[patch] PR fortran/61669

[Steven Bosscher]

Hello,

This bug is an error recovery issue. A data declaration is parsed and
accepted, and added to gfc_current_ns->data, but the statement is
rejected. The rejected data decl is not rolled back, causing memory
corruption later on.

Proposed fix is to roll back DATA for rejected statements.

Bootstrapped&tested on powerpc64-unknown-linux-gnu. OK for trunk?

Ciao!
Steven

fortran/
        PR fortran/61669
        * gfortran.h (struct gfc_namespace): Add OLD_DATA field.
        * decl.c (gfc_reject_data): New function.
        * parse.c *use_modules): Record roll-back point.
        (next_statement): Likewise.
        (reject_statement): Roll back to last accepted DATA.

testsuite/
        PR fortran/61669
        * gfortran.dg/pr61669.f90: New test.

Index: fortran/gfortran.h
===================================================================
--- fortran/gfortran.h  (revision 214350)
+++ fortran/gfortran.h  (working copy)
@@ -1625,7 +1625,7 @@ typedef struct gfc_namespace
   gfc_st_label *st_labels;
   /* This list holds information about all the data initializers in
      this namespace.  */
-  struct gfc_data *data;
+  struct gfc_data *data, *old_data;
 
   gfc_charlen *cl_list, *old_cl_list;
 
@@ -2941,6 +2941,7 @@ void gfc_free_omp_namelist (gfc_omp_namelist *);
 void gfc_free_equiv (gfc_equiv *);
 void gfc_free_equiv_until (gfc_equiv *, gfc_equiv *);
 void gfc_free_data (gfc_data *);
+void gfc_reject_data (gfc_namespace *);
 void gfc_free_case_list (gfc_case *);
 
 /* matchexp.c -- FIXME too?  */
Index: fortran/decl.c
===================================================================
--- fortran/decl.c      (revision 214350)
+++ fortran/decl.c      (working copy)
@@ -178,7 +178,21 @@ gfc_free_data_all (gfc_namespace *ns)
     }
 }
 
+/* Reject data parsed since the last restore point was marked.  */
 
+void
+gfc_reject_data (gfc_namespace *ns)
+{
+  gfc_data *d;
+
+  while (ns->data && ns->data != ns->old_data)
+    {
+      d = ns->data->next;
+      free (ns->data);
+      ns->data = d;
+    }
+}
+
 static match var_element (gfc_data_variable *);
 
 /* Match a list of variables terminated by an iterator and a right
Index: fortran/parse.c
===================================================================
--- fortran/parse.c     (revision 214350)
+++ fortran/parse.c     (working copy)
@@ -118,6 +118,7 @@ use_modules (void)
   gfc_warning_check ();
   gfc_current_ns->old_cl_list = gfc_current_ns->cl_list;
   gfc_current_ns->old_equiv = gfc_current_ns->equiv;
+  gfc_current_ns->old_data = gfc_current_ns->data;
   last_was_use_stmt = false;
 }
 
@@ -1097,6 +1098,7 @@ next_statement (void)
 
   gfc_current_ns->old_cl_list = gfc_current_ns->cl_list;
   gfc_current_ns->old_equiv = gfc_current_ns->equiv;
+  gfc_current_ns->old_data = gfc_current_ns->data;
   for (;;)
     {
       gfc_statement_label = NULL;
@@ -2045,6 +2047,8 @@ reject_statement (void)
   gfc_free_equiv_until (gfc_current_ns->equiv, gfc_current_ns->old_equiv);
   gfc_current_ns->equiv = gfc_current_ns->old_equiv;
 
+  gfc_reject_data (gfc_current_ns);
+
   gfc_new_block = NULL;
   gfc_undo_symbols ();
   gfc_clear_warning ();
Index: testsuite/gfortran.dg/pr61669.f90
===================================================================
--- testsuite/gfortran.dg/pr61669.f90   (revision 0)
+++ testsuite/gfortran.dg/pr61669.f90   (working copy)
@@ -0,0 +1,8 @@
+! { dg-do compile }
+      write (*,"(a)") char(12)
+      CHARACTER*80 A /"A"/      ! { dg-error "Unexpected data declaration 
statement" }
+      REAL*4 B                  ! { dg-error "Unexpected data declaration 
statement" }
+      write (*,"(a)") char(12)
+      DATA B / 0.02 /
+      END
+