add tests for multi-byte chars

Author: y21

tests/ui/manual_c_str_literals.fixed

@@ -47,6 +47,11 @@ fn main() {
     let _: *const _ = "foo".as_ptr(); // not a C-string
     let _: *const _ = "".as_ptr();
     let _: *const _ = c"foo".as_ptr().cast::<i8>();
+    let _ = "电脑".as_ptr();
+    let _ = "电脑\\".as_ptr();
+    let _ = c"电脑\\".as_ptr();
+    let _ = c"电脑".as_ptr();
+    let _ = c"电脑".as_ptr();
 
     // Macro cases, don't lint:
     cstr!("foo");

tests/ui/manual_c_str_literals.rs

@@ -47,6 +47,11 @@ fn main() {
     let _: *const _ = "foo".as_ptr(); // not a C-string
     let _: *const _ = "".as_ptr();
     let _: *const _ = b"foo\0".as_ptr().cast::<i8>();
+    let _ = "电脑".as_ptr();
+    let _ = "电脑\\".as_ptr();
+    let _ = "电脑\\\0".as_ptr();
+    let _ = "电脑\0".as_ptr();
+    let _ = "电脑\x00".as_ptr();
 
     // Macro cases, don't lint:
     cstr!("foo");

tests/ui/manual_c_str_literals.stderr

@@ -61,5 +61,23 @@ error: manually constructing a nul-terminated string
 LL |     let _: *const _ = b"foo\0".as_ptr().cast::<i8>();
    |                       ^^^^^^^^ help: use a `c""` literal: `c"foo"`
 
-error: aborting due to 10 previous errors
+error: manually constructing a nul-terminated string
+  --> $DIR/manual_c_str_literals.rs:52:13
+   |
+LL |     let _ = "电脑\\\0".as_ptr();
+   |             ^^^^^^^^^^ help: use a `c""` literal: `c"电脑\\"`
+
+error: manually constructing a nul-terminated string
+  --> $DIR/manual_c_str_literals.rs:53:13
+   |
+LL |     let _ = "电脑\0".as_ptr();
+   |             ^^^^^^^^ help: use a `c""` literal: `c"电脑"`
+
+error: manually constructing a nul-terminated string
+  --> $DIR/manual_c_str_literals.rs:54:13
+   |
+LL |     let _ = "电脑\x00".as_ptr();
+   |             ^^^^^^^^^^ help: use a `c""` literal: `c"电脑"`
+
+error: aborting due to 13 previous errors