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[Patch, Fortran] PR fortran/37779: Diagnose missing RECURSIVE, part 2


Hi all,

this is a follow-up patch for PR 37779, to detect cases like this:

SUBROUTINE foo ()
  CALL bar ()
CONTAINS
  SUBROUTINE bar ()
    CALL foo () ! { dg-error "recursive call to non-recursive foo" }
  END SUBROUTINE bar
END SUBROUTINE foo

Because bar is contained in foo, it can only ever be called from within foo; thus, if bar calls foo, too, this is necessarily an illegal recursive call.

I did refactor and clean-up recursive-ness detection in resolve.c a bit, and hope I did get it all right (the ENTRY handling, too). No regressions on GNU/Linux-x86-32.

Ok for trunk (4.4)? Or should we wait even with this patch for 4.5? I believe this is enough of a bug-fix to go in for 4.4, though.

Cheers,
Daniel

--
Done:  Arc-Bar-Cav-Rog-Sam-Val-Wiz
To go: Hea-Kni-Mon-Pri-Ran-Tou
2008-11-29  Daniel Kraft  <d@domob.eu>

	PR fortran/37779
	* gfortran.h (struct gfc_entry_list): Fixed typo in comment.
	* resolve.c (is_illegal_recursion): New method.
	(resolve_procedure_expression): Use new is_illegal_recursion instead of
	direct check and handle function symbols correctly.
	(resolve_actual_arglist): Removed useless recursion check.
	(resolve_function): Use is_illegal_recursion instead of direct check.
	(resolve_call): Ditto.

2008-11-29  Daniel Kraft  <d@domob.eu>

	PR fortran/37779
	* gfortran.dg/recursive_check_1.f: Changed expected error message to
	the more general new one.
	* gfortran.dg/recursive_check_2.f90: Ditto.
	* gfortran.dg/entry_18.f90: Ditto.
	* gfortran.dg/recursive_check_4.f03: Do "the same" check also for
	FUNCTIONS, as this is different in details from SUBROUTINES.
	* gfortran.dg/recursive_check_6.f03: New test.
Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(revision 142157)
+++ gcc/fortran/gfortran.h	(working copy)
@@ -1157,7 +1157,7 @@ typedef struct gfc_entry_list
   int id;
   /* The LABEL_EXPR marking this entry point.  */
   tree label;
-  /* The nest item in the list.  */
+  /* The next item in the list.  */
   struct gfc_entry_list *next;
 }
 gfc_entry_list;
Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c	(revision 142158)
+++ gcc/fortran/resolve.c	(working copy)
@@ -1073,6 +1073,58 @@ count_specific_procs (gfc_expr *e)
 }
 
 
+/* See if a call to sym could possibly be a not allowed RECURSION because of
+   a missing RECURIVE declaration.  This means that either sym is the current
+   context itself, or sym is the parent of a contained procedure calling its
+   non-RECURSIVE containing procedure.
+   This also works if sym is an ENTRY.  */
+
+static bool
+is_illegal_recursion (gfc_symbol* sym, gfc_namespace* context)
+{
+  gfc_symbol* proc_sym;
+  gfc_symbol* context_proc;
+
+  gcc_assert (sym->attr.flavor == FL_PROCEDURE);
+
+  /* If we've got an ENTRY, find real procedure.  */
+  if (sym->attr.entry && sym->ns->entries)
+    proc_sym = sym->ns->entries->sym;
+  else
+    proc_sym = sym;
+
+  /* If sym is RECURSIVE, all is well of course.  */
+  if (proc_sym->attr.recursive || gfc_option.flag_recursive)
+    return false;
+
+  /* Find the context procdure's "real" symbol if it has entries.  */
+  context_proc = (context->entries ? context->entries->sym
+				   : context->proc_name);
+  if (!context_proc)
+    return true;
+
+  /* A call from sym's body to itself is recursion, of course.  */
+  if (context_proc == proc_sym)
+    return true;
+
+  /* The same is true if context is a contained procedure and sym the
+     containing one.  */
+  if (context_proc->attr.contained)
+    {
+      gfc_symbol* parent_proc;
+
+      gcc_assert (context->parent);
+      parent_proc = (context->parent->entries ? context->parent->entries->sym
+					      : context->parent->proc_name);
+
+      if (parent_proc == proc_sym)
+	return true;
+    }
+
+  return false;
+}
+
+
 /* Resolve a procedure expression, like passing it to a called procedure or as
    RHS for a procedure pointer assignment.  */
 
