From 24666443898c142944b4156c22d04130b9db645b Mon Sep 17 00:00:00 2001 From: varkor Date: Sun, 25 Feb 2018 23:05:06 +0000 Subject: [PATCH] Ensure main() always has external linkage This ensures that the entry function is never elided due to inlining, even with `inline(always)`. Fixes #47783. There were a couple of possible ways of addressing this issue; I simply picked the one that seemed most direct. A warning could be appropriate, but considering using inlining hints in other places it doesn't apply also throws no warnings, and it seems like an edge case anyway, I haven't added one for now. --- src/librustc_mir/monomorphize/item.rs | 5 ++++- src/test/run-pass/inlined-main.rs | 12 ++++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-) create mode 100644 src/test/run-pass/inlined-main.rs diff --git a/src/librustc_mir/monomorphize/item.rs b/src/librustc_mir/monomorphize/item.rs index 549919a2c8919..7c86f5a4b1a84 100644 --- a/src/librustc_mir/monomorphize/item.rs +++ b/src/librustc_mir/monomorphize/item.rs @@ -118,10 +118,13 @@ pub trait MonoItemExt<'a, 'tcx>: fmt::Debug { match *self.as_mono_item() { MonoItem::Fn(ref instance) => { + let entry_def_id = + tcx.sess.entry_fn.borrow().map(|(id, _)| tcx.hir.local_def_id(id)); // If this function isn't inlined or otherwise has explicit // linkage, then we'll be creating a globally shared version. if self.explicit_linkage(tcx).is_some() || - !instance.def.requires_local(tcx) + !instance.def.requires_local(tcx) || + Some(instance.def_id()) == entry_def_id { return InstantiationMode::GloballyShared { may_conflict: false } } diff --git a/src/test/run-pass/inlined-main.rs b/src/test/run-pass/inlined-main.rs new file mode 100644 index 0000000000000..1288c37d615cd --- /dev/null +++ b/src/test/run-pass/inlined-main.rs @@ -0,0 +1,12 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#[inline(always)] +fn main() {}