C++ PATCH to start C++14 constexpr support

commit 9bf3eee3ac0225c7aea376d85e51e5da987fc401
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Oct 2 15:51:03 2014 -0400

    	* semantics.c (constexpr_fn_retval): Ignore declarations in C++14.
    	(var_in_constexpr_fn): New.
    	(cxx_eval_constant_expression): Look into DECL_INITIAL.
    	(potential_constant_expression_1): Allow constexpr-local vars.

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index fe1651e..857af76 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -5833,6 +5833,7 @@  extern tree maybe_constant_value (tree);
 extern tree maybe_constant_init (tree);
 extern bool is_sub_constant_expr (tree);
 extern bool reduced_constant_expression_p (tree);
+extern bool var_in_constexpr_fn (tree);
 extern void explain_invalid_constexpr_fn (tree);
 extern vec<tree> cx_error_context (void);
 extern bool is_this_parameter (tree);
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 7569826..6c6a5c8 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -8018,6 +8018,8 @@  constexpr_fn_retval (tree body)
     case DECL_EXPR:
       if (TREE_CODE (DECL_EXPR_DECL (body)) == USING_DECL)
 	return NULL_TREE;
+      if (cxx_dialect >= cxx14)
+	return NULL_TREE;
       return error_mark_node;
 
     case CLEANUP_POINT_EXPR:
@@ -9596,6 +9598,14 @@  cxx_eval_trinary_expression (const constexpr_call *call, tree t,
   return val;
 }
 
+bool
+var_in_constexpr_fn (tree t)
+{
+  tree ctx = DECL_CONTEXT (t);
+  return (cxx_dialect >= cxx14 && ctx && TREE_CODE (ctx) == FUNCTION_DECL
+	  && DECL_DECLARED_CONSTEXPR_P (ctx));
+}
+
 /* Attempt to reduce the expression T to a constant value.
    On failure, issue diagnostic and return error_mark_node.  */
 /* FIXME unify with c_fully_fold */
@@ -9635,6 +9645,11 @@  cxx_eval_constant_expression (const constexpr_call *call, tree t,
       if (TREE_CODE (r) == TARGET_EXPR
 	  && TREE_CODE (TARGET_EXPR_INITIAL (r)) == CONSTRUCTOR)
 	r = TARGET_EXPR_INITIAL (r);
+      if (DECL_P (r) && var_in_constexpr_fn (r)
+	  && DECL_INITIAL (r))
+	r = cxx_eval_constant_expression (call, DECL_INITIAL (r),
+					  allow_non_constant, false,
+					  non_constant_p, overflow_p);
       if (DECL_P (r))
 	{
 	  if (!allow_non_constant)
@@ -10320,6 +10335,7 @@  potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags)
 
     case VAR_DECL:
       if (want_rval && !decl_constant_var_p (t)
+	  && !var_in_constexpr_fn (t)
 	  && !dependent_type_p (TREE_TYPE (t)))
         {
           if (flags & tf_error)
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-local1.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-local1.C
new file mode 100644
index 0000000..39c3ee8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-local1.C
@@ -0,0 +1,9 @@ 
+// { dg-do compile { target c++14 } }
+
+constexpr int f(int i) { int j = i+1; return j; }
+
+constexpr int i = f(41);
+
+#define SA(X) static_assert((X),#X)
+
+SA(i==42);

commit 239f96028401a2836208f21f3432c4be91265740
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Oct 3 06:15:02 2014 -0400

    	* decl.c (start_decl): Complain about static/thread_local vars
    	in constexpr function.
    	(check_for_uninitialized_const_var): Also uninitialized vars.
    	* parser.c (cp_parser_jump_statement): And gotos.
    	(cp_parser_asm_operand_list): And asm.
    	(cp_parser_try_block): And try.
    	* semantics.c (ensure_literal_type_for_constexpr_object): And
    	non-literal.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 7856dd8..9c8ecc0 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -4767,6 +4767,16 @@  start_decl (const cp_declarator *declarator,
       DECL_THIS_STATIC (decl) = 1;
     }
 
+  if (current_function_decl && VAR_P (decl)
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
+    {
+      if (DECL_THREAD_LOCAL_P (decl))
+	error ("%qD declared %<thread_local%> in %<constexpr%> function",
+	       decl);
+      else if (TREE_STATIC (decl))
+	error ("%qD declared %<static%> in %<constexpr%> function", decl);
+    }
+
   if (!processing_template_decl && VAR_P (decl))
     start_decl_1 (decl, initialized);
 
