Introduce IR and parser support for ML functions.
Representing function arguments is still TODO.
Supporting instructions other than return is also TODO.

PiperOrigin-RevId: 202570934
diff --git a/test/IR/parser-errors.mlir b/test/IR/parser-errors.mlir
index d742b6b..e60bf78 100644
--- a/test/IR/parser-errors.mlir
+++ b/test/IR/parser-errors.mlir
@@ -47,3 +47,13 @@
 bb42:        ; expected-error {{expected terminator}}
   return
 }
+
+; -----
+
+mlfunc @foo()
+mlfunc @bar() ; expected-error {{expected '{' in ML function}}
+
+; -----
+
+mlfunc @no_return() {
+}        ; expected-error {{ML function must end with return statement}}