Auto merge of #25387 - eddyb:syn-file-loader, r=nikomatsakis

This allows compiling entire crates from memory or preprocessing source files before they are tokenized.

Minor API refactoring included, which is a [breaking-change] for libsyntax users:
* `ParseSess::{next_node_id, reserve_node_ids}` moved to rustc's `Session`
* `new_parse_sess` -> `ParseSess::new`
* `new_parse_sess_special_handler` -> `ParseSess::with_span_handler`
* `mk_span_handler` -> `SpanHandler::new`
* `default_handler` -> `Handler::new`
* `mk_handler` -> `Handler::with_emitter`
* `string_to_filemap(sess source, path)` -> `sess.codemap().new_filemap(path, source)`

1 files changed, 2 insertions, 2 deletions

diff --git a/src/librustc_driver/test.rs b/src/librustc_driver/test.rs
index a8cf7533179..b53f2b1dcfa 100644
--- a/src/librustc_driver/test.rs
+++ b/src/librustc_driver/test.rs
@@ -105,9 +105,9 @@ fn test_env<F>(source_string: &str,
     let codemap =
         CodeMap::new();
     let diagnostic_handler =
-        diagnostic::mk_handler(true, emitter);
+        diagnostic::Handler::with_emitter(true, emitter);
     let span_diagnostic_handler =
-        diagnostic::mk_span_handler(diagnostic_handler, codemap);
+        diagnostic::SpanHandler::new(diagnostic_handler, codemap);
 
     let sess = session::build_session_(options, None, span_diagnostic_handler);
     rustc_lint::register_builtins(&mut sess.lint_store.borrow_mut(), Some(&sess));