4b6a68e447
(Includes a regression test, which needed to go into `compile-fail/` due to weaknesses when combining `#[deny(warnings)]` with `tcx.sess.span_warn(..)`) (updated with review feedback from arielb1.)
57 lines
1.9 KiB
Rust
57 lines
1.9 KiB
Rust
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Issue 34101: Circa 2016-06-05, `fn inline` below issued an
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// erroneous warning from the elaborate_drops pass about moving out of
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// a field in `Foo`, which has a destructor (and thus cannot have
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// content moved out of it). The reason that the warning is erroneous
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// in this case is that we are doing a *replace*, not a move, of the
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// content in question, and it is okay to replace fields within `Foo`.
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//
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// Another more subtle problem was that the elaborate_drops was
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// creating a separate drop flag for that internally replaced content,
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// even though the compiler should enforce an invariant that any drop
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// flag for such subcontent of `Foo` will always have the same value
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// as the drop flag for `Foo` itself.
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//
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// This test is structured in a funny way; we cannot test for emission
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// of the warning in question via the lint system, and therefore
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// `#![deny(warnings)]` does nothing to detect it.
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//
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// So instead we use `#[rustc_error]` and put the test into
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// `compile_fail`, where the emitted warning *will* be caught.
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#![feature(rustc_attrs)]
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struct Foo(String);
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impl Drop for Foo {
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fn drop(&mut self) {}
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}
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fn inline() {
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// (dummy variable so `f` gets assigned `var1` in MIR for both fn's)
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let _s = ();
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let mut f = Foo(String::from("foo"));
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f.0 = String::from("bar");
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}
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fn outline() {
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let _s = String::from("foo");
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let mut f = Foo(_s);
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f.0 = String::from("bar");
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}
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#[rustc_error]
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fn main() { //~ ERROR compilation successful
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inline();
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outline();
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}
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