Merge pull request gcc-mirror#56 from iains/contracts-nonattr-p2900-3…

…-4-3

Contracts nonattr p2900 3 4 3

gcc/cp/contracts.cc

@@ -2769,6 +2769,33 @@ start_function_contracts (tree decl1)
   if (!handle_contracts_p (decl1))
     return;
 
+  /* Check that the user did not try to shadow a function parameter with the
+     specified postcondition result name.  */
+  if (flag_contracts_nonattr)
+    for (tree ca = DECL_CONTRACTS (decl1); ca; ca = CONTRACT_CHAIN (ca))
+      if (POSTCONDITION_P (CONTRACT_STATEMENT (ca)))
+	if (tree id = POSTCONDITION_IDENTIFIER (CONTRACT_STATEMENT (ca)))
+	  {
+	    if (TREE_CODE (id) == PARM_DECL)
+	      id = DECL_NAME (id);
+	    gcc_checking_assert (id && TREE_CODE (id) == IDENTIFIER_NODE);
+	    tree seen = lookup_name (id);
+	    if (seen
+		&& TREE_CODE (seen) == PARM_DECL
+		&& DECL_CONTEXT (seen)
+		&& DECL_CONTEXT (seen) == decl1)
+	      {
+		auto_diagnostic_group d;
+		error_at (EXPR_LOCATION (CONTRACT_STATEMENT (ca)),
+			  "contract postcondition result names must not shadow"
+			  " function parameters");
+		inform (DECL_SOURCE_LOCATION (seen), "parameter declared here");
+		POSTCONDITION_IDENTIFIER (CONTRACT_STATEMENT (ca))
+		  = error_mark_node;
+		CONTRACT_CONDITION (CONTRACT_STATEMENT (ca)) = error_mark_node;
+	      }
+	  }
+
   /* For cdtors, we evaluate the contracts check inline.  */
   if (!outline_contracts_p (decl1))
     return;
@@ -2778,7 +2805,6 @@ start_function_contracts (tree decl1)
   /* Do we already have declarations generated ? */
   if (!DECL_PRE_FN (decl1) && !DECL_POST_FN (decl1))
     build_contract_function_decls (decl1);
-
 }
 
 /* If we have a precondition function and it's valid, call it.  */

gcc/cp/decl.cc

@@ -5982,6 +5982,21 @@ start_decl (const cp_declarator *declarator,
       return error_mark_node;
     }
 
+  if (flag_contracts_nonattr
+      && TREE_CODE (decl) == FUNCTION_DECL
+      && !processing_template_decl
+      && DECL_RESULT (decl)
+      && is_auto (TREE_TYPE (DECL_RESULT (decl))))
+    for (tree contract = DECL_CONTRACTS (decl); contract;
+	 contract = CONTRACT_CHAIN (contract))
+      if (POSTCONDITION_P (CONTRACT_STATEMENT (contract))
+	  && POSTCONDITION_IDENTIFIER (CONTRACT_STATEMENT (contract)))
+	{
+	  error_at (DECL_SOURCE_LOCATION (decl),
+		    "postconditions with deduced result name types must only"
+		    " appear on function definitions");
+	  return error_mark_node;
+	}
   /* Save the DECL_INITIAL value in case it gets clobbered to assist
      with attribute validation.  */
   initial = DECL_INITIAL (decl);

gcc/testsuite/g++.dg/contracts/cpp26/p2900-3-3-4-part1.C

@@ -0,0 +1,19 @@
+// { dg-options "-std=c++26 -fcontracts -fcontracts-nonattr" }
+
+int bad_mr_shadow (int r)
+  post (r: r > 5) // { dg-error "contract postcondition result names must not shadow function parameters" }
+  { return r + 1; }
+
+auto no_deduced_res_types_on_non_defs (int x) // { dg-error "postconditions with deduced result name types must only appear on function definitions" }
+  pre (x > 1)
+  post (r: r > 17); 
+
+// =====
+
+auto f2() post (r : r > 0) // OK, type of r is deduced below.
+{ return 5; }
+
+template <typename T>
+auto f3 () post (r: r > 0); // OK, postcondition instantiated with template
+
+auto f4 () post (true); // OK, return value not named