PR c++/87152 - range-based for loops with initializer broken in templates.

	* constexpr.c (potential_constant_expression_1) <case RANGE_FOR_STMT>:
	Recur into RANGE_FOR_INIT_STMT.
	* cp-tree.def: Add RANGE_FOR_INIT_STMT to RANGE_FOR_STMT.
	* cp-tree.h (RANGE_FOR_INIT_STMT): Define.
	* dump.c (cp_dump_tree) <case RANGE_FOR_STMT>: Also dump
	RANGE_FOR_INIT_STMT.
	* pt.c (tsubst_expr) <case RANGE_FOR_STMT>: Recur into
	RANGE_FOR_INIT_STMT.
	* semantics.c (begin_range_for_stmt): Adjust call to build_stmt.
	Do put the init statement in RANGE_FOR_INIT_STMT.
	(finish_range_for_decl): Pop it for templates.

	* g++.dg/cpp2a/range-for11.C: New test.
	* g++.dg/cpp2a/range-for12.C: New test.
	* g++.dg/cpp2a/range-for13.C: New test.
	* g++.dg/cpp2a/range-for14.C: New test.
	* g++.dg/cpp2a/range-for15.C: New test.
	* g++.dg/cpp2a/range-for16.C: New test.
	* g++.dg/cpp2a/range-for17.C: New test.
	* g++.dg/cpp2a/range-for18.C: New test.
	* g++.dg/parse/error61.C (foo): Adjust dg-error.

From-SVN: r264158

7 files changed, 32 insertions, 10 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 42e70cd..70c462c 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,18 @@
+2018-09-07  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/87152 - range-based for loops with initializer broken in templates.
+	* constexpr.c (potential_constant_expression_1) <case RANGE_FOR_STMT>:
+	Recur into RANGE_FOR_INIT_STMT.
+	* cp-tree.def: Add RANGE_FOR_INIT_STMT to RANGE_FOR_STMT.
+	* cp-tree.h (RANGE_FOR_INIT_STMT): Define.
+	* dump.c (cp_dump_tree) <case RANGE_FOR_STMT>: Also dump
+	RANGE_FOR_INIT_STMT.
+	* pt.c (tsubst_expr) <case RANGE_FOR_STMT>: Recur into
+	RANGE_FOR_INIT_STMT.
+	* semantics.c (begin_range_for_stmt): Adjust call to build_stmt.
+	Do put the init statement in RANGE_FOR_INIT_STMT.
+	(finish_range_for_decl): Pop it for templates.
+
 2018-09-06  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	* decl.c (check_initializer): Call cp_complete_array_type.
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index f646519..6c26890 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -5767,6 +5767,8 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
       return true;
 
     case RANGE_FOR_STMT:
+      if (!RECUR (RANGE_FOR_INIT_STMT (t), any))
+	return false;
       if (!RECUR (RANGE_FOR_EXPR (t), any))
 	return false;
       if (!RECUR (RANGE_FOR_BODY (t), any))
diff --git a/gcc/cp/cp-tree.def b/gcc/cp/cp-tree.def
index 1b0326f..c64225d 100644
--- a/gcc/cp/cp-tree.def
+++ b/gcc/cp/cp-tree.def
@@ -301,9 +301,10 @@ DEFTREECODE (IF_STMT, "if_stmt", tcc_statement, 4)
 DEFTREECODE (FOR_STMT, "for_stmt", tcc_statement, 5)
 
 /* Used to represent a range-based `for' statement. The operands are
-   RANGE_FOR_DECL, RANGE_FOR_EXPR, RANGE_FOR_BODY, and RANGE_FOR_SCOPE,
-   RANGE_FOR_UNROLL respectively.  Only used in templates.  */
-DEFTREECODE (RANGE_FOR_STMT, "range_for_stmt", tcc_statement, 5)
+   RANGE_FOR_DECL, RANGE_FOR_EXPR, RANGE_FOR_BODY, RANGE_FOR_SCOPE,
+   RANGE_FOR_UNROLL, and RANGE_FOR_INIT_STMT, respectively.  Only used in
+   templates.  */
+DEFTREECODE (RANGE_FOR_STMT, "range_for_stmt", tcc_statement, 6)
 
