Merge pull request gcc-mirror#93 from NinaRanns/const_param_check_fixes

fixing detection of non-const parameters in re-declarations

Author: villevoutilainen

gcc/cp/contracts.cc

@@ -2782,30 +2782,58 @@ constify_contract_access(tree decl)
   return decl;
 }
 
-/* Do not allow non-const by-value params being used in postconditions.  */
+/* If declaration DECL is a PARM_DECL and it appears in a postcondition, then
+   check that it is not a non-const by-value param. LOCATION is where the
+   expression was found and is used for diagnostic purposes.  */
 
-bool
-maybe_reject_param_in_postcondition (tree decl)
+void
+maybe_reject_param_in_postcondition (tree decl, location_t location)
 {
   if (flag_contracts_nonattr
-      && !TREE_READONLY (decl)
       && TREE_CODE (decl) == PARM_DECL
       && should_constify_contract
       && processing_postcondition
-      && !dependent_type_p (TREE_TYPE (decl))
-      && !CP_TYPE_CONST_P (TREE_TYPE (decl))
       && !(REFERENCE_REF_P (decl)
 	   && TREE_CODE (TREE_OPERAND (decl, 0)) == PARM_DECL)
 	   /* Return value parameter has DECL_ARTIFICIAL flag set. The flag
 	    * presence of the flag should be sufficient to distinguish the
 	    * return value parameter in this context. */
 	   && !(DECL_ARTIFICIAL (decl)))
     {
-      error_at (DECL_SOURCE_LOCATION (decl),
-		"a value parameter used in a postcondition must be const");
-      return true;
+      set_parm_used_in_post (decl);
+
+      if (!CP_TYPE_CONST_P(TREE_TYPE (decl)) && !TREE_READONLY(decl))
+	{
+	  error_at (location,
+		    "a value parameter used in a postcondition must be const");
+	  inform (DECL_SOURCE_LOCATION(decl), "parameter declared here");
+	}
+    }
+}
+
+/* Check if parameters used in postconditions are const qualified on
+   a redeclaration that does not specify contracts.  */
+
+void
+check_param_in_redecl (tree olddecl, tree newdecl)
+{
+  tree t1 = FUNCTION_FIRST_USER_PARM(olddecl);
+  tree t2 = FUNCTION_FIRST_USER_PARM(newdecl);
+  for (; t1 && t1 != void_list_node;
+  t1 = TREE_CHAIN (t1), t2 = TREE_CHAIN (t2))
+    {
+      if (parm_used_in_post_p(t1))
+	{
+	  set_parm_used_in_post (t2);
+	  if (!CP_TYPE_CONST_P(TREE_TYPE (t2)) && !TREE_READONLY(t2))
+	    {
+	      error_at (DECL_SOURCE_LOCATION(t2),
+	      "value parameter %qE used in a postcondition must be const", t2);
+	      inform (DECL_SOURCE_LOCATION(olddecl),
+	      "previous declaration here");
+	    }
+	}
     }
-  return false;
 }
 
 void
@@ -3277,8 +3305,9 @@ p2900_duplicate_contracts (tree newdecl, tree olddecl)
 
   if (old_contracts && !new_contracts)
     /* We allow re-declarations to omit contracts declared on the initial decl.
-       In fact, this is required if the conditions contain lambdas.  */
-    ;
+       In fact, this is required if the conditions contain lambdas.  Check if
+       all the parameters are correctly const qualified. */
+    check_param_in_redecl (olddecl, newdecl);
   else if (contract_any_deferred_p (new_contracts))
     /* TODO: stash these and figure out how to process them later.  */
     ;

gcc/cp/cp-tree.h

@@ -565,6 +565,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
       DECL_SELF_REFERENCE_P (in a TYPE_DECL)
       DECL_INVALID_OVERRIDER_P (in a FUNCTION_DECL)
       DECL_UNINSTANIATED_TEMPLATE_FRIEND_P (in TEMPLATE_DECL)
+      parm_used_in_post_p (in PARM_DECL)
    5: DECL_INTERFACE_KNOWN.
    6: DECL_THIS_STATIC (in VAR_DECL, FUNCTION_DECL or PARM_DECL)
       DECL_FIELD_IS_BASE (in FIELD_DECL)
@@ -8943,8 +8944,8 @@ extern tree grok_contract			(tree, tree, tree, cp_expr, location_t);
 extern tree finish_contract_condition		(cp_expr);
 extern void update_late_contract		(tree, tree, cp_expr);
 extern tree constify_contract_access            (tree);
-extern bool maybe_reject_param_in_postcondition (tree);
-
+extern void maybe_reject_param_in_postcondition (tree, location_t);
+extern void check_param_in_redecl 		(tree, tree);
 extern tree view_as_const                       (tree);
 extern tree maybe_contract_wrap_call	        (tree, tree);
 extern bool emit_contract_wrapper_func          (bool);
@@ -9025,6 +9026,24 @@ strip_contract_const_wrapper (tree exp)
     return exp;
 }
 
