From f9275e1092232fcb8ec117fc4acca990f57cba15 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Sun, 17 Jan 2021 15:06:47 +0100
Subject: [PATCH] Skip linking if it is not required

This allows to use `--emit=metadata,obj` and other metadata
+ non-link combinations.

Fixes #81117.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 compiler/rustc_codegen_ssa/src/back/link.rs |  6 ++----
 compiler/rustc_session/src/config.rs        | 14 ++++++++++++++
 src/test/ui/emit-metadata-obj.rs            |  7 +++++++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/emit-metadata-obj.rs

diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 728795cf50b85..50a561644dab9 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -74,7 +74,7 @@ pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
             }
         });
 
-        if outputs.outputs.should_codegen() {
+        if outputs.outputs.should_link() {
             let tmpdir = TempFileBuilder::new()
                 .prefix("rustc")
                 .tempdir()
@@ -123,9 +123,7 @@ pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
                 }
             };
 
-            if sess.opts.output_types.should_codegen()
-                && !preserve_objects_for_their_debuginfo(sess)
-            {
+            if sess.opts.output_types.should_link() && !preserve_objects_for_their_debuginfo(sess) {
                 for module in &codegen_results.modules {
                     remove_temps_from_module(module);
                 }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 0cafdec1495bb..49833601c9e91 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -403,6 +403,20 @@ impl OutputTypes {
             OutputType::Metadata | OutputType::DepInfo => false,
         })
     }
+
+    // Returns `true` if any of the output types require linking.
+    pub fn should_link(&self) -> bool {
+        self.0.keys().any(|k| match *k {
+            OutputType::Bitcode
+            | OutputType::Assembly
+            | OutputType::LlvmAssembly
+            | OutputType::Mir
+            | OutputType::Metadata
+            | OutputType::Object
+            | OutputType::DepInfo => false,
+            OutputType::Exe => true,
+        })
+    }
 }
 
 /// Use tree-based collections to cheaply get a deterministic `Hash` implementation.
diff --git a/src/test/ui/emit-metadata-obj.rs b/src/test/ui/emit-metadata-obj.rs
new file mode 100644
index 0000000000000..334c7cc5b8101
--- /dev/null
+++ b/src/test/ui/emit-metadata-obj.rs
@@ -0,0 +1,7 @@
+// compile-flags:--emit=metadata,obj
+// build-pass
+
+// A test for the emission of metadata + obj and other metadata + non-link
+// combinations. See issue #81117.
+
+fn main() {}