typespec in forall and implied-do

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

F2008 introduced the inclusion of a typespec in a forall
statement, and thn F2018 a typespec was allowed in an
implied-do.  There may even be a few bug reports.

Consider,

   program foo

      implicit none

      integer, parameter :: n = 9
      integer a(n,n), b(n), j

      b = [(k, integer :: k = 1, n)] 
      if (any(b /= [1, 2, 3, 4, 5, 6, 7, 8, 9])) stop 1
 
      a = 0
      forall (integer :: i = 1:n) a(i,i) = b(i)
      do j = 1, n
         if (a(j,j) /= b(j)) stop j
      end do

      call bar

      contains

         subroutine bar
            real x(n)
            x = [(sqrt(real(p)), integer :: p = 1, n)]
            print '(*(F8.2,1X))', x
         end subroutine bar

   end program foo

This patch allows the above to compile and execute.
It has only had some light testing, and I do not know
if nested forall and implied-do loops do work.  Feel
free to commit as I cannot.

diff --git a/gcc/fortran/match.cc b/gcc/fortran/match.cc
index 8b8b6e79c8b..3fd2a80caad 100644
--- a/gcc/fortran/match.cc
+++ b/gcc/fortran/match.cc
@@ -968,9 +968,39 @@ gfc_match_iterator (gfc_iterator *iter, int init_flag)
   gfc_expr *var, *e1, *e2, *e3;
   locus start;
   match m;
+  gfc_typespec ts;
+  bool seen_ts;
 
   e1 = e2 = e3 = NULL;
 
+  /* Match an optional "integer ::" type-spec. */
+  start = gfc_current_locus;
+  seen_ts = false;
+  gfc_clear_ts (&ts);
+  m = gfc_match_type_spec (&ts);
+  if (m == MATCH_YES)
+    {
+      seen_ts = (gfc_match (" ::") == MATCH_YES);
+
+      if (seen_ts)
+	{
+	  if (!gfc_notify_std (GFC_STD_F2018, "Optional type-spec "
+			       "included in implied-do loop at %C"))
+	    goto cleanup;
+
+	  if (ts.type != BT_INTEGER)
+	    {
+	      gfc_error ("Type in type-spec at %C shall be INTEGER");
+	      goto cleanup;
+	    }
+	}
+    }
+  else if (m == MATCH_ERROR)
+    goto cleanup;
+
+  if (!seen_ts)
+    gfc_current_locus = start;
+
   /* Match the start of an iterator without affecting the symbol table.  */
 
   start = gfc_current_locus;
@@ -984,6 +1014,14 @@ gfc_match_iterator (gfc_iterator *iter, int init_flag)
   if (m != MATCH_YES)
     return MATCH_NO;
 
+  if (seen_ts && var->ts.type == BT_UNKNOWN)
+    {
+      var->ts.type = ts.type;
+      var->ts.kind = ts.kind;
+      var->symtree->n.sym->ts.type = ts.type;
+      var->symtree->n.sym->ts.kind = ts.kind;
+    }
+
   if (var->symtree->n.sym->attr.dimension)
     {
       gfc_error ("Loop variable at %C cannot be an array");
@@ -2396,6 +2434,9 @@ match_forall_header (gfc_forall_iterator **phead, gfc_expr **mask)
   gfc_forall_iterator *head, *tail, *new_iter;
   gfc_expr *msk;
   match m;
+  locus start;
+  gfc_typespec ts;
+  bool seen_ts;
 
   gfc_gobble_whitespace ();
 
@@ -2405,12 +2446,48 @@ match_forall_header (gfc_forall_iterator **phead, gfc_expr **mask)
   if (gfc_match_char ('(') != MATCH_YES)
     return MATCH_NO;
 
+  /* Match an optional "integer ::" type-spec. */
+  start = gfc_current_locus;
+  seen_ts = false;
+  gfc_clear_ts (&ts);
+  m = gfc_match_type_spec (&ts);
+  if (m == MATCH_YES)
+    {
+      seen_ts = (gfc_match (" ::") == MATCH_YES);
+
+      if (seen_ts)
+	{
+	  if (!gfc_notify_std (GFC_STD_F2008, "Optional type-spec "
+			       "included in FORALL at %C"))
+	    goto cleanup;
+
+	  if (ts.type != BT_INTEGER)
+	    {
+	      gfc_error ("Type in type-spec at %C shall be INTEGER");
+	      goto cleanup;
+	    }
+	}
+    }
+  else if (m == MATCH_ERROR)
+    goto cleanup;
+
+  if (!seen_ts)
+    gfc_current_locus = start;
+
   m = match_forall_iterator (&new_iter);
   if (m == MATCH_ERROR)
     goto cleanup;
   if (m == MATCH_NO)
     goto syntax;
 
+  if (seen_ts && new_iter->var->ts.type == BT_UNKNOWN)
+    {
+      new_iter->var->ts.type = ts.type;
+      new_iter->var->ts.kind = ts.kind;
+      new_iter->var->symtree->n.sym->ts.type = ts.type;
+      new_iter->var->symtree->n.sym->ts.kind = ts.kind;
+    }
+
   head = tail = new_iter;
 
   for (;;)