 /* Used to represent a 'while' statement. The operands are WHILE_COND
    and WHILE_BODY, respectively.  */
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index df441fc..b78e9eb 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4923,6 +4923,7 @@ more_aggr_init_expr_args_p (const aggr_init_expr_arg_iterator *iter)
 #define RANGE_FOR_BODY(NODE)	TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 2)
 #define RANGE_FOR_SCOPE(NODE)	TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 3)
 #define RANGE_FOR_UNROLL(NODE)	TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 4)
+#define RANGE_FOR_INIT_STMT(NODE) TREE_OPERAND (RANGE_FOR_STMT_CHECK (NODE), 5)
 #define RANGE_FOR_IVDEP(NODE)	TREE_LANG_FLAG_6 (RANGE_FOR_STMT_CHECK (NODE))
 
 #define SWITCH_STMT_COND(NODE)	TREE_OPERAND (SWITCH_STMT_CHECK (NODE), 0)
diff --git a/gcc/cp/dump.c b/gcc/cp/dump.c
index 9c1e5fc..d9b868b 100644
--- a/gcc/cp/dump.c
+++ b/gcc/cp/dump.c
@@ -301,6 +301,7 @@ cp_dump_tree (void* dump_info, tree t)
 
     case RANGE_FOR_STMT:
       dump_stmt (di, t);
+      dump_child ("init", RANGE_FOR_INIT_STMT (t));
       dump_child ("decl", RANGE_FOR_DECL (t));
       dump_child ("expr", RANGE_FOR_EXPR (t));
       dump_child ("body", RANGE_FOR_BODY (t));
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 0a618a5..892a387 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -16815,6 +16815,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
         stmt = (processing_template_decl
 		? begin_range_for_stmt (NULL_TREE, NULL_TREE)
 		: begin_for_stmt (NULL_TREE, NULL_TREE));
+	RECUR (RANGE_FOR_INIT_STMT (t));
         decl = RANGE_FOR_DECL (t);
         decl = tsubst (decl, args, complain, in_decl);
         maybe_push_decl (decl);
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 676de01..f3e5d83 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -1101,8 +1101,8 @@ begin_range_for_stmt (tree scope, tree init)
 {
   begin_maybe_infinite_loop (boolean_false_node);
 
-  tree r = build_stmt (input_location, RANGE_FOR_STMT,
-		       NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE);
+  tree r = build_stmt (input_location, RANGE_FOR_STMT, NULL_TREE, NULL_TREE,
+		       NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE);
 
   if (scope == NULL_TREE)
     {
@@ -1110,22 +1110,23 @@ begin_range_for_stmt (tree scope, tree init)
       scope = begin_for_scope (&init);
     }
 
-  /* RANGE_FOR_STMTs do not use nor save the init tree, so we
-     pop it now.  */
-  if (init)
-    pop_stmt_list (init);
+  /* Since C++20, RANGE_FOR_STMTs can use the init tree, so save it.  */
+  RANGE_FOR_INIT_STMT (r) = init;
   RANGE_FOR_SCOPE (r) = scope;
 
   return r;
 }
 
 /* Finish the head of a range-based for statement, which may
-   be given by RANGE_FOR_STMT. DECL must be the declaration
+   be given by RANGE_FOR_STMT.  DECL must be the declaration
    and EXPR must be the loop expression. */
 
 void
 finish_range_for_decl (tree range_for_stmt, tree decl, tree expr)
 {
+  if (processing_template_decl)
+    RANGE_FOR_INIT_STMT (range_for_stmt)
+      = pop_stmt_list (RANGE_FOR_INIT_STMT (range_for_stmt));
   RANGE_FOR_DECL (range_for_stmt) = decl;
   RANGE_FOR_EXPR (range_for_stmt) = expr;
   add_stmt (range_for_stmt);