C++: show private field accessor hints for const accesses (PR c++/84892)

gcc/cp/ChangeLog:
	PR c++/84892
	* search.c (field_accessor_p): Use class_of_this_parm rather than
	type_of_this_parm, to check that "this" is a "const T *", rather
	than a "T *const".

gcc/testsuite/ChangeLog:
	PR c++/84892
	* g++.dg/other/accessor-fixits-1.C
	(test_access_const_t1_color): New.
	(test_deref_const_t1_color): New.
	* g++.dg/other/accessor-fixits-5.C: New testcase.

From-SVN: r258716

gcc/cp/ChangeLog

+2018-03-21  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/84892
+	* search.c (field_accessor_p): Use class_of_this_parm rather than
+	type_of_this_parm, to check that "this" is a "const T *", rather
+	than a "T *const".
+
 2018-03-21  Nathan Sidwell  <nathan@acm.org>
 
 	* class.c (finish_struct_anon_r): Refactor, deprecate anything

gcc/cp/search.c

@@ -1747,8 +1747,8 @@ field_accessor_p (tree fn, tree field_decl, bool const_p)
      that the "this" parameter is const.  */
   if (const_p)
     {
-      tree this_type = type_of_this_parm (fntype);
-      if (!TYPE_READONLY (this_type))
+      tree this_class = class_of_this_parm (fntype);
+      if (!TYPE_READONLY (this_class))
 	return false;
     }
 

gcc/testsuite/ChangeLog

+2018-03-21  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/84892
+	* g++.dg/other/accessor-fixits-1.C
+	(test_access_const_t1_color): New.
+	(test_deref_const_t1_color): New.
+	* g++.dg/other/accessor-fixits-5.C: New testcase.
+
 2018-03-21  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/83126

gcc/testsuite/g++.dg/other/accessor-fixits-1.C

@@ -35,6 +35,28 @@ int test_access_t1_color (t1 &ref)
      { dg-end-multiline-output "" } */
 }
 
+int test_access_const_t1_color (const t1 &ref)
+{
+  return ref.m_color; // { dg-error ".int t1::m_color. is private within this context" }
+  /* { dg-begin-multiline-output "" }
+   return ref.m_color;
+              ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+
+  /* { dg-begin-multiline-output "" }
+   int m_color;
+       ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+  // { dg-message "field .int t1::m_color. can be accessed via .int t1::get_color\\(\\) const." "" { target *-*-* } .-12 }
+  /* { dg-begin-multiline-output "" }
+   return ref.m_color;
+              ^~~~~~~
+              get_color()
+     { dg-end-multiline-output "" } */
+}
+
 int test_access_t1_shape (t1 &ref)
 {
   return ref.m_shape; // { dg-error ".int t1::m_shape. is protected within this context" }
@@ -79,6 +101,28 @@ int test_deref_t1_color (t1 *ptr)
      { dg-end-multiline-output "" } */
 }
 
+int test_deref_const_t1_color (const t1 *ptr)
+{
+  return ptr->m_color; // { dg-error ".int t1::m_color. is private within this context" }
+  /* { dg-begin-multiline-output "" }
+   return ptr->m_color;
+               ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+
+  /* { dg-begin-multiline-output "" }
+   int m_color;
+       ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+  // { dg-message "field .int t1::m_color. can be accessed via .int t1::get_color\\(\\) const." "" { target *-*-* } .-12 }
+  /* { dg-begin-multiline-output "" }
+   return ptr->m_color;
+               ^~~~~~~
+               get_color()
+     { dg-end-multiline-output "" } */
+}
+
 int test_deref_t1_shape (t1 *ptr)
 {
   return ptr->m_shape; // { dg-error ".int t1::m_shape. is protected within this context" }

gcc/testsuite/g++.dg/other/accessor-fixits-5.C

+// PR c++/84892
+// { dg-options "-fdiagnostics-show-caret" }
+
+class S {
+private:
+  bool field;
+
+public:
+  bool get_field() const {
+    return field;
+  }
+};
+
+bool thingy(const S & s) {
+  return s.field; // { dg-error "'bool S::field' is private within this context" }
+  /* { dg-begin-multiline-output "" }
+   return s.field;
+            ^~~~~
+     { dg-end-multiline-output "" } */
+
+  // { dg-message "declared private here" "" { target *-*-* } 6 }
+  /* { dg-begin-multiline-output "" }
+   bool field;
+        ^~~~~
+     { dg-end-multiline-output "" } */
+ 
+  // { dg-message "field 'bool S::field' can be accessed via 'bool S::get_field\\(\\) const'" "" { target *-*-* } .-12 }
+  /* { dg-begin-multiline-output "" }
+   return s.field;
+            ^~~~~
+            get_field()
+     { dg-end-multiline-output "" } */
+}