fix miri step debug printing

RalfJung · RalfJung · commit 2468b23ad583 · 2019-12-08T10:48:06.000+01:00
diff --git a/src/librustc_mir/interpret/step.rs b/src/librustc_mir/interpret/step.rs
@@ -304,7 +304,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         if !self.stack.is_empty() {
             // This should change *something*
             debug_assert!(self.cur_frame() != old_stack || self.frame().block != old_bb);
-            info!("// {:?}", self.frame().block);
+            if let Some(block) = self.frame().block {
+                info!("// executing {:?}", block);
+            }
         }
         Ok(())
     }

Original file line number	Diff line number	Diff line change
`@@ -304,7 +304,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {`
`304`	`304`	`if !self.stack.is_empty() {`
`305`	`305`	`// This should change something`
`306`	`306`	`debug_assert!(self.cur_frame() != old_stack \|\| self.frame().block != old_bb);`
`307`		`- info!("// {:?}", self.frame().block);`
	`307`	`+ if let Some(block) = self.frame().block {`
	`308`	`+ info!("// executing {:?}", block);`
	`309`	`+ }`
`308`	`310`	`}`
`309`	`311`	`Ok(())`
`310`	`312`	`}`