C++: show private field accessor hints with -g and optimization (PR c++/84994)

gcc/cp/ChangeLog:
	PR c++/84994
	* constexpr.c (constexpr_fn_retval): Make non-"static".
	* cp-tree.h (constexpr_fn_retval): New decl.
	* search.c (direct_accessor_p): Update leading comment.
	(reference_accessor_p): Likewise.
	(field_accessor_p): Replace check that function body is a
	RETURN_EXPR with a call to constexpr_fn_retval.  Fix
	indentation of "field_type" decl.

gcc/testsuite/ChangeLog:
	PR c++/84994
	* g++.dg/other/accessor-fixits-1.C: Move to...
	* g++.dg/torture/accessor-fixits-1.C: ...here.
	* g++.dg/other/accessor-fixits-2.C: Move to...
	* g++.dg/torture/accessor-fixits-2.C: ...here.
	* g++.dg/other/accessor-fixits-3.C: Move to...
	* g++.dg/torture/accessor-fixits-3.C: ...here.
	* g++.dg/other/accessor-fixits-4.C: Move to...
	* g++.dg/torture/accessor-fixits-4.C: ...here.
	* g++.dg/other/accessor-fixits-5.C: Move to...
	* g++.dg/torture/accessor-fixits-5.C: ...here.
	* g++.dg/torture/accessor-fixits-6.C: New testcase.
	* g++.dg/torture/accessor-fixits-7.C: New testcase.
	* g++.dg/torture/accessor-fixits-8.C: New testcase.

From-SVN: r258731

gcc/cp/ChangeLog

+2018-03-21  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/84994
+	* constexpr.c (constexpr_fn_retval): Make non-"static".
+	* cp-tree.h (constexpr_fn_retval): New decl.
+	* search.c (direct_accessor_p): Update leading comment.
+	(reference_accessor_p): Likewise.
+	(field_accessor_p): Replace check that function body is a
+	RETURN_EXPR with a call to constexpr_fn_retval.  Fix
+	indentation of "field_type" decl.
+
 2018-03-21  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/84804

gcc/cp/constexpr.c

@@ -657,7 +657,7 @@ get_function_named_in_call (tree t)
    return value if suitable, error_mark_node for a statement not allowed in
    a constexpr function, or NULL_TREE if no return value was found.  */
 
-static tree
+tree
 constexpr_fn_retval (tree body)
 {
   switch (TREE_CODE (body))

gcc/cp/cp-tree.h

@@ -7424,6 +7424,7 @@ extern bool literal_type_p                      (tree);
 extern tree register_constexpr_fundef           (tree, tree);
 extern bool is_valid_constexpr_fn		(tree, bool);
 extern bool check_constexpr_ctor_body           (tree, tree, bool);
+extern tree constexpr_fn_retval		(tree);
 extern tree ensure_literal_type_for_constexpr_object (tree);
 extern bool potential_constant_expression       (tree);
 extern bool is_constant_expression (tree);

gcc/cp/search.c

@@ -1657,8 +1657,7 @@ field_access_p (tree component_ref, tree field_decl, tree field_type)
 
    Specifically, a simple accessor within struct S of the form:
        T get_field () { return m_field; }
-   should have a DECL_SAVED_TREE of the form:
-       <return_expr
+   should have a constexpr_fn_retval (saved_tree) of the form:
 	 <init_expr:T
 	   <result_decl:T
 	   <nop_expr:T
@@ -1666,7 +1665,7 @@ field_access_p (tree component_ref, tree field_decl, tree field_type)
 	       <indirect_ref:S>
 		 <nop_expr:P*
 		   <parm_decl (this)>
-		 <field_decl (FIELD_DECL)>>>.  */
+		 <field_decl (FIELD_DECL)>>>>>.  */
 
 static bool
 direct_accessor_p (tree init_expr, tree field_decl, tree field_type)
@@ -1690,8 +1689,7 @@ direct_accessor_p (tree init_expr, tree field_decl, tree field_type)
 
    Specifically, a simple accessor within struct S of the form:
        T& get_field () { return m_field; }
-   should have a DECL_SAVED_TREE of the form:
-       <return_expr
+   should have a constexpr_fn_retval (saved_tree) of the form:
 	 <init_expr:T&
 	   <result_decl:T&
 	   <nop_expr: T&
@@ -1757,16 +1755,19 @@ field_accessor_p (tree fn, tree field_decl, bool const_p)
   if (saved_tree == NULL_TREE)
     return false;
 