@@ -1081,16 +1133,18 @@ resolve_procedure_expression (gfc_expr* 
 {
   gfc_symbol* sym;
 
-  if (expr->ts.type != BT_PROCEDURE || expr->expr_type != EXPR_VARIABLE)
+  if (expr->expr_type != EXPR_VARIABLE)
     return SUCCESS;
   gcc_assert (expr->symtree);
+
   sym = expr->symtree->n.sym;
-  gcc_assert (sym->attr.flavor == FL_PROCEDURE);
+  if (sym->attr.flavor != FL_PROCEDURE
+      || (sym->attr.function && sym->result == sym))
+    return SUCCESS;
 
   /* A non-RECURSIVE procedure that is used as procedure expression within its
      own body is in danger of being called recursively.  */
-  if (!sym->attr.recursive && sym == gfc_current_ns->proc_name
-      && !gfc_option.flag_recursive)
+  if (is_illegal_recursion (sym, gfc_current_ns))
     gfc_warning ("Non-RECURSIVE procedure '%s' at %L is possibly calling"
 		 " itself recursively.  Declare it RECURSIVE or use"
 		 " -frecursive", sym->name, &expr->where);
@@ -1203,15 +1257,6 @@ resolve_actual_arglist (gfc_actual_argli
 	  /* Just in case a specific was found for the expression.  */
 	  sym = e->symtree->n.sym;
 
-	  if (sym->attr.entry && sym->ns->entries
-		&& sym->ns == gfc_current_ns
-		&& !sym->ns->entries->sym->attr.recursive)
-	    {
-	      gfc_error ("Reference to ENTRY '%s' at %L is recursive, but"
-			 " procedure '%s' is not declared as RECURSIVE",
-			 sym->name, &e->where, sym->ns->entries->sym->name);
-	    }
-
 	  /* If the symbol is the function that names the current (or
 	     parent) scope, then we really have a variable reference.  */
 
@@ -2455,22 +2500,19 @@ resolve_function (gfc_expr *expr)
    * call themselves.  */
   if (expr->value.function.esym && !expr->value.function.esym->attr.recursive)
     {
-      gfc_symbol *esym, *proc;
+      gfc_symbol *esym;
       esym = expr->value.function.esym;
-      proc = gfc_current_ns->proc_name;
-      if (esym == proc)
-      {
-	gfc_error ("Function '%s' at %L cannot call itself, as it is not "
-		   "RECURSIVE", name, &expr->where);
-	t = FAILURE;
-      }
 
-      if (esym->attr.entry && esym->ns->entries && proc->ns->entries
-	  && esym->ns->entries->sym == proc->ns->entries->sym)
+      if (is_illegal_recursion (esym, gfc_current_ns))
       {
-	gfc_error ("Call to ENTRY '%s' at %L is recursive, but function "
-		   "'%s' is not declared as RECURSIVE",
-		   esym->name, &expr->where, esym->ns->entries->sym->name);
+	if (esym->attr.entry && esym->ns->entries)
+	  gfc_error ("ENTRY '%s' at %L cannot be called recursively, as"
+		     " function '%s' is not RECURSIVE",
+		     esym->name, &expr->where, esym->ns->entries->sym->name);
+	else
+	  gfc_error ("Function '%s' at %L cannot be called recursively, as it"
+		     " is not RECURSIVE", esym->name, &expr->where);
+
 	t = FAILURE;
       }
     }
@@ -2919,25 +2961,17 @@ resolve_call (gfc_code *c)
 
