Borrow spliced values instead of moving them

Closes #13

maud/src/lib.rs

@@ -85,8 +85,8 @@ pub mod rt {
     ///
     /// See <https://github.com/rust-lang/rust/issues/16617>
     #[inline]
-    pub fn write_fmt<T: fmt::Display>(w: &mut fmt::Write, value: T) -> fmt::Result {
-        write!(w, "{}", value)
+    pub fn write_fmt<T: fmt::Display>(w: &mut fmt::Write, value: &T) -> fmt::Result {
+        write!(w, "{}", *value)
     }
 
     pub struct Escaper<'a, 'b: 'a> {

maud_macros/src/render.rs

@@ -96,12 +96,12 @@ impl<'cx> Renderer<'cx> {
         let w = self.w;
         let expr = match escape {
             Escape::PassThru =>
-                quote_expr!(self.cx, ::maud::rt::write_fmt($w, $expr)),
+                quote_expr!(self.cx, ::maud::rt::write_fmt($w, &$expr)),
             Escape::Escape =>
                 quote_expr!(self.cx,
                     ::maud::rt::write_fmt(
                         &mut ::maud::rt::Escaper { inner: $w },
-                        $expr)),
+                        &$expr)),
         };
         let stmt = self.cx.stmt_expr(self.cx.expr_try(expr.span, expr));
         self.push(stmt);