(ty::Tuple(fields), _) => {
self.emit_tuple_wrap_err(&mut err, span, found, fields)
}
+ // If a byte was expected and the found expression is a char literal
+ // containing a single ASCII character, perhaps the user meant to write `b'c'` to
+ // specify a byte literal
+ (ty::Uint(ty::UintTy::U8), ty::Char) => {
+ if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span)
+ && let Some(code) = code.strip_prefix('\'').and_then(|s| s.strip_suffix('\''))
+ && code.chars().next().map_or(false, |c| c.is_ascii())
+ {
+ err.span_suggestion(
+ span,
+ "if you meant to write a byte literal, prefix with `b`",
+ format!("b'{}'", escape_literal(code)),
+ Applicability::MachineApplicable,
+ );
+ }
+ }
// If a character was expected and the found expression is a string literal
// containing a single character, perhaps the user meant to write `'c'` to
// specify a character literal (issue #92479)
--- /dev/null
+// Tests that a suggestion is issued for type mismatch errors when a
+// u8 is expected and a char literal which is ASCII is supplied.
+
+fn foo(_t: u8) {}
+
+fn main() {
+ let _x: u8 = 'X';
+ //~^ ERROR: mismatched types [E0308]
+ //~| HELP: if you meant to write a byte literal, prefix with `b`
+
+ foo('#');
+ //~^ ERROR: mismatched types [E0308]
+ //~| HELP: if you meant to write a byte literal, prefix with `b`
+
+ // Do not issue the suggestion if the char literal isn't ASCII
+ let _t: u8 = '€';
+ //~^ ERROR: mismatched types [E0308]
+}
--- /dev/null
+error[E0308]: mismatched types
+ --> $DIR/type-mismatch-byte-literal.rs:7:18
+ |
+LL | let _x: u8 = 'X';
+ | -- ^^^ expected `u8`, found `char`
+ | |
+ | expected due to this
+ |
+help: if you meant to write a byte literal, prefix with `b`
+ |
+LL | let _x: u8 = b'X';
+ | ~~~~
+
+error[E0308]: mismatched types
+ --> $DIR/type-mismatch-byte-literal.rs:11:9
+ |
+LL | foo('#');
+ | --- ^^^ expected `u8`, found `char`
+ | |
+ | arguments to this function are incorrect
+ |
+note: function defined here
+ --> $DIR/type-mismatch-byte-literal.rs:4:4
+ |
+LL | fn foo(_t: u8) {}
+ | ^^^ ------
+help: if you meant to write a byte literal, prefix with `b`
+ |
+LL | foo(b'#');
+ | ~~~~
+
+error[E0308]: mismatched types
+ --> $DIR/type-mismatch-byte-literal.rs:16:18
+ |
+LL | let _t: u8 = '€';
+ | -- ^^^ expected `u8`, found `char`
+ | |
+ | expected due to this
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.