Update warning message in warning-nobacktrace mode

Author: atsmtat

src/helpers.rs

@@ -404,12 +404,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         match reject_with {
             RejectOpWith::Abort => isolation_abort_error(op_name),
             RejectOpWith::WarningWithoutBacktrace => {
-                let msg = format!("`{}` was made to return an error due to isolation", op_name);
-                let mut warn = this.tcx.sess.struct_warn(&msg);
-                warn.note("run with -Zmiri-isolation-error=warn to get warning with a backtrace");
-                warn.note("run with -Zmiri-isolation-error=ignore to hide warning");
-                warn.note("run with -Zmiri-disable-isolation to disable isolation");
-                warn.emit();
+                this.tcx.sess.warn(&format!("`{}` was made to return an error due to isolation", op_name));
                 Ok(())
             }
             RejectOpWith::Warning => {

tests/run-pass/current_dir_with_isolation.rs

@@ -1,4 +1,7 @@
 // compile-flags: -Zmiri-isolation-error=warn-nobacktrace
+// normalize-stderr-test "(getcwd|GetCurrentDirectoryW)" -> "$$GET"
+// normalize-stderr-test "(chdir|SetCurrentDirectoryW)" -> "$$SET"
+
 use std::env;
 use std::io::ErrorKind;
 

tests/run-pass/current_dir_with_isolation.stderr

@@ -1,12 +1,4 @@
-warning: `getcwd` was made to return an error due to isolation
-  |
-  = note: run with -Zmiri-isolation-error=warn to get warning with a backtrace
-  = note: run with -Zmiri-isolation-error=ignore to hide warning
-  = note: run with -Zmiri-disable-isolation to disable isolation
+warning: `$GET` was made to return an error due to isolation
 
-warning: `chdir` was made to return an error due to isolation
-  |
-  = note: run with -Zmiri-isolation-error=warn to get warning with a backtrace
-  = note: run with -Zmiri-isolation-error=ignore to hide warning
-  = note: run with -Zmiri-disable-isolation to disable isolation
+warning: `$SET` was made to return an error due to isolation