DEC comparisons - allow Hollerith constants in comparisons.

The -fdec option enables the use of Hollerith comparisons in comparisons
with INTEGER, COMPLEX, REAL and CHARACTER expressions.

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

	* gfortran.texi: Update Hollerith constants support for character types
	and use in comparisons.
	* invoke.texi: Tidy up list of options. Update description of
	-fdec-char-conversions.
	* resolve.c (is_character_based): New.
	(Convert_hollerith_to_character): New.  (convert_to_numeric): New.
	(resolve_operator): If both sides are character based and -fdec is
	enabled convert Hollerith to character. If an operand is Hollerith, the
	other is numeric and -fdec is enabled convert to numeric.
	(resolve_ordinary_assign): Add check for -fdec-char-conversions for
	assignment of character literals.

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

	* gfortran.dg/dec-comparison-character_1.f90: New test.
	* gfortran.dg/dec-comparison-character_2.f90: New test.
	* gfortran.dg/dec-comparison-character_3.f90: New test.
	* gfortran.dg/dec-comparison-complex_1.f90: New test.
	* gfortran.dg/dec-comparison-complex_2.f90: New test.
	* gfortran.dg/dec-comparison-complex_3.f90: New test.
	* gfortran.dg/dec-comparison-int_1.f90: New test.
	* gfortran.dg/dec-comparison-int_2.f90: New test.
	* gfortran.dg/dec-comparison-int_3.f90: New test.
	* gfortran.dg/dec-comparison-real_1.f90: New test.
	* gfortran.dg/dec-comparison-real_2.f90: New test.
	* gfortran.dg/dec-comparison-real_3.f90: New test.
	* gfortran.dg/dec-comparison.f90: New test.


Co-Authored-By: Jim MacArthur <jim.macarthur@codethink.co.uk>

From-SVN: r278674

4 files changed, 101 insertions, 24 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 5607724..95e2213 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,4 +1,17 @@
-2019-11-20  Janne Blomqvist  <jb@gcc.gnu.org>
+2019-11-25  Mark Eggleston  <mark.eggleston@codethink.com>
+	    Jim MacArthur  <jim.macarthur@codethink.co.uk>
+
+	* gfortran.texi: Update Hollerith constants support for character types
+	and use in comparisons.
+	* invoke.texi: Tidy up list of options. Update description of
+	-fdec-char-conversions.
+	* resolve.c (is_character_based): New.
+	(Convert_hollerith_to_character): New.  (convert_to_numeric): New.
+	(resolve_operator): If both sides are character based and -fdec is
+	enabled convert Hollerith to character. If an operand is Hollerith, the
+	other is numeric and -fdec is enabled convert to numeric.
+	(resolve_ordinary_assign): Add check for -fdec-char-conversions for
+	assignment of character literals.2019-11-20  Janne Blomqvist  <jb@gcc.gnu.org>
 
 	PR fortran/92463
 	Revert r269139
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi
index a34ac5a..96be58b 100644
--- a/gcc/fortran/gfortran.texi
+++ b/gcc/fortran/gfortran.texi
@@ -1916,14 +1916,14 @@ in I/O operations.
 @subsection Hollerith constants support
 @cindex Hollerith constants
 
-GNU Fortran supports Hollerith constants in assignments, function
-arguments, and @code{DATA} statements.  A Hollerith constant is written
-as a string of characters preceded by an integer constant indicating the
-character count, and the letter @code{H} or @code{h}, and stored in
-bytewise fashion in a numeric (@code{INTEGER}, @code{REAL}, or
-@code{COMPLEX}) or @code{LOGICAL} variable.  The constant will be padded
-with spaces or truncated to fit the size of the variable in which it is
-stored.
+GNU Fortran supports Hollerith constants in assignments, @code{DATA}
+statements, function and subroutine arguments. A Hollerith constant is
+written as a string of characters preceded by an integer constant 
+indicating the character count, and the letter @code{H} or
+@code{h}, and stored in bytewise fashion in a numeric (@code{INTEGER},
+@code{REAL}, or @code{COMPLEX}), @code{LOGICAL} or @code{CHARACTER} variable.
+The constant will be padded with spaces or truncated to fit the size of
+the variable in which it is stored.
 
 Examples of valid uses of Hollerith constants:
 @smallexample
@@ -1951,10 +1951,22 @@ case where the intent is specifically to initialize a numeric variable
 with a given byte sequence.  In these cases, the same result can be
 obtained by using the @code{TRANSFER} statement, as in this example.
 @smallexample
-      INTEGER(KIND=4) :: a
-      a = TRANSFER ("abcd", a)     ! equivalent to: a = 4Habcd
+      integer(kind=4) :: a
+      a = transfer ("abcd", a)     ! equivalent to: a = 4Habcd
 @end smallexample
 
+The use of the @option{-fdec} option extends support of Hollerith constants
+to comparisons:
+@smallexample
+      integer*4 a
+      a = 4hABCD
+      if (a .ne. 4habcd) then
+        write(*,*) "no match"
+      end if
+@end smallexample
+
+Supported types are numeric (@code{INTEGER}, @code{REAL}, or @code{COMPLEX}),
+and @code{CHARACTER}.
 
