re PR fortran/52846 ([F2008] Support submodules)

2015-09-17  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/52846
	PR fortran/67588
	* module.c : Add static no_module_procedures.
	(gfc_match_submodule): Correct memory leakage caused during the
	freeing of use_lists.
	(mio_symbol_attribute): Reset above if module procedure is
	encountered.
	(gfc_dump_module): Set above and exit without writing smod file
	if it reset.
	* gfortran.texi : Add section on submodule support.

2015-09-17  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/52846
	* gfortran.dg/public_private_module_5.f90: Add module procedure
	trigger_smod to ensure that the smod file is written.

From-SVN: r227855

gcc/fortran/ChangeLog

+2015-09-17  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/52846
+	PR fortran/67588
+	* module.c : Add static no_module_procedures.
+	(gfc_match_submodule): Correct memory leakage caused during the
+	freeing of use_lists.
+	(mio_symbol_attribute): Reset above if module procedure is
+	encountered.
+	(gfc_dump_module): Set above and exit without writing smod file
+	if it reset.
+	* gfortran.texi : Add section on submodule support.
+
 2015-09-10  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/67526

gcc/fortran/gfortran.texi

@@ -1047,6 +1047,14 @@ of @code{ISO_FORTRAN_ENV}.
 and experimental support for multiple images with the @option{-fcoarray=lib}
 flag.
 
+@item Submodules are supported. It should noted that @code{MODULEs} do not
+produce the smod file needed by the descendent @code{SUBMODULEs} unless they
+contain at least one @code{MODULE PROCEDURE} interface. The reason for this is
+that @code{SUBMODULEs} are useless without @code{MODULE PROCEDUREs}. See
+http://j3-fortran.org/doc/meeting/207/15-209.txt for a discussion and a draft
+interpretation. Adopting this interpretation has the advantage that code that
+does not use submodules does not generate smod files.
+
 @item The @code{DO CONCURRENT} construct is supported.
 
 @item The @code{BLOCK} construct is supported.

gcc/fortran/module.c

@@ -193,6 +193,11 @@ static gzFile module_fp;
 static const char *module_name;
 /* The name of the .smod file that the submodule will write to.  */
 static const char *submodule_name;
+
+/* Suppress the output of a .smod file by module, if no module
+   procedures have been seen.  */
+static bool no_module_procedures;
+
 static gfc_use_list *module_list;
 
 /* If we're reading an intrinsic module, this is its ID.  */
@@ -798,7 +803,7 @@ gfc_match_submodule (void)
   /* Just retain the ultimate .(s)mod file for reading, since it
      contains all the information in its ancestors.  */
   use_list = module_list;
-  for (; module_list->next; use_list = use_list->next)
+  for (; module_list->next; use_list = module_list)
     {
       module_list = use_list->next;
       free (use_list);
@@ -2222,7 +2227,10 @@ mio_symbol_attribute (symbol_attribute *attr)
       if (attr->array_outer_dependency)
 	MIO_NAME (ab_attribute) (AB_ARRAY_OUTER_DEPENDENCY, attr_bits);
       if (attr->module_procedure)
+	{
 	MIO_NAME (ab_attribute) (AB_MODULE_PROCEDURE, attr_bits);
+	  no_module_procedures = false;
+	}
 
       mio_rparen ();
 
@@ -6081,9 +6089,10 @@ gfc_dump_module (const char *name, int dump_flag)
   else
     dump_smod =false;
 
+  no_module_procedures = true;
   dump_module (name, dump_flag);
 
-  if (dump_smod)
+  if (no_module_procedures || dump_smod)
     return;
 
   /* Write a submodule file from a module.  The 'dump_smod' flag switches

gcc/testsuite/ChangeLog

+2015-09-17  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/52846
+	* gfortran.dg/public_private_module_5.f90: Add module procedure
+	trigger_smod to ensure that the smod file is written.
+
 2015-09-17  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	* gcc.target/aarch64/copysign_1.c: New.

gcc/testsuite/gfortran.dg/submodule_5.f08

@@ -10,6 +10,14 @@ module foo_interface
   type foo
     character(len=16), private :: byebye = "adieu, world!   "
   end type foo
+
+! This interface is required to trigger the output of an .smod file.
+! See http://j3-fortran.org/doc/meeting/207/15-209.txt
+  interface
+    integer module function trigger_smod ()
+    end function
+  end interface
+
 end module
 
 module foo_interface_brother