1 files changed, 51 insertions, 0 deletions
diff --git a/tests/ui-fulldeps/auxiliary/parser.rs b/tests/ui-fulldeps/auxiliary/parser.rs
new file mode 100644
index 00000000000..4ea0d814b1f
--- /dev/null
+++ b/tests/ui-fulldeps/auxiliary/parser.rs
@@ -0,0 +1,51 @@
+#![feature(rustc_private)]
+
+extern crate rustc_ast;
+extern crate rustc_driver;
+extern crate rustc_errors;
+extern crate rustc_parse;
+extern crate rustc_session;
+extern crate rustc_span;
+
+use rustc_ast::ast::{DUMMY_NODE_ID, Expr};
+use rustc_ast::mut_visit::MutVisitor;
+use rustc_ast::node_id::NodeId;
+use rustc_ast::ptr::P;
+use rustc_ast::token;
+use rustc_errors::Diag;
+use rustc_parse::parser::Recovery;
+use rustc_session::parse::ParseSess;
+use rustc_span::{DUMMY_SP, FileName, Span};
+
+pub fn parse_expr(psess: &ParseSess, source_code: &str) -> Option<P<Expr>> {
+    let parser = rustc_parse::unwrap_or_emit_fatal(rustc_parse::new_parser_from_source_str(
+        psess,
+        FileName::anon_source_code(source_code),
+        source_code.to_owned(),
+    ));
+
+    let mut parser = parser.recovery(Recovery::Forbidden);
+    let mut expr = parser.parse_expr().map_err(Diag::cancel).ok()?;
+    if parser.token != token::Eof {
+        return None;
+    }
+
+    Normalize.visit_expr(&mut expr);
+    Some(expr)
+}
+
+// Erase Span information that could distinguish between identical expressions
+// parsed from different source strings.
+struct Normalize;
+
+impl MutVisitor for Normalize {
+    const VISIT_TOKENS: bool = true;
+
+    fn visit_id(&mut self, id: &mut NodeId) {
+        *id = DUMMY_NODE_ID;
+    }
+
+    fn visit_span(&mut self, span: &mut Span) {
+        *span = DUMMY_SP;
+    }
+}