1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/rust/proc-macro-hack/src/error.rs b/third_party/rust/proc-macro-hack/src/error.rs
new file mode 100644
index 0000000000..7334a53d9a
--- /dev/null
+++ b/third_party/rust/proc-macro-hack/src/error.rs
@@ -0,0 +1,39 @@
+use proc_macro::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+
+pub struct Error {
+    span: Span,
+    msg: String,
+}
+
+impl Error {
+    pub fn new(span: Span, msg: impl Into<String>) -> Self {
+        Error {
+            span,
+            msg: msg.into(),
+        }
+    }
+}
+
+pub fn compile_error(err: Error) -> TokenStream {
+    // compile_error!($msg)
+    TokenStream::from_iter(vec![
+        TokenTree::Ident(Ident::new("compile_error", err.span)),
+        TokenTree::Punct({
+            let mut punct = Punct::new('!', Spacing::Alone);
+            punct.set_span(err.span);
+            punct
+        }),
+        TokenTree::Group({
+            let mut group = Group::new(Delimiter::Brace, {
+                TokenStream::from_iter(vec![TokenTree::Literal({
+                    let mut string = Literal::string(&err.msg);
+                    string.set_span(err.span);
+                    string
+                })])
+            });
+            group.set_span(err.span);
+            group
+        }),
+    ])
+}