Fortran: error handling of global entity appearing in COMMON block [PR103259]

gcc/fortran/ChangeLog:

	PR fortran/103259
	* resolve.cc (resolve_common_vars): Avoid NULL pointer dereference
	when a symbol's location is not set.

gcc/testsuite/ChangeLog:

	PR fortran/103259
	* gfortran.dg/pr103259.f90: New test.

(cherry picked from commit 7e9f20f5517429cfaadec14d6b04705e59078565)

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index a1a91dc425f1f8d32839102eab6a38566bbf38ef..565b212c4c8e6bd2b526b7c980d806b13a350600 100644 (file)
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -953,9 +953,15 @@ resolve_common_vars (gfc_common_head *common_block, bool named_common)
     {
       gsym = gfc_find_gsymbol (gfc_gsym_root, csym->name);
       if (gsym && (gsym->type == GSYM_MODULE || gsym->type == GSYM_PROGRAM))
-       gfc_error_now ("Global entity %qs at %L cannot appear in a "
-                       "COMMON block at %L", gsym->name,
-                       &gsym->where, &csym->common_block->where);
+       {
+         if (csym->common_block)
+           gfc_error_now ("Global entity %qs at %L cannot appear in a "
+                          "COMMON block at %L", gsym->name,
+                          &gsym->where, &csym->common_block->where);
+         else
+           gfc_error_now ("Global entity %qs at %L cannot appear in a "
+                          "COMMON block", gsym->name, &gsym->where);
+       }
 
       /* gfc_add_in_common may have been called before, but the reported errors
         have been ignored to continue parsing.

diff --git a/gcc/testsuite/gfortran.dg/pr103259.f90 b/gcc/testsuite/gfortran.dg/pr103259.f90
new file mode 100644 (file)
index 0000000..f78ff26
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr103259.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! PR fortran/103259 - ICE in resolve_common_vars
+! Contributed by G.Steinmetz
+
+module m
+  integer :: p
+  common /c/ p
+end
+program p ! { dg-error "cannot appear in a COMMON block" }
+  use m   ! { dg-error "is also the name of the current program unit" }
+end