From fd32fe9bb9cc97a5a3d97ab0f6ab673d8c81fa88 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 12 Aug 2020 10:18:21 +0200
Subject: [PATCH] fix span of stack size error

---
 src/librustc_mir/const_eval/machine.rs               | 12 ++++++++----
 src/librustc_mir/interpret/machine.rs                |  8 --------
 src/librustc_mir/transform/const_prop.rs             |  8 ++++++++
 src/test/ui/consts/uninhabited-const-issue-61744.rs  |  4 ++--
 .../ui/consts/uninhabited-const-issue-61744.stderr   |  9 ++++-----
 5 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/src/librustc_mir/const_eval/machine.rs b/src/librustc_mir/const_eval/machine.rs
index 3a753a0edb665..2d0e68d58943f 100644
--- a/src/librustc_mir/const_eval/machine.rs
+++ b/src/librustc_mir/const_eval/machine.rs
@@ -301,12 +301,16 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         Ok(())
     }
 
-    fn after_stack_push(ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx> {
-        // Enforce stack size limit.
-        if !ecx.tcx.sess.recursion_limit().value_within_limit(ecx.stack().len()) {
+    #[inline(always)]
+    fn init_frame_extra(
+        ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        frame: Frame<'mir, 'tcx>,
+    ) -> InterpResult<'tcx, Frame<'mir, 'tcx>> {
+        // Enforce stack size limit. Add 1 because this is run before the new frame is pushed.
+        if !ecx.tcx.sess.recursion_limit().value_within_limit(ecx.stack().len() + 1) {
             throw_exhaust!(StackFrameLimitReached)
         } else {
-            Ok(())
+            Ok(frame)
         }
     }
 
diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index 634f3c96e6c9f..5cab4ba37e3a5 100644
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -409,12 +409,4 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
     ) -> Self::PointerTag {
         ()
     }
-
-    #[inline(always)]
-    fn init_frame_extra(
-        _ecx: &mut InterpCx<$mir, $tcx, Self>,
-        frame: Frame<$mir, $tcx>,
-    ) -> InterpResult<$tcx, Frame<$mir, $tcx>> {
-        Ok(frame)
-    }
 }
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index 6cf296f2a3fda..3b39d5f66b78f 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -281,6 +281,14 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx>
         Ok(())
     }
 
+    #[inline(always)]
+    fn init_frame_extra(
+        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        frame: Frame<'mir, 'tcx>,
+    ) -> InterpResult<'tcx, Frame<'mir, 'tcx>> {
+        Ok(frame)
+    }
+
     #[inline(always)]
     fn stack(
         ecx: &'a InterpCx<'mir, 'tcx, Self>,
diff --git a/src/test/ui/consts/uninhabited-const-issue-61744.rs b/src/test/ui/consts/uninhabited-const-issue-61744.rs
index 55f42d84f9cb0..15436f9c1b2cf 100644
--- a/src/test/ui/consts/uninhabited-const-issue-61744.rs
+++ b/src/test/ui/consts/uninhabited-const-issue-61744.rs
@@ -1,11 +1,11 @@
 // build-fail
 
 pub const unsafe fn fake_type<T>() -> T {
-    hint_unreachable() //~ ERROR evaluation of constant value failed
+    hint_unreachable()
 }
 
 pub const unsafe fn hint_unreachable() -> ! {
-    fake_type()
+    fake_type() //~ ERROR evaluation of constant value failed
 }
 
 trait Const {
diff --git a/src/test/ui/consts/uninhabited-const-issue-61744.stderr b/src/test/ui/consts/uninhabited-const-issue-61744.stderr
index fc908b2b2225f..024f9782d4a67 100644
--- a/src/test/ui/consts/uninhabited-const-issue-61744.stderr
+++ b/src/test/ui/consts/uninhabited-const-issue-61744.stderr
@@ -1,11 +1,9 @@
 error[E0080]: evaluation of constant value failed
-  --> $DIR/uninhabited-const-issue-61744.rs:4:5
+  --> $DIR/uninhabited-const-issue-61744.rs:8:5
    |
 LL |     hint_unreachable()
-   |     ^^^^^^^^^^^^^^^^^^
+   |     ------------------
    |     |
-   |     reached the configured maximum number of stack frames
-   |     inside `fake_type::<!>` at $DIR/uninhabited-const-issue-61744.rs:4:5
    |     inside `fake_type::<!>` at $DIR/uninhabited-const-issue-61744.rs:4:5
    |     inside `fake_type::<!>` at $DIR/uninhabited-const-issue-61744.rs:4:5
    |     inside `fake_type::<!>` at $DIR/uninhabited-const-issue-61744.rs:4:5
@@ -72,8 +70,9 @@ LL |     hint_unreachable()
    |     inside `fake_type::<i32>` at $DIR/uninhabited-const-issue-61744.rs:4:5
 ...
 LL |     fake_type()
-   |     -----------
+   |     ^^^^^^^^^^^
    |     |
+   |     reached the configured maximum number of stack frames
    |     inside `hint_unreachable` at $DIR/uninhabited-const-issue-61744.rs:8:5
    |     inside `hint_unreachable` at $DIR/uninhabited-const-issue-61744.rs:8:5
    |     inside `hint_unreachable` at $DIR/uninhabited-const-issue-61744.rs:8:5