   /* Subroutines without the RECURSIVE attribution are not allowed to
    * call themselves.  */
-  if (csym && !csym->attr.recursive)
+  if (csym && is_illegal_recursion (csym, gfc_current_ns))
     {
-      gfc_symbol *proc;
-      proc = gfc_current_ns->proc_name;
-      if (csym == proc)
-      {
-	gfc_error ("SUBROUTINE '%s' at %L cannot call itself, as it is not "
-		   "RECURSIVE", csym->name, &c->loc);
-	t = FAILURE;
-      }
-
-      if (csym->attr.entry && csym->ns->entries && proc->ns->entries
-	  && csym->ns->entries->sym == proc->ns->entries->sym)
-      {
-	gfc_error ("Call to ENTRY '%s' at %L is recursive, but subroutine "
-		   "'%s' is not declared as RECURSIVE",
+      if (csym->attr.entry && csym->ns->entries)
+	gfc_error ("ENTRY '%s' at %L cannot be called recursively, as"
+		   " subroutine '%s' is not RECURSIVE",
 		   csym->name, &c->loc, csym->ns->entries->sym->name);
-	t = FAILURE;
-      }
+      else
+	gfc_error ("SUBROUTINE '%s' at %L cannot be called recursively, as it"
+		   " is not RECURSIVE", csym->name, &c->loc);
+
+      t = FAILURE;
     }
 
   /* Switch off assumed size checking and do this again for certain kinds
Index: gcc/testsuite/gfortran.dg/recursive_check_1.f
===================================================================
--- gcc/testsuite/gfortran.dg/recursive_check_1.f	(revision 142157)
+++ gcc/testsuite/gfortran.dg/recursive_check_1.f	(working copy)
@@ -1,17 +1,17 @@
 ! { dg-do compile }
 ! PR fortran/26551
       SUBROUTINE SUB()
-      CALL SUB() ! { dg-error "cannot call itself, as it is not RECURSIVE" }
+      CALL SUB() ! { dg-error "is not RECURSIVE" }
       END SUBROUTINE
 
       FUNCTION FUNC() RESULT (FOO)
       INTEGER FOO
-      FOO = FUNC() ! { dg-error "cannot call itself, as it is not RECURSIVE" }
+      FOO = FUNC() ! { dg-error "is not RECURSIVE" }
       END FUNCTION
 
       SUBROUTINE SUB2()
       ENTRY ENT2()
-      CALL ENT2() ! { dg-error "is not declared as RECURSIVE" }
+      CALL ENT2() ! { dg-error "is not RECURSIVE" }
       END SUBROUTINE
 
       function func2()
@@ -19,7 +19,7 @@
       func2 = 42
       return
       entry c() result (foo)
-      foo = b() ! { dg-error "is not declared as RECURSIVE" }
+      foo = b() ! { dg-error "is not RECURSIVE" }
       return
       entry b() result (bar)
       bar = 12
Index: gcc/testsuite/gfortran.dg/recursive_check_4.f03
===================================================================
--- gcc/testsuite/gfortran.dg/recursive_check_4.f03	(revision 142158)
+++ gcc/testsuite/gfortran.dg/recursive_check_4.f03	(working copy)
@@ -16,6 +16,16 @@ CONTAINS
     procptr => test ! { dg-warning "Non-RECURSIVE" }
   END SUBROUTINE test
 
