Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(revision 164550)
+++ gcc/fortran/gfortran.h	(working copy)
@@ -2111,6 +2111,13 @@ typedef struct gfc_code
     gfc_inquire *inquire;
     gfc_wait *wait;
     gfc_dt *dt;
+
+    /* For transfer, store whether this is reading or writing.  */
+    /* XXX: Can we in some other way determine in resolve_transfer whether
+       we are reading or writing?  Possibly via global variables, but that
+       does not feel right.  */
+    io_kind transfer_io_kind;
+
     gfc_forall_iterator *forall_iterator;
     struct gfc_code *which_construct;
     int stop_code;
@@ -2827,7 +2834,7 @@ gfc_try gfc_resolve_filepos (gfc_filepos
 void gfc_free_inquire (gfc_inquire *);
 gfc_try gfc_resolve_inquire (gfc_inquire *);
 void gfc_free_dt (gfc_dt *);
-gfc_try gfc_resolve_dt (gfc_dt *, locus *);
+gfc_try gfc_resolve_dt (gfc_dt *, locus *, gfc_exec_op);
 void gfc_free_wait (gfc_wait *);
 gfc_try gfc_resolve_wait (gfc_wait *);
 
Index: gcc/fortran/io.c
===================================================================
--- gcc/fortran/io.c	(revision 164549)
+++ gcc/fortran/io.c	(working copy)
@@ -1505,13 +1505,31 @@ resolve_tag (const io_tag *tag, gfc_expr
 	return FAILURE;
     }
 
+  if (tag == &tag_newunit)
+    {
+      if (gfc_notify_std (GFC_STD_F2008, "Fortran 2008: NEWUNIT specifier"
+			  " at %L", &e->where) == FAILURE)
+	return FAILURE;
+    }
+
+  /* NEWUNIT, IOSTAT, SIZE and IOMSG are variable definition contexts.  */
+  if (tag == &tag_newunit || tag == &tag_iostat
+      || tag == &tag_size || tag == &tag_iomsg)
+    {
+      char context[64];
+
+      sprintf (context, _("%s tag"), tag->name);
+      if (gfc_check_vardef_context (e, false, context) == FAILURE)
+	return FAILURE;
+    }
+  
   if (tag == &tag_convert)
     {
       if (gfc_notify_std (GFC_STD_GNU, "Extension: CONVERT tag at %L",
 			  &e->where) == FAILURE)
 	return FAILURE;
     }
-  
+
   return SUCCESS;
 }
 
@@ -2716,10 +2734,16 @@ gfc_free_dt (gfc_dt *dt)
 /* Resolve everything in a gfc_dt structure.  */
 
 gfc_try
-gfc_resolve_dt (gfc_dt *dt, locus *loc)
+gfc_resolve_dt (gfc_dt *dt, locus *loc, gfc_exec_op op)
 {
   gfc_expr *e;
 
+  /* XXX: Is there a way to get whether we are READing or WRITing without
+     this new extra argument?  Note that below there is code doing something
+     like that based on extra_comma, but it does not really look like
+     a general method to me.  What if extra_comma is not present?  */
+  gcc_assert (op == EXEC_READ || op == EXEC_WRITE);
+
   RESOLVE_TAG (&tag_format, dt->format_expr);
   RESOLVE_TAG (&tag_rec, dt->rec);
   RESOLVE_TAG (&tag_spos, dt->pos);
@@ -2790,6 +2814,12 @@ gfc_resolve_dt (gfc_dt *dt, locus *loc)
 	  gfc_error ("Internal unit with vector subscript at %L", &e->where);
 	  return FAILURE;
 	}
+
+      /* If we are writing, make sure the internal unit can be changed.  */
+      if (op == EXEC_WRITE
+	  && gfc_check_vardef_context (e, false, _("internal unit in WRITE"))
+	       == FAILURE)
+	return FAILURE;
     }
 
   if (e->rank && e->ts.type != BT_CHARACTER)
@@ -2801,10 +2831,36 @@ gfc_resolve_dt (gfc_dt *dt, locus *loc)
   if (e->expr_type == EXPR_CONSTANT && e->ts.type == BT_INTEGER
       && mpz_sgn (e->value.integer) < 0)
     {
-      gfc_error ("UNIT number in statement at %L must be non-negative", &e->where);
+      gfc_error ("UNIT number in statement at %L must be non-negative",
+		 &e->where);
       return FAILURE;
     }
 
