Support legacy PARAMETER statements with -std=legacy.

	gcc/fortran/
	* decl.c (gfc_match_parameter): Allow omitted '()' with -std=legacy.
	* parse.c (decode_statement): Match "parameter" before assignments.
	* gfortran.texi: Document.

	gcc/testsuite/gfortran.dg/
	* dec_parameter_1.f: New test.
	* dec_parameter_2.f90: Likewise.
	* dec_parameter_3.f90: Likewise.
	* dec_parameter_4.f90: Likewise.

From-SVN: r241823

4 files changed, 35 insertions, 3 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index d47eeb0..baec7bf 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-03  Fritz O. Reese <fritzoreese@gmail.com>
+
+	* decl.c (gfc_match_parameter): Allow omitted '()' with -std=legacy.
+	* parse.c (decode_statement): Match "parameter" before assignments.
+	* gfortran.texi: Document.
+
 2016-11-02  Fritz O. Reese <fritzoreese@gmail.com>
 
 	* lang.opt, invoke.texi: New argument -Wargument-mismatch.
diff --git a/gcc/fortran/decl.c b/gcc/fortran/decl.c
index f18eb41..0120ceb 100644
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -7821,10 +7821,16 @@ cleanup:
 match
 gfc_match_parameter (void)
 {
+  const char *term = " )%t";
   match m;
 
   if (gfc_match_char ('(') == MATCH_NO)
-    return MATCH_NO;
+    {
+      /* With legacy PARAMETER statements, don't expect a terminating ')'.  */
+      if (!gfc_notify_std (GFC_STD_LEGACY, "PARAMETER without '()' at %C"))
+	return MATCH_NO;
+      term = " %t";
+    }
 
   for (;;)
     {
@@ -7832,7 +7838,7 @@ gfc_match_parameter (void)
       if (m != MATCH_YES)
 	break;
 
-      if (gfc_match (" )%t") == MATCH_YES)
+      if (gfc_match (term) == MATCH_YES)
 	break;
 
       if (gfc_match_char (',') != MATCH_YES)
diff --git a/gcc/fortran/gfortran.texi b/gcc/fortran/gfortran.texi
index e65c2de..cd2c5a5 100644
--- a/gcc/fortran/gfortran.texi
+++ b/gcc/fortran/gfortran.texi
@@ -1471,6 +1471,7 @@ compatibility extensions along with those enabled by @option{-std=legacy}.
 * .XOR. operator::
 * Bitwise logical operators::
 * Extended I/O specifiers::
+* Legacy PARAMETER statements::
 @end menu
 
 @node Old-style kind specifications
@@ -2696,6 +2697,23 @@ supported on other systems.
 
 @end table
 
+@node Legacy PARAMETER statements
+@subsection Legacy PARAMETER statements
+@cindex PARAMETER
+
+For compatibility, GNU Fortran supports legacy PARAMETER statements without
+parentheses with @option{-std=legacy}.  A warning is emitted if used with
+@option{-std=gnu}, and an error is acknowledged with a real Fortran standard
+flag (@option{-std=f95}, etc...).  These statements take the following form:
+
+@smallexample
+implicit real (E)
+parameter e = 2.718282
+real c
+parameter c = 3.0e8
+@end smallexample
+
+
 @node Extensions not implemented in GNU Fortran
 @section Extensions not implemented in GNU Fortran
 @cindex extensions, not implemented
diff --git a/gcc/fortran/parse.c b/gcc/fortran/parse.c
index 2aa2afc..0ee054a 100644
--- a/gcc/fortran/parse.c
+++ b/gcc/fortran/parse.c
@@ -352,6 +352,9 @@ decode_statement (void)
     }
   gfc_matching_function = false;
 
+  /* Legacy parameter statements are ambiguous with assignments so try parameter
+     first.  */
+  match ("parameter", gfc_match_parameter, ST_PARAMETER);
 
   /* Match statements whose error messages are meant to be overwritten
      by something better.  */
@@ -528,7 +531,6 @@ decode_statement (void)
 
     case 'p':
       match ("print", gfc_match_print, ST_WRITE);
-      match ("parameter", gfc_match_parameter, ST_PARAMETER);
       match ("pause", gfc_match_pause, ST_PAUSE);
       match ("pointer", gfc_match_pointer, ST_ATTR_DECL);
       if (gfc_match_private (&st) == MATCH_YES)