+  INTEGER FUNCTION test2 () RESULT (x)
+    IMPLICIT NONE
+    PROCEDURE(test2), POINTER :: procptr
+
+    CALL bar (test2) ! { dg-warning "Non-RECURSIVE" }
+    procptr => test2 ! { dg-warning "Non-RECURSIVE" }
+
+    x = 1812
+  END FUNCTION test2
+
   INTEGER FUNCTION func ()
     ! Using a result variable is ok of course!
     func = 42 ! { dg-bogus "Non-RECURSIVE" }
Index: gcc/testsuite/gfortran.dg/recursive_check_2.f90
===================================================================
--- gcc/testsuite/gfortran.dg/recursive_check_2.f90	(revision 142157)
+++ gcc/testsuite/gfortran.dg/recursive_check_2.f90	(working copy)
@@ -12,6 +12,6 @@
    return
  contains
    function barbar ()
-     barbar = b () ! { dg-error "is not declared as RECURSIVE" }
+     barbar = b () ! { dg-error "is not RECURSIVE" }
    end function barbar
  end function
Index: gcc/testsuite/gfortran.dg/recursive_check_6.f03
===================================================================
--- gcc/testsuite/gfortran.dg/recursive_check_6.f03	(revision 0)
+++ gcc/testsuite/gfortran.dg/recursive_check_6.f03	(revision 0)
@@ -0,0 +1,66 @@
+! { dg-do compile }
+
+! PR fortran/37779
+! Check that a call to a procedure's containing procedure counts as recursive
+! and is rejected if the containing procedure is not RECURSIVE.
+
+MODULE m
+  IMPLICIT NONE
+
+CONTAINS
+
+  SUBROUTINE test_sub ()
+    CALL bar ()
+  CONTAINS
+    SUBROUTINE bar ()
+      IMPLICIT NONE
+      PROCEDURE(test_sub), POINTER :: procptr
+
+      CALL test_sub () ! { dg-error "not RECURSIVE" }
+      procptr => test_sub ! { dg-warning "Non-RECURSIVE" }
+      CALL foobar (test_sub) ! { dg-warning "Non-RECURSIVE" }
+    END SUBROUTINE bar
+  END SUBROUTINE test_sub
+
+  INTEGER FUNCTION test_func () RESULT (x)
+    x = bar ()
+  CONTAINS
+    INTEGER FUNCTION bar ()
+      IMPLICIT NONE
+      PROCEDURE(test_func), POINTER :: procptr
+
+      bar = test_func () ! { dg-error "not RECURSIVE" }
+      procptr => test_func ! { dg-warning "Non-RECURSIVE" }
+      CALL foobar (test_func) ! { dg-warning "Non-RECURSIVE" }
+    END FUNCTION bar
+  END FUNCTION test_func
+
+  SUBROUTINE sub_entries ()
+  ENTRY sub_entry_1 ()
+  ENTRY sub_entry_2 ()
+    CALL bar ()
+  CONTAINS
+    SUBROUTINE bar ()
+      CALL sub_entry_1 () ! { dg-error "is not RECURSIVE" }
+    END SUBROUTINE bar
+  END SUBROUTINE sub_entries
+
+  INTEGER FUNCTION func_entries () RESULT (x)
+  ENTRY func_entry_1 () RESULT (x)
+  ENTRY func_entry_2 () RESULT (x)
+    x = bar ()
+  CONTAINS
+    INTEGER FUNCTION bar ()
+      bar = func_entry_1 () ! { dg-error "is not RECURSIVE" }
+    END FUNCTION bar
+  END FUNCTION func_entries
+
+  SUBROUTINE main ()
+    CALL test_sub ()
+    CALL sub_entries ()
+    PRINT *, test_func (), func_entries ()
+  END SUBROUTINE main
+
+END MODULE m
+
+! { dg-final { cleanup-modules "m" } }
Index: gcc/testsuite/gfortran.dg/entry_18.f90
===================================================================
--- gcc/testsuite/gfortran.dg/entry_18.f90	(revision 142157)
+++ gcc/testsuite/gfortran.dg/entry_18.f90	(working copy)
@@ -27,7 +27,7 @@ subroutine subb( g )
        end function
    end interface
    real :: x, y
-   call mysub( glocalb ) ! { dg-error "is recursive" }
+   call mysub( glocalb ) ! { dg-warning "Non-RECURSIVE" }
    return
 entry glocalb( x, y )
    y = x

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