+  /* If we are reading and have a namelist, check that all namelist symbols
+     can appear in a variable definition context.  */
+  if (op == EXEC_READ && dt->namelist)
+    {
+      gfc_namelist* n;
+      for (n = dt->namelist->namelist; n; n = n->next)
+	{
+	  gfc_expr* e;
+	  gfc_try t;
+
+	  e = gfc_get_variable_expr (gfc_find_sym_in_symtree (n->sym));
+	  t = gfc_check_vardef_context (e, false, NULL);
+	  gfc_free_expr (e);
+
+	  if (t == FAILURE)
+	    {
+	      gfc_error ("NAMELIST '%s' in READ statement at %L contains"
+			 " the symbol '%s' which may not appear in a"
+			 " variable definition context",
+			 dt->namelist->name, loc, n->sym->name);
+	      return FAILURE;
+	    }
+	}
+    }
+
   if (dt->extra_comma
       && gfc_notify_std (GFC_STD_GNU, "Extension: Comma before i/o "
 			 "item list at %L", &dt->extra_comma->where) == FAILURE)
@@ -2854,6 +2910,7 @@ gfc_resolve_dt (gfc_dt *dt, locus *loc)
 		 &dt->format_label->where);
       return FAILURE;
     }
+
   return SUCCESS;
 }
 
@@ -3012,50 +3069,8 @@ match_io_element (io_kind k, gfc_code **
 		   io_kind_name (k));
     }
 
-  if (m == MATCH_YES)
-    switch (k)
-      {
-      case M_READ:
-	if (expr->symtree->n.sym->attr.intent == INTENT_IN)
-	  {
-	    gfc_error ("Variable '%s' in input list at %C cannot be "
-		       "INTENT(IN)", expr->symtree->n.sym->name);
-	    m = MATCH_ERROR;
-	  }
-
-	if (gfc_pure (NULL)
-	    && gfc_impure_variable (expr->symtree->n.sym)
-	    && current_dt->io_unit
-	    && current_dt->io_unit->ts.type == BT_CHARACTER)
-	  {
-	    gfc_error ("Cannot read to variable '%s' in PURE procedure at %C",
-		       expr->symtree->n.sym->name);
-	    m = MATCH_ERROR;
-	  }
-
-	if (gfc_check_do_variable (expr->symtree))
-	  m = MATCH_ERROR;
-
-	break;
-
-      case M_WRITE:
-	if (current_dt->io_unit
-	    && current_dt->io_unit->ts.type == BT_CHARACTER
-	    && gfc_pure (NULL)
-	    && current_dt->io_unit->expr_type == EXPR_VARIABLE
-	    && gfc_impure_variable (current_dt->io_unit->symtree->n.sym))
-	  {
-	    gfc_error ("Cannot write to internal file unit '%s' at %C "
-		       "inside a PURE procedure",
-		       current_dt->io_unit->symtree->n.sym->name);
-	    m = MATCH_ERROR;
-	  }
-
-	break;
-
-      default:
-	break;
-      }
+  if (m == MATCH_YES && k == M_READ && gfc_check_do_variable (expr->symtree))
+    m = MATCH_ERROR;
 
   if (m != MATCH_YES)
     {
@@ -3066,6 +3081,7 @@ match_io_element (io_kind k, gfc_code **
   cp = gfc_get_code ();
   cp->op = EXEC_TRANSFER;
   cp->expr1 = expr;
+  cp->ext.transfer_io_kind = k;
 
   *cpp = cp;
   return MATCH_YES;
@@ -3973,41 +3989,54 @@ gfc_resolve_inquire (gfc_inquire *inquir
 {
   RESOLVE_TAG (&tag_unit, inquire->unit);
   RESOLVE_TAG (&tag_file, inquire->file);
-  RESOLVE_TAG (&tag_iomsg, inquire->iomsg);
-  RESOLVE_TAG (&tag_iostat, inquire->iostat);
-  RESOLVE_TAG (&tag_exist, inquire->exist);
-  RESOLVE_TAG (&tag_opened, inquire->opened);
-  RESOLVE_TAG (&tag_number, inquire->number);
-  RESOLVE_TAG (&tag_named, inquire->named);
-  RESOLVE_TAG (&tag_name, inquire->name);
-  RESOLVE_TAG (&tag_s_access, inquire->access);
-  RESOLVE_TAG (&tag_sequential, inquire->sequential);
-  RESOLVE_TAG (&tag_direct, inquire->direct);
-  RESOLVE_TAG (&tag_s_form, inquire->form);
-  RESOLVE_TAG (&tag_formatted, inquire->formatted);
-  RESOLVE_TAG (&tag_unformatted, inquire->unformatted);
-  RESOLVE_TAG (&tag_s_recl, inquire->recl);
-  RESOLVE_TAG (&tag_nextrec, inquire->nextrec);
-  RESOLVE_TAG (&tag_s_blank, inquire->blank);
-  RESOLVE_TAG (&tag_s_position, inquire->position);
-  RESOLVE_TAG (&tag_s_action, inquire->action);
-  RESOLVE_TAG (&tag_read, inquire->read);
-  RESOLVE_TAG (&tag_write, inquire->write);
-  RESOLVE_TAG (&tag_readwrite, inquire->readwrite);
-  RESOLVE_TAG (&tag_s_delim, inquire->delim);
-  RESOLVE_TAG (&tag_s_pad, inquire->pad);
-  RESOLVE_TAG (&tag_s_encoding, inquire->encoding);
-  RESOLVE_TAG (&tag_s_round, inquire->round);
-  RESOLVE_TAG (&tag_iolength, inquire->iolength);
-  RESOLVE_TAG (&tag_convert, inquire->convert);
-  RESOLVE_TAG (&tag_strm_out, inquire->strm_pos);
-  RESOLVE_TAG (&tag_s_async, inquire->asynchronous);
-  RESOLVE_TAG (&tag_s_sign, inquire->sign);
-  RESOLVE_TAG (&tag_s_round, inquire->round);
-  RESOLVE_TAG (&tag_pending, inquire->pending);
-  RESOLVE_TAG (&tag_size, inquire->size);
   RESOLVE_TAG (&tag_id, inquire->id);
 
