re PR fortran/89103 (Allow blank format items in format strings)

2019-06-19  Jim MacArthur  <jim.macarthur@codethink.co.uk>
	    Mark Eggleston  <mark.eggleston@codethink.com>

	PR fortran/89103
	* gfortran.texi: Add -fdec-blank-format-item
	* invoke.texi: Add option to list of options.
	* invoke.texi: Add to section on Commas in FORMAT specifications.
	* io.c (check_format): At FMT_RPAREN goto finished if
	-fdec-blank-format-item otherwise set error string.
	* lang.opt: Add new option.
	* options.c (set_dec_flags): Add SET_BITFLAG for
	flag_dec_format_defaults.

	* gfortran.dg/dec_format_empty_item_1.f: New test.
	* gfortran.dg/dec_format_empty_item_2.f: New test.
	* gfortran.dg/dec_format_empty_item_3.f: New test.

Co-Authored-By: Mark Eggleston <mark.eggleston@codethink.com>

From-SVN: r272467

gcc/fortran/ChangeLog

+2019-06-19  Jim MacArthur  <jim.macarthur@codethink.co.uk>
+	    Mark Eggleston  <mark.eggleston@codethink.com>
+	
+	PR fortran/89103
+	* gfortran.texi: Add -fdec-blank-format-item
+	* invoke.texi: Add option to list of options.
+	* invoke.texi: Add to section on Commas in FORMAT specifications.
+	* io.c (check_format): At FMT_RPAREN goto finished if
+	-fdec-blank-format-item otherwise set error string.
+	* lang.opt: Add new option.
+	* options.c (set_dec_flags): Add SET_BITFLAG for
+	flag_dec_format_defaults.
+
 2019-06-18  Julian Brown  <julian@codesourcery.com>
 
 	PR fortran/90921

gcc/fortran/gfortran.texi

@@ -1761,11 +1761,16 @@ When omitted, the count is implicitly assumed to be one.
 
 To support legacy codes, GNU Fortran allows the comma separator
 to be omitted immediately before and after character string edit
-descriptors in @code{FORMAT} statements.
+descriptors in @code{FORMAT} statements.  A comma with no following format
+decriptor is permited if the @option{-fdec-blank-format-item} is given on
+the command line. This is considered non-conforming code and is
+discouraged.
 
 @smallexample
        PRINT 10, 2, 3
 10     FORMAT ('FOO='I1' BAR='I2)
+       print 20, 5, 6
+20     FORMAT (I3, I3,)
 @end smallexample
 
 

gcc/fortran/invoke.texi

@@ -119,10 +119,10 @@ by type.  Explanations are in the following sections.
 @gccoptlist{-fall-intrinsics -fbackslash -fcray-pointer -fd-lines-as-code @gol
 -fd-lines-as-comments -fdec -fdec-structure -fdec-intrinsic-ints @gol
 -fdec-static -fdec-math -fdec-include -fdec-format-defaults @gol
--fdefault-double-8 -fdefault-integer-8 -fdefault-real-8 -fdefault-real-10 @gol
--fdefault-real-16 -fdollar-ok -ffixed-line-length-@var{n} @gol
--ffixed-line-length-none -fpad-source -ffree-form @gol
--ffree-line-length-@var{n} -ffree-line-length-none @gol
+-fdec-blank-format-item -fdefault-double-8 -fdefault-integer-8 @gol
+-fdefault-real-8 -fdefault-real-10 -fdefault-real-16 -fdollar-ok @gol
+-ffixed-line-length-@var{n} -ffixed-line-length-none -fpad-source @gol
+-ffree-form -ffree-line-length-@var{n} -ffree-line-length-none @gol
 -fimplicit-none -finteger-4-integer-8 -fmax-identifier-length @gol
 -fmodule-private -ffixed-form -fno-range-check -fopenacc -fopenmp @gol
 -freal-4-real-10 -freal-4-real-16 -freal-4-real-8 -freal-8-real-10 @gol
@@ -289,6 +289,11 @@ be on a single line and can use line continuations.
 Enable format specifiers F, G and I to be used without width specifiers,
 default widths will be used instead.
 