+/* Indicate if PARM_DECL DECL is ODR used in a postcondition.  */
+
+inline void
+set_parm_used_in_post (tree decl, bool constify = true)
+{
+  gcc_checking_assert (TREE_CODE (decl) == PARM_DECL);
+  DECL_LANG_FLAG_4 (decl) = constify;
+}
+
+/* Test if PARM_DECL is ODR used in a postcondition.  */
+
+inline bool
+parm_used_in_post_p (const_tree decl)
+{
+  /* Check if this parameter is odr used within a function's postcondition  */
+  return ((TREE_CODE (decl) == PARM_DECL) && DECL_LANG_FLAG_4 (decl));
+}
+
 /* Inline bodies.  */
 
 inline tree

gcc/cp/decl.cc

@@ -2273,6 +2273,7 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
 		 declaration of the function or function template in the
 		 translation unit."  */
 	      check_no_redeclaration_friend_default_args (olddecl, newdecl);
+
 	    }
 	}
     }

gcc/cp/pt.cc

@@ -22373,7 +22373,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	  /* force_paren_expr can also create a VIEW_CONVERT_EXPR.  */
 	  RETURN (finish_parenthesized_expr (op));
 
-	maybe_reject_param_in_postcondition (op);
+	maybe_reject_param_in_postcondition (op, EXPR_LOCATION (t));
 
 	if (flag_contracts_nonattr && should_constify_contract
 	    && processing_contract_condition)

gcc/cp/search.cc

@@ -2273,6 +2273,8 @@ check_override_contracts (tree fndecl)
 	      inform (DECL_SOURCE_LOCATION (basefn),
 		      "overridden function is %qD", basefn);
 	    }
+
+	  check_param_in_redecl (basefn, fndecl);
 	}
     }
 }

gcc/cp/semantics.cc

@@ -5019,7 +5019,7 @@ finish_id_expression_1 (tree id_expression,
 	}
     }
 
-  maybe_reject_param_in_postcondition (decl);
+  maybe_reject_param_in_postcondition (decl, location);
   if (flag_contracts_nonattr && should_constify_contract
 	&& processing_contract_condition)
     decl = constify_contract_access(decl);

gcc/testsuite/g++.dg/contracts/cpp26/P2900R13-virtual-func/postcondition-const-check-redecl.C

@@ -0,0 +1,42 @@
+// { dg-do compile }
+// { dg-options "-std=c++23 -fcontracts -fcontracts-nonattr -fcontracts-nonattr-inheritance-mode=P2900R13 " }
+
+struct NTClass {
+  //TODO, make non trivial when https://github.com/NinaRanns/gcc/issues/21 is solved
+//  NTClass(){};
+//  ~NTClass(){};
+};
+
+template <typename... ARGS>
+bool check(ARGS... args){ return true;}
+
+
+struct Base
+{
+  virtual void f (const NTClass i);
+
+}  ;
+
+struct Derived : Base
+{
+  virtual void f (const NTClass i)  post (check (i));
+  virtual void g (const NTClass i) pre ( check (i)) post (true);
+};
+
+struct DerivedV : virtual Base
+{
+  virtual void f (const NTClass i)  post (check (i));
+  virtual void g (const NTClass i) pre ( check (i)) post (true);
+};
+
+void
+Derived::f (NTClass i){} // { dg-error "used in a postcondition must be const" }
+
+void
+DerivedV::f (NTClass i){} // { dg-error "used in a postcondition must be const" }
+
+void
+Derived::g (NTClass i){}
+
+void
+DerivedV::g (NTClass i){}

gcc/testsuite/g++.dg/contracts/cpp26/P3653-virtual-func/postcondition-const-check-redecl.C

@@ -0,0 +1,42 @@
+// { dg-do compile }
+// { dg-options "-std=c++23 -fcontracts -fcontracts-nonattr -fcontracts-nonattr-inheritance-mode=P3653 " }
+
+struct NTClass {
+  //TODO, make non trivial when https://github.com/NinaRanns/gcc/issues/21 is solved
+//  NTClass(){};
+//  ~NTClass(){};
+};
+
+template <typename... ARGS>
+bool check(ARGS... args){ return true;}
+
+
+struct Base
+{
+  virtual void f (const NTClass i);
+
+}  ;
+
+struct Derived : Base
+{
+  virtual void f (const NTClass i)  post (check (i));
+  virtual void g (const NTClass i) pre ( check (i)) post (true);
+};
+
+struct DerivedV : virtual Base
+{
+  virtual void f (const NTClass i)  post (check (i));
+  virtual void g (const NTClass i) pre ( check (i)) post (true);
+};
+
+void
+Derived::f (NTClass i){} // { dg-error "used in a postcondition must be const" }
+
+void
+DerivedV::f (NTClass i){} // { dg-error "used in a postcondition must be const" }
+
+void
+Derived::g (NTClass i){}
+
+void
+DerivedV::g (NTClass i){}