mirror of https://github.com/rust-lang/rust
45 lines
1.4 KiB
Rust
45 lines
1.4 KiB
Rust
//@ test-mir-pass: ElaborateDrops
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//@ needs-unwind
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// this tests move up progration, which is not yet implemented
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// EMIT_MIR basic_assignment.main.ElaborateDrops.diff
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// EMIT_MIR basic_assignment.main.SimplifyCfg-initial.after.mir
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// Check codegen for assignments (`a = b`) where the left-hand-side is
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// not yet initialized. Assignments tend to be absent in simple code,
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// so subtle breakage in them can leave a quite hard-to-find trail of
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// destruction.
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fn main() {
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// CHECK-LABEL: fn main(
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// CHECK: debug nodrop_x => [[nodrop_x:_.*]];
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// CHECK: debug nodrop_y => [[nodrop_y:_.*]];
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// CHECK: debug drop_x => [[drop_x:_.*]];
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// CHECK: debug drop_y => [[drop_y:_.*]];
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// CHECK-NOT: drop([[nodrop_x]])
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// CHECK-NOT: drop([[nodrop_y]])
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// CHECK-NOT: drop([[drop_x]])
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// CHECK: [[drop_tmp:_.*]] = move [[drop_x]];
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// CHECK-NOT: drop([[drop_x]])
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// CHECK-NOT: drop([[drop_tmp]])
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// CHECK: [[drop_y]] = move [[drop_tmp]];
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// CHECK-NOT: drop([[drop_x]])
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// CHECK-NOT: drop([[drop_tmp]])
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// CHECK: drop([[drop_y]])
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// CHECK-NOT: drop([[drop_x]])
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// CHECK-NOT: drop([[drop_tmp]])
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let nodrop_x = false;
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let nodrop_y;
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// Since boolean does not require drop, this can be a simple
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// assignment:
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nodrop_y = nodrop_x;
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let drop_x: Option<Box<u32>> = None;
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let drop_y;
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// Since the type of `drop_y` has drop, we generate a `replace`
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// terminator:
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drop_y = drop_x;
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}
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