Support char-like byte literals.

tests/rust/const_generics_byte.rs

@@ -0,0 +1,29 @@
+// Name mangling can cope with char-like byte literals.
+
+#[repr(C)]
+pub struct Parser<const OPEN: u8, const CLOSE: u8> {
+    pub buf: *mut u8,
+    pub len: usize,
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn init_parens_parser(p: *mut Parser<b'(', b')'>, buf: *mut u8, len: usize) {
+    unsafe {
+        *p = Parser { buf, len };
+    }
+}
+
+// The same type as above, because `b'(' == 40 && b')' == 41`. And it happens
+// to mangle to the same C identifier. It doesn't always work out that way!
+#[no_mangle]
+pub unsafe extern "C" fn destroy_parens_parser(p: *mut Parser<40, 41>) {
+    // nothing to do
+}
+
+
+#[no_mangle]
+pub unsafe extern "C" fn init_braces_parser(p: *mut Parser<b'{', b'}'>, buf: *mut u8, len: usize) {
+    unsafe {
+        *p = Parser { buf, len };
+    }
+}