1 files changed, 28 insertions, 23 deletions
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 1232411d1ec..79ae1d62915 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -4086,32 +4086,37 @@ impl<'a> Parser<'a> {
     fn parse_ty_param_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, TyParamBounds> {
         let mut bounds = Vec::new();
         loop {
-            let has_parens = self.eat(&token::OpenDelim(token::Paren));
-            let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
-            if self.check_lifetime() {
-                if let Some(question_span) = question {
-                    self.span_err(question_span,
-                                  "`?` may only modify trait bounds, not lifetime bounds");
-                }
-                bounds.push(RegionTyParamBound(self.expect_lifetime()));
-                if has_parens {
-                    self.expect(&token::CloseDelim(token::Paren))?;
-                    self.span_err(self.prev_span,
-                                  "parenthesized lifetime bounds are not supported");
-                }
-            } else if self.check_keyword(keywords::For) || self.check_path() {
-                let lo = self.span;
-                let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-                let path = self.parse_path(PathStyle::Type)?;
-                let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
-                let modifier = if question.is_some() {
-                    TraitBoundModifier::Maybe
+            let is_bound_start = self.check_path() || self.check_lifetime() ||
+                                 self.check(&token::Question) ||
+                                 self.check_keyword(keywords::For) ||
+                                 self.check(&token::OpenDelim(token::Paren));
+            if is_bound_start {
+                let has_parens = self.eat(&token::OpenDelim(token::Paren));
+                let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None };
+                if self.token.is_lifetime() {
+                    if let Some(question_span) = question {
+                        self.span_err(question_span,
+                                      "`?` may only modify trait bounds, not lifetime bounds");
+                    }
+                    bounds.push(RegionTyParamBound(self.expect_lifetime()));
                 } else {
-                    TraitBoundModifier::None
-                };
-                bounds.push(TraitTyParamBound(poly_trait, modifier));
+                    let lo = self.span;
+                    let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
+                    let path = self.parse_path(PathStyle::Type)?;
+                    let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span));
+                    let modifier = if question.is_some() {
+                        TraitBoundModifier::Maybe
+                    } else {
+                        TraitBoundModifier::None
+                    };
+                    bounds.push(TraitTyParamBound(poly_trait, modifier));
+                }
                 if has_parens {
                     self.expect(&token::CloseDelim(token::Paren))?;
+                    if let Some(&RegionTyParamBound(..)) = bounds.last() {
+                        self.span_err(self.prev_span,
+                                      "parenthesized lifetime bounds are not supported");
+                    }
                 }
             } else {
                 break