From c9f7a3d2060a7b2c6f691f4f4b32328edffcf5bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Thu, 11 Jul 2019 16:59:19 -0700
Subject: [PATCH] Emit dropped unemitted errors to aid in ICE debugging

---
 src/librustc_errors/diagnostic_builder.rs |  9 ++++++---
 src/libsyntax/parse/parser.rs             | 13 +++++++------
 src/libsyntax/util/parser_testing.rs      |  6 +++---
 3 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/librustc_errors/diagnostic_builder.rs b/src/librustc_errors/diagnostic_builder.rs
index fc74e43ff5739..41d0638f7c6bd 100644
--- a/src/librustc_errors/diagnostic_builder.rs
+++ b/src/librustc_errors/diagnostic_builder.rs
@@ -380,10 +380,13 @@ impl<'a> Debug for DiagnosticBuilder<'a> {
 impl<'a> Drop for DiagnosticBuilder<'a> {
     fn drop(&mut self) {
         if !panicking() && !self.cancelled() {
-            let mut db = DiagnosticBuilder::new(self.handler,
-                                                Level::Bug,
-                                                "Error constructed but not emitted");
+            let mut db = DiagnosticBuilder::new(
+                self.handler,
+                Level::Bug,
+                "the following error was constructed but not emitted",
+            );
             db.emit();
+            self.emit();
             panic!();
         }
     }
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 83dbff6b2d574..871fc0e7062d6 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -6666,12 +6666,13 @@ impl<'a> Parser<'a> {
     }
 
     /// Reads a module from a source file.
-    fn eval_src_mod(&mut self,
-                    path: PathBuf,
-                    directory_ownership: DirectoryOwnership,
-                    name: String,
-                    id_sp: Span)
-                    -> PResult<'a, (ast::Mod, Vec<Attribute> )> {
+    fn eval_src_mod(
+        &mut self,
+        path: PathBuf,
+        directory_ownership: DirectoryOwnership,
+        name: String,
+        id_sp: Span,
+    ) -> PResult<'a, (ast::Mod, Vec<Attribute>)> {
         let mut included_mod_stack = self.sess.included_mod_stack.borrow_mut();
         if let Some(i) = included_mod_stack.iter().position(|p| *p == path) {
             let mut err = String::from("circular modules: ");
diff --git a/src/libsyntax/util/parser_testing.rs b/src/libsyntax/util/parser_testing.rs
index f850960624ce7..2ef32d37d44cd 100644
--- a/src/libsyntax/util/parser_testing.rs
+++ b/src/libsyntax/util/parser_testing.rs
@@ -34,7 +34,7 @@ fn with_error_checking_parse<'a, T, F>(s: String, ps: &'a ParseSess, f: F) -> T
 }
 
 /// Parse a string, return a crate.
-pub fn string_to_crate (source_str : String) -> ast::Crate {
+pub fn string_to_crate(source_str : String) -> ast::Crate {
     let ps = ParseSess::new(FilePathMapping::empty());
     with_error_checking_parse(source_str, &ps, |p| {
         p.parse_crate_mod()
@@ -42,7 +42,7 @@ pub fn string_to_crate (source_str : String) -> ast::Crate {
 }
 
 /// Parse a string, return an expr
-pub fn string_to_expr (source_str : String) -> P<ast::Expr> {
+pub fn string_to_expr(source_str : String) -> P<ast::Expr> {
     let ps = ParseSess::new(FilePathMapping::empty());
     with_error_checking_parse(source_str, &ps, |p| {
         p.parse_expr()
@@ -50,7 +50,7 @@ pub fn string_to_expr (source_str : String) -> P<ast::Expr> {
 }
 
 /// Parse a string, return an item
-pub fn string_to_item (source_str : String) -> Option<P<ast::Item>> {
+pub fn string_to_item(source_str : String) -> Option<P<ast::Item>> {
     let ps = ParseSess::new(FilePathMapping::empty());
     with_error_checking_parse(source_str, &ps, |p| {
         p.parse_item()