-  if (TREE_CODE (saved_tree) != RETURN_EXPR)
+  /* Attempt to extract a single return value from the function,
+     if it has one.  */
+  tree retval = constexpr_fn_retval (saved_tree);
+  if (retval == NULL_TREE || retval == error_mark_node)
     return false;
-
-  tree init_expr = TREE_OPERAND (saved_tree, 0);
-  if (TREE_CODE (init_expr) != INIT_EXPR)
+  /* Require an INIT_EXPR.  */
+  if (TREE_CODE (retval) != INIT_EXPR)
     return false;
+  tree init_expr = retval;
 
   /* Determine if this is a simple accessor within struct S of the form:
        T get_field () { return m_field; }.  */
-   tree field_type = TREE_TYPE (field_decl);
+  tree field_type = TREE_TYPE (field_decl);
   if (cxx_types_compatible_p (TREE_TYPE (init_expr), field_type))
     return direct_accessor_p (init_expr, field_decl, field_type);
 

gcc/testsuite/ChangeLog

+2018-03-21  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c++/84994
+	* g++.dg/other/accessor-fixits-1.C: Move to...
+	* g++.dg/torture/accessor-fixits-1.C: ...here.
+	* g++.dg/other/accessor-fixits-2.C: Move to...
+	* g++.dg/torture/accessor-fixits-2.C: ...here.
+	* g++.dg/other/accessor-fixits-3.C: Move to...
+	* g++.dg/torture/accessor-fixits-3.C: ...here.
+	* g++.dg/other/accessor-fixits-4.C: Move to...
+	* g++.dg/torture/accessor-fixits-4.C: ...here.
+	* g++.dg/other/accessor-fixits-5.C: Move to...
+	* g++.dg/torture/accessor-fixits-5.C: ...here.
+	* g++.dg/torture/accessor-fixits-6.C: New testcase.
+	* g++.dg/torture/accessor-fixits-7.C: New testcase.
+	* g++.dg/torture/accessor-fixits-8.C: New testcase.
+
 2018-03-21  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* gcc.dg/tree-ssa/pr84512.c: xfail on 64-bit SPARC.

gcc/testsuite/g++.dg/torture/accessor-fixits-6.C

+// PR c++/84994
+/* Ensure that fix-it hints are offered at every optimization level, even when
+   "-g" is enabled (coverage for every optimization level without -g is given
+   by the other cases within g++.dg/torture/accessor-fixits-*.C).  */
+// { dg-additional-options "-g" }
+
+class foo
+{
+public:
+  double get_ratio() const { return m_ratio; }
+
+private:
+  double m_ratio; // { dg-line field_decl }
+};
+
+void test(foo *ptr)
+{
+  if (ptr->m_ratio >= 0.5) // { dg-error "'double foo::m_ratio' is private within this context" }
+    ;
+  // { dg-message "declared private here" "" { target *-*-* } field_decl }
+  // { dg-message "'double foo::m_ratio' can be accessed via 'double foo::get_ratio\\(\\) const'" "" { target *-*-* } .-3 }
+}

gcc/testsuite/g++.dg/torture/accessor-fixits-7.C

+class foo
+{
+public:
+  double get_ratio() const;
+
+private:
+  double m_ratio; // { dg-line field_decl }
+};
+
+double
+foo::get_ratio() const
+{
+  return m_ratio;
+}
+
+void test(foo *ptr)
+{
+  if (ptr->m_ratio >= 0.5) // { dg-error "'double foo::m_ratio' is private within this context" }
+    ;
+  // { dg-message "declared private here" "" { target *-*-* } field_decl }
+  // { dg-message "'double foo::m_ratio' can be accessed via 'double foo::get_ratio\\(\\) const'" "" { target *-*-* } .-3 }
+}

gcc/testsuite/g++.dg/torture/accessor-fixits-8.C

+// { dg-options "-fdiagnostics-show-caret" }
+
+class t1
+{
+public:
+  int get_doubled_field () const { return m_field * 2; }
+  int get_guarded_field_1 () const { if (m_field) return m_field; else return 42; }
+  int get_guarded_field_2 () const { return m_field ? m_field : 42; }
+  int with_unreachable () const { __builtin_unreachable (); return m_field; }
+  void no_return () { }
+
+private:
+  int m_field; // { dg-line field_decl }
+};
+
+int test (t1 *ptr)
+{
+  return ptr->m_field; // { dg-error ".int t1::m_field. is private within this context" }
+  /* { dg-begin-multiline-output "" }
+   return ptr->m_field;
+               ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+  // { dg-message "declared private here" "" { target *-*-* } field_decl }
+  /* { dg-begin-multiline-output "" }
+   int m_field;
+       ^~~~~~~
+     { dg-end-multiline-output "" } */
+
+  /* We shouldn't issue a suggestion: none of the member functions are suitable returns.  */
+}