c++: Fix array of char typedef in template (PR90966).

Since Martin Sebor's patch for PR 71625 to change braced array initializers
to STRING_CST in some cases, we need to be ready for STRING_CST with types
that are changed by tsubst.  fold_convert doesn't know how to deal with
STRING_CST, which is reasonable; we really shouldn't expect it to here.  So
let's handle STRING_CST separately.

	PR c++/90966
	* pt.c (tsubst_copy) [STRING_CST]: Don't use fold_convert.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d8fc647120e0f74f7ee670ee5e3d142932b374be..9b1e506c8ccc55980d2f7c81d9f0eb98e10cbfd0 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,5 +1,8 @@
 2020-01-28  Jason Merrill  <jason@redhat.com>
 
+       PR c++/90966
+       * pt.c (tsubst_copy) [STRING_CST]: Don't use fold_convert.
+
        PR c++/93279 - ICE with lambda in member operator.
        * name-lookup.c (maybe_save_operator_binding): Don't remember
        class-scope bindings.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 692005b148ab147784125140853fbd38ef0c1505..c7245efa2b2680f4213dffc66b00bec156ab2939 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -16187,7 +16187,6 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 
     case INTEGER_CST:
     case REAL_CST:
-    case STRING_CST:
     case COMPLEX_CST:
       {
        /* Instantiate any typedefs in the type.  */
@@ -16197,6 +16196,18 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
        return r;
       }
 
+    case STRING_CST:
+      {
+       tree type = tsubst (TREE_TYPE (t), args, complain, in_decl);
+       r = t;
+       if (type != TREE_TYPE (t))
+         {
+           r = copy_node (t);
+           TREE_TYPE (r) = type;
+         }
+       return r;
+      }
+
     case PTRMEM_CST:
       /* These can sometimes show up in a partial instantiation, but never
         involve template parms.  */

diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-array10.C b/gcc/testsuite/g++.dg/cpp0x/initlist-array10.C
new file mode 100644 (file)
index 0000000..fb9e136
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-array10.C
@@ -0,0 +1,14 @@
+// PR c++/90966
+// { dg-do compile { target c++11 } }
+
+template<typename I>
+void f()
+{
+  using S = signed char;
+  constexpr const S v[]{0};
+}
+
+int main()
+{
+  f<int>();
+}