librustc: Disallow "mut" from distributing over bindings.

This is the backwards-incompatible part of per-binding-site "mut".

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libsyntax/parse/obsolete.rs b/src/libsyntax/parse/obsolete.rs
index 32508f3b477..383faf22037 100644
--- a/src/libsyntax/parse/obsolete.rs
+++ b/src/libsyntax/parse/obsolete.rs
@@ -62,6 +62,7 @@ pub enum ObsoleteSyntax {
     ObsoleteFixedLengthVectorType,
     ObsoleteNamedExternModule,
     ObsoleteMultipleLocalDecl,
+    ObsoleteMutWithMultipleBindings,
 }
 
 impl to_bytes::IterBytes for ObsoleteSyntax {
@@ -223,6 +224,11 @@ impl Parser {
                 "instead of e.g. `let a = 1, b = 2`, write \
                  `let (a, b) = (1, 2)`."
             ),
+            ObsoleteMutWithMultipleBindings => (
+                "`mut` with multiple bindings",
+                "use multiple local declarations instead of e.g. `let mut \
+                 (x, y) = ...`."
+            ),
         };
 
         self.report(sp, kind, kind_str, desc);