From 451f1287839451fc097a406fad1a9160c22c280a Mon Sep 17 00:00:00 2001
From: varkor <github@varkor.com>
Date: Thu, 7 Feb 2019 14:58:47 +0100
Subject: [PATCH] Parse negative literals in const generic arguments

---
 src/libsyntax/parse/parser.rs                            | 3 +--
 src/test/ui/const-generics/const-expression-parameter.rs | 4 ++++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index d9195ebe312..d71145893c3 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -5796,8 +5796,7 @@ impl<'a> Parser<'a> {
                 } else {
                     // FIXME(const_generics): this currently conflicts with emplacement syntax
                     // with negative integer literals.
-                    let lit = self.parse_lit()?;
-                    self.mk_expr(lit.span, ExprKind::Lit(lit), ThinVec::new())
+                    self.parse_literal_maybe_minus()?
                 };
                 let value = AnonConst {
                     id: ast::DUMMY_NODE_ID,
diff --git a/src/test/ui/const-generics/const-expression-parameter.rs b/src/test/ui/const-generics/const-expression-parameter.rs
index c582c596bfc..f4e9008dbd0 100644
--- a/src/test/ui/const-generics/const-expression-parameter.rs
+++ b/src/test/ui/const-generics/const-expression-parameter.rs
@@ -14,6 +14,10 @@ fn foo_b() {
     u32_identity::<1 + 2>(); //~ ERROR expected one of `,` or `>`, found `+`
 }
 
+fn foo_c() {
+    u32_identity::< -1 >(); // ok
+}
+
 fn main() {
     u32_identity::<5>(); // ok
 }