From e67050e8b6cbf48d041eb5f3993d620402073a7a Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Wed, 27 Feb 2019 17:41:25 +0100
Subject: [PATCH 1/2] Don't promote function calls to nonpromotable things

---
 src/librustc_mir/transform/qualify_consts.rs |  7 ++-----
 src/test/ui/consts/invalid_promotion.rs      | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)
 create mode 100644 src/test/ui/consts/invalid_promotion.rs

diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index 285c674643f2e..73ac68c4ac3b4 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -507,7 +507,7 @@ impl Qualif for IsNotPromotable {
     fn in_call(
         cx: &ConstCx<'_, 'tcx>,
         callee: &Operand<'tcx>,
-        _args: &[Operand<'tcx>],
+        args: &[Operand<'tcx>],
         _return_ty: Ty<'tcx>,
     ) -> bool {
         if cx.mode == Mode::Fn {
@@ -520,10 +520,7 @@ impl Qualif for IsNotPromotable {
             }
         }
 
-        // FIXME(eddyb) do we need "not promotable" in anything
-        // other than `Mode::Fn` by any chance?
-
-        false
+        Self::in_operand(cx, callee) || args.iter().any(|arg| Self::in_operand(cx, arg))
     }
 }
 
diff --git a/src/test/ui/consts/invalid_promotion.rs b/src/test/ui/consts/invalid_promotion.rs
new file mode 100644
index 0000000000000..f98406e50e9ae
--- /dev/null
+++ b/src/test/ui/consts/invalid_promotion.rs
@@ -0,0 +1,18 @@
+// compile-pass
+// note this was only reproducible with lib crates
+// compile-flags: --crate-type=lib
+
+pub struct Hz;
+
+impl Hz {
+    pub const fn num(&self) -> u32 {
+        42
+    }
+    pub const fn normalized(&self) -> Hz {
+        Hz
+    }
+
+    pub const fn as_u32(&self) -> u32 {
+        self.normalized().num() // this used to promote the `self.normalized()`
+    }
+}

From 8c16507045a76ef616533ec29626f6ce6be40a6c Mon Sep 17 00:00:00 2001
From: Oliver Scherer <github35764891676564198441@oli-obk.de>
Date: Fri, 1 Mar 2019 17:10:29 +0100
Subject: [PATCH 2/2] Schedule the demolition of `IsNotPromotable`

---
 src/librustc_mir/transform/qualify_consts.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index 73ac68c4ac3b4..f7b7754cea7bc 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -499,6 +499,8 @@ impl Qualif for IsNotConst {
 
 // Refers to temporaries which cannot be promoted as
 // promote_consts decided they weren't simple enough.
+// FIXME(oli-obk,eddyb): Remove this flag entirely and
+// solely process this information via `IsNotConst`.
 struct IsNotPromotable;
 
 impl Qualif for IsNotPromotable {