rustc_error: make ErrorReported impossible to construct

There are a few places were we have to construct it, though, and a few
places that are more invasive to change. To do this, we create a
constructor with a long obvious name.

Author: mark-i-m

src/parse/macros/lazy_static.rs

@@ -16,7 +16,7 @@ pub(crate) fn parse_lazy_static(
         ($method:ident $(,)* $($arg:expr),* $(,)*) => {
             match parser.$method($($arg,)*) {
                 Ok(val) => {
-                    if parser.sess.span_diagnostic.has_errors() {
+                    if parser.sess.span_diagnostic.has_errors().is_some() {
                         parser.sess.span_diagnostic.reset_err_count();
                         return None;
                     } else {

src/parse/macros/mod.rs

@@ -28,7 +28,7 @@ fn parse_macro_arg<'a, 'b: 'a>(parser: &'a mut Parser<'b>) -> Option<MacroArg> {
             let mut cloned_parser = (*parser).clone();
             match $parser(&mut cloned_parser) {
                 Ok(x) => {
-                    if parser.sess.span_diagnostic.has_errors() {
+                    if parser.sess.span_diagnostic.has_errors().is_some() {
                         parser.sess.span_diagnostic.reset_err_count();
                     } else {
                         // Parsing succeeded.

src/parse/session.rs

@@ -235,7 +235,7 @@ impl ParseSess {
     }
 
     pub(super) fn has_errors(&self) -> bool {
-        self.parse_sess.span_diagnostic.has_errors()
+        self.parse_sess.span_diagnostic.has_errors().is_some()
     }
 
     pub(super) fn reset_errors(&self) {