From 7f1ce451401b21155923174480f8be9e0b8cf499 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 19 Oct 2019 13:13:31 +0200
Subject: [PATCH 1/2] add test for calling non-const fn

---
 src/test/ui/consts/miri_unleashed/non_const_fn.rs | 12 ++++++++++++
 .../ui/consts/miri_unleashed/non_const_fn.stderr  | 15 +++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 src/test/ui/consts/miri_unleashed/non_const_fn.rs
 create mode 100644 src/test/ui/consts/miri_unleashed/non_const_fn.stderr

diff --git a/src/test/ui/consts/miri_unleashed/non_const_fn.rs b/src/test/ui/consts/miri_unleashed/non_const_fn.rs
new file mode 100644
index 0000000000000..01ce6b904e370
--- /dev/null
+++ b/src/test/ui/consts/miri_unleashed/non_const_fn.rs
@@ -0,0 +1,12 @@
+// compile-flags: -Zunleash-the-miri-inside-of-you
+#![allow(const_err)]
+
+// A test demonstrating that we prevent calling non-const fn during CTFE.
+
+fn foo() {}
+
+const C: () = foo(); //~ WARN: skipping const checks
+
+fn main() {
+    println!("{:?}", C); //~ ERROR: evaluation of constant expression failed
+}
diff --git a/src/test/ui/consts/miri_unleashed/non_const_fn.stderr b/src/test/ui/consts/miri_unleashed/non_const_fn.stderr
new file mode 100644
index 0000000000000..ad8154bd2c686
--- /dev/null
+++ b/src/test/ui/consts/miri_unleashed/non_const_fn.stderr
@@ -0,0 +1,15 @@
+warning: skipping const checks
+  --> $DIR/non_const_fn.rs:8:15
+   |
+LL | const C: () = foo();
+   |               ^^^^^
+
+error[E0080]: evaluation of constant expression failed
+  --> $DIR/non_const_fn.rs:11:22
+   |
+LL |     println!("{:?}", C);
+   |                      ^ referenced constant has errors
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.

From 38fd74f22af7eec30d11d421bcbeaa891c7f7436 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 19 Oct 2019 15:52:08 +0200
Subject: [PATCH 2/2] show the proper diagnostics

---
 .../ui/consts/miri_unleashed/non_const_fn.rs     |  3 ++-
 .../ui/consts/miri_unleashed/non_const_fn.stderr | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/test/ui/consts/miri_unleashed/non_const_fn.rs b/src/test/ui/consts/miri_unleashed/non_const_fn.rs
index 01ce6b904e370..e1ac4306575da 100644
--- a/src/test/ui/consts/miri_unleashed/non_const_fn.rs
+++ b/src/test/ui/consts/miri_unleashed/non_const_fn.rs
@@ -1,11 +1,12 @@
 // compile-flags: -Zunleash-the-miri-inside-of-you
-#![allow(const_err)]
+#![warn(const_err)]
 
 // A test demonstrating that we prevent calling non-const fn during CTFE.
 
 fn foo() {}
 
 const C: () = foo(); //~ WARN: skipping const checks
+//~^ WARN any use of this value will cause an error
 
 fn main() {
     println!("{:?}", C); //~ ERROR: evaluation of constant expression failed
diff --git a/src/test/ui/consts/miri_unleashed/non_const_fn.stderr b/src/test/ui/consts/miri_unleashed/non_const_fn.stderr
index ad8154bd2c686..7a574b34304cb 100644
--- a/src/test/ui/consts/miri_unleashed/non_const_fn.stderr
+++ b/src/test/ui/consts/miri_unleashed/non_const_fn.stderr
@@ -4,8 +4,22 @@ warning: skipping const checks
 LL | const C: () = foo();
    |               ^^^^^
 
+warning: any use of this value will cause an error
+  --> $DIR/non_const_fn.rs:8:15
+   |
+LL | const C: () = foo();
+   | --------------^^^^^-
+   |               |
+   |               calling non-const function `foo`
+   |
+note: lint level defined here
+  --> $DIR/non_const_fn.rs:2:9
+   |
+LL | #![warn(const_err)]
+   |         ^^^^^^^^^
+
 error[E0080]: evaluation of constant expression failed
-  --> $DIR/non_const_fn.rs:11:22
+  --> $DIR/non_const_fn.rs:12:22
    |
 LL |     println!("{:?}", C);
    |                      ^ referenced constant has errors