Hello,
this fixes an old error-recovery bug.
Tested on x86_64-pc-linux-gnu.
OK for master?
-- >8 --
Keep memory of the content of the current interface body being parsed
and restore it to its previous state if it has been modified at the time
a parse attempt fails.
This fixes memory errors and random segmentation faults caused by
dangling symbol pointers kept in interfaces' linked lists of symbols.
If a parsing attempt fails and symbols are freed, they should also be
removed from the current interface linked list.
As the list of symbol is a linked list, and parsing only adds new
symbols to the head of the list, all that is needed to track the
previous content of the list is a pointer to its previous head.
This adds such a pointer, and the restoration of the list of symbols
to that pointer on error.
PR fortran/48776
gcc/fortran/ChangeLog:
* gfortran.h (gfc_drop_interface_elements_before): New prototype.
(gfc_current_interface_head): Return a reference to the pointer.
* interface.cc (gfc_current_interface_head): Ditto.
(free_interface_elements_until): New function, generalizing
gfc_free_interface.
(gfc_free_interface): Use free_interface_elements_until.
(gfc_drop_interface_elements_before): New function.
* parse.cc
(current_interface_ptr, previous_interface_head): New static variables.
(current_interface_valid_p, get_current_interface_ptr): New functions.
(decode_statement): Initialize previous_interface_head.
(reject_statement): Restore current interface pointer to point to
previous_interface_head.
gcc/testsuite/ChangeLog:
* gfortran.dg/interface_procedure_1.f90: New test.
---
gcc/fortran/gfortran.h| 3 +-
gcc/fortran/interface.cc | 43 ---
gcc/fortran/parse.cc | 54 +++
.../gfortran.dg/interface_procedure_1.f90 | 23
4 files changed, 115 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/gfortran.dg/interface_procedure_1.f90
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index fd47000a88e..0fabe7badde 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -3824,6 +3824,7 @@ bool gfc_ref_dimen_size (gfc_array_ref *, int dimen,
mpz_t *, mpz_t *);
/* interface.cc -- FIXME: some of these should be in symbol.cc */
void gfc_free_interface (gfc_interface *);
+void gfc_drop_interface_elements_before (gfc_interface **, gfc_interface *);
bool gfc_compare_derived_types (gfc_symbol *, gfc_symbol *);
bool gfc_compare_types (gfc_typespec *, gfc_typespec *);
bool gfc_check_dummy_characteristics (gfc_symbol *, gfc_symbol *,
@@ -3843,7 +3844,7 @@ void gfc_free_formal_arglist (gfc_formal_arglist *);
bool gfc_extend_assign (gfc_code *, gfc_namespace *);
bool gfc_check_new_interface (gfc_interface *, gfc_symbol *, locus);
bool gfc_add_interface (gfc_symbol *);
-gfc_interface *gfc_current_interface_head (void);
+gfc_interface *_current_interface_head (void);
void gfc_set_current_interface_head (gfc_interface *);
gfc_symtree* gfc_find_sym_in_symtree (gfc_symbol*);
bool gfc_arglist_matches_symbol (gfc_actual_arglist**, gfc_symbol*);
diff --git a/gcc/fortran/interface.cc b/gcc/fortran/interface.cc
index ea82056e9e3..c01df0460d7 100644
--- a/gcc/fortran/interface.cc
+++ b/gcc/fortran/interface.cc
@@ -78,18 +78,47 @@ along with GCC; see the file COPYING3. If not see
gfc_interface_info current_interface;
+/* Free the leading members of the gfc_interface linked list given in INTR
+ up to the END element (exclusive: the END element is not freed).
+ If END is not nullptr, it is assumed that END is in the linked list starting
+ with INTR. */
+
+static void
+free_interface_elements_until (gfc_interface *intr, gfc_interface *end)
+{
+ gfc_interface *next;
+
+ for (; intr != end; intr = next)
+{
+ next = intr->next;
+ free (intr);
+}
+}
+
+
/* Free a singly linked list of gfc_interface structures. */
void
gfc_free_interface (gfc_interface *intr)
{
- gfc_interface *next;
+ free_interface_elements_until (intr, nullptr);
+}
- for (; intr; intr = next)
-{
- next = intr->next;
- free (intr);
-}
+
+/* Update the interface pointer given by IFC_PTR to make it point to TAIL.
+ It is expected that TAIL (if non-null) is in the list pointed to by
+ IFC_PTR, hence the tail of it. The members of the list before TAIL are
+ freed before the pointer reassignment. */
+
+void
+gfc_drop_interface_elements_before (gfc_interface **ifc_ptr,
+ gfc_interface *tail)
+{
+ if (ifc_ptr == nullptr)
+return;
+
+ free_interface_elements_until (*ifc_ptr, tail);
+ *ifc_ptr = tail;
}
@@ -4953,7 +4982,7 @@ gfc_add_interface (gfc_symbol *new_sym)
}
-gfc_interface *
+gfc_interface *&
gfc_current_interface_head (void)
{
switch (current_interface.type)
diff