@@ -5135,15 +5145,20 @@  check_for_uninitialized_const_var (tree decl)
      7.1.6 */
   if (VAR_P (decl)
       && TREE_CODE (type) != REFERENCE_TYPE
-      && CP_TYPE_CONST_P (type)
+      && (CP_TYPE_CONST_P (type) || var_in_constexpr_fn (decl))
       && !DECL_INITIAL (decl))
     {
       tree field = default_init_uninitialized_part (type);
       if (!field)
 	return;
 
-      permerror (DECL_SOURCE_LOCATION (decl),
-		 "uninitialized const %qD", decl);
+      if (CP_TYPE_CONST_P (type))
+	permerror (DECL_SOURCE_LOCATION (decl),
+		   "uninitialized const %qD", decl);
+      else
+	error_at (DECL_SOURCE_LOCATION (decl),
+		  "uninitialized variable %qD in %<constexpr%> function",
+		  decl);
 
       if (CLASS_TYPE_P (type))
 	{
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 0050b8d..18cae5b 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -10915,6 +10915,10 @@  cp_parser_jump_statement (cp_parser* parser)
       break;
 
     case RID_GOTO:
+      if (parser->in_function_body
+	  && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
+	error ("%<goto%> in %<constexpr%> function");
+
       /* Create the goto-statement.  */
       if (cp_lexer_next_token_is (parser->lexer, CPP_MULT))
 	{
@@ -16484,6 +16488,11 @@  cp_parser_asm_definition (cp_parser* parser)
 
   /* Look for the `asm' keyword.  */
   cp_parser_require_keyword (parser, RID_ASM, RT_ASM);
+
+  if (parser->in_function_body
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
+    error ("%<asm%> in %<constexpr%> function");
+
   /* See if the next token is `volatile'.  */
   if (cp_parser_allow_gnu_extensions_p (parser)
       && cp_lexer_next_token_is_keyword (parser->lexer, RID_VOLATILE))
@@ -21441,6 +21450,10 @@  cp_parser_try_block (cp_parser* parser)
   tree try_block;
 
   cp_parser_require_keyword (parser, RID_TRY, RT_TRY);
+  if (parser->in_function_body
+      && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
+    error ("%<try%> in %<constexpr%> function");
+
   try_block = begin_try_block ();
   cp_parser_compound_statement (parser, NULL, true, false);
   finish_try_block (try_block);
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 6c6a5c8..5d1aafc 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -7537,7 +7537,9 @@  tree
 ensure_literal_type_for_constexpr_object (tree decl)
 {
   tree type = TREE_TYPE (decl);
-  if (VAR_P (decl) && DECL_DECLARED_CONSTEXPR_P (decl)
+  if (VAR_P (decl)
+      && (DECL_DECLARED_CONSTEXPR_P (decl)
+	  || var_in_constexpr_fn (decl))
       && !processing_template_decl)
     {
       tree stype = strip_array_types (type);
@@ -7546,8 +7548,12 @@  ensure_literal_type_for_constexpr_object (tree decl)
 	   when we try to initialize the variable.  */;
       else if (!literal_type_p (type))
 	{
-	  error ("the type %qT of constexpr variable %qD is not literal",
-		 type, decl);
+	  if (DECL_DECLARED_CONSTEXPR_P (decl))
+	    error ("the type %qT of constexpr variable %qD is not literal",
+		   type, decl);
+	  else
+	    error ("variable %qD of non-literal type %qT in %<constexpr%> "
+		   "function", decl, type);
 	  explain_non_literal_class (type);
 	  return NULL;
 	}
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C b/gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C
new file mode 100644
index 0000000..ae3dcc6
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C
@@ -0,0 +1,17 @@ 
+// { dg-do compile { target c++14 } }
+
+struct A { A(); };
+
+constexpr int f(int i) {
+  static int j = i;		// { dg-error "static" }
+  thread_local int l = i;	// { dg-error "thread_local" }
+  goto foo;			// { dg-error "goto" }
+ foo:
+  asm("foo");			// { dg-error "asm" }
+  int k;			// { dg-error "uninitialized" }
+  A a;				// { dg-error "non-literal" }
+  return i;
+}
+
+// FIXME remove
+// { dg-prune-output "return" }