re PR c++/79650 (ICE on invalid c++ code with label arithmetic in…

re PR c++/79650 (ICE on invalid c++ code with label arithmetic in convert_nontype_argument (pt.c:6515))

	PR c++/79650
	* pt.c (convert_nontype_argument): Diagnose
	reduced_constant_expression_p expressions that aren't INTEGER_CST.

	* g++.dg/template/pr79650.C: New test.

From-SVN: r255623

gcc/cp/ChangeLog

+2017-12-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/79650
+	* pt.c (convert_nontype_argument): Diagnose
+	reduced_constant_expression_p expressions that aren't INTEGER_CST.
+
 2017-12-13  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/81061

gcc/cp/pt.c

@@ -6577,7 +6577,19 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
 		return NULL_TREE;
 	      /* else cxx_constant_value complained but gave us
 		 a real constant, so go ahead.  */
-	      gcc_assert (TREE_CODE (expr) == INTEGER_CST);
+	      if (TREE_CODE (expr) != INTEGER_CST)
+		{
+		  /* Some assemble time constant expressions like
+		     (intptr_t)&&lab1 - (intptr_t)&&lab2 or
+		     4 + (intptr_t)&&var satisfy reduced_constant_expression_p
+		     as we can emit them into .rodata initializers of
+		     variables, yet they can't fold into an INTEGER_CST at
+		     compile time.  Refuse them here.  */
+		  gcc_checking_assert (reduced_constant_expression_p (expr));
+		  error_at (loc, "template argument %qE for type %qT not "
+				 "a constant integer", expr, type);
+		  return NULL_TREE;
+		}
 	    }
 	  else
 	    return NULL_TREE;

gcc/testsuite/ChangeLog

+2017-12-14  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/79650
+	* g++.dg/template/pr79650.C: New test.
+
 2017-12-14  Richard Sandiford  <richard.sandiford@linaro.org>
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>

gcc/testsuite/g++.dg/template/pr79650.C

+// PR c++/79650
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+typedef __INTPTR_TYPE__ intptr_t;
+template<intptr_t> struct A {};
+
+void
+foo ()
+{
+  static int a, b;
+lab1:
+lab2:
+  A<(intptr_t)&&lab1 - (__INTPTR_TYPE__)&&lab2> c;	// { dg-error "not a constant integer" }
+  A<(intptr_t)&&lab1 - (__INTPTR_TYPE__)&&lab1> d;
+  A<(intptr_t)&a - (intptr_t)&b> e;			// { dg-error "is not a constant expression" }
+  A<(intptr_t)&a - (intptr_t)&a> f;
+  A<(intptr_t)sizeof(a) + (intptr_t)&a> g;		// { dg-error "not a constant integer" }
+  A<(intptr_t)&a> h;					// { dg-error "conversion from pointer type" }
+}