demangle: always print parentheses for __alignof__ argument

Also update to current demangle-expected from GCC trunk.

Author: ianlancetaylor

ast.go

@@ -2082,6 +2082,11 @@ func (u *Unary) print(ps *printState) {
 			ps.writeByte('(')
 			ps.print(expr)
 			ps.writeByte(')')
+		} else if op, ok := u.Op.(*Operator); ok && op.Name == "__alignof__" {
+			// Always use parentheses for __alignof__ argument.
+			ps.writeByte('(')
+			ps.print(expr)
+			ps.writeByte(')')
 		} else {
 			parenthesize(ps, expr)
 		}

testdata/demangle-expected

@@ -1469,3 +1469,22 @@ f(A<X{.a.b[3 ... 4]=(1)}>)
 # PR 96143
 _Z2F2IZ1FvEUlvE_EN1AIT_E1XES2_
 A<F()::{lambda()#1}>::X F2<F()::{lambda()#1}>(F()::{lambda()#1})
+
+# PR 88115
+_Z1fIiEvDTv111__alignof__T_E
+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)
+
+_Z1fI1AEDtdtfp_srT_1xES1_
+decltype ({parm#1}.A::x) f<A>(A)
+
+_Z2f6IP1AEDtptfp_gssr1A1BE1xET_
+decltype ({parm#1}->(::A::B::x)) f6<A*>(A*)