Support foo.bar in constant expressions

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-01-25: olly
+	    Constant expressions now support member access with `.` such as
+	    `foo.bar`.  Previous this only worked in a case like `x->foo.bar`.
+
 2022-01-25: olly
 	    #2091 Support most cases of `sizeof` applied to an expression
 	    in constant expressions.  Previously there was only support for

Examples/test-suite/constant_expr.i

@@ -14,4 +14,11 @@ isPointer = false
 };
 };
 
+// Test handling of ID PERIOD ID in constant expressions (supported since 4.1.0).
+struct A {
+    int i;
+};
+constexpr A a{42};
+const int N = a.i;
+
 %}

Source/CParse/parser.y

@@ -6521,12 +6521,10 @@ exprmem        : ID ARROW ID {
 		 $$ = $1;
 		 Printf($$.val, "->%s", $3);
 	       }
-/* This generates a shift-reduce
 	       | ID PERIOD ID {
 		 $$.val = NewStringf("%s.%s", $1, $3);
 		 $$.type = 0;
 	       }
-*/
 	       | exprmem PERIOD ID {
 		 $$ = $1;
 		 Printf($$.val, ".%s", $3);