From 9ef134dcad9f3bb213318f94d89793f75bc8efc5 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Thu, 21 Jun 2018 13:01:16 -0500
Subject: [PATCH] translate / export weak lang items

see #51671 for details

fixes #51671
fixes #51342
---
 src/librustc/middle/weak_lang_items.rs         | 10 ++++++++++
 src/librustc_mir/monomorphize/collector.rs     |  1 +
 .../run-make-fulldeps/issue-51671/Makefile     | 13 +++++++++++++
 src/test/run-make-fulldeps/issue-51671/app.rs  | 18 ++++++++++++++++++
 4 files changed, 42 insertions(+)
 create mode 100644 src/test/run-make-fulldeps/issue-51671/Makefile
 create mode 100644 src/test/run-make-fulldeps/issue-51671/app.rs

diff --git a/src/librustc/middle/weak_lang_items.rs b/src/librustc/middle/weak_lang_items.rs
index 3c2ea047218..1d147eef054 100644
--- a/src/librustc/middle/weak_lang_items.rs
+++ b/src/librustc/middle/weak_lang_items.rs
@@ -17,6 +17,7 @@
 use syntax::ast;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
+use hir::def_id::DefId;
 use hir::intravisit::{Visitor, NestedVisitorMap};
 use hir::intravisit;
 use hir;
@@ -145,6 +146,15 @@ fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
     }
 }
 
+impl<'a, 'tcx, 'gcx> TyCtxt<'a, 'tcx, 'gcx> {
+    pub fn is_weak_lang_item(&self, item_def_id: DefId) -> bool {
+        let lang_items = self.lang_items();
+        let did = Some(item_def_id);
+
+        $(lang_items.$name() == did)||+
+    }
+}
+
 ) }
 
 weak_lang_items! {
diff --git a/src/librustc_mir/monomorphize/collector.rs b/src/librustc_mir/monomorphize/collector.rs
index 96aeb969d89..c5f2730b9de 100644
--- a/src/librustc_mir/monomorphize/collector.rs
+++ b/src/librustc_mir/monomorphize/collector.rs
@@ -1031,6 +1031,7 @@ fn is_root(&self, def_id: DefId) -> bool {
             MonoItemCollectionMode::Lazy => {
                 self.entry_fn == Some(def_id) ||
                 self.tcx.is_reachable_non_generic(def_id) ||
+                self.tcx.is_weak_lang_item(def_id) ||
                 self.tcx.codegen_fn_attrs(def_id).flags.contains(
                     CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
             }
diff --git a/src/test/run-make-fulldeps/issue-51671/Makefile b/src/test/run-make-fulldeps/issue-51671/Makefile
new file mode 100644
index 00000000000..bdb5ca81720
--- /dev/null
+++ b/src/test/run-make-fulldeps/issue-51671/Makefile
@@ -0,0 +1,13 @@
+-include ../tools.mk
+
+ifdef IS_WINDOWS
+# Do nothing on MSVC.
+all:
+	exit 0
+else
+all:
+	$(RUSTC) --emit=obj app.rs
+	nm $(TMPDIR)/app.o | $(CGREP) rust_begin_unwind
+	nm $(TMPDIR)/app.o | $(CGREP) rust_eh_personality
+	nm $(TMPDIR)/app.o | $(CGREP) rust_oom
+endif
diff --git a/src/test/run-make-fulldeps/issue-51671/app.rs b/src/test/run-make-fulldeps/issue-51671/app.rs
new file mode 100644
index 00000000000..c524b4dab31
--- /dev/null
+++ b/src/test/run-make-fulldeps/issue-51671/app.rs
@@ -0,0 +1,18 @@
+#![crate_type = "bin"]
+#![feature(lang_items)]
+#![feature(panic_implementation)]
+#![no_main]
+#![no_std]
+
+use core::panic::PanicInfo;
+
+#[panic_implementation]
+fn panic(_: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[lang = "eh_personality"]
+fn eh() {}
+
+#[lang = "oom"]
+fn oom() {}
-- 
2.44.0