re PR fortran/35719 (pointer to zero sized array not associated)

2008-05-11  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/35719
	* trans.c (gfc_call_malloc): If size equals zero, allocate one
	byte; don't return a null pointer.

2008-05-11  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/35719
	* gfortran.dg/associated_5.f90:  New test.

From-SVN: r135187

gcc/fortran/ChangeLog

+2008-05-11  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/35719
+	* trans.c (gfc_call_malloc): If size equals zero, allocate one
+	byte; don't return a null pointer.
+
 2008-05-10  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	PR fortran/36197

gcc/fortran/trans.c

@@ -440,12 +440,12 @@ gfc_trans_runtime_check (tree cond, stmtblock_t * pblock, locus * where,
 
 /* Call malloc to allocate size bytes of memory, with special conditions:
       + if size < 0, generate a runtime error,
-      + if size == 0, return a NULL pointer,
+      + if size == 0, return a malloced area of size 1,
       + if malloc returns NULL, issue a runtime error.  */
 tree
 gfc_call_malloc (stmtblock_t * block, tree type, tree size)
 {
-  tree tmp, msg, negative, zero, malloc_result, null_result, res;
+  tree tmp, msg, negative, malloc_result, null_result, res;
   stmtblock_t block2;
 
   size = gfc_evaluate_now (size, block);
@@ -468,6 +468,10 @@ gfc_call_malloc (stmtblock_t * block, tree type, tree size)
 
   /* Call malloc and check the result.  */
   gfc_start_block (&block2);
+
+  size = fold_build2 (MAX_EXPR, size_type_node, size,
+		      build_int_cst (size_type_node, 1));
+
   gfc_add_modify_expr (&block2, res,
 		       build_call_expr (built_in_decls[BUILT_IN_MALLOC], 1,
 		       size));
@@ -481,13 +485,7 @@ gfc_call_malloc (stmtblock_t * block, tree type, tree size)
   gfc_add_expr_to_block (&block2, tmp);
   malloc_result = gfc_finish_block (&block2);
 
-  /* size == 0  */
-  zero = fold_build2 (EQ_EXPR, boolean_type_node, size,
-		      build_int_cst (size_type_node, 0));
-  tmp = fold_build2 (MODIFY_EXPR, pvoid_type_node, res,
-		     build_int_cst (pvoid_type_node, 0));
-  tmp = fold_build3 (COND_EXPR, void_type_node, zero, tmp, malloc_result);
-  gfc_add_expr_to_block (block, tmp);
+  gfc_add_expr_to_block (block, malloc_result);
 
   if (type != NULL)
     res = fold_convert (type, res);

gcc/testsuite/ChangeLog

+2008-05-11  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/35719
+	* gfortran.dg/associated_5.f90:  New test.
+
 2008-05-11  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	* gcc.target/mips/scc-1.c: Require mips16_attribute, and add

gcc/testsuite/gfortran.dg/associated_5.f90

+! { dg-do run }
+! PR 35719 - associated used to fail with zero-sized automatic arrays
+! Test case contributed by Dick Hendrickson
+
+      program try_mf1053
+
+      call       mf1053 (  1,   2,   3,   4)
+      end
+
+      SUBROUTINE MF1053 (nf1, nf2, nf3, nf4)
+      INTEGER, pointer :: ptr(:,:)
+      INTEGER, target  :: ILA1(NF2,NF4:NF3)
+
+      ptr => ILA1
+
+      if (ASSOCIATED (ptr, ILA1(NF1:NF2,NF4:NF3) ) ) call abort
+      if ( .not. ASSOCIATED(ptr) )  call abort
+
+      END SUBROUTINE