Fix invalid suggestions for non-ASCII characters in byte constants

5 files changed, 69 insertions, 12 deletions

diff --git a/src/test/ui/attributes/key-value-non-ascii.stderr b/src/test/ui/attributes/key-value-non-ascii.stderr
index 1d4b0d5b2b1..01a07ad3b0e 100644
--- a/src/test/ui/attributes/key-value-non-ascii.stderr
+++ b/src/test/ui/attributes/key-value-non-ascii.stderr
@@ -2,10 +2,12 @@ error: non-ASCII character in byte constant
   --> $DIR/key-value-non-ascii.rs:3:19
    |
 LL | #[rustc_dummy = b"ffi.rs"]
-   |                   ^
-   |                   |
-   |                   byte constant must be ASCII
-   |                   help: use a \xHH escape for a non-ASCII byte: `\xFB03`
+   |                   ^ byte constant must be ASCII
+   |
+help: if you meant to use the UTF-8 encoding of 'ffi', use \xHH escapes
+   |
+LL | #[rustc_dummy = b"/xEF/xAC/x83.rs"]
+   |                   ^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/parser/byte-literals.stderr b/src/test/ui/parser/byte-literals.stderr
index 55be113e16b..b9fb42088d9 100644
--- a/src/test/ui/parser/byte-literals.stderr
+++ b/src/test/ui/parser/byte-literals.stderr
@@ -36,10 +36,12 @@ error: non-ASCII character in byte constant
   --> $DIR/byte-literals.rs:10:7
    |
 LL |     b'é';
-   |       ^
-   |       |
-   |       byte constant must be ASCII
-   |       help: use a \xHH escape for a non-ASCII byte: `\xE9`
+   |       ^ byte constant must be ASCII
+   |
+help: if you meant to use the unicode code point for 'é', use a \xHH escape
+   |
+LL |     b'\xE9';
+   |       ^^^^
 
 error[E0763]: unterminated byte constant
   --> $DIR/byte-literals.rs:11:6
diff --git a/src/test/ui/parser/byte-string-literals.stderr b/src/test/ui/parser/byte-string-literals.stderr
index 3a5a8b331d3..4f22a16224f 100644
--- a/src/test/ui/parser/byte-string-literals.stderr
+++ b/src/test/ui/parser/byte-string-literals.stderr
@@ -24,10 +24,12 @@ error: non-ASCII character in byte constant
   --> $DIR/byte-string-literals.rs:6:7
    |
 LL |     b"é";
-   |       ^
-   |       |
-   |       byte constant must be ASCII
-   |       help: use a \xHH escape for a non-ASCII byte: `\xE9`
+   |       ^ byte constant must be ASCII
+   |
+help: if you meant to use the unicode code point for 'é', use a \xHH escape
+   |
+LL |     b"\xE9";
+   |       ^^^^
 
 error: raw byte string must be ASCII
   --> $DIR/byte-string-literals.rs:7:10
diff --git a/src/test/ui/suggestions/multibyte-escapes.rs b/src/test/ui/suggestions/multibyte-escapes.rs
new file mode 100644
index 00000000000..fd5d46a4e92
--- /dev/null
+++ b/src/test/ui/suggestions/multibyte-escapes.rs
@@ -0,0 +1,18 @@
+// Regression test for #87397.
+
+fn main() {
+    b'µ';
+    //~^ ERROR: non-ASCII character in byte constant
+    //~| HELP: if you meant to use the unicode code point for 'µ', use a \xHH escape
+    //~| NOTE: byte constant must be ASCII
+
+    b'字';
+    //~^ ERROR: non-ASCII character in byte constant
+    //~| NOTE: this multibyte character does not fit into a single byte
+    //~| NOTE: byte constant must be ASCII
+
+    b"字";
+    //~^ ERROR: non-ASCII character in byte constant
+    //~| HELP: if you meant to use the UTF-8 encoding of '字', use \xHH escapes
+    //~| NOTE: byte constant must be ASCII
+}
diff --git a/src/test/ui/suggestions/multibyte-escapes.stderr b/src/test/ui/suggestions/multibyte-escapes.stderr
new file mode 100644
index 00000000000..bb4f8e8c304
--- /dev/null
+++ b/src/test/ui/suggestions/multibyte-escapes.stderr
@@ -0,0 +1,33 @@
+error: non-ASCII character in byte constant
+  --> $DIR/multibyte-escapes.rs:4:7
+   |
+LL |     b'µ';
+   |       ^ byte constant must be ASCII
+   |
+help: if you meant to use the unicode code point for 'µ', use a \xHH escape
+   |
+LL |     b'\xB5';
+   |       ^^^^
+
+error: non-ASCII character in byte constant
+  --> $DIR/multibyte-escapes.rs:9:7
+   |
+LL |     b'字';
+   |       ^^
+   |       |
+   |       byte constant must be ASCII
+   |       this multibyte character does not fit into a single byte
+
+error: non-ASCII character in byte constant
+  --> $DIR/multibyte-escapes.rs:14:7
+   |
+LL |     b"字";
+   |       ^^ byte constant must be ASCII
+   |
+help: if you meant to use the UTF-8 encoding of '字', use \xHH escapes
+   |
+LL |     b"\xE5\xAD\x97";
+   |       ^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+