Fortran: fix NULL pointer dereference on overlapping initialization [PR50410]

gcc/fortran/ChangeLog:

	PR fortran/50410
	* trans-expr.cc (gfc_conv_structure): Check for NULL pointer.

gcc/testsuite/ChangeLog:

	PR fortran/50410
	* gfortran.dg/data_initialized_4.f90: New test.

(cherry picked from commit 6fb253a25dff13253d63553f02e0fe72c5e3ab4e)

diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 3f3f0123dc34de792d3b7ccb417cf4513f228d2c..d9de93260a685cbaed016579f2a186876a6f17b0 100644 (file)
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -9364,7 +9364,7 @@ gfc_conv_structure (gfc_se * se, gfc_expr * expr, int init)
   cm = expr->ts.u.derived->components;
 
   for (c = gfc_constructor_first (expr->value.constructor);
-       c; c = gfc_constructor_next (c), cm = cm->next)
+       c && cm; c = gfc_constructor_next (c), cm = cm->next)
     {
       /* Skip absent members in default initializers and allocatable
         components.  Although the latter have a default initializer

diff --git a/gcc/testsuite/gfortran.dg/data_initialized_4.f90 b/gcc/testsuite/gfortran.dg/data_initialized_4.f90
new file mode 100644 (file)
index 0000000..156b660
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/data_initialized_4.f90
@@ -0,0 +1,16 @@
+! { dg-do compile }
+! { dg-additional-options "-std=legacy" }
+!
+! PR fortran/50410
+!
+! Silently allow overlapping initialization in legacy mode (used to ICE)
+
+program p
+  implicit none
+  type t
+     integer :: g = 1
+  end type t
+  type(t) :: u = t(2)
+  data u%g /3/
+  print *, u    ! this might print "2"
+end