 @node Character conversion
 @subsection Character conversion
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index 46ee3c9..0bc054f 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -117,17 +117,17 @@ by type.  Explanations are in the following sections.
 @item Fortran Language Options
 @xref{Fortran Dialect Options,,Options controlling Fortran dialect}.
 @gccoptlist{-fall-intrinsics -fallow-argument-mismatch -fallow-invalid-boz @gol
--fbackslash -fcray-pointer -fd-lines-as-code -fd-lines-as-comments -fdec @gol
--fdec-char-conversions -fdec-structure -fdec-intrinsic-ints -fdec-static @gol
--fdec-math -fdec-include -fdec-format-defaults -fdec-blank-format-item @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 -fimplicit-none @gol
--finteger-4-integer-8 -fmax-identifier-length -fmodule-private @gol
--ffixed-form -fno-range-check -fopenacc -fopenmp -freal-4-real-10 @gol
--freal-4-real-16 -freal-4-real-8 -freal-8-real-10 -freal-8-real-16 @gol
--freal-8-real-4 -std=@var{std} -ftest-forall-temp
+-fbackslash -fcray-pointer -fd-lines-as-code -fd-lines-as-comments @gol
+-fdec -fdec-char-conversions -fdec-structure -fdec-intrinsic-ints @gol
+-fdec-static -fdec-math -fdec-include -fdec-format-defaults @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
+-freal-8-real-16 -freal-8-real-4 -std=@var{std} -ftest-forall-temp
 }
 
 @item Preprocessing Options
@@ -283,7 +283,7 @@ If @option{-fd-lines-as-code}/@option{-fd-lines-as-comments} are unset, then
 
 @item -fdec-char-conversions
 @opindex @code{fdec-char-conversions}
-Enable the use of character literals in assignments and data statements
+Enable the use of character literals in assignments and @code{DATA} statements
 for non-character variables.
 
 @item -fdec-structure
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 2371a9e..278dad3 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -3900,6 +3900,42 @@ impure_function_callback (gfc_expr **e, int *walk_subtrees ATTRIBUTE_UNUSED,
   return 0;
 }
 
+/* Return true if TYPE is character based, false otherwise.  */
+
+static int
+is_character_based (bt type)
+{
+  return type == BT_CHARACTER || type == BT_HOLLERITH;
+}
+
+
+/* If expression is a hollerith, convert it to character and issue a warning
+   for the conversion.  */
+
+static void
+convert_hollerith_to_character (gfc_expr *e)
+{
+  if (e->ts.type == BT_HOLLERITH)
+    {
+      gfc_typespec t;
+      gfc_clear_ts (&t);
+      t.type = BT_CHARACTER;
+      t.kind = e->ts.kind;
+      gfc_convert_type_warn (e, &t, 2, 1);
+    }
+}
+
+/* Convert to numeric and issue a warning for the conversion.  */
+
+static void
+convert_to_numeric (gfc_expr *a, gfc_expr *b)
+{
+  gfc_typespec t;
+  gfc_clear_ts (&t);
+  t.type = b->ts.type;
+  t.kind = b->ts.kind;
+  gfc_convert_type_warn (a, &t, 2, 1);
+}
 
 /* Resolve an operator expression node.  This can involve replacing the
    operation with a user defined function call.  */
@@ -4100,6 +4136,15 @@ resolve_operator (gfc_expr *e)
     case INTRINSIC_EQ_OS:
     case INTRINSIC_NE:
     case INTRINSIC_NE_OS:
+
+      if (flag_dec
+	  && is_character_based (op1->ts.type)
+	  && is_character_based (op2->ts.type))
+	{
+	  convert_hollerith_to_character (op1);
+	  convert_hollerith_to_character (op2);
+	}
+
       if (op1->ts.type == BT_CHARACTER && op2->ts.type == BT_CHARACTER
 	  && op1->ts.kind == op2->ts.kind)
 	{
@@ -4137,6 +4182,13 @@ resolve_operator (gfc_expr *e)
 	  if (op1->ts.type == BT_REAL && !gfc_boz2real (op2, op1->ts.kind))
 	    return false;
 	}
+      if (flag_dec
+	  && op1->ts.type == BT_HOLLERITH && gfc_numeric_ts (&op2->ts))
+	convert_to_numeric (op1, op2);
+
+      if (flag_dec
+	  && gfc_numeric_ts (&op1->ts) && op2->ts.type == BT_HOLLERITH)
+	convert_to_numeric (op2, op1);
 
       if (gfc_numeric_ts (&op1->ts) && gfc_numeric_ts (&op2->ts))
 	{
@@ -10693,7 +10745,7 @@ resolve_ordinary_assign (gfc_code *code, gfc_namespace *ns)
 
   if ((gfc_numeric_ts (&lhs->ts) || lhs->ts.type == BT_LOGICAL)
       && rhs->ts.type == BT_CHARACTER
-      && rhs->expr_type != EXPR_CONSTANT)
+      && (rhs->expr_type != EXPR_CONSTANT || !flag_dec_char_conversions))
     {
       /* Use of -fdec-char-conversions allows assignment of character data
 	 to non-character variables.  This not permited for nonconstant