[C++ Patch] Improve grok_array_decl location

[Paolo Carlini]

Hi,

for this error message about the types involved in array subscripting I 
think we can exploit the available location argument and point to the 
open square bracket instead of simply using input_location. Tested 
x86_64-linux.

Thanks, Paolo Carlini.

////////////////////////

/cp
2019-08-13  Paolo Carlini  <paolo.carl...@oracle.com>

        * decl2.c (grok_array_decl): Use the location of the open square
        bracket in error message about invalid types.

/testsuite
2019-08-13  Paolo Carlini  <paolo.carl...@oracle.com>

        * g++.dg/conversion/simd4.C: Test locations.
Index: cp/decl2.c
===================================================================
--- cp/decl2.c  (revision 274330)
+++ cp/decl2.c  (working copy)
@@ -434,8 +434,8 @@ grok_array_decl (location_t loc, tree array_expr,
        array_expr = p2, index_exp = i1;
       else
        {
-         error ("invalid types %<%T[%T]%> for array subscript",
-                type, TREE_TYPE (index_exp));
+         error_at (loc, "invalid types %<%T[%T]%> for array subscript",
+                   type, TREE_TYPE (index_exp));
          return error_mark_node;
        }
 
Index: testsuite/g++.dg/conversion/simd4.C
===================================================================
--- testsuite/g++.dg/conversion/simd4.C (revision 274330)
+++ testsuite/g++.dg/conversion/simd4.C (working copy)
@@ -12,13 +12,13 @@ void
 foo ()
 {
   b[t];
-  b[u];                // { dg-error "invalid types" }
-  b[v];                // { dg-error "invalid types" }
-  b[w];                // { dg-error "invalid types" }
+  b[u];                // { dg-error "4:invalid types" }
+  b[v];                // { dg-error "4:invalid types" }
+  b[w];                // { dg-error "4:invalid types" }
   t[b];
-  u[b];                // { dg-error "invalid types" }
-  v[b];                // { dg-error "invalid types" }
-  w[b];                // { dg-error "invalid types" }
+  u[b];                // { dg-error "4:invalid types" }
+  v[b];                // { dg-error "4:invalid types" }
+  w[b];                // { dg-error "4:invalid types" }
   new int[t];
   new int[u];  // { dg-error "new-declarator must have integral" }
   new int[v];  // { dg-error "new-declarator must have integral" }