000..b80f95b79 --- /dev/null +++ b/src/test/ui/cleanup-rvalue-scopes.rs @@ -0,0 +1,130 @@ +// run-pass +#![allow(unused_braces)] +#![allow(non_snake_case)] +#![allow(unused_variables)] +// Test that destructors for rvalue temporaries run either at end of +// statement or end of block, as appropriate given the temporary +// lifetime rules. + +#![feature(box_patterns)] + +use std::ops::Drop; + +static mut FLAGS: u64 = 0; + +struct Box<T> { f: T } +struct AddFlags { bits: u64 } + +fn AddFlags(bits: u64) -> AddFlags { + AddFlags { bits: bits } +} + +fn arg(exp: u64, _x: &AddFlags) { + check_flags(exp); +} + +fn pass<T>(v: T) -> T { + v +} + +fn check_flags(exp: u64) { + unsafe { + let x = FLAGS; + FLAGS = 0; + println!("flags {}, expected {}", x, exp); + assert_eq!(x, exp); + } +} + +impl AddFlags { + fn check_flags<'a>(&'a self, exp: u64) -> &'a AddFlags { + check_flags(exp); + self + } + + fn bits(&self) -> u64 { + self.bits + } +} + +impl Drop for AddFlags { + fn drop(&mut self) { + unsafe { + FLAGS = FLAGS + self.bits; + } + } +} + +macro_rules! end_of_block { + ($pat:pat, $expr:expr) => ( + { + println!("end_of_block({})", stringify!({let $pat = $expr;})); + + { + // Destructor here does not run until exit from the block. + let $pat = $expr; + check_flags(0); + } + check_flags(1); + } + ) +} + +macro_rules! end_of_stmt { + ($pat:pat, $expr:expr) => ( + { + println!("end_of_stmt({})", stringify!($expr)); + + { + // Destructor here run after `let` statement + // terminates. + let $pat = $expr; + check_flags(1); + } + + check_flags(0); + } + ) +} + +pub fn main() { + + // In all these cases, we trip over the rules designed to cover + // the case where we are taking addr of rvalue and storing that + // addr into a stack slot, either via `let ref` or via a `&` in + // the initializer. + + end_of_block!(_x, AddFlags(1)); + end_of_block!(_x, &AddFlags(1)); + end_of_block!(_x, & &AddFlags(1)); + end_of_block!(_x, Box { f: AddFlags(1) }); + end_of_block!(_x, Box { f: &AddFlags(1) }); + end_of_block!(_x, Box { f: &AddFlags(1) }); + end_of_block!(_x, pass(AddFlags(1))); + end_of_block!(ref _x, AddFlags(1)); + end_of_block!(AddFlags { bits: ref _x }, AddFlags(1)); + end_of_block!(&AddFlags { bits }, &AddFlags(1)); + end_of_block!((_, ref _y), (AddFlags(1), 22)); + end_of_block!(box ref _x, std::boxed::Box::new(AddFlags(1))); + end_of_block!(box _x, std::boxed::Box::new(AddFlags(1))); + end_of_block!(_, { { check_flags(0); &AddFlags(1) } }); + end_of_block!(_, &((Box { f: AddFlags(1) }).f)); + end_of_block!(_, &(([AddFlags(1)])[0])); + + // LHS does not create a ref binding, so temporary lives as long + // as statement, and we do not move the AddFlags out: + end_of_stmt!(_, AddFlags(1)); + end_of_stmt!((_, _), (AddFlags(1), 22)); + + // `&` operator appears inside an arg to a function, + // so it is not prolonged: + end_of_stmt!(ref _x, arg(0, &AddFlags(1))); + + // autoref occurs inside receiver, so temp lifetime is not + // prolonged: + end_of_stmt!(ref _x, AddFlags(1).check_flags(0).bits()); + + // No reference is created on LHS, thus RHS is moved into + // a temporary that lives just as long as the statement. + end_of_stmt!(AddFlags { bits }, AddFlags(1)); +} |