re PR fortran/69520 (Implement reversal of -fcheck options)

2016-03-12  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
	    Harold Anlauf  <anlauf@gmx.de>

	PR fortran/69520
	* invoke.texi: Explain use of the 'no-' construct within the
	-fcheck= option.
	* options.c (gfc_handle_runtime_check_option): Enable use of
	'no-' prefix for the various options with -fcheck= to allow
	negating previously enabled check options.

Co-Authored-By: Harald Anlauf <anlauf@gmx.de>

From-SVN: r234167

gcc/fortran/ChangeLog

+2016-03-12  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
+	    Harold Anlauf  <anlauf@gmx.de>
+
+	PR fortran/69520
+	* invoke.texi: Explain use of the 'no-' construct within the
+	-fcheck= option.
+	* options.c (gfc_handle_runtime_check_option): Enable use of
+	'no-' prefix for the various options with -fcheck= to allow
+	negating previously enabled check options.
+
 2016-03-12  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/70031

gcc/fortran/invoke.texi

@@ -1398,7 +1398,8 @@ library needs to be linked.
 @cindex checking array temporaries
 
 Enable the generation of run-time checks; the argument shall be
-a comma-delimited list of the following keywords.
+a comma-delimited list of the following keywords.  Prefixing a check with
+@option{no-} disables it if it was activated by a previous specification.
 
 @table @asis
 @item @samp{all}
@@ -1444,6 +1445,13 @@ Note: This check does not work for OpenMP programs and is disabled if used
 together with @option{-frecursive} and @option{-fopenmp}.
 @end table
 
+Example: Assuming you have a file @file{foo.f90}, the command
+@smallexample
+  gfortran -fcheck=all,no-array-temps foo.f90
+@end smallexample
+will compile the file with all checks enabled as specified above except
+warnings for generated array temporaries.
+
 
 @item -fbounds-check
 @opindex @code{fbounds-check}

gcc/fortran/options.c

@@ -515,6 +515,15 @@ gfc_handle_runtime_check_option (const char *arg)
 	      result = 1;
 	      break;
 	    }
+	  else if (optname[n] && pos > 3 && strncmp ("no-", arg, 3) == 0
+		   && strncmp (optname[n], arg+3, pos-3) == 0)
+	    {
+	      gfc_option.rtcheck &= ~optmask[n];
+	      arg += pos;
+	      pos = 0;
+	      result = 1;
+	      break;
+	    }
 	}
       if (!result)
 	gfc_fatal_error ("Argument to %<-fcheck%> is not valid: %s", arg);