From ed6c6c9a11f7deddbd1f209c5e7de12bc420c550 Mon Sep 17 00:00:00 2001
From: Masaki Hara <ackie.h.gmai@gmail.com>
Date: Sun, 14 May 2017 21:37:50 +0900
Subject: Disallow underscore suffix for string-like literals.

---
 src/libsyntax/parse/lexer/mod.rs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

(limited to 'src/libsyntax/parse')

diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index a83b19c7334..480049f845c 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -479,11 +479,7 @@ impl<'a> StringReader<'a> {
         }
 
         self.with_str_from(start, |string| {
-            if string == "_" {
-                None
-            } else {
-                Some(Symbol::intern(string))
-            }
+            Some(Symbol::intern(string))
         })
     }
 
-- 
cgit 1.4.1-3-g733a5


From 0b8c3de678065b82ae955b65192b7927b467f7a6 Mon Sep 17 00:00:00 2001
From: Masaki Hara <ackie.h.gmai@gmail.com>
Date: Wed, 31 May 2017 16:43:47 +0900
Subject: Add warning cycle #42326.

---
 src/libsyntax/parse/lexer/mod.rs                    | 15 ++++++++++++++-
 src/test/parse-fail/underscore-suffix-for-string.rs |  9 ++++++++-
 2 files changed, 22 insertions(+), 2 deletions(-)

(limited to 'src/libsyntax/parse')

diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index 480049f845c..e8fbc00d36f 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -479,7 +479,20 @@ impl<'a> StringReader<'a> {
         }
 
         self.with_str_from(start, |string| {
-            Some(Symbol::intern(string))
+            if string == "_" {
+                self.sess.span_diagnostic
+                    .struct_span_warn(mk_sp(start, self.pos),
+                                      "underscore literal suffix is not allowed")
+                    .warn("this was previously accepted by the compiler but is \
+                          being phased out; it will become a hard error in \
+                          a future release!")
+                    .note("for more information, see issue #42326 \
+                          <https://github.com/rust-lang/rust/issues/42326>")
+                    .emit();
+                None
+            } else {
+                Some(Symbol::intern(string))
+            }
         })
     }
 
diff --git a/src/test/parse-fail/underscore-suffix-for-string.rs b/src/test/parse-fail/underscore-suffix-for-string.rs
index a19bbe08377..05de5f8e194 100644
--- a/src/test/parse-fail/underscore-suffix-for-string.rs
+++ b/src/test/parse-fail/underscore-suffix-for-string.rs
@@ -9,5 +9,12 @@
 // except according to those terms.
 
 fn main() {
-    let a = "Foo"_; //~ ERROR string literal with a suffix is invalid
+    let _ = "Foo"_;
+    //~^ WARNING underscore literal suffix is not allowed
+    //~| WARNING this was previously accepted
+    //~| NOTE issue #42326
 }
+
+FAIL
+//~^ ERROR
+//~| NOTE
-- 
cgit 1.4.1-3-g733a5