PR c++/90825 - endless recursion when evaluating sizeof.

	PR c++/90832 - endless recursion when evaluating sizeof.
	* constexpr.c (cxx_eval_constant_expression): Don't recurse on the
	result of fold_sizeof_expr if is returns a SIZEOF_EXPR.
	* typeck.c (cxx_sizeof_expr): Only return a SIZEOF_EXPR if the operand
	is instantiation-dependent.

	* g++.dg/cpp0x/constexpr-sizeof2.C: New test.
	* g++.dg/cpp0x/constexpr-sizeof3.C: New test.

From-SVN: r272221

gcc/cp/ChangeLog

 2019-06-12  Marek Polacek  <polacek@redhat.com>
 
+	PR c++/90825 - endless recursion when evaluating sizeof.
+	PR c++/90832 - endless recursion when evaluating sizeof.
+	* constexpr.c (cxx_eval_constant_expression): Don't recurse on the
+	result of fold_sizeof_expr if is returns a SIZEOF_EXPR.
+	* typeck.c (cxx_sizeof_expr): Only return a SIZEOF_EXPR if the operand
+	is instantiation-dependent.
+
 	PR c++/90736 - bogus error with alignof.
 	* constexpr.c (adjust_temp_type): Use cv_unqualified type.
 

gcc/cp/constexpr.c

@@ -4810,9 +4810,19 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
       break;
 
     case SIZEOF_EXPR:
-      r = cxx_eval_constant_expression (ctx, fold_sizeof_expr (t), lval,
-					non_constant_p, overflow_p,
-					jump_target);
+      r = fold_sizeof_expr (t);
+      /* In a template, fold_sizeof_expr may merely create a new SIZEOF_EXPR,
+	 which could lead to an infinite recursion.  */
+      if (TREE_CODE (r) != SIZEOF_EXPR)
+	r = cxx_eval_constant_expression (ctx, r, lval,
+					  non_constant_p, overflow_p,
+					  jump_target);
+      else
+	{
+	  *non_constant_p = true;
+	  gcc_assert (ctx->quiet);
+	}
+
       break;
 
     case COMPOUND_EXPR:

gcc/cp/typeck.c

@@ -1690,7 +1690,7 @@ cxx_sizeof_expr (tree e, tsubst_flags_t complain)
   if (e == error_mark_node)
     return error_mark_node;
 
-  if (processing_template_decl)
+  if (instantiation_dependent_uneval_expression_p (e))
     {
       e = build_min (SIZEOF_EXPR, size_type_node, e);
       TREE_SIDE_EFFECTS (e) = 0;

gcc/testsuite/ChangeLog

+2019-06-11  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/90825 - endless recursion when evaluating sizeof.
+	PR c++/90832 - endless recursion when evaluating sizeof.
+	* g++.dg/cpp0x/constexpr-sizeof2.C: New test.
+	* g++.dg/cpp0x/constexpr-sizeof3.C: New test.
+
 2019-06-12  Martin Sebor  <msebor@redhat.com>
 
 	PR middle-end/90676

gcc/testsuite/g++.dg/cpp0x/constexpr-sizeof2.C

+// PR c++/90825 - endless recursion when evaluating sizeof.
+// { dg-do compile { target c++11 } }
+
+class address {
+  char host_[63];
+public:
+  static constexpr unsigned buffer_size() noexcept { return sizeof(host_); }
+};
+
+template <class Archive>
+void load()
+{
+  char host[address::buffer_size()];
+}

gcc/testsuite/g++.dg/cpp0x/constexpr-sizeof3.C

+// PR c++/90832 - endless recursion when evaluating sizeof.
+// { dg-do compile { target c++11 } }
+
+class B
+{
+ template <typename T> friend struct A;
+ B() {}
+};
+
+template <typename T>
+struct A
+{
+ A() noexcept(sizeof(B{})) { }
+};
+
+struct C
+{
+ C()
+ {
+ static_assert( sizeof(A<int>{}), "" );
+ }
+};