fortran: Release symbols in reversed order [PR106050]

Release symbols in reversed order wrt the order they were allocated.
This fixes an error recovery ICE in the case of a misplaced
derived type declaration.  Such a declaration creates nested
symbols, one for the derived type and one for each type parameter,
which should be immediately released as the declaration is
rejected.  This breaks if the derived type is released first.
As the type parameter symbols are in the namespace of the derived
type, releasing the derived type releases the type parameters, so
one can't access them after that, even to release them.  Hence,
the type parameters should be released first.

	PR fortran/106050

gcc/fortran/ChangeLog:

	* symbol.cc (gfc_restore_last_undo_checkpoint): Release symbols
	in reverse order.

gcc/testsuite/ChangeLog:

	* gfortran.dg/pdt_33.f90: New test.

diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc
index 90023f0ad73a8ead427799be96c8f5f9154fe2ec..aa3cdc98c86f06ce7e514aff07e3d9fec9148fbd 100644 (file)
--- a/gcc/fortran/symbol.cc
+++ b/gcc/fortran/symbol.cc
@@ -3661,7 +3661,7 @@ gfc_restore_last_undo_checkpoint (void)
   gfc_symbol *p;
   unsigned i;
 
-  FOR_EACH_VEC_ELT (latest_undo_chgset->syms, i, p)
+  FOR_EACH_VEC_ELT_REVERSE (latest_undo_chgset->syms, i, p)
     {
       /* Symbol in a common block was new. Or was old and just put in common */
       if (p->common_block

diff --git a/gcc/testsuite/gfortran.dg/pdt_33.f90 b/gcc/testsuite/gfortran.dg/pdt_33.f90
new file mode 100644 (file)
index 0000000..0521513
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pdt_33.f90
@@ -0,0 +1,15 @@
+! { dg-do compile }
+!
+! PR fortran/106050
+! The following used to trigger an error recovery ICE by releasing
+! the symbol T before the symbol K which was leading to releasing
+! K twice as it's in T's namespace.
+!
+! Contributed by G. Steinmetz <gscfq@t-online.de>
+
+program p
+   a = 1
+   type t(k)                  ! { dg-error "Unexpected derived type declaration" }
+      integer, kind :: k = 4  ! { dg-error "not allowed outside a TYPE definition" }
+   end type                   ! { dg-error "Expecting END PROGRAM" }
+end