+@item -fdec-blank-format-item
+@opindex @code{fdec-blank-format-item}
+Enable a blank format item at the end of a format specification i.e. nothing
+following the final comma.
+
 @item -fdollar-ok
 @opindex @code{fdollar-ok}
 @cindex @code{$}

gcc/fortran/io.c

@@ -762,6 +762,15 @@ format_item_1:
       error = unexpected_end;
       goto syntax;
 
+    case FMT_RPAREN:
+      if (flag_dec_blank_format_item)
+	goto finished;
+      else
+	{
+	  error = G_("Missing item in format string at %L");
+	  goto syntax;
+	}
+
     default:
       error = unexpected_element;
       goto syntax;

gcc/fortran/lang.opt

@@ -444,6 +444,10 @@ fdec
 Fortran Var(flag_dec)
 Enable all DEC language extensions.
 
+fdec-blank-format-item
+Fortran Var(flag_dec_blank_format_item)
+Enable the use of blank format items in format strings.
+
 fdec-include
 Fortran Var(flag_dec_include)
 Enable legacy parsing of INCLUDE as statement.

gcc/fortran/options.c

@@ -75,6 +75,7 @@ set_dec_flags (int value)
   SET_BITFLAG (flag_dec_math, value, value);
   SET_BITFLAG (flag_dec_include, value, value);
   SET_BITFLAG (flag_dec_format_defaults, value, value);
+  SET_BITFLAG (flag_dec_blank_format_item, value, value);
 }
 
 /* Finalize DEC flags.  */

gcc/testsuite/ChangeLog

+2019-06-19  Jim MacArthur  <jim.macarthur@codethink.co.uk>
+	    Mark Eggleston  <mark.eggleston@codethink.com>
+
+	PR fortran/89103
+	* gfortran.dg/dec_format_empty_item_1.f: New test.
+	* gfortran.dg/dec_format_empty_item_2.f: New test.
+	* gfortran.dg/dec_format_empty_item_3.f: New test. 
+
 2019-06-19  Kugan Vivekanandarajah  <kugan.vivekanandarajah@linaro.org>
 
 	* gcc.target/aarch64/pr88834.c: Move from here...

gcc/testsuite/gfortran.dg/dec_format_empty_item_1.f

+! { dg-do run }
+! { dg-options "-fdec" }
+!
+! Test blank/empty format items in format string
+!
+! Test case contributed by Jim MacArthur <jim.macarthur@codethink.co.uk>
+! Modified by Mark Eggleston <mark.eggleston@codethink.com>
+!
+        PROGRAM blank_format_items
+          INTEGER A/0/
+
+          OPEN(1, status="scratch")
+          WRITE(1, 10) 100
+          REWIND(1)
+          READ(1, 10) A
+          IF (a.NE.100) STOP 1
+          PRINT 10, A
+10        FORMAT( I5,)
+        END

gcc/testsuite/gfortran.dg/dec_format_empty_item_2.f

+! { dg-do run }
+! { dg-options "-fdec-blank-format-item" }
+!
+! Test blank/empty format items in format string
+!
+! Test case contributed by Jim MacArthur <jim.macarthur@codethink.co.uk>
+! Modified by Mark Eggleston <mark.eggleston@codethink.com>
+!
+        PROGRAM blank_format_items
+          INTEGER A/0/
+
+          OPEN(1, status="scratch")
+          WRITE(1, 10) 100
+          REWIND(1)
+          READ(1, 10) A
+          IF (a.NE.100) STOP 1
+          PRINT 10, A
+10        FORMAT( I5,)
+        END

gcc/testsuite/gfortran.dg/dec_format_empty_item_3.f

+! { dg-do compile }
+! { dg-options "-fdec -fno-dec-blank-format-item" }
+!
+! Test blank/empty format items in format string
+!
+! Test case contributed by Jim MacArthur <jim.macarthur@codethink.co.uk>
+! Modified by Mark Eggleston <mark.eggleston@codethink.com>
+!
+        PROGRAM blank_format_items
+          INTEGER A/0/
+
+          OPEN(1, status="scratch")
+          WRITE(1, 10) 100 ! { dg-error "FORMAT label 10 at" }
+          REWIND(1)
+          READ(1, 10) A ! { dg-error "FORMAT label 10 at" }
+          IF (a.NE.100) STOP 1
+          PRINT 10, A ! { dg-error "FORMAT label 10 at" }
+ 10       FORMAT( I5,) ! { dg-error "Missing item" }
+        END