+  /* For INQUIRE, all tags except FILE, ID and UNIT are variable definition
+     contexts.  Thus, use an extended RESOLVE_TAG macro for that.  */
+#define INQUIRE_RESOLVE_TAG(tag, expr) \
+  RESOLVE_TAG (tag, expr); \
+  if (expr) \
+    { \
+      char context[64]; \
+      sprintf (context, _("%s tag with INQUIRE"), (tag)->name); \
+      if (gfc_check_vardef_context ((expr), false, context) == FAILURE) \
+	return FAILURE; \
+    }
+  INQUIRE_RESOLVE_TAG (&tag_iomsg, inquire->iomsg);
+  INQUIRE_RESOLVE_TAG (&tag_iostat, inquire->iostat);
+  INQUIRE_RESOLVE_TAG (&tag_exist, inquire->exist);
+  INQUIRE_RESOLVE_TAG (&tag_opened, inquire->opened);
+  INQUIRE_RESOLVE_TAG (&tag_number, inquire->number);
+  INQUIRE_RESOLVE_TAG (&tag_named, inquire->named);
+  INQUIRE_RESOLVE_TAG (&tag_name, inquire->name);
+  INQUIRE_RESOLVE_TAG (&tag_s_access, inquire->access);
+  INQUIRE_RESOLVE_TAG (&tag_sequential, inquire->sequential);
+  INQUIRE_RESOLVE_TAG (&tag_direct, inquire->direct);
+  INQUIRE_RESOLVE_TAG (&tag_s_form, inquire->form);
+  INQUIRE_RESOLVE_TAG (&tag_formatted, inquire->formatted);
+  INQUIRE_RESOLVE_TAG (&tag_unformatted, inquire->unformatted);
+  INQUIRE_RESOLVE_TAG (&tag_s_recl, inquire->recl);
+  INQUIRE_RESOLVE_TAG (&tag_nextrec, inquire->nextrec);
+  INQUIRE_RESOLVE_TAG (&tag_s_blank, inquire->blank);
+  INQUIRE_RESOLVE_TAG (&tag_s_position, inquire->position);
+  INQUIRE_RESOLVE_TAG (&tag_s_action, inquire->action);
+  INQUIRE_RESOLVE_TAG (&tag_read, inquire->read);
+  INQUIRE_RESOLVE_TAG (&tag_write, inquire->write);
+  INQUIRE_RESOLVE_TAG (&tag_readwrite, inquire->readwrite);
+  INQUIRE_RESOLVE_TAG (&tag_s_delim, inquire->delim);
+  INQUIRE_RESOLVE_TAG (&tag_s_pad, inquire->pad);
+  INQUIRE_RESOLVE_TAG (&tag_s_encoding, inquire->encoding);
+  INQUIRE_RESOLVE_TAG (&tag_s_round, inquire->round);
+  INQUIRE_RESOLVE_TAG (&tag_iolength, inquire->iolength);
+  INQUIRE_RESOLVE_TAG (&tag_convert, inquire->convert);
+  INQUIRE_RESOLVE_TAG (&tag_strm_out, inquire->strm_pos);
+  INQUIRE_RESOLVE_TAG (&tag_s_async, inquire->asynchronous);
+  INQUIRE_RESOLVE_TAG (&tag_s_sign, inquire->sign);
+  INQUIRE_RESOLVE_TAG (&tag_s_round, inquire->round);
+  INQUIRE_RESOLVE_TAG (&tag_pending, inquire->pending);
+  INQUIRE_RESOLVE_TAG (&tag_size, inquire->size);
+#undef INQUIRE_RESOLVE_TAG
+
   if (gfc_reference_st_label (inquire->err, ST_LABEL_TARGET) == FAILURE)
     return FAILURE;
 
Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c	(revision 164550)
+++ gcc/fortran/resolve.c	(working copy)
@@ -7916,6 +7916,11 @@ resolve_transfer (gfc_code *code)
 		      && exp->expr_type != EXPR_FUNCTION))
     return;
 
+  /* If we are reading, the variable will be changed.  */
+  if (code->ext.transfer_io_kind == M_READ
+      && gfc_check_vardef_context (exp, false, _("item in READ")) == FAILURE)
+    return;
+
   sym = exp->symtree->n.sym;
   ts = &sym->ts;
 
@@ -9059,7 +9064,7 @@ resolve_code (gfc_code *code, gfc_namesp
 
 	case EXEC_READ:
 	case EXEC_WRITE:
-	  if (gfc_resolve_dt (code->ext.dt, &code->loc) == FAILURE)
+	  if (gfc_resolve_dt (code->ext.dt, &code->loc, code->op) == FAILURE)
 	    break;
 
 	  resolve_branch (code->ext.dt->err, code);
Index: gcc/testsuite/gfortran.dg/io_constraints_7.f03
===================================================================
--- gcc/testsuite/gfortran.dg/io_constraints_7.f03	(revision 0)
+++ gcc/testsuite/gfortran.dg/io_constraints_7.f03	(revision 0)
@@ -0,0 +1,37 @@
+! { dg-do compile }
+
+! PR fortran/45776
+! Variable definition context checks related to IO.
+
+! Contributed by Daniel Kraft, d@domob.eu.
+
+module m
+  implicit none
+  integer, protected :: a
+  character(len=128), protected :: msg
+end module m
+
+program main
+  use :: m
+  integer :: x
+  logical :: bool
+
+  write (*, iostat=a) 42 ! { dg-error "variable definition context" }
+  write (*, iomsg=msg) 42 ! { dg-error "variable definition context" }
+  read (*, '(I2)', advance='no', size=a) x ! { dg-error "variable definition context" }
+
+  ! These are ok.
+  inquire (unit=a)
+  inquire (file=msg, id=a, pending=bool)
+  inquire (file=msg)
+
+  ! These not, but list is not extensive.
+  inquire (unit=1, number=a) ! { dg-error "variable definition context" }
+  inquire (unit=1, encoding=msg) ! { dg-error "variable definition context" }
+  inquire (unit=1, formatted=msg) ! { dg-error "variable definition context" }
+
+  open (newunit=a, file="foo") ! { dg-error "variable definition context" }
+  close (unit=a)
+end program main
+
+! { dg-final { cleanup-modules "m" } }
Index: gcc/testsuite/gfortran.dg/newunit_2.f90
===================================================================
--- gcc/testsuite/gfortran.dg/newunit_2.f90	(revision 0)
+++ gcc/testsuite/gfortran.dg/newunit_2.f90	(revision 0)
@@ -0,0 +1,15 @@
+! { dg-do compile }
+! { dg-options "-std=f95" }
+
+! PR40008 F2008: Add NEWUNIT= for OPEN statement 
+! Check for rejection with pre-F2008 standard.
+
+! Contributed by Daniel Kraft, d@domob.eu.
+
+program main
+  character(len=25) :: str
+  integer(1) :: myunit
+
+  open (newunit=myunit, file="some_file") ! { dg-error "Fortran 2008" }
+  close (unit=myunit)
+end program main
Index: gcc/testsuite/gfortran.dg/io_constraints_6.f03
===================================================================
--- gcc/testsuite/gfortran.dg/io_constraints_6.f03	(revision 0)
+++ gcc/testsuite/gfortran.dg/io_constraints_6.f03	(revision 0)
@@ -0,0 +1,40 @@
+! { dg-do compile }
+
+! PR fortran/45776
+! Variable definition context checks related to IO.
+
+! Contributed by Daniel Kraft, d@domob.eu.
+
+module m
+  implicit none
+
+  integer, protected :: a
+  character(len=128), protected :: str
+end module m
+
+program main
+  use :: m
+  integer, parameter :: b = 42
+  integer :: x
+  character(len=128) :: myStr
+
+  namelist /definable/ x, myStr
+  namelist /undefinable/ x, a
+
+  ! These are invalid.
+  read (myStr, *) a ! { dg-error "variable definition context" }
+  read (myStr, *) x, b ! { dg-error "variable definition context" }
+  write (str, *) 5 ! { dg-error "variable definition context" }
+  read (*, nml=undefinable) ! { dg-error "contains the symbol 'a' which may not" }
+
+  ! These are ok.
+  read (str, *) x
+  write (myStr, *) a
+  write (myStr, *) b
+  print *, a, b
+  write (*, nml=undefinable)
+  read (*, nml=definable)
+  write (*, nml=definable)
+end program main
+
+! { dg-final { cleanup-modules "m" } }
