Document why the volatile read is used

gnzlbg · gnzlbg · commit 3b6b4899bf69 · 2019-03-26T13:43:57.000+01:00
diff --git a/src/libcore/hint.rs b/src/libcore/hint.rs
@@ -122,6 +122,7 @@ pub fn black_box<T>(dummy: T) -> T {
             )
         )
     )] {
+        // asm.js and emscripten do not support inline assembly
         unsafe {
             let ret = crate::ptr::read_volatile(&dummy);
             crate::mem::forget(dummy);

Original file line number	Diff line number	Diff line change
`@@ -122,6 +122,7 @@ pub fn black_box<T>(dummy: T) -> T {`
`122`	`122`	`)`
`123`	`123`	`)`
`124`	`124`	`)] {`
	`125`	`+ // asm.js and emscripten do not support inline assembly`
`125`	`126`	`unsafe {`
`126`	`127`	`let ret = crate::ptr::read_volatile(&dummy);`
`127`	`128`	`crate::mem::forget(dummy);`