1 files changed, 38 insertions, 0 deletions
diff --git a/tests/ui/proc-macro/auxiliary/cond_plugin.rs b/tests/ui/proc-macro/auxiliary/cond_plugin.rs
new file mode 100644
index 00000000000..8d3c4ec239a
--- /dev/null
+++ b/tests/ui/proc-macro/auxiliary/cond_plugin.rs
@@ -0,0 +1,38 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+#![feature(proc_macro_quote)]
+
+extern crate proc_macro;
+
+use proc_macro::*;
+
+#[proc_macro]
+pub fn cond(input: TokenStream) -> TokenStream {
+    let mut conds = Vec::new();
+    let mut input = input.into_iter().peekable();
+    while let Some(tree) = input.next() {
+        let cond = match tree {
+            TokenTree::Group(tt) => tt.stream(),
+            _ => panic!("Invalid input"),
+        };
+        let mut cond_trees = cond.clone().into_iter();
+        let test = cond_trees.next().expect("Unexpected empty condition in `cond!`");
+        let rhs = cond_trees.collect::<TokenStream>();
+        if rhs.is_empty() {
+            panic!("Invalid macro usage in cond: {}", cond);
+        }
+        let is_else = match test {
+            TokenTree::Ident(ref word) => &*word.to_string() == "else",
+            _ => false,
+        };
+        conds.push(if is_else || input.peek().is_none() {
+            quote!({ $rhs })
+        } else {
+            quote!(if $test { $rhs } else)
+        });
+    }
+
+    conds.into_iter().flat_map(|x| x.into_iter()).collect()
+}