[PATCH] PR fortran/91650 -- BOZ cannot be an output IO list item

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

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The attached patch has been tested on x86_64-*-freebsd.
I plan to commit this patch tomorrow if there are no objections.

A BOZ literal constant cannot appear in an output IO list.  By
default, the patch will generate an error.  The -fallow-invalid-boz
option can be used to degrade the error into an warning.  The
resulting executable then has historic broken gfortran behavior.

2019-09-03  Steven G. Kargl  <kargl@gcvc.gnu.org>

	PR fortran/91650
	* io.c (match_io_element):  An output IO list item cannot be a BOZ.

2019-09-03  Steven G. Kargl  <kargl@gcvc.gnu.org>

	PR fortran/91650
	* gfortran.dg/pr91650_1.f90: New test.
	* gfortran.dg/pr91650_2.f90: Ditto.

-- 
Steve

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Index: gcc/fortran/io.c
===================================================================
--- gcc/fortran/io.c	(revision 275343)
+++ gcc/fortran/io.c	(working copy)
@@ -3675,6 +3675,15 @@ match_io_element (io_kind k, gfc_code **cpp)
       if (m == MATCH_NO)
 	gfc_error ("Expected expression in %s statement at %C",
 		   io_kind_name (k));
+
+      if (m == MATCH_YES && expr->ts.type == BT_BOZ)
+	{
+	  if (gfc_invalid_boz ("BOZ literal constant at %L cannot appear in "
+				"an output IO list", &gfc_current_locus))
+	    return MATCH_ERROR;
+	  if (!gfc_boz2int (expr, gfc_max_integer_kind))
+	    return MATCH_ERROR;
+	};
     }
 
   if (m == MATCH_YES && k == M_READ && gfc_check_do_variable (expr->symtree))
Index: gcc/testsuite/gfortran.dg/pr91650_1.f90
===================================================================
--- gcc/testsuite/gfortran.dg/pr91650_1.f90	(nonexistent)
+++ gcc/testsuite/gfortran.dg/pr91650_1.f90	(working copy)
@@ -0,0 +1,8 @@
+! { dg-do compile }
+! PR fortran/91650
+! Code contributed by Gerhard Steinmetz.
+program p
+   print *, b'10110' ! { dg-error "cannot appear in an output IO list" }
+   print *, o'10110' ! { dg-error "cannot appear in an output IO list" }
+   print *, z'10110' ! { dg-error "cannot appear in an output IO list" }
+end
Index: gcc/testsuite/gfortran.dg/pr91650_2.f90
===================================================================
--- gcc/testsuite/gfortran.dg/pr91650_2.f90	(nonexistent)
+++ gcc/testsuite/gfortran.dg/pr91650_2.f90	(working copy)
@@ -0,0 +1,13 @@
+! { dg-do compile }
+! { dg-options "-fallow-invalid-boz" }
+! PR fortran/91650
+! Code contributed by Gerhard Steinmetz.
+program p
+   character(len=60) str
+   write(str,*) b'10110' ! { dg-warning "cannot appear in an output IO list" }
+   if (trim(adjustl(str)) /= '22') stop 1
+   write(str,*) o'10110' ! { dg-warning "cannot appear in an output IO list" }
+   if (trim(adjustl(str)) /= '4168') stop 2
+   write(str,*) z'10110' ! { dg-warning "cannot appear in an output IO list" }
+   if (trim(adjustl(str)) /= '65808') stop 3
+end