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Auto merge of #62331 - wesleywiser:fix_early_return_leak, r=matthewjasper

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Fix leak when early returning out of `box` syntax

Fixes #62289

r? @matthewjasper
This commit is contained in:
bors 2019-07-14 05:25:08 +00:00
commit 03a68d6973
2 changed files with 92 additions and 1 deletions
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2
src/librustc_mir/build/expr/as_rvalue.rs
View File

@ -128,7 +128,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
expr_span,
scope,
result,
value.ty,
expr.ty,
);
}

91
src/test/mir-opt/issue-62289.rs Normal file
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@ -0,0 +1,91 @@
// check that we don't forget to drop the Box if we early return before
// initializing it
// ignore-tidy-linelength
// ignore-wasm32-bare compiled with panic=abort by default
#![feature(box_syntax)]
fn test() -> Option<Box<u32>> {
Some(box (None?))
}
fn main() {
test();
}
// END RUST SOURCE
// START rustc.test.ElaborateDrops.before.mir
// fn test() -> std::option::Option<std::boxed::Box<u32>> {
// ...
// bb0: {
// StorageLive(_1);
// StorageLive(_2);
// _2 = Box(u32);
// StorageLive(_3);
// StorageLive(_4);
// _4 = std::option::Option::<u32>::None;
// _3 = const <std::option::Option<u32> as std::ops::Try>::into_result(move _4) -> [return: bb2, unwind: bb3];
// }
// bb1 (cleanup): {
// resume;
// }
// bb2: {
// StorageDead(_4);
// _5 = discriminant(_3);
// switchInt(move _5) -> [0isize: bb10, 1isize: bb5, otherwise: bb4];
// }
// bb3 (cleanup): {
// drop(_2) -> bb1;
// }
// bb4: {
// unreachable;
// }
// bb5: {
// StorageLive(_6);
// _6 = ((_3 as Err).0: std::option::NoneError);
// StorageLive(_8);
// StorageLive(_9);
// _9 = _6;
// _8 = const <std::option::NoneError as std::convert::From<std::option::NoneError>>::from(move _9) -> [return: bb7, unwind: bb3];
// }
// bb6: {
// return;
// }
// bb7: {
// StorageDead(_9);
// _0 = const <std::option::Option<std::boxed::Box<u32>> as std::ops::Try>::from_error(move _8) -> [return: bb8, unwind: bb3];
// }
// bb8: {
// StorageDead(_8);
// StorageDead(_6);
// drop(_2) -> bb9;
// }
// bb9: {
// StorageDead(_2);
// StorageDead(_1);
// StorageDead(_3);
// goto -> bb6;
// }
// bb10: {
// StorageLive(_10);
// _10 = ((_3 as Ok).0: u32);
// (*_2) = _10;
// StorageDead(_10);
// _1 = move _2;
// drop(_2) -> [return: bb12, unwind: bb11];
// }
// bb11 (cleanup): {
// drop(_1) -> bb1;
// }
// bb12: {
// StorageDead(_2);
// _0 = std::option::Option::<std::boxed::Box<u32>>::Some(move _1,);
// drop(_1) -> bb13;
// }
// bb13: {
// StorageDead(_1);
// StorageDead(_3);
// goto -> bb6;
// }
// }
// END rustc.test.ElaborateDrops.before.mir