[gcc r11-6293] c++: Fix demangling of x.operator type

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:71690493322238d0fb9be776d9fceed0a7bf727e

commit r11-6293-g71690493322238d0fb9be776d9fceed0a7bf727e
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Dec 19 13:10:01 2020 -0500

    c++: Fix demangling of x.operator type
    
    d_operator_name decides whether "cv" indicates a cast or a conversion
    operator based on is_expression.  "on" specifies that we want the conversion
    operator.
    
    libiberty/ChangeLog:
    
            * cp-demangle.c (d_unqualified_name): Clear is_expression.
            * testsuite/demangle-expected: Add tests.

Diff:
---
 libiberty/cp-demangle.c               | 8 +++++++-
 libiberty/testsuite/demangle-expected | 6 ++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/libiberty/cp-demangle.c b/libiberty/cp-demangle.c
index a9f8e759ff5..96f43b65ad6 100644
--- a/libiberty/cp-demangle.c
+++ b/libiberty/cp-demangle.c
@@ -1632,9 +1632,15 @@ d_unqualified_name (struct d_info *di)
     ret = d_source_name (di);
   else if (IS_LOWER (peek))
     {
+      int was_expr = di->is_expression;
       if (peek == 'o' && d_peek_next_char (di) == 'n')
-	d_advance (di, 2);
+	{
+	  d_advance (di, 2);
+	  /* Treat cv as naming a conversion operator.  */
+	  di->is_expression = 0;
+	}
       ret = d_operator_name (di);
+      di->is_expression = was_expr;
       if (ret != NULL && ret->type == DEMANGLE_COMPONENT_OPERATOR)
 	{
 	  di->expansion += sizeof "operator" + ret->u.s_operator.op->len - 2;
diff --git a/libiberty/testsuite/demangle-expected b/libiberty/testsuite/demangle-expected
index 4ad9da82f2c..6e3e6716def 100644
--- a/libiberty/testsuite/demangle-expected
+++ b/libiberty/testsuite/demangle-expected
@@ -1476,3 +1476,9 @@ void f<int>(decltype (__alignof__(int)))
 
 _Z1fIiEvDTv111__alignof__tlT_EE
 void f<int>(decltype (__alignof__(int{})))
+
+_Z1gI1AEv1SIXadsrT_oncviEE
+void g<A>(S<&A::operator int>)
+
+_Z1jI1AEDTcldtfp_oncvPT_EES1_
+decltype (({parm#1}.(operator A*))()) j<A>(A)