[gcc r11-6331] compiler: parenthesize channel type strings if necessary

[Ian Lance Taylor <ian@gcc.gnu.org>]

https://gcc.gnu.org/g:085fd2a46e512638a4d7a96e07eaf3b8b021a567

commit r11-6331-g085fd2a46e512638a4d7a96e07eaf3b8b021a567
Author: Ian Lance Taylor <iant@golang.org>
Date:   Wed Dec 23 16:32:30 2020 -0800

    compiler: parenthesize channel type strings if necessary
    
    Avoid the ambiguity between "chan <- (chan int)" and "chan (<- chan int)".
    This parenthesizes the same way as the gc compiler.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/279961

Diff:
---
 gcc/go/gofrontend/MERGE    |  2 +-
 gcc/go/gofrontend/types.cc | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 600d9769624..1e461f06e95 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-8d49adead59b8103f3bfeebd53ee508eda5ee94a
+d67579759e1769c08148304b2d378ec0b05637d6
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/types.cc b/gcc/go/gofrontend/types.cc
index 16f0eb59a50..7d4c47f1c42 100644
--- a/gcc/go/gofrontend/types.cc
+++ b/gcc/go/gofrontend/types.cc
@@ -8845,7 +8845,22 @@ Channel_type::do_reflection(Gogo* gogo, std::string* ret) const
   if (!this->may_receive_)
     ret->append("<-");
   ret->push_back(' ');
+
+  bool need_paren = false;
+  if (this->may_send_
+      && this->may_receive_
+      && this->element_type_->channel_type() != NULL
+      && this->element_type_->unalias()->named_type() == NULL
+      && !this->element_type_->channel_type()->may_send())
+    {
+      ret->push_back('(');
+      need_paren = true;
+    }
+
   this->append_reflection(this->element_type_, gogo, ret);
+
+  if (need_paren)
+    ret->push_back(')');
 }